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  • 1
    ISSN: 1432-0789
    Keywords: Key words Waste water irrigation ; Heavy metals ; Soil organic matter ; Microbial biomass ; Microbial activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effect of long-term waste water irrigation (up to 80 years) on soil organic matter, soil microbial biomass and its activities was studied in two agricultural soils (Vertisols and Leptosols) irrigated for 25, 65 and 80 years respectively at Irrigation District 03 in the Valley of Mezquital near Mexico City. In the Vertisols, where larger amounts of water have been applied than in the Leptosols, total organic C (TOC) contents increased 2.5-fold after 80 years of irrigation. In the Leptosols, however, the degradability of the organic matter tended to increase with irrigation time. It appears that soil organic matter accumulation was not due to pollutants nor did microbial biomass:TOC ratios and qCO2 values indicate a pollutant effect. Increases in soil microbial biomass C and activities were presumably due to the larger application of organic matter. However, changes in soil microbial communities occurred, as denitrification capacities increased greatly and adenylate energy charge (AEC) ratios were reduced after long-term irrigation. These changes were supposed to be due to the addition of surfactants, especially alkylbenzene sulfonates (effect on denitrification capacity) and the addition of sodium and salts (effect on AEC) through waste water irrigation. Heavy metals contained in the sewage do not appear to be affecting soil processes yet, due to their low availability. Detrimental effects on soil microbial communities can be expected, however, from further increases in pollutant concentrations due to prolonged application of untreated waste water or an increase in mobility due to higher mineralization rates.
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  • 2
    ISSN: 1432-0789
    Keywords: Keywords Soil microbial biomass ; Soil enzymes ; Particle-size fractions ; Heavy metals ; Phospholipid fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Particle-size fractionation of a heavy metal polluted soil was performed to study the influence of environmental pollution on microbial community structure, microbial biomass, microbial residues and enzyme activities in microhabitats of a Calcaric Phaeocem. In 1987, the soil was experimentally contaminated with four heavy metal loads: (1) uncontaminated controls; (2) light (300 ppm Zn, 100 ppm Cu, 50 ppm Ni, 50 ppm V and 3 ppm Cd); (3) medium; and (4) heavy pollution (two- and threefold the light load, respectively). After 10 years of exposure, the highest concentrations of microbial ninhydrin-reactive nitrogen were found in the clay (2–0.1 μm) and silt fractions (63–2 μm), and the lowest were found in the coarse sand fraction (2,000–250 μm). The phospholipid fatty acid analyses (PLFA) and denaturing gradient gel electrophoresis (DGGE) separation of 16S rRNA gene fragments revealed that the microbial biomass within the clay fraction was predominantly due to soil bacteria. In contrast, a high percentage of fungal-derived PLFA 18 : 2ω6 was found in the coarse sand fraction. Bacterial residues such as muramic acid accumulated in the finer fractions in relation to fungal residues. The fractions also differed with respect to substrate utilization: Urease was located mainly in the 〈2 μm fraction, alkaline phosphatase and arylsulfatase in the 2–63 μm fraction, and xylanase activity was equally distributed in all fractions. Heavy metal pollution significantly decreased the concentration of ninhydrin-reactive nitrogen of soil microorganisms in the silt and clay fraction and thus in the bulk soil. Soil enzyme activity was reduced significantly in all fractions subjected to heavy metal pollution in the order arylsulfatase 〉phosphatase 〉urease 〉xylanase. Heavy metal pollution did not markedly change the similarity pattern of the DGGE profiles and amino sugar concentrations. Therefore, microbial biomass and enzyme activities seem to be more sensitive than 16S rRNA gene fragments and microbial amino-sugar-N to heavy metal treatment.
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  • 3
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    Environmental geology 39 (2000), S. 1015-1028 
    ISSN: 1432-0495
    Keywords: Key words Contaminants ; Heavy metals ; Organochlorines ; Fluvial sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Sediments have been used to detect sources of contamination in a catchment of the Port Jackson (Sydney Harbour) estuary and to evaluate the effects of different land-use practices on the fluvial environment. Mean enrichment (mean concentrations over pre-anthropogenic background) of size-normalized (〈62.5 μm) aquatic sediment is 10 × for Cu, 20× for Pb and 90× for Zn adjacent to industrialized areas and 2×, 7× and 7×, respectively for these metals in highly urbanized subcatchments. Diffuse sources contribute minor metals to fluvial sediment even in the most underdeveloped subcatchment (2×, 3× and 3× for Cu, Pb and Zn respectively). Organochlorine pesticide residue concentrations parallel heavy-metal trends due to a common mixed industrial base. Effects-based sediment criteria suggest that some adverse biological impacts are probably occurring in streams flowing through the industrial areas. This interpretation is supported by sequential extraction data which show that a moderate proportion of total heavy metals, especially Zn, is associated with the more bioavailable exchangeable/adsorbed phases in these aquatic sediments. High total suspended solid loads in water downstream of one of the industrial centers, and high particle-bound Cu and Pb concentrations, suggest that most contaminants exiting the catchment do so in association with the solid phase.
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  • 4
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    Environmental geology 39 (2000), S. 1059-1062 
    ISSN: 1432-0495
    Keywords: Key words River water ; Bed sediment ; Trace metal ; Heavy metals ; River pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The water and bed-sediment pollution status of the Padma River was determined by analysis of representative samples for selected metals and ions. Water and bed-sediment samples were collected at a T-dam, Rajshahi, Bangladesh, for 7 months. Water and silt-metal content analysis was performed using atomic absorption spectrophotometry or other analytical methods. The data showed the variation of the metal ion-levels in water as follows: Ca 17.11–48.37 ppm, Na 17.51–20.09 ppm, K 1.00–3.60 ppm, Cr 2.80–7.00 ppm, and SO4 4.17–5.48 ppm; in bed sediment, the levels were Cr 35–1050 ppm and Pb 12–48 ppm. The occurrence of Na, K and Ca was in the normal range (US EPA permissible limit), but the levels of Cr in water were much higher than the permissible limit. The SO4 ion content was well below the pollution level. The concentration of Pb in the bed sediment was within the permissible limit for the standard International Atomic Energy Agency (IAEA) Soil-5a, but the concentration of Cr in the bed sediment was significantly higher than the permissible limit for the standard IAEA Soil-5a. Thus the Padma river water was polluted with Cr. The occurrence of some ions showed a monthly variation.
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  • 5
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    Environmental geology 39 (2000), S. 1095-1101 
    ISSN: 1432-0495
    Keywords: Key words Factorial analysis ; Heavy metals ; Estuarine waters ; Huelva coast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The estuary of Odiel and Tinto rivers, located on the southwestern coast of the Iberian Peninsula, receives acidic fluvial water discharges with high concentrations of sulphates and heavy metals from these rivers. In addition, a big industrial complex which efflues directly on the system is located in the same estuary. The effluents induce the presence in the estuary of high concentrations of heavy metals and phospates (nutrients). The application of factorial analysis techniques on the nutrients and heavy metal concentrations in 46 water samples taken from 32 different sampling stations located along the estuary, allows three groups of elements and compounds with a distinct origin to be determinated. So, Cu and Zn have a clear fluvial provenance, whereas PO4 and As are clearly industrial wastes and Cl, K, Ca, Li, Rb and Sr come from the sea. From the factorial analyses we can deduce the existence of two agents controlling the behavior of the analyzed elements, which are: the tidal exchange with the open sea and the fluvial supply.
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  • 6
    ISSN: 1432-0495
    Keywords: Key words East Germany ; Erzgebirge ; Eutrophication ; Heavy metals ; Lake sediments ; Mining ; Pollution development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract. The Malter Reservoir is situated about 30 km south of Dresden (eastern Germany) in a historical mining area of the eastern Erzgebirge. It was built in 1913 for the protection from floodwaters, droughts and for generating electricity. The river Rote Weißeritz is the main source of clastic input into the lake. Geochemical and sedimentological data of gravity-and piston-cores, recovered from the deepest point of the lake, document the environmental history of the drainage area since 1963. 137Cs dating gives an average sedimentation rate of ∼2.9 cm/year. Within the whole core, heavy metals are strongly enriched (parentheses refer to enrichment factors as compared with average shale): cadmium (290), silver (140), bismuth (90), antimony (25), lead (21), zinc (14), tin (13), uranium (9), tungsten (9), molybdenum (5), copper (4), thallium (3) and chromium (2). Enrichments are detectable for the whole registered time-period of 81 years. Peaks of up to 27 mg/kg silver, 37 mg/kg bismuth, 91 mg/kg cadmium, 410 mg/kg chromium, 240 mg/kg copper, 20 mg/kg molybdenum, 14000 mg/kg phosphorus, 740 mg/kg lead, 6,5 mg/kg antimony, 74 mg/kg tin, 52 mg/kg tungsten and 1900 mg/kg zinc reflect local events caused by human impact. Inputs from different pollution sources at different times are represented by highly variable elemental concentrations and ratios within the core. High pH values within the water and the sediment column, the large adsorption capacity of the fine-grained Corg.-rich sediment, and the presence of low Eh-values and sulphide ions in the sediment prevent the remobilisation of the toxic elements. Erosion of these contaminated sediments during floods, channel flows or resuspension during removal of the sediments may lead to a downstream transfer of pollutants. Contents of P and Corg., as well as diatom abundance, indicate a change from oligotrophic to eutrophic conditions in the lake during ∼1940–1950. This was mainly caused by high agricultural activity in the drainage area. Reduced contents of Cu, Zn, Cd and Cr since the reunification of East and West Germany are obviously caused by increasing environmental protection measures, such as wastewater purification and especially the closing of contaminating industries.
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  • 7
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    Environmental geology 39 (2000), S. 945-950 
    ISSN: 1432-0495
    Keywords: Water quality ; Heavy metals ; Pollution ; Groundwater ; Canal water ; Soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
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  • 8
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    Environmental geology 39 (2000), S. 1216-1226 
    ISSN: 1432-0495
    Keywords: Key words Bioaccumulation ; Heavy metals ; Oyster ; Sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Oysters and sediment have been collected from most major US Gulf of Mexico bays and estuaries each year since 1986. Selected samples of oyster soft tissue, shell and sediments were analyzed for Cd, Cr, Cu, Fe, Mn, Pb, and Zn for this study. Concentrations varied considerably from place to place but ratios of metals remained relatively constant. Cu and Zn are greatly enriched in oyster tissues, which is related to their physiological function. Cd is enriched in oyster shell because of the easy substitution between Cd and Ca. The concentrations of Pb and Cr in oysters are significantly lower than that in sediment, suggesting a good discrimination against these metals by oysters. Metal variations are a result of both nature and human activity.
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  • 9
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    Environmental geology 39 (2000), S. 603-610 
    ISSN: 1432-0495
    Keywords: Key words Soils ; Heavy metals ; Anthropogenic impacts ; Vietnam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  This work is part of a research study which is intended to study the degree of anthropogenic influences of the trace metal distribution of soils from Danang-Hoian area (Vietnam). Cu, Ni, Zn and Zr show significant effects in most of the cultivated soil categories, especially in the industrial soils. Extremely high levels of Pb (up to 742 μg/g) are observed in the industrial soil category, which shows an enrichment factor 114 as compared to rural soils. Cd shows only a relative local enrichment with the maximum level of 4.6 μg/g in urban soils. Sequential extraction was performed in selected samples to evaluate the geochemical trace metals. The result indicates that Zn and Cr are mainly found in the crystal and amorphous Fe oxide bounded forms. The contents of Cr in these fractions comprise more than 94% of total extractable Cr. In the case of Zn, 85% of total extractable Zn is in fractions FV and FVI. Cu is mainly found in the organic fraction at an average of 39.3% of total extractable content. On the other hand, heavy metal contents show an increasing tendency in the fine fraction (silt and clay).
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  • 10
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    Biogeochemistry 49 (2000), S. 37-51 
    ISSN: 1573-515X
    Keywords: Arbuscular mycorrhizae/Vesicular-arbuscular mycorrhizae (AM/VAM) ; annual grasslands ; benomyl ; nitrogen limitation ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nutrient availability limits plant production acrossa wide range of terrestrial ecosystems. In this studyof a Californian annual grassland community, theinfluence of arbuscular mycorrhizal (AM) associationson plant nutrient acquisition was investigated usingfactorial combinations of nitrogen (N), phosphorus (P)and benomyl fungicide. N additions resulted in asignificant increase in shoot biomass demonstratingthat plant productivity in these soils was N-limited. The effect of P additions consistently depended onfungicide treatment. In the absence of benomyl, shootP accumulation was unaltered by P addition. In thepresence of benomyl, P addition significantlyincreased shoot P accumulation and was associated witha consistent trend towards enhanced shoot biomass.The induction of P-deficiency with benomylapplication suggests that effective P acquisition byAM may contribute to the strong N-limitation ofproduction observed in many terrestrial ecosystems.
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  • 11
    ISSN: 1573-515X
    Keywords: Bouteloua eriopoda ; Chihuahuan Desert ; desertification ; hydrology ; Larrea tridentata ; nitrogen ; nutrient budgets ; phosphorus ; runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Losses of dissolved nutrients (N, P, K, Ca, Mg, Na,Cl, and SO4) in runoff were measured on grasslandand shrubland plots in the Chihuahuan desert ofsouthern New Mexico. Runoff began at a lowerthreshold of rainfall in shrublands than ingrasslands, and the runoff coefficient averaged 18.6%in shrubland plots over a 7-year period. In contrast,grassland plots lost 5.0 to 6.3% of incidentprecipitation in runoff during a 5.5-year period. Nutrient losses from shrubland plots were greater thanfrom grassland plots, with nitrogen losses averaging0.33 kg ha−1 yr−1 vs0.15 kg ha−1 yr−1, respectively, during a 3-year period. Thegreater nutrient losses in shrublands were due tohigher runoff, rather than higher nutrientconcentrations in runoff. In spite of these nutrientlosses in runoff, all plots showed net accumulationsof most elements due to inputs from atmosphericdeposition. Therefore, loss of soil nutrients byhillslope runoff cannot, by itself, account for thedepletion of soil fertility associated withdesertification in the Chihuahuan desert.
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  • 12
    ISSN: 1573-515X
    Keywords: aquatic plants ; dissolved organic carbon ; nutrient cycling ; phosphorus ; sediments ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Release of oxygen from the roots ofaquatic macrophytes into anaerobic sediments canaffect the quantity of interstitial dissolved organicmatter and nutrients that are available to bacteria. Nutrient and dissolved organic carbon (DOC)concentrations were compared between subsurface(interstitial) waters of unvegetated sediments andsediments among stands of the emergent herbaceousmacrophyte Juncus effusus L. in a lotic wetlandecosystem. Concentrations of inorganic nitrogen(NH4 +, NO3 -, and NO2 -)were greater from sediments of the unvegetatedcompared to the vegetated zone. DOC concentrations ofinterstitial waters were greater in sediments of theunvegetated zone both in the winter and springcompared to those from the vegetated zone. AlthoughDOC concentrations in hydrosoils collected from bothzones increased from winter to spring, bacterialproductivity per mg DOC in spring decreased comparedto winter. Greater initial bacterial productivityoccurred on DOM collected from the vegetated comparedto the unvegetated zone in winter samples (days 1 and4), with increased bacterial productivity on samplescollected from the unvegetated zone at the end of thestudy (day 20). Bacterial productivity wassignificantly greater on all sampling days on DOM fromvegetated samples compared to unvegetated samples. In nutrient enrichment experiments, bacterialproductivity was significantly increased (p 〈 0.05)with phosphorus but not nitrogen only amendments.
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  • 13
    ISSN: 1573-515X
    Keywords: carbon ; landscape geochemical flows ; model ; nitrogen ; phosphorus ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The importance of landscape geochemical flows wasinvestigated using a dynamic model simulating carbon,nitrogen and phosphorus cycling in riverine wetlands,which has been described in a previous paper. Thehydro-geomorphic unit (HGMU) concept was incorporatedin the model by defining a separate, completeunit-model for each unit (HGMU) within the wetland.These unit-models were connected by defining the flowsof nitrogen and phosphorus between them. These flows,also called landscape geochemical flows, usuallyconsist of flows of water containing N and P. The model was applied to a site at Kismeldon Meadows,in south-western England. This site consists of twounits, a slope and a floodplain, separated by a ditch,which catches most of the run off and shallowgroundwater flows from the slope. Only an estimated1% of the N and P that leaves the slope unit in thewater outflow reaches the floodplain unit; the rest iscaught in the system of ditches, which prevent thegeochemical flows taking their natural course. Toexamine the influence of this system of ditches, themodel was run for the same site, but without theditches. This is comparable to a situation of arestored site, where run off and shallow groundwaterflows containing nutrients, can freely get from theslope to the floodplain. The computer simulation experiment reconnecting theslope and floodplain showed that this (1) increasedthe nutrient input into the floodplain, causing ahigher biomass production, and (2) increased thewetness of the floodplain, causing slowerdecomposition, which together (3) led to a faster soilorganic matter accumulation in the floodplain.Nutrient inflows became relatively more importantcompared to atmospheric deposition, especially forphosphorus. By connecting the slope and the floodplainmore nitrogen and less phosphorus flowed into theriver.
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  • 14
    ISSN: 1573-515X
    Keywords: chloride ; internal eutrophication ; nitrogen ; peat soil ; phosphorus ; phytometer ; sulphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Inputs of surface waters high in chloride and sulphateincreased the availability of nutrients in fenpeatlands. This `internal eutrophication' wasdemonstrated with test plants (`phytometers') andthrough water and soil analysis. Three experiments arepresented in which the level of chloride and/orsulphate was increased to 3 mmolc l−1. Inexperiment 1 chloride levels were increased from 0.5to 3 mmolc l−1 as CaCl2 or NaCl. Inexperiment 2 and 3 similar increased levels forchloride and sulphate (3 mmolc l−1; as NaCland Na2SO4) were used. The following resultswere found: (i) No differences in soil total-N and total-P werefound before and after the treatments in any of thethree experiments. (ii) Experiment 1 showed a significant increase inBio-Available P (BAP) in pots planted with Anthoxanthum odoratum as well as in bare pots for theNaCl and CaCl2 treatments. The plants in thesetreatments had taken up much more P. (iii) Experiment 2 showed an increase in soil BAPafter treatment with chloride and sulphate in potsplanted with Anthoxanthum odoratum. The chloridetreatment had no effect on plant biomass, whereas thesulphate treatment resulted in a reduction in rootbiomass and root N and P content. The shoots showedan increase in P content in the sulphate and chloridetreatments, while N content remained the same. (iv) In experiment 3, treatments with chloride andsulphate led to significantly increased biomass and Puptake of Anthoxanthum odoratum. Again, noeffects on N uptake were found. These experiments provide evidence for distinctlyincreased availability of phosphate in peat soils whenthese come into contact with water with evenmoderately increased sulphate or chloride levels.Surface water originating from the Rhine river, whichis enriched in chloride and sulphate, is oftensupplied to fen reserves in The Netherlands, tocompensate for water losses due to agriculturaldrainage in the region. The results of this study showthat phosphate availability to the vegetation may risedrastically, with detrimental effects on the speciesdensity and the occurrence of rare species in thevegetation. Hence, supply of this water should beavoided.
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  • 15
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    Biogeochemistry 51 (2000), S. 1-32 
    ISSN: 1573-515X
    Keywords: aluminum ; floodplain forests ; iron ; organic matter ; P sorption capacity ; phosphorus ; soil ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We examined spatial and temporal variationsin soil chemistry in a floodplain forest landscape todetermine the effects of flooding on aluminum (Al) andiron (Fe) oxide biogeochemistry and inorganicphosphorus (Pi) sorption capacity. Whenpreviously sorbed Pi was considered, the sorptioncapacities of floodplain and adjacent upland soilswere comparable, suggesting that floodplain soilsrepresent a second line of defense protectingdownstream aquatic ecosystems from agriculturalrun-off. Pi sorption capacity was highlycorrelated with oxalate-extractable Al (Alo)(rs = 0.78); Alo and percent organic matter(OM) were also highly correlated (rs = 0.72),suggesting the importance of OM-Al complexes in thesesoils. The correlation of oxalate-extractable Fe(Feo) with OM (rs = 0.64) was improved(rs = 0.80) by removing lower elevation (swale)soils, suggesting that flooding inhibits theassociation of Feo with OM. Fe oxidecrystallinity decreased during seasonal flooding, buttotal extractable Fe did not change significantly. Fesolubilized during flooding was either replaced bysediment deposition (252 ± 3 mmol kg−1yr−1), and/or reprecipitated locally. Al oxidecrystallinity also decreased during flooding due to asignificant decline in NaOH-extractable Al (AlN). AlN concentrations subsequently returned topre-flooding levels, but sediment Al inputs (57 ±3 mmol kg−1 yr−1), were insufficient to account for this recovery. Observed Fetransformations suggest the importance offlooding-induced declines in soil redox potential toFe biogeochemistry; observed Al transformationssuggest the importance of complexation reactions withsoil OM to Al biogeochemistry in this floodplainforest.
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  • 16
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    Biology and fertility of soils 30 (1999), S. 160-167 
    ISSN: 1432-0789
    Keywords: Key words Sludge ; Heavy metals ; Xenobiotica ; Soil quality ; Soil microbial activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Sludge amendments increase the input of carbon and nutrients to the soil. However, the soil concentrations of heavy metals and xenobiotica can also increase due to sludge amendments, with possible effects on soil microorganisms and soil fertility. Therefore, we studied the effects on soil microorganisms and soil chemistry in two arable soils after 12 and 16 years of sewage sludge amendment (0, 1 and 3 dry matter ha–1 year–1). The sludge amendments were combined with nitrogen addition at three rates according to crop requirements, and all combinations were replicated 4 times, giving a total number of 36 parcels at each experimental site in a non-randomised block design. Univariate data evaluation as well as principal component analysis and discriminant function analysis (DFA) were used to identify differences between treatments in microbial and chemical parameters. The DFA showed that acid and alkaline phosphatase, potential ammonium oxidation and total nitrogen were the most important parameters to discriminate between a priori defined groups of sludge treatments. Among the heavy metals, copper showed the highest increase in soil concentration with sludge amendments, but this increase was still not high enough to have a significant influence on the measured parameters. None of the xenobiotica investigated was found in high soil concentrations. In conclusion, the present study showed that the sewage sludge affected several of the biological and chemical parameters investigated. However, no severe negative effects on soil microorganisms were detected at these moderate levels of sludge amendment.
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  • 17
    ISSN: 1432-0789
    Keywords: Key words Phosphorus dynamics ; Olsen ; phosphorus ; Soil phosphorus fractions ; Manure ; Soybean-wheat rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soil P availability and efficiency of applied P may be improved through an understanding of soil P dynamics in relation to management practices in a cropping system. Our objectives in this study were to evaluate changes in plant-available (Olsen) P and in different inorganic P (Pi) and organic P (P0) fractions in soil as related to repeated additions of manure and fertilizer P under a soybean-wheat rotation. A field experiment on a Typic Haplustert was conducted from 1992 to 1995 wherein the annual treatments included four rates of fertilizer P (0, 11, 22 and 44 kg ha–1 applied to both soybean and wheat) in the absence and presence of 16 t ha–1 of manure (applied to soybean only). With regular application of fertilizer P to each crop the level of Olsen P increased significantly and linearly through the years in both manured and unmanured plots. The mean P balance required to raise Olsen P by 1 mg kg–1 was 17.9 kg ha–1 of fertilizer P in unmanured plots and 5.6 kg ha–1 of manure plus fertilizer P in manured plots. The relative sizes of labile [NaHCO3-extractable Pi (NaHCO3-Pi) and NaHCO3-extractable P0 (NaHCO3-P0)], moderately labile [NaOH-extractable Pi (NaOH-Pi) and NaOH-extractable P0 (NaOH-P0)] and stable [HCl-extractable P (HCl-P) and H2SO4/H2O2-extractable P (resisual-P)] P pools were in a 1 : 2.9 : 7.6 ratio. Application of fertilizer P and manure significantly increased NaHCO3-Pi and -P0 and NaOH-Pi, and -P0 fractions and also total P. However, HCl-P and residual-P were not affected. The changes in NaHCO3-Pi, NaOH-Pi and NaOH-P0 fractions were significantly correlated with the apparent P balance and were thought to represent biologically dynamic soil P and act as major sources and sinks of plant-available P.
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  • 18
    ISSN: 1432-0789
    Keywords: Key words Organic fertilization ; Soil microbial biomass carbon ; Metabolic quotient ; Bioavailability ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  We studied the long-term effects (12 years) of municipal refuse compost addition on the total organic carbon (TOC), the amount and activity of the microbial biomass (soil microbial biomass C, BC and metabolic quotient qCO2) and heavy metal bioavaiability in soils as compared to manuring with mineral fertilizers (NPK) and farmyard manure (FYM). In addition, we studied the relationships between among the available fraction [Diethylenetriaminopentacetic acid (DTPA) extractable] of heavy metals and their total content, TOC and BC. After 12 years of repeated treatments, the TOC and BC of control and mineral fertilized plots did not differ. Soils treated with FYM and composts showed a significant increase in TOC and BC in response to the increasing amounts of organic C added. Values of the BC/TOC ratio ranged from 1.4 to 2, without any significative differences among soil treatments. The qCO2 increased in the organic-amended soil and may have indicated microbial stress. The total amounts of metals in treated soils were lower than the levels permitted by the European Union in agricultural soils. DTPA-extractable metals increased in amended soils in response to organic C. A multiple regression analysis with stepwise selection of variables was carried out in order to discriminate between the influence exerted on DTPA-extractable metals by their total content, TOC and BC. Results showed that each metal behaved quite differently, suggesting that different mechanisms might be involved in metal bioavailability
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  • 19
    ISSN: 1573-0417
    Keywords: carbon isotopes ; diatoms ; lake management ; nitrogen isotopes ; phosphorus ; radium-226 ; sediments ; trophic state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We explored the use of carbon and nitrogen isotopes (δ13C and δ15N) in sedimented organic matter (OM) as proxy indicators of trophic state change in Florida lakes. Stable isotope data from four 210Pb-dated sediment cores were compared stratigraphically with established proxies for historical trophic state (diatom-inferred limnetic total phosphorus, sediment C/N ratio) and indicators of cultural disturbance (sediment total P and 226Ra activity). Diatom-based limnetic total P inferences indicate a transition from oligo-mesotrophy to meso-eutrophy in Clear Lake, and from eutrophy to hypereutrophy in Lakes Parker, Hollingsworth and Griffin. In cores from all four lakes, the carbon isotopic signature of accumulated OM generally tracks trophic state inferences and cultural impact assessments based on other variables. Oldest sediments in the records yield lower diatom-inferred total limnetic P concentrations and display relatively low δ13C values. In the Clear, Hollingsworth and Parker records, diatom-inferred nutrient concentrations increase after ca. AD 1900, and are associated stratigraphically with higher δ13C values in sediment OM. In the Lake Griffin core, both proxies display slight increases before ~1900, but highest values occur over the last ~100 years. As Lakes Clear, Hollingsworth and Parker became increasingly nutrient-enriched over the past century, the δ15N of sedimented organic matter decreased. This reflects, in part, the increasing relative contribution of nitrogen-fixing cyanobacteria to sedimented organic matter as primary productivity increased in these waterbodies. The Lake Griffin core displays a narrow range of both δ13C and δ15N values. Despite the complexity of carbon and nitrogen cycles in lakes, stratigraphic agreement between diatom-inferred changes in limnetic total P and the stable isotope signatures of sedimented OM suggests that δ13C and δ15N reflect shifts in historic lake trophic state.
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  • 20
    ISSN: 1573-0417
    Keywords: diatoms ; Everglades ; phosphorus ; wetland ; calibration ; multivariate ; Florida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationship between diatom taxa preserved in surface soils and environmental variables at 31 sites in Water Conservation Area 2A (WCA-2A) of the Florida Everglades was explored using multivariate analyses. Surface soils were collected along a phosphorus (P) gradient and analyzed for diatoms, total P, % nitrogen (N), %carbon (C), calcium (Ca), and biogenic silica (BSi). Phosphorus varied from 315-1781 μg g-1, and was not found to be correlated with the other geochemical variables. Canonical correspondence analysis (CCA) was used to examine which environmental variables correlated most closely with the distributions in diatom taxa. Canonical correspondence analysis with forward selection, constrained and partial CCA, and Monte Carlo permutation tests of significance show the most significant changes in diatom assemblages along the P gradient (p 〈 0.01), with additional species differences correlated with soil C, N, Ca, and BSi. Weighted-averaging (WA) regression and calibration models of diatom assemblages to P and BSi were developed. The diatom-based inference model for soil [P] had a high apparent r2 (0.86) with RMSEboot = 218 μg g-1. Indicator diatom species identified by assessing species WA optima and WA tolerance to [P], such as Nitzschia amphibia and N. palea for high [P] (~1300-1400 μ g-1) and Achnanthes minutissima var. scotica and Mastogloia smithii for low [P] (~400-600 μg g-1), may be useful as monitoring tools for eutrophication in WCA-2A as well as other areas of the Everglades. Diatom assemblages analyzed by cluster analysis were related to location within WCA-2A, and dominant taxa within clusters are discussed in relation to the geochemical variables measured as well as hydrology and pH. Diversity of diatom assemblages and a ‘Disturbance Index’ based on diatom data are discussed in relation to the historically P-limited Everglades ecosystem. Diatom assemblages should be very useful for reconstructions of [P] through time in the Florida Everglades, provided diatoms are well preserved in soil cores.
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  • 21
    ISSN: 1432-0495
    Keywords: Key words Sediments ; Mineralogy ; Geochemistry ; Heavy metals ; Biogeochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract We have studied sediments of the Piscinas beach (SW Sardinia, Italy), which is supplied by two streams that wash mine dumps of abandoned lead and zinc mines at Montevecchio and Ingurtosu, situated inland from the supply basin of the beach itself. A study of the texture, mineralogy and geochemistry of the sediments was conducted for the purpose of assessing the possible influence of the mine waste on the composition of the sediments, looking for any anomalous enrichments in heavy metals. Furthermore, to evaluate and quantify metal release into the sea, samples of Posidonia oceanica, a bioaccumulator marine plant, were also examined. The results indicate that the distribution of heavy metals in the foreshore sediments is particularly affected by the contribution of the streams, while in the shoreface the distribution is affected by the currents that disperse the sediments both out to sea and southwards. The metal contents of the Posidonia oceanica are correlated with the different stages of activity of the mines.
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  • 22
    ISSN: 1432-0495
    Keywords: Key words Anthropogenic pollution ; Heavy metals ; Ganga Plain ; Monsoon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The Ganga Plain is one of the most densely populated regions and one of the largest groundwater repositories of the Earth. For several decades, the drainage basin of the Ganga Plain has been used for the disposal of domestic and industrial wastes which has adversely affected the quality of water, sediments and agricultural soils of the plain. The concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Zn and organic carbon were determined in river sediments and soils of the Ganga Plain in the Kanpur-Unnao industrial region in 1994 and 1995 (pre-monsoon period of April–May). High contents (maximum values) of C-org (12.0 wt. %), Cr (3.40 wt. %), Sn (1.92 wt. %), Zn (4000 mg/kg), Pb (646 mg/kg), Cu (408 mg/kg), Ni (502 mg/kg) and Cd (9.8 mg/kg) in sediments (〈20 μm fraction); and C-org (5.9 wt. %), Cr (2.16 wt. %), Sn (1.21 wt %), Zn (975 mg/kg) and Ni (482 mg/kg) in soils (〈20 μm) in the pre-monsoon period of 1994 were found. From 1994 to 1995 the contents of Fe and Sn in sediments increase whereas those of C-org, Cd, Cu, Ni and Zn decrease. Considering the analytical errors, Al, Co, Cr, Mn and Pb do not show any change in their concentrations. In soils, the contents of Cd, Fe and Sn increase whereas those of Ni decrease from 1994 to 1995. Aluminium, Co, Cr, Cu, Mn, Pb and Zn do not show any change in their concentrations from 1994 to 1995. About 90% of the contents of Cd, Cr and Sn; 50–75% of C-org, Cu and Zn; and 25% of Co, Ni and Pb in sediments are derived from the anthropogenic input in relation to the natural background values, whereas in soils this is the case for about 90% of Cr and Sn; about 75% of Cd; and about 25% of C-org, Cu, Ni and Zn. The sediments of the study area show enrichment factors of 23.6 for Cr, 14.7 for Cd, 12.2 for Sn, 3.6 for C-org, 3.2 for Zn, 2.6 for Cu and 1.6 for Ni. The soils are enriched with factors of 10.7 for Cr, 9.0 for Sn, 3.6 for Cd, 1.8 for Ni and 1.5 for Cu and Zn, respectively.
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  • 23
    ISSN: 1432-0495
    Keywords: Key words Particulate matter ; Heavy metals ; Tropical river ; Seasonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Temporal and spatial variability of particulate metal concentrations (Cu, Cr, Zn, Mn and Fe) were investigated in the lower drainage basin of the Paraíba do Sul River. The results showed that the spatial variability was not important for all the studied metals, however, temporal variations seems to be considerable. In general, two distinct behaviors were observed for particulate heavy metals: (1) metal concentration increase together with water flow (Fe and Cu) and (2) concentration decrease with increasing water flux (Zn, Cr and Mn). The Fe and Cu behavior is probably due to the strong association of these metals with surface runoff, although their sources seem to be distinct. Iron probably originates from the regional soils rich in iron oxides, and Cu is possibly associated to the large-scale use of copper fungicides in the sugar cane plantations. The opposite trend observed for Zn, Cr and Mn probably reflects the importance of the industrial and urban effluents as a secondary source of these elements for the system. Their behavior is probably associated with the dilution effect caused by the input of a suspended matter poor in these metals originated from the surface runoff during the rainy season.
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  • 24
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    Environmental geology 37 (1999), S. 107-111 
    ISSN: 1432-0495
    Keywords: Key words Karst ; Heavy metals ; Soil contamination ; Sequential extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The response of a Wilderness cherty loam series soil to repeated dosages of metals (as sewage sludge) using a two-step sequential extraction procedure was investigated. Variations in metal content between amended and control soils were related to organic matter, clay content, and clay mineralogy. Of the four metals investigated, Cu was found to accumulate in the top 20 cm of amended soils; Pb and Zn were present in even smaller amounts with respect to the control soils, and Cr concentrations were unaffected with respect to both depth and amendment. None of the metals indicated accumulation in deeper (〉20 cm) parts of the soil profile. Overall, results suggest that the metals remobilize in the top 20 cm, being readily uptaken by the fescue grass growing in this lot. Precipitation of insoluble forms of metal into deeper parts of the soil profile was proven unlikely based on the distribution of metal concentrations throughout the profile.
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  • 25
    ISSN: 1432-0495
    Keywords: Key words Oka River ; Spain ; Sediments ; Heavy metals ; Geochemical fractionation ; Lithogenic effects ; Anthropogenic inputs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The Oka River basin is located in the Urdaibai National Biosphere Reserve, North Spain. In order to obtain a preliminary view of its environmental conditions, nitric acid extractable Fe, Mn, Zn, Pb, Cu, Cr, Ni and Co, organic matter content (L.O.I.), geochemical fractionation of heavy metals and mineralogical composition were analysed in surficial sediments (fraction 〈63 μm) collected in October 1991. Relatively high concentrations of metals occurred in a sampling site upstream, due to a local natural enrichment controlled by weathering of volcanic rocks. Geochemical fractionation confirmed the lithogenic origin of metals, which were mainly associated to the detrital phase. The significant increase of heavy metals found in some samples collected in the municipal area of Gernika suggested a pollution effect, related to anthropogenic wastes. Large amounts of metallic slags have been found mixed with the sediments upstream from this locality. Nevertheless, in view of their composition, it is unlikely that these slags constitute a significant source of heavy metals in the studied area. In a second sampling in October 1997 an apparent decreasing trend in some heavy metal levels was noted, particularly for Pb and Cu. Nowadays, enrichment factors relative to background values confirm moderate anthropogenic influence on Zn, Pb, Cu, Cr and Ni concentrations. However, heavy metal levels in the Oka river sediments are much lower than those detected in other major rivers of the Basque Country (Nervión, Urumea, Deba).
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  • 26
    ISSN: 1432-0495
    Keywords: Key words Damodar River ; Heavy metals ; Grain size ; Chemical fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The distribution of Si, Al, Fe, Mn, Cu, Zn, Ni and Cr in different grain-size fractions and geochemical association of Fe, Mn, Cu and Zn with 〈63-μm size fraction of bed sediments of Damodar River has been studied. In general, concentrations of heavy metals tend to increase as the size fractions get finer. However at two sites, near mining areas, the coarser particles show similar or even higher heavy metal concentrations than finer ones. The higher residence time and/or presence of coarser particles from mining wastes are possibly responsible for higher metal content in the coarser size fractions. The chemical fractionation study shows that lithogenic is the major chemical phase for heavy metals. Fe and Mn are the major elements of the lithogenic lattice, constituting 34–63% and 22–59%, respectively, of total concentrations. Fe-Mn oxide and organic bound fractions are significant phases in the non-lithogenic fraction. The carbonate fraction is less significant for heavy metal scavenging in the present environment and shows the following order of abundance Zn〉Cu〉Mn〉Fe. The exchangeable fraction of the Damodar sediments contains very low amounts of heavy metals suggesting poor bioavailability of metals.
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  • 27
    ISSN: 1432-0495
    Keywords: Key words Acid mine drainage ; Heavy metals ; Contamination ; Bioavailability ; Rehabilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Past mining and smelting of sulphide ore (pyrite-chalcopyrite-sphalerite) at the abandoned Gulf Creek mine has resulted in a stream highly contaminated by acid mine drainage (pH: 2.2–3.4), as well as degradation of local soil and vegetation. Physical dispersion of secondary metal-bearing minerals from abandoned ore and waste dumps into Gulf Creek and adsorption and coprecipitation of dissolved metals and metalloids in the stream bed cause elevated Ag, As, Cd, Cu, Fe, Pb and Zn values in stream sediments. The bioavailability of individual heavy metals to freshwater organisms changes downstream, however, selective bioaccumulation processes in algae reject readily bioavailable Zn and concentrate less bioavailable Cu. Polluted soils in the vicinity of the mine and smelter sites are subject to continuing soil erosion and either support no vegetation, or a depauperate flora with certain species showing bioaccumulation of metals and resistance to high metal contents. Rehabilitation of disturbed areas should involve covering and sealing sulphidic mine waste or removal of ore and waste dumps, installation of a physical and chemical plant or construction of a wetland environment (plus anoxic lime drains), and import of topsoil and planting of local, metal-tolerant plant species.
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  • 28
    ISSN: 1573-515X
    Keywords: acidification ; anthropogenic nitrogen ; cations ; nitrate leaching ; nitric oxide ; nitrous oxide ; nutrient limitation ; phosphorus ; productivity ; tropical ecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Human activities have more than doubled the inputs of nitrogen (N) into terrestrial systems globally. The sources and distribution of anthropogenic N, including N fertilization and N fixed during fossil fuel combustion, are rapidly shifting from the temperate zone to a more global distribution. The consequences of anthropogenic N deposition for ecosystem processes and N losses have been studied primarily in N-limited ecosystems in the temperate zone; there is reason to expect that tropical ecosystems, where plant growth is most often limited by some other resource, will respond differently to increasing deposition. In this paper, we assess the likely direct and indirect effects of increasing anthropogenic N inputs on tropical ecosytem processes. We conclude that anthropogenic inputs of N into tropical forests are unlikely to increase productivity and may even decrease it due to indirect effects on acidity and the availability of phosphorus and cations. We also suggest that the direct effects of anthropogenic N deposition on N cycling processes will lead to increased fluxes at the soilwater and soil-air interfaces, with little or no lag in response time. Finally, we discuss the uncertainties inherent in this analysis, and outline future research that is needed to address those uncertainties.
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  • 29
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    Biogeochemistry 46 (1999), S. 179-202 
    ISSN: 1573-515X
    Keywords: carbon dioxide ; grazing ; nitrogen fixation ; nitrogen limitation ; phosphorus ; shade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The widespread occurrence ofN limitation to net primary production (NPP) and other ecosystem processes, despite the ubiquitous occurrence ofN-fixing symbioses, remains a significant puzzle in terrestrial ecology. We describe a simple simulation model for an ecosystem containing a generic nonfixer and a symbioticN fixer, based on: (1) a higher cost forN acquisition byN fixers than nonfixers; (2) growth of fixers and fixation ofN only when lowN availability limits the growth of nonfixers, and other resources are available; and (3) losses of fixedN from the system only when the quantity of availableN exceeds plant and microbial demands. Despite the disadvantages faced by theN fixer under these conditions,N fixation and loss adjustN availability close to the availability of other resources, and biomass and NPP in this simple model can be substantially but only transientlyN limited. We then modify the model by adding: (1) losses ofN in forms other than excess availableN (e.g., dissolved organicN, trace gases produced by nitrification); and (2) constraints to the growth and activity ofN fixers imposed by differential effects of shading,P limitation, and grazing. The combination of these processes is sufficient to describe an open system, with input from both precipitation andN fixation, that is nevertheless stronglyN-limited at equilibrium. This model is useful for exploring causes and consequences of constraints toN fixation, and hence ofN limitation, and we believe it will also be useful for evaluating howN fixation and limitation interact with elevatedCO 2 and other components of global enviromental change.
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  • 30
    ISSN: 1573-515X
    Keywords: estuaries ; lakes ; marine ; nitrogen ; phosphorus ; rivers ; streams ; temperate ; tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will lead to greatly increased primary production in freshwaters and large changes in tropical freshwater communities. Increased freshwater nutrient flux will also lead to an expansion of the high production, N- and light-limited zones around river deltas, a switch from P- to N-limitation in calcareous marine systems, with large changes in the community composition of fragile mangrove and reef systems. Key information gaps are highlighted, including data on mechanisms of nutrient transport and atmospheric deposition in the tropics, nutrient and material retention capacities of tropical impoundments, and N/P coupling and stoichiometric impacts of nutrient supplies on tropical aquatic communities. The current base of biogeochemical data suggests that alterations in the N-cycle will have greater impacts on tropical aquatic ecosystems than those already observed in the temperate zone.
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  • 31
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    Biogeochemistry 44 (1999), S. 93-118 
    ISSN: 1573-515X
    Keywords: Everglades National Park ; mangrove soils ; organic matter ; nitrogen ; phosphorus ; sedimentation ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The distribution and accumulation of organic matter, nitrogen (N) and phosphorus (P) in mangrove soils at four sites along the Shark River estuary of south Florida were investigated with empirical measures and a process-based model. The mangrove nutrient model (NUMAN) was developed from the SEMIDEC marsh organic matter model and parameterized with data from mangrove wetlands. The soil characteristics in the four mangrove sites varied greatly in both concentrations and profiles of soil carbon, N and P. Organic matter decreased from 82% in the upstream locations to 30% in the marine sites. Comparisons of simulated and observed results demonstrated that landscape gradients of soil characteristics along the estuary can be adequately modeled by accounting for plant production, litter decomposition and export, and allochthonous input of mineral sediments. Model sensitivity analyses suggest that root production has a more significant effect on soil composition than litter fall. Model simulations showed that the greatest change in organic matter, N, and P occurred from the soil surface to 5 cm depth. The rapid decomposition of labile organic matter was responsible for this decrease in organic matter. Simulated N mineralization rates decreased quickly with depth, which corresponded with the decrease of labile organic matter. The increase in organic matter content and decrease in soil bulk density from mangrove sites at downstream locations compared to those at upstream locations was controlled mainly by variation in allochthonous inputs of mineral matter at the mouth of the estuary, along with gradients in mangrove root production. Research on allochthonouns sediment input and in situ root production of mangroves is limited compared to their significance to understanding nutrient biogeochemistry of these wetlands. More accurate simulations of temporal patterns of nutrient characteristics with depth will depend on including the effects of disturbance such as hurricanes on sediment redistribution and biomass production.
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  • 32
    ISSN: 1573-515X
    Keywords: Chaohu Lake ; chemical fertilizer ; cycling ; denitrification ; multipond system ; nitrogen ; nutrient budget ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract During a two-year field study, an annual nutrient budget and cycles were developed for a small agricultural watershed. The study emphasized the integrated unit of the watershed in understanding the biogeochemistry. It was found that the total nutrient input was 39.1× 104 kg nitrogen and 3.91×104 kg phosphorus in the year 1995, of which the greatest input of nutrients to the watershed was chemical fertilizer application, reaching 34.7×104 kg (676 kg/ha) nitrogen and 3.88×104 kg (76 kg/ha) phosphorus. The total nutrient output from the watershed was 13.55×104 kg nitrogen and 0.40×104 kg phosphorus, while the largest output of nitrogen was denitrification, accounting for 44.1% of N output; the largest output of phosphorus was sale of crops, accounting for 99.4% of P output. The results show that the nutrient input is larger than output, demonstrating that there is nutrient surplus within the watershed, a surplus which may become a potential source of nonpoint pollution to area waters. The research showed that both denitrification and volatilization of nitrogen are key ways of nitrogen loss from the watershed. This suggests that careful management of fertilizer application will be important for the sustainable development of agriculture. The research demonstrated that a multipond system within the watershed had high retention rate for both water and nutrients, benefiting the water, nutrient and sediment recycling in the terrestrial ecosystem and helping to reduce agricultural nonpoint pollution at its source. Therefore, this unique watershed system should be recommended due to its great potential relevance for sustainable agricultural development.
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  • 33
    ISSN: 1573-515X
    Keywords: Chihuahuan desert ; desert ; desertification ; grassland ; nitrogen ; nutrient budgets ; phosphorus ; runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Rainfall simulation experiments were performed in areas of semiarid grassland (Bouteloua eriopoda) and arid shrubland (Larrea tridentata) in the Chihuahuan desert of New Mexico. The objective was to compare the runoff of nitrogen (N) and phosphorus (P) from these habitats to assess whether losses of soil nutrients are associated with the invasion of grasslands by shrubs. Runoff losses from grass- and shrub-dominated plots were similar, and much less than from bare plots located in the shrubland. Weighted average concentrations of total dissolved N compounds in runoff were greatest in the grassland (1.72 mg/1) and lowest in bare plots in the shrubland (0.55 mg/1). More than half of the N transported in runoff was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was highly correlated to the total volume of discharge. We estimate that the total annual loss of N in runoff is 0.25 kg/ha/yr in grasslands and 0.43 kg/ha/yr in shrublands — consistent with the depletion of soil N during desertification of these habitats. Losses of P from both habitats were very small.
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  • 34
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    Biogeochemistry 44 (1999), S. 93-118 
    ISSN: 1573-515X
    Keywords: Everglades National Park ; mangrove soils ; organic matter ; nitrogen ; phosphorus ; sedimentation ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The distribution and accumulation of organic matter, nitrogen (N) and phosphorus (P) in mangrove soils at four sites along the Shark River estuary of south Florida were investigated with empirical measures and a process-based model. The mangrove nutrient model (NUMAN) was developed from the SEMIDEC marsh organic matter model and parameterized with data from mangrove wetlands. The soil characteristics in the four mangrove sites varied greatly in both concentrations and profiles of soil carbon, N and P. Organic matter decreased from 82% in the upstream locations to 30% in the marine sites. Comparisons of simulated and observed results demonstrated that landscape gradients of soil characteristics along the estuary can be adequately modeled by accounting for plant production, litter decomposition and export, and allochthonous input of mineral sediments. Model sensitivity analyses suggest that root production has a more significant effect on soil composition than litter fall. Model simulations showed that the greatest change in organic matter, N, and P occurred from the soil surface to 5 cm depth. The rapid decomposition of labile organic matter was responsible for this decrease in organic matter. Simulated N mineralization rates decreased quickly with depth, which corresponded with the decrease of labile organic matter. The increase in organic matter content and decrease in soil bulk density from mangrove sites at downstream locations compared to those at upstream locations was controlled mainly by variation in allochthonous inputs of mineral matter at the mouth of the estuary, along with gradients in mangrove root production. Research on allochthonouns sediment input and in situ root production of mangroves is limited compared to their significance to understanding nutrient biogeochemistry of these wetlands. More accurate simulations of temporal patterns of nutrient characteristics with depth will depend on including the effects of disturbance such as hurricanes on sediment redistribution and biomass production.
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  • 35
    ISSN: 1573-515X
    Keywords: Chaohu Lake ; chemical fertilizer ; cycling ; denitrification ; multipond system ; nitrogen ; nutrient budget ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract During a two-year field study, an annual nutrient budget and cycles were developed for a small agricultural watershed. The study emphasized the integrated unit of the watershed in understanding the biogeochemistry. It was found that the total nutrient input was 39.1 × 104 kg nitrogen and 3.91 × 104 kg phosphorus in the year 1995, of which the greatest input of nutrients to the watershed was chemical fertilizer application, reaching 34.7 × 104 kg (676 kg/ha) nitrogen and 3.88 × 104 kg (76 kg/ha) phosphorus. The total nutrient output from the watershed was 13.55 × 104 kg nitrogen and 0.40 × 104 kg phosphorus, while the largest output of nitrogen was denitrification, accounting for 44.1% of N output; the largest output of phosphorus was sale of crops, accounting for 99.4% of P output. The results show that the nutrient input is larger than output, demonstrating that there is nutrient surplus within the watershed, a surplus which may become a potential source of nonpoint pollution to area waters. The research showed that both denitrification and volatilization of nitrogen are key ways of nitrogen loss from the watershed. This suggests that careful management of fertilizer application will be important for the sustainable development of agriculture. The research demonstrated that a multipond system within the watershed had high retention rate for both water and nutrients, benefiting the water, nutrient and sediment recycling in the terrestrial ecosystem and helping to reduce agricultural nonpoint pollution at its source. Therefore, this unique watershed system should be recommended due to its great potential relevance for sustainable agricultural development.
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  • 36
    ISSN: 1573-515X
    Keywords: atmospheric deposition ; moss ; bog ; nitrogen ; phosphorus ; water table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen additions as NH4NO3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m−2 yr−1 were made toSphagnum magellanicurn cores at two-week intervalsin situ at four sites across Europe, i.e. Lakkasuo (Finland). Männikjärve (Estonia), Moidach More (UK) and Côte de Braveix (France). The same treatments were applied in a glasshouse experiment in Neuchâtel (Switzerland) in which the water table depth was artificially maintained at 7, 17 and 37 cm below the moss surface. In the field, N assimilation in excess of values in wet deposition occurred in the absence of growth, but varied widely between sites, being absent in Lakkasuo (moss N∶P ratio 68) and greatest in Moidach More (N∶P 21). In the glasshouse, growth was reduced by lowering the water table without any apparent effect on N assimilation. Total N content of the moss in field sites increased as the mean depth of water table increased indicating growth limitation leading to increased N concentrations which could reduce the capacity for N retention. Greater contents of NH4 + in the underlying peat at 30 cm depth, both in response to NH4NO3 addition and in the unamended cores confirmed poor retention of inorganic N by the moss at Lakkasuo. Nitrate contents in the profiles at Lakkasuo, Moidach More, and Côte de Braveix were extremely low, even in the N10 treatment, but in Männikjärve, where the mean depth of water table was greatest and retention absent, appreciable amounts of NO3 − were detected in all cores. It is concluded that peatland drainage would reduce the capture of inorganic N in atmospheric deposition bySphagnum mosses.
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  • 37
    ISSN: 1573-515X
    Keywords: estuaries ; lakes ; marine ; nitrogen ; phosphorus ; rivers ; streams ; temperate ; tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Published data and analyses from temperate and tropical aquatic systems are used to summarize knowledge about the potential impact of land-use alteration on the nitrogen biogeochemistry of tropical aquatic ecosystems, identify important patterns and recommend key needs for research. The tropical N-cycle is traced from pre-disturbance conditions through the phases of disturbance, highlighting major differences between tropical and temperate systems that might influence development strategies in the tropics. Analyses suggest that tropical freshwaters are more frequently N-limited than temperate zones, while tropical marine systems may show more frequent P limitation. These analyses indicate that disturbances to pristine tropical lands will lead to greatly increased primary production in freshwaters and large changes in tropical freshwater communities. Increased freshwater nutrient flux will also lead to an expansion of the high production, N- and light-limited zones around river deltas, a switch from P- to N-limitation in calcareous marine systems, with large changes in the community composition of fragile mangrove and reef systems. Key information gaps are highlighted, including data on mechanisms of nutrient transport and atmospheric deposition in the tropics, nutrient and material retention capacities of tropical impoundments, and N/P coupling and stoichiometric impacts of nutrient supplies on tropical aquatic communities. The current base of biogeochemical data suggests that alterations in the N-cycle will have greater impacts on tropical aquatic ecosystems than those already observed in the temperate zone.
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  • 38
    ISSN: 1573-515X
    Keywords: acidification ; anthropogenic nitrogen ; cations ; nitrate leaching ; nitric oxide ; nitrous oxide ; nutrient limitation ; phosphorus ; productivity ; tropical ecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Human activities have more than doubled the inputs of nitrogen (N) into terrestrial systems globally. The sources and distribution of anthropogenic N, including N fertilization and N fixed during fossil fuel combustion, are rapidly shifting from the temperate zone to a more global distribution. The consequences of anthropogenic N deposition for ecosystem processes and N losses have been studied primarily in N-limited ecosystems in the temperate zone; there is reason to expect that tropical ecosystems, where plant growth is most often limited by some other resource, will respond differently to increasing deposition. In this paper, we assess the likely direct and indirect effects of increasing anthropogenic N inputs on tropical ecosytem processes. We conclude that anthropogenic inputs of N into tropical forests are unlikely to increase productivity and may even decrease it due to indirect effects on acidity and the availability of phosphorus and cations. We also suggest that the direct effects of anthropogenic N deposition on N cycling processes will lead to increased fluxes at the soil-water and soil-air interfaces, with little or no lag in response time. Finally, we discuss the uncertainties inherent in this analysis, and outline future research that is needed to address those uncertainties.
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  • 39
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    Biogeochemistry 46 (1999), S. 179-202 
    ISSN: 1573-515X
    Keywords: carbon dioxide ; grazing ; nitrogen fixation ; nitrogen limitation ; phosphorus ; shade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The widespread occurrence of N limitation to net primary production (NPP) and other ecosystem processes, despite the ubiquitous occurrence of N-fixing symbioses, remains a significant puzzle in terrestrial ecology. We describe a simple simulation model for an ecosystem containing a generic nonfixer and a symbiotic N fixer, based on: (1) a higher cost for N acquisition by N fixers than nonfixers; (2) growth of fixers and fixation of N only when low N availability limits the growth of nonfixers, and other resources are available; and (3) losses of fixed N from the system only when the quantity of available N exceeds plant and microbial demands. Despite the disadvantages faced by the N fixer under these conditions, N fixation and loss adjust N availability close to the availability of other resources, and biomass and NPP in this simple model can be substantially but only transiently N limited. We then modify the model by adding: (1) losses of N in forms other than excess available N (e.g., dissolved organic N, trace gases produced by nitrification); and (2) constraints to the growth and activity of N fixers imposed by differential effects of shading, P limitation, and grazing. The combination of these processes is sufficient to describe an open system, with input from both precipitation and N fixation, that is nevertheless strongly N-limited at equilibrium. This model is useful for exploring causes and consequences of constraints to N fixation, and hence of N limitation, and we believe it will also be useful for evaluating how N fixation and limitation interact with elevated CO2 and other components of global enviromental change.
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  • 40
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    Biogeochemistry 47 (1999), S. 25-38 
    ISSN: 1573-515X
    Keywords: Hedley fractionation ; phosphorus ; Ruttenberg fractionation ; soil phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We used l6 soils to compare the Hedley method for soil phosphorus fractionation to an alternative method recently developed by Ruttenberg to differentiate among P fractions in marine sediments. For forms of labile and Fe-bound P in soils, these methods were poorly correlated, with the Hedley fractionation showing a greater ability to discriminate among variations in plant-available P. For Ca-bound P, total organic P, and total P, the methods were well correlated (r2 = 0.93, 0.48, 0.74, respectively), although the sum of P measured in the Ruttenberg extractions is only 45% of the total P recovered by the Hedley fractionation. The Hedley fractionation seems superior when an index of plant-available phosphorus and a separation of organic and inorganic forms is needed, whereas the Ruttenberg method allows a separation of CaCO3-bound P from apatite-P, which is potentially useful in calcareous soils.
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  • 41
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    Biogeochemistry 47 (1999), S. 25-38 
    ISSN: 1573-515X
    Keywords: Hedley fractionation ; phosphorus ; Ruttenberg fractionation ; soil phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We used 16 soils to compare the Hedley method for soil phosphorus fractionation to an alternative method recently developed by Ruttenberg to differentiate among P fractions in marine sediments. For forms of labile and Fe-bound P in soils, these methods were poorly correlated, with the Hedley fractionation showing a greater ability to discriminate among variations in plant-available P. For Ca-bound P, total organic P, and total P, the methods were well correlated (r2=0.93, 0.48, 0.74, respectively), although the sum of P measured in the Ruttenberg extractions is only 45% of the total P recovered by the Hedley fractionation. The Hedley fractionation seems superior when an index of plant-available phosphorus and a separation of organic and inorganic forms is needed, whereas the Ruttenberg method allows a separation of CaCO3-bound P from apatite-P, which is potentially useful in calcareous soils.
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  • 42
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    Bulletin of engineering geology and the environment 57 (1999), S. 273-280 
    ISSN: 1435-9537
    Keywords: Key words Pollution ; Heavy metals ; Arsenic ; Mine tailings ; River Medjerda ; Tunisia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Résumé Dans le district minier de Fej Hcine, situé dans le Nord-Ouest de la Tunisie, l'oued Medjerda et son principal affluent El Melah sont pollués par les métaux lourds et l'arsenic. Les études géochimiques réalisées ont montré une nette diminution des concentrations en métaux depuis l'arrêt des activités minières, et cela bien que les sédiments des oueds contiennent encore des teneurs élevées par rapport au fond géochimique local, particulièrement en arsenic et en zinc. À la frontière tuniso-algérienne, la concentration en arsenic dans les eaux de l'oued Medjerda peut excéder 1 mg/l. Les tests de lixiviation effectués sur des échantillons de minerai, de rejets de flottation et d'amas arsénifère, montrent que les teneurs en Zn, Pb, Cu et Cd ne dépassent pas 1 mg/l dans les solutions de lixiviation, alors que celles de l'arsenic atteignent respectivement 5, 344 et 9400 mg/l. L'étude a montré que la pollution a pour origine non seulement les activités minières mais aussi les occurrences minérales présentes dans le district minier, ainsi qu'une autre source située en Algérie.
    Notes: Abstract  In the Fej Hcine mining area of north-west Tunisia, the Medjerda River and its principal tributary, El Melah, are polluted by heavy metals and arsenic. The geochemical studies undertaken have indicated pronounced falls in the concentrations of metals since the mining activities ceased, although the river sediments still contain higher levels than the local host rocks, particularly arsenic and zinc. At the Tunisia/Algeria border, arsenic concentrations in the Medjerda waters can exceed 1 mg/l. Leaching tests on samples of ore, flotation tailings and an arseniferous mass indicate that whilst Zn, Pb, Cu and Cd concentrations do not exceed 1 mg/l in the leachate solutions, arsenic levels reach 5, 344 and 9,400 mg/l respectively. The study has shown that the pollution originates not only from the mining activities but also from the mineral occurrences present in the mining district and from another source within Algeria.
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  • 43
    ISSN: 1573-515X
    Keywords: atmospheric deposition ; moss ; bog ; nitrogen ; phosphorus ; water table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen additions as NH4NO3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m-2 yr-1 were made to Sphagnum magellanicum cores at two-week intervals in situ at four sites across Europe, i.e. Lakkasuo (Finland), Männikjärve (Estonia), Moidach More (UK) and Côte de Braveix (France). The same treatments were applied in a glasshouse experiment in Neuchâtel (Switzerland) in which the water table depth was artificially maintained at 7, 17 and 37 cm below the moss surface. In the field, N assimilation in excess of values in wet deposition occurred in the absence of growth, but varied widely between sites, being absent in Lakkasuo (moss N:P ratio 68) and greatest in Moidach More (N:P 21). In the glasshouse, growth was reduced by lowering the water table without any apparent effect on N assimilation. Total N content of the moss in field sites increased as the mean depth of water table increased indicating growth limitation leading to increased N concentrations which could reduce the capacity for N retention. Greater contents of NH4+ in the underlying peat at 30 cm depth, both in response to NH4NO3 addition and in the unamended cores confirmed poor retention of inorganic N by the moss at Lakkasuo. Nitrate contents in the profiles at Lakkasuo, Moidach More, and Côte de Braveix were extremely low, even in the N10 treatment, but in Männikjärve, where the mean depth of water table was greatest and retention absent, appreciable amounts of NO3- were detected in all cores. It is concluded that peatland drainage would reduce the capture of inorganic N in atmospheric deposition by Sphagnum mosses.
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  • 44
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    Biogeochemistry 45 (1999), S. 197-221 
    ISSN: 1573-515X
    Keywords: intertidal marshes ; phosphorus ; sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We examined forms of solid phosphorus fractions in intertidal marsh sediments along a salinity (0–22‰) gradient in a river-dominated estuary and in a marine-dominated salt marsh with insignificant freshwater input. Freshwater marsh sediments had the highest ratio of organic N:P of between 28:1 and 47:1 mol:mol, compared to 21:1 to 31:1 mol:mol in the saltmarshes, which is consistent with a trend toward P-limitation of primary production in freshwater and N-limitation in salt marshes. However, total P concentration, 24.7 ± 11.1 µmol P g dw-1 (±1 SD) averaged over the upper meter of sediment, was greatest in the freshwater marsh where bioavailablity of P is apparently limited. In the freshwater marsh the greatest fraction of total P (24–51%) was associated with humic acids, while the importance of humic-P decreased with increasing salinity to 1–23% in the salt marshes. Inorganic P contributed considerably less to total sediment P in the freshwater marsh (15–40%) than in the salt marshes (33–85%). In reduced sediments at all sites, phosphate bound to aluminum oxides and clays was an important inorganic P pool irrespective of salinity. Inorganic P associated with ferric iron [Fe(III)] phases was most abundant in surface sediments of freshwater and brackish marshes, while Ca-bound P dominated inorganic P pools in the salt marshes. Thus, our results showed that particle-bound P in marsh sediments exhibited changes in chemical association along the salinity gradient of an estuarine system, which is a likely consequence of changes in ionic strength and the availability of iron and calcium.
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  • 45
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    Biogeochemistry 45 (1999), S. 197-221 
    ISSN: 1573-515X
    Keywords: intertidal marshes ; phosphorus ; sediments
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    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We examined forms of solid phosphorus fractions in intertidal marsh sediments along a salinity (0–22%.) gradient in a river-dominated estuary and in a marine-dominated salt marsh with insignificant freshwater input. Freshwater marsh sediments had the highest ratio of organic N:P of between 28:1 and 47:1 mol:mol, compared to 21∶1 to 31∶1 mol∶mol in the saltmarshes, which is consistent with a trend toward P-limitation of primary production in freshwater and N-limitation in salt marshes. However, total P concentration, 24.7±11.1μmol P g dw−1 (±1 SD) averaged over the upper meter of sediment, was greatest in the freshwater marsh where bioavailablity of P is apparently limited. In the freshwater marsh the greatest fraction of total P (24–51%.) was associated with humic acids, while the importance of humic-P decreased with increasing salinity to 1–23%. in the salt marshes. Inorganic P contributed considerably less to total sediment P in the freshwater marsh (15–40%.) than in the salt marshes (33–85%.). In reduced sediments at all sites, phosphate bound to aluminum oxides and clays was an important inorganic P pool irrespective of salinity. Inorganic P associated with ferric iron [Fe(III)] phases was most abundant in surface sediments of freshwater and brackish marshes, while Ca-bound P dominated inorganic P pools in the salt marshes. Thus, our results showed that particle-bound P in marsh sediments exhibited changes in chemical association along the salinity gradient of an estuarine system, which is a likely consequence of changes in ionic strength and the availability of iron and calcium.
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  • 46
    ISSN: 1573-515X
    Keywords: Chihuahuan desert ; desert ; desertification ; grassland ; nitrogen ; nutrient budgets ; phosphorus ; runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Rainfall simulation experiments were performed in areas of semiarid grassland (Bouteloua eriopoda) and arid shrubland (Larrea tridentata) in the Chihuahuan desert of New Mexico. The objective was to compare the runoff of nitrogen (N) and phosphorus (P) from these habitats to assess whether losses of soil nutrients are associated with the invasion of grasslands by shrubs. Runoff losses from grass- and shrub-dominated plots were similar, and much less than from bare plots located in the shrubland. Weighted average concentrations of total dissolved N compounds in runoff were greatest in the grassland (1.72 mg/l) and lowest in bare plots in the shrubland (0.55 mg/l). More than half of the N transported in runoff was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was highly correlated to the total volume of discharge. We estimate that the total annual loss of N in runoff is 0.25 kg/ha/yr in grasslands and 0.43 kg/ha/yr in shrublands – consistent with the depletion of soil N during desertification of these habitats. Losses of P from both habitats were very small.
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  • 47
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    Journal of paleolimnology 20 (1998), S. 47-55 
    ISSN: 1573-0417
    Keywords: diatoms ; spatial variability ; canonical correspondence analysis ; lake eutrophication ; transfer functions ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatom analyses were undertaken of sediment cores covering a range of water depths in a small eutrophic lake (Lough Augher, Co. Tyrone, N. Ireland). The significance of between-core variability in diatom relative frequency stratigraphy was assessed by Canonical Correspondence Analysis (CCA) where the ordination axes were constrained to external environmental variables (sediment depth, core location coordinates, water depth, effective fetch, distance-from-shore and distance-from-inflow). After the removal of the effect of sediment age by partialling it out, the resultant first two axes from the partial-CCA were significantly correlated with water depth and distance-from-shore, indicating non-uniform diatom stratigraphies across the lake. Despite this variability, all cores show the same succession of species and, therefore, record the eutrophication of the lake. Diatom-inferred total phosphorus (DI-TP) was inferred for six cores using weighted averaging regression and calibration. Apart from considerable differences of DI-TP in surficial sediment samples, there was good between-core repeatability of DI-TP profiles. These data support the use of DI-TP for establishing background nutrient concentrations for lakes, and associated implications for lake restoration schemes using single cores. Comparisons of DI-TP profiles and total diatom accumulation rate data for the individual cores indicate that diatom production peaked prior to the maximum TP concentrations in the lake.
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  • 48
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    Journal of paleolimnology 20 (1998), S. 31-46 
    ISSN: 1573-0417
    Keywords: phosphorus ; Lake Okeechobee ; lead-210 dating ; eutrophication ; phosphorus loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Phosphorus accumulation rates in depositional zone sediments of Lake Okeechobee were determined in 11 mud-zone cores and two peat-zone cores dated by 210Pb. Although difficulties were encountered in interpreting 210Pb data from some sites, reliable dating of sediments from the mud zone of this shallow lake is possible. Sediment accumulation rates in this zone have increased during the present century by an average of about twofold, and accumulation of organic sediments in the lake during pre-settlement times apparently was much slower than during the past century. Concentrations of all forms of sedimentary P but especially nonapatite inorganic-P and organic-P also have increased since pre-settlement times and especially since about 1940. Annual P accumulation rates in the lake's sediments have increased about fourfold during the 1900s, with most of the increase occurring in the past 40–50 years. The recent accumulation rate of sedimentary P (past ~ 10 years) agrees within a factor of 1.5 with the net retention of P in the lake calculated from published input-output mass balances.
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  • 49
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    Environmental geology 36 (1998), S. 118-126 
    ISSN: 1432-0495
    Keywords: Key words River sediments ; Heavy metals ; Lead isotopes ; Geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Heavy metal and metalloid concentrations within stream-estuary sediments (〈180-μm size fraction) in north-eastern New South Wales largely represent natural background values. However, element concentrations (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Zn) of Hunter River sediments within the heavily industrialized and urbanized Newcastle region exceed upstream background values by up to one order of magnitude. High element concentrations have been found within sediments of the Newcastle Harbour and Throsby Creek which drains into urbanized and light industry areas. Observed Pb enrichments and low 208Pb/204Pb, 207Pb/204Pb and 206Pb/204Pb ratios are likely caused by atmospheric deposition of Pb additives from petrol and subsequent Pb transport by road run-off waters into the local drainage system. Sediments of the Richmond River and lower Manning, Macleay, Clarence, Brunswick and Tweed River generally display no evidence for anthropogenic heavy metal and metalloid contamination (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Zn). However, the rivers and their tributaries possess localized sedimentary traps with elevated heavy metal concentrations (Cu, Pb, Zn). Lead isotope data indicate that anthropogenic Pb provides a detectable contribution to investigated sediments. Such contributions are evident at sample sites close to sewage outlets and in the vicinity of the Pacific Highway. In addition, As concentrations of Richmond River sediments gradually increase downstream. This geochemical trend may be the result of As mobilization from numerous cattle-dip sites within the region into the drainage system and subsequent accumulation of As in downstream river and estuary sediments.
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  • 50
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    Environmental geology 33 (1998), S. 96-108 
    ISSN: 1432-0495
    Keywords: Key words Atmospheric transport ; Heavy metals ; Natural emissions ; Risk assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The scientific literature of the past 25 years indicates a lack of consensus over the relative significance of anthropogenic and natural sources of metals in rural and remote ecosystems, meaning areas located several hundred to several thousand kilometers from industrial point sources. Geoscience perspectives are needed to address the critical information gaps associated with this issue, particularly where information on the significance and variability of naturally occurring metals is required. Uncertainties in source apportionment need to be addressed by improving methods of fingerprinting sources of airborne particles, and establishing identities of individual particles on the basis of characteristic morphologies and chemical composition. Further research is required to obtain robust estimates of total metal emissions to the atmosphere and to the oceans in order to determine the relative contribution from anthropogenic sources. Such research must involve a systematic attempt to obtain spatially and temporally representative data on the natural release of metals at the global scale. Moreover, a clear understanding of all local natural and anthropogenic loadings to an ecosystem is required before firm conclusions can be drawn about the relative importance of long-range atmospheric transport.
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  • 51
    ISSN: 1432-0495
    Keywords: Key words Stable isotopes ; Heavy metals ; Zebra mussels ; Lake Erie
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    Topics: Geosciences
    Notes: Abstract  Dreissena polymorpha is an exotic freshwater bivalve species which was introduced into the Great Lakes system in the fall of 1985 through the release of ballast water from European freighters. Utilizing individual growth rings of the shells, the stable isotope distribution (δ18O and δ13C) was determined for the life history of selected samples which were collected from the western basin of Lake Erie. These bivalves deposit their shell in near equilibrium with the ambient water and thus reflect any annual variation of the system in the isotopic records held within their shells. Observed values for δ18O range from -6.64 to –9.46‰ with an average value of –7.69‰ PDB, while carbon values ranged from –0.80 to –4.67‰ with an average value of –1.76‰ PDB. Dreissena polymorpha shells incorporate metals into their shells during growth. Individual shell growth increments were analyzed for Pb, Fe, Mg, Mn, Cd, Cu, and V concentrations. The shells show increased uptake of certain metals during periods of isotopic enrichment which correspond with warmer water temperatures. Since metals are incorporated into the shells, the organism may be useful as a biomonitor of metal pollution within aquatic environments.
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  • 52
    ISSN: 1432-0495
    Keywords: Key words Channel processes ; River sediments ; River pollution ; Heavy metals ; Upper Silesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  An evaluation of the influence of channel processes (erosion, accumulation, processing of channel sediments) on the dispersal of heavy metals in bottom sediments was carried out in the channels of the Sztoła and Biała Przemsza rivers in Upper Silesia, Poland. These rivers receive waters from a Zn and Pb mine. Mine waters transport a large amount of fine-grained sediments contaminated with heavy metals. The polluted material is accumulated in these stream courses and mixed with nearly homogeneous sandy sediment derived from erosion of the river banks and bed. Because these alluvia are easily set in motion, the distribution of heavy metal concentration in the channel in fraction 〈1 mm reflects differences in physical processes of sedimentation in its cross-section. The minimal values in active channel and maximal in the near-bank zone are typical for those channel sections where heavy metals, present in a solid state, are transported as a suspended load (normally the largest part of a polluted river course). In short sections heavy metals associated with the grains of a large mass which has accumulated in the active channel are transported as a bed load and the typical distribution pattern is reversed (in fractions both 〈1 mm and 〈0.063 mm). Such regularities can be disturbed in localities where strong, turbulent flow or frequent eddying occur and Mn oxides and hydrooxides and associated elements precipitate. The smallest variation in heavy metal concentration in the homogenous, fine-grained bank sediments which are trapped by plants below water level is a feature which recommends these localities as being the most suitable for monitoring of river pollution.
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  • 53
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    Environmental geology 34 (1998), S. 214-222 
    ISSN: 1432-0495
    Keywords: Key words Hudson River ; Estuary ; Heavy metals ; Turbidity maximum ; Mud
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    Topics: Geosciences
    Notes: Abstract  In the Hudson River estuary, fine mud and toxic metals are enriched in the upstream turbidity maximum. The mechanisms causing the enrichment were assessed through the analysis of suspended-sediment concentration (SSC) (bottom and surface), particle size, and trace metal distributions. Bottom SSCs varied across the study area by a factor of ten, and the turbidity maximum activity was observed in between kilometers 45 and 80. The particle-size analysis defined two accumulation modes: 〈4.65 and 〉22.1 μm. The ratio of the fine-to-coarse mode increased from 1.75 to 2.75 in the turbidity maximum. The fine mud concentration (55–60%) in the turbidity maximum was found to have a high correlation (r=0.98;p〈0.005) with the concentration of 〈2-μm particles. A conceptual model was derived in order to understand the possible mechanisms by which fine mud (and specifically 〈2-μm particles) is concentrated. The two dominant size modes were analyzed for toxic metals. The upstream tributaries are major sources of metals compared to point sources at downstream locations. In the turbidity maximum, Cd, Cu, Zn, and Pb are significantly enriched compared to average shale metal values and ERM toxicity guidelines by 580, 42, 10, 16 and 12, 7, 2.4, 1.4 times, respectively. Decreasing metal concentrations downstream of the turbidity maximum imply that Haverstraw Bay acts as temporary storage for fine particles and enriched metals. It is demonstrated in this study that toxic metals are enriched in Haverstraw Bay due to the mud accumulation. The high levels of toxic metals in the sediments of the Hudson River estuary are a major concern because human activities (dredging and river traffic) cause resuspension of sediments and can change the mobility patterns of bioavailable contaminants.
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  • 54
    ISSN: 1432-0495
    Keywords: Key words Magnetic susceptibility ; Sea-floor sediments ; Heavy metals ; Hong Kong
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    Topics: Geosciences
    Notes: Abstract  Magnetic susceptibility measurements were conducted on 24 vibrocores obtained from an area located off the northeastern coast of Lantau Island in Hong Kong. High intensities of magnetic susceptibility were detected in the uppermost sections of the majority of the cores. Several magnetic parameters measured for one of the cores suggest that the variations in the magnetic characteristics over depth are mainly due to varying concentrations of the magnetic minerals. Since a strong correlation has been found between magnetic susceptibility and the heavy metals Pb, Cu, Zn and Cr, an anthropogenic contamination origin is thought to be the cause. The present study shows that magnetic susceptibility is a fast, inexpensive and non-destructive method for the detection and mapping of contaminated sediments.
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    Environmental geology 33 (1998), S. 224-230 
    ISSN: 1432-0495
    Keywords: Key words Historical mining ; Groundwater pollution ; Surface-water pollution ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The focus of this research was to determine the impact of abandoned mines on surface water and groundwater in the historical mining districts of the Cerbat Mountains, Arizona. The surface water in the mining areas was found to be contaminated by various combinations and concentrations of heavy metals. Elevated arsenic, cadmium, and iron concentrations were detected in most surface-water samples, while lead, copper, and zinc contamination differed from region to region, depending on the ore mined. The groundwater was seriously polluted by arsenic, cadmium, lead, zinc, iron, and manganese in the immediate vicinity of mines that processed ore on the site, such as the Tennessee Mine near Chloride. Chloride's groundwater, however, showed no evidence of contamination. Three possible explanations are discussed: immobilization of the heavy metals in the soil by chemical reactions and adsorption, dilution effects due to the rainy season in spring, or the existence of different groundwater systems.
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  • 56
    ISSN: 1432-0495
    Keywords: Key words Sulfide oxidation ; Mine tailings ; Heavy metals ; Metal attenuation
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    Topics: Geosciences
    Notes: Abstract  The oxidation and the subsequent dissolution of sulfide minerals within the Copper Cliff tailings area have led to the release of heavy metals such as Fe, Ni, and Co to the tailings pore water. Dissolved concentrations in excess of 10 g/l Fe and 2.2 g/l Ni have been detected within the shallow pore water of the tailings, with increasing depth these concentrations decrease to or near analytical detection limits. Geochemical modelling of the pore-water chemistry suggests that pH-buffering reactions are occurring within the shallow oxidized zones, and that secondary phases are precipitating at or near the underlying hardpan and transition zones. Mineralogical study of the tailings confirmed the presence of goethite, jarosite, gypsum, native sulfur, and a vermiculite-type clay mineral. Goethite, jarosite, and native sulfur form alteration rims and pseudo-morphs of the sulfide minerals. Interstitial cements, composed of goethite, jarosite, and gypsum, locally bind the tailings particles, forming hardpan layers. Microprobe analyses of the goethite indicate that it contains up to 0.6 weight % Ni, suggesting that the goethite is a repository for Ni. Other sinks detected for heavy metals include jarosite and a vemiculite-type clay mineral which locally contains up to 1.6 weight % Ni. To estimate the mass and distribution of heavy metals associated with the secondary phases within the shallow tailings, a series of chemical extractions was completed. The experimental design permitted four fractions of the tailings to be evaluated independently. These four fractions consisted of a water-soluble, an acid-leachable, and a reducible fraction, as well as the whole-rock total. Twenty-five percent of the total mass of heavy metals was removed in the acid-leaching experiments, and 100% of the same components were removed in the reduction experiments. The data suggest that precipitation/coprecipitation reactions are providing an effective sink for most of the heavy metals released by sulfide mineral oxidation. In light of these results, potential decommissioning strategies should be evaluated with the recognition that changing the geochemical conditions may alter the stability of the secondary phases within the shallow tailings.
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  • 57
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    Biogeochemistry 42 (1998), S. 169-187 
    ISSN: 1573-515X
    Keywords: aridisols ; desertification ; erosion ; geostatistics ; Larrea tridentata ; nitrogen ; phosphorus ; Prosopis glandulosa ; soil heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Geostatistical analyses show that the distribution of soil N, P and K is strongly associated with the presence of shrubs in desert habitats. Shrubs concentrate the biogeochemical cycle of these elements in ‘islands of fertility’ that are localized beneath their canopies, while adjacent barren, intershrub spaces are comparatively devoid of biotic activity. Both physical and biological processes are involved in the formation of shrub islands. Losses of semiarid grassland in favor of invading shrubs initiate these changes in the distribution of soil nutrients, which may promote the further invasion and persistence of shrubs and cause potential feedbacks between desertification and the Earth's climate system.
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  • 58
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    Environmental geochemistry and health 20 (1998), S. 123-133 
    ISSN: 1573-2983
    Keywords: Heavy metals ; lead and copper pollution ; household dust
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract Despite some progress in reducing the average lead level in the USA, the streets of Cincinnati, Ohio, are still contaminated by heavy metals. High levels of heavy metals will have significant unequivocal ecological impacts and pose a potential health hazard. This study evaluates the level of heavy- metal contamination in household dust and examines its relationships with the external environment. Samples of outdoor and indoor dust were collected from middle-income residential homes in the Greater Cincinnati Metropolitan District and the metal content was analysed by inductively coupled plasma atomic emission spectrophotometry. Results showed that the mean levels of lead in outdoor and indoor dusts are 650 μg g⊃-1 and 377 μg g⊃-1 and the copper levels are 253 μg g⊃-1 and 510 μg g⊃-1, respectively. The median levels are 156 μg g⊃-1 and 139 μg g⊃-1 for outdoor and indoor lead dusts and 35 μg g⊃-1 and 124 μg g⊃-1 for outdoor and indoor copper dusts. The degree of contamination may be ascribable to the age of the dwelling unit and the neighbourhood, the time when the unit was last painted, the presence of pets and the type of space heating. In addition, car exhausts seems to be a possible source of contamination.
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  • 59
    ISSN: 1432-0495
    Keywords: Key words Lake sediments ; Heavy metals ; Geochemistry ; Element fluxes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The accumulation of heavy metals and trace elements has been investigated in a well laminated sequence of Holocene and late Pleistocene lake sediments composed of diatomaceous gyttja, tuff and silt and clay sediments. Varve chronology of the annually deposited gyttja yielded a continuous high-resolution time sequence and allowed the absolute age dating of the sediment. Fluxes of elements remained largely uniform from the late Pleistocene into the Holocene (12 867–2 364 VT years ago; VT: varve time, years before 1950). Higher trace element and heavy metal fluxes occur from 2 322 to 862 VT years ago and reached their maxima in the uppermost sediments (〈845 VT years ago). These increasing element fluxes correlate with increasing inputs of clastic material. The changing accumulation rates are the result of elevated soil erosion in the lake catchment caused by human settlement, deforestation and agricultural activities. Thus disturbances of the natural geochemical cycles of the Holzmaar region have occurred since the beginning of the Iron Age and especially since the beginning of the Middle Ages.
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  • 60
    ISSN: 1432-0495
    Keywords: Key words ICP-MS laser ablation ; Tree-ring profiles ; Heavy metals ; Pollution history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Laser ablation ICP-MS analysis of tree rings provides a rapid and sensitive method for investigating element concentrations and fluctuations in trees along time profiles. Time profiles obtained from pine and birch trees from a strongly polluted area in northwest Russia and a slightly polluted area at the Norwegian-Russian border show that single trees behave rather individualistically in terms of heavy metal contents as observed in the yearly growth rings. The obtained profiles can not be linked to the pollution history of the area. No correlation between pollution levels of the soils and observed metal content in tree rings can be established.
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  • 61
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    Environmental geology 33 (1997), S. 1-12 
    ISSN: 1432-0495
    Keywords: Key wordsAcid mine drainage ; Sulfide oxidation ; Goethite ; Jarosite ; Heavy metals ; Hydrated ferrous sulfates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This study investigates the retention of heavy metals in secondary precipitates from a sulfidic mine rock dump and underlying podzolic soils by means of mineralogical and chemical extraction methods. The rock dump, which is at least 50 years old, consists of a 5–10-cm-thick leached zone and an underlying 110–115-cm-thick accumulation zone. Optical microscopy and electron microprobe analyses confirm that pyrrhotite weathering has proceeded much further in the leached horizon relative to the accumulation horizon. The weathering of sulfides in the leached zone has resulted in the migration of most heavy metals to the accumulation zone or underlying soils, where they are retained in more stable phases such as secondary ferric minerals, including goethite and jarosite. Some metals are temporarily retained in hydrated ferrous sulfates (e.g., melanterite, rozenite).
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  • 62
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    Environmental geology 29 (1997), S. 78-83 
    ISSN: 1432-0495
    Keywords: Key words Sea urchins ; Heavy metals ; Pollution ; Spain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Portman Bay presents elevated quantities of metals and heavy metals in the sediments and rocky outcrops. The calcitic skeletons of the sea urchins that live there present elevated concentrations of Mn, Fe, Zn, and Pb (249, 273, 32, and 59 ppm) in comparison with control zones (beach of La Vila) where the concentrations for these elements are 5, 7, 8, and 2 ppm, respectively. Two species of sea urchins have been studied: Paracentrotus lividus and Arbacia lixula. The different compositions between the plates and the spines of their skeletons have also been studied.
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    Environmental geology 30 (1997), S. 224-230 
    ISSN: 1432-0495
    Keywords: Key words Sediment ; Washington ; DC ; Pollution ; phosphorus ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Sediments in the rivers and basins around Washington, DC, have high concentrations of phosphorus, which, based on geographic distributions, is largely derived from urban runoff and municipal sewage. Dissolved-particulate phosphate exchange reactions and biological uptake of dissolved phosphorus from the water column may be an added source of phosphorus to the sediments. Concentrations of total sedimentary phosphorus ranged from 24 to 56 μm P/g-dw, and were highest in areas near combined sewer outfalls. As a part of this study, sedimentary phosphorus was fractionated into Fe-P, Ca-P, Al-P, and organic phases using a selective-sequential leaching procedure. The distribution of the phases in all sediments analyzed follow the order , Fe-P〉Ca-P〉Al-P. Spatial variations in the amounts of phosphorus in the different phases is related to the sources of phosphorus to the area. The proportions of occluded Al-P and organic P are 10–20% of the total P, respectively. This suggests that phosphorus from natural sources is small compared to anthropogenic inputs in this area. The high leachable Fe-P and Ca-P in these sediments might contribute a substantial amount of P to the water column under conditions of remobilization.
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  • 64
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    Biogeochemistry 37 (1997), S. 237-252 
    ISSN: 1573-515X
    Keywords: freshwater ; limitation ; marine ; nitrogen ; phosphorus ; ratio ; stoichiometry ; trace elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen supply is often assumed to limitmarine primary production. A global analysis of totalnitrogen (N) to phosphorus (P) molar ratios shows thattotal N:P is low (〈16:1) in some estuarine andcoastal ecosystems, but up to 100:1 in open oceans.This implies that elements other than N may limitmarine production, except in human impacted, estuarineor coastal ecosystems. This pattern may reconcileconflicting enrichment studies, because N additionfrequently increases phytoplankton growth where totalN:P is expected to be low, but P, Fe, or Si augmentphytoplankton growth in waters where total N:P ishigh. Comparison of total N:P stoichiometry betweenmarine and freshwaters yields a model of the form ofthe aquatic N:P cycle.
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  • 65
    ISSN: 1573-515X
    Keywords: carbon ; nitrogen ; Ohio River ; phosphorus ; Red field ratios ; dissolved organic matter ; rivers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A 12-month study was conducted to measure the concentrations ofdissolved organic matter (DOC, TDN, TDP) in four sites within a119 km long reach of the Ohio River, near Louisville, KY. In thisstudy we test whether specific geomorphological and biologicalfactors influenced variations in dissolved organic matter.Concentrations of DOC in the river averaged ≈1200μmol/L, and varied by nearly two orders of magnitudeseasonally (mean DOC during base flow ≈620 μmol/L).Peak periods for DOC at all sites were during April–May. Thesite nearest a navigation dam (deeper, lower current velocities)had significantly lower concentrations of TDN and greater C:Nratios than upstream sites. The largest tributary entering thisreach (Kentucky River) had no significant effect on levels of DOMin the main river, despite having significantly greaterconcentrations of TDN and lower levels of DOC during most monthsof the year. Concentrations of DOC, TDN, and TDP were notsignificantly different in littoral and pelagic habitats at allsites studied, suggesting little floodplain influence on DOM inthis constricted-channel section of the Ohio River. C:N ratios ofDOM in the Ohio were significantly different among seasons; C:Nexceeded or equaled Redfield ratios in summer and fall (6 to 10),but were below Redfield (1.8 to 3.0) during winter and spring.Regression models suggest that total phytoplankton densities andflow conditions are the two most important factors regulating DOMin this very large river.
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  • 66
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    Biogeochemistry 37 (1997), S. 63-75 
    ISSN: 1573-515X
    Keywords: nutrient limitation ; soil development ; nitrogen ; phosphorus ; chronosequence ; Hawai'i
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Walker & Syers (1976) proposed a conceptual model that describesthe pattern and regulation of soil nutrient pools and availability during long-term soil and ecosystem development. Their model implies that plantproduction generally should be limited by N on young soils and by P on oldsoils; N and P supply should more or less equilibrate onintermediate-aged soils. We tested the application of this model to nutrientlimitation, using a well characterized substrate age sequence in Hawaiianmontane rain forest. Earlier experiments had evaluated nutrient limitationin forests on a young (300 y) and an old (4,100,000 y) substrate on the samedevelopmental sequence; N alone limited tree growth on the youngsubstrate, while P alone did so on the old one. An additional fertilizerexperiment based on replicated treatments with N, P, and all othernutrients combined, applied in individually and in all factorialcombinations, was established in an intermediate-aged site in theLaupahoehoe Forest Reserve, Hawaii. Here, diameter increments of thedominant tree Metrosideros polymorpha increased slightly with Nadditions, and nearly doubled when N and P were added together.Additions of elements other than N and P had no significant effecton growth. These results show that N and P had equilibrated (relativeto plant requirements) in the intermediate aged site. Together withthe earlier experiments, these results suggest that the Walker and Syersmodel provides a useful starting point for explaining the nature anddistribution of nutrient limitation in forest ecosystems.
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  • 67
    ISSN: 1432-0789
    Keywords: Soil bacteria ; [3H]-Thymidine ; [14C]-Leucine ; Temperature ; Metal tolerance ; Heavy metals ; Soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of temperature on the growth rate and metal toxicity in soil bacterial communities extracted from unpolluted and polluted soils were investigated using the thymidine and leucine incorporation techniques. An agricultural soil, which was contaminated in the laboratory with Cu, Cd, Zn, Ni or Pb, and an uncontaminated forest soil were used. Measurements were made at 0°C and 20°C. Leucine incorporation was found to be as sensitive to heavy metals as thymidine incorporation in the short-term trial used to indicate heavy metal tolerance. Similar IC50 values (the log of the metal concentration that reduced incorporation to 50%) were also obtained at 0 and 20°C, independently of the technique used. Metal tolerance could thus be measured using both techniques at any temperature in the range 0–20°C. In the long-term experiment different temperature-growth relationships were obtained on the basis of the rate of thymidine or leucine incorporation into bacterial assemblages from unpolluted and polluted soils, as judged from the minimum temperature values. This could not be attributed to the metal addition alone since different patterns were observed when different metals were added to the soil. Thus, the minimum temperature for thymidine incorporation was similar in Cu-polluted and unpolluted soil, while in soils polluted with Cd and Zn the minimum temperature increased by 2°C, and Ni and Pb additions increased the minimum temperature by 4°C compared to the unpolluted soil. This suggested that heavy metal pollution led to bacterial communities showing different temperature characteristics to those in the corresponding unpolluted soil. Similar observations were deduced from the minimum temperatures required for leucine incorporation. Three groups of bacterial communities were distinguished according to the growth response to temperature in polluted soils, one group in Cu-polluted soil, a second group in soil polluted with Zn and Cd, and a third group in soils polluted with Ni and Pb.
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    Biology and fertility of soils 23 (1996), S. 299-306 
    ISSN: 1432-0789
    Keywords: Heavy metals ; Soil microbial biomass ; Soil enzymes ; Functional diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three soil types-Calcaric Phaeozem, Eutric Cambisol and Dystric Lithosol-in large container pots were experimentally contaminated with heavy metals at four different levels (light pollution: 300 ppm Zn, 100 ppm Cu, 50 ppm Ni, 50 ppm V and 3 ppm Cd; medium pollution: twofold concentrations; heavy pollution: threefold concentrations; uncontaminated control). We investigated the prognostic potential of 16 soil microbial properties (microbial biomass, respiration, N-mineralization, 13 soil enzymes involved in cycling of C, N, P and S) with regard to their ability to differentiate the four contamination levels. Microbial biomass and enzyme activities decreased with increasing heavy metal pollution, but the amount of decrease differed among the enzymes. Enzymes involved in the C-cycling were least affected, whereas vartous enzyme activities related to the cycling of N, P and S showed a considerable decrease in activity. In particular, arylsulfatase and phosphatase activities were dramatically affected. Their activity decreased to a level of a few percent of their activities in the corresponding unpolluted controls. The data suggest that aside from the loss of rare biochemical capabilities-such as the growth of organisms at the expense of aromatics (Reber 1992)-heavy metal contaminated soils lose very common biochemical propertities which are necessary for the functioning of the ecosystem. Cluster analysis as well as discriminant analysis underline the similarity of the enzyme activity pattern among the controls and among the polluted soils. The trend toward a significant functional diversity loss becomes obvious already at the lowest pollution level. This implies that concentrations of heavy metals in soils near the current EC limits will most probably lead to a considerable reduction in decomposition and nutrient cycling rates. We conclude that heavy metal pollution severely decreases the functional diversity of the soil microbial community and impairs specific pathways of nutrient cycling.
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    Environmental geology 27 (1996), S. 54-58 
    ISSN: 1432-0495
    Keywords: Heavy metals ; Statistics ; River sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Statisticalt tests were used to determine lead, copper, and chromium enrichment in sediments from the Lower Branch of the Rouge River in southeast Michigan, USA. Both absolute metal concentrations and ratios of trace metal to conservative metal concentrations were used to compare sampled sites along the Lower Branch of the Rouge River to background sites in the headwaters region. Concentration ratios were used to reduce the effects of certain chemical and physical characteristics on the level of metal contained in a given sediment. Results from the comparison of sample sites to the background reveal metal enrichment at several sites, particularly along the highly urbanized, downstream section of the river. This section of the Lower Branch of the Rouge River exhibits significant lead and copper contamination, as well as measurable chromium enrichment when using either concentrations alone or ratios as methods of comparison. The areas of metal enrichment appear to coincide closely with areas of known anthropogenic activities. Of particular interest, however, is the enrichment of lead and copper at two upstream sites where the statistical tests suggest an anthropogenic source for the enrichment, but where no previously known cultural activities existed. These data prompted a historical search of records, which discovered several abandoned landfills immediately upstream of the metal enrichment sites.
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    Environmental geology 27 (1996), S. 155-163 
    ISSN: 1432-0495
    Keywords: Key words Radiometric dates ; Heavy metals ; Anthropogenic input ; Cauvery basin ; Remobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Eleven cores were collected from the Cauvery basin. Radiometric dates were used to determine modern sediment accumulation rates. Sediment accumulation rates ranged from 0.4 to 4 mm yr–1. Heavy metal concentration decreases with the increase of depth. The heavy metal concentrations at certain depths are attributed to the irregular input of metals and their remobilization. Heavy metal accumulations have been computed using sediment accumulation rates, and accumulation rates show an additional anthropogenic input of metals and sediments in the recent past. Factor analysis and correlation analysis show the diverse source and accumulation mechanism influencing the metal distribution in the basin.
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    Environmental geology 27 (1996), S. 155-163 
    ISSN: 1432-0495
    Keywords: Radiometric dates ; Heavy metals ; Anthropogenic input ; Cauvery basin ; Remobilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Eleven cores were collected from the Cauvery basin. Radiometric dates were used to determine modern sediment accumulation rates. Sediment accumulation rates ranged from 0.4 to 4 mm yr−. Heavy metal concentration decreases with the increase of depth. The heavy metal concentrations at certain depths are attributed to the irregular input of metals and their remobilization. Heavy metal accumulations have been computed using sediment accumulation rates, and accumulation rates show an additional anthropogenic input of metals and sediments in the recent past. Factor analysis and correlation analysis show the diverse source and accumulation mechanism influencing the metal distribution in the basin.
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  • 72
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    Biology and fertility of soils 23 (1996), S. 33-37 
    ISSN: 1432-0789
    Keywords: Soil organic C ; Soil microbial biomass ; Crop residue decomposition ; Soil C balance ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil C balances were calculated in a field experiment started in 1956. Treatments include a fallow and soils receiving different N fertilizers or organic amendments. By assuming the absence of a priming effect, the degree of mineralization of crop residues and organic amendments was calculated. Crop residue mineralization was not affected by a more than 50% decrease in the size of the microbial biomass in soil fertilized with (NH4)2SO4, which had caused the pH of this soil to drop from 6.6 to 4.4. More C had accumulated per unit C input in peat-and sewage sludge-amended soils than in any of the other soils, suggesting that peat and sewage sludge were more resistant to microbial attack. Recalcitrance of substrate C was an adequate explanation for the low ratio of biomass C to soil C in the peat-amended soils, but not in the sewage sludge-amended soil. There was a close linear relationship (r=0.94) between the content of microbial biomass C in the soil measured in 1990 and cumulative C losses from the soil since 1956. Compared to the relationship between soil biomass C and soil organic C concentrations, the linear relationship between microbial C and cumulative C losses suggested that the significantly reduced biomass in the sewage sludge-amended soil was at least partially due to the presence of toxic substances (presumably elevated heavy metal concentrations) in this soil and was probably not affected by the somewhat low pH (5.3) in this soil.
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  • 73
    ISSN: 1432-0789
    Keywords: Key words Soil bacteria ; [3H]-Thymidine ; [14C]-Leucine ; Temperature ; Metal tolerance ; Heavy metals ; Soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of temperature on the growth rate and metal toxicity in soil bacterial communities extracted from unpolluted and polluted soils were investigated using the thymidine and leucine incorporation techniques. An agricultural soil, which was contaminated in the laboratory with Cu, Cd, Zn, Ni or Pb, and an uncontaminated forest soil were used. Measurements were made at 0°C and 20°C. Leucine incorporation was found to be as sensitive to heavy metals as thymidine incorporation in the short-term trial used to indicate heavy metal tolerance. Similar IC50 values (the log of the metal concentration that reduced incorporation to 50%) were also obtained at 0 and 20°C, independently of the technique used. Metal tolerance could thus be measured using both techniques at any temperature in the range 0–20°C. In the long-term experiment different temperature–growth relationships were obtained on the basis of the rate of thymidine or leucine incorporation into bacterial assemblages from unpolluted and polluted soils, as judged from the minimum temperature values. This could not be attributed to the metal addition alone since different patterns were observed when different metals were added to the soil. Thus, the minimum temperature for thymidine incorporation was similar in Cu-polluted and unpolluted soil, while in soils polluted with Cd and Zn the minimum temperature increased by 2°C, and Ni and Pb additions increased the minimum temperature by 4°C compared to the unpolluted soil. This suggested that heavy metal pollution led to bacterial communities showing different temperature characteristics to those in the corresponding unpolluted soil. Similar observations were deduced from the minimum temperatures required for leucine incorporation. Three groups of bacterial communities were distinguished according to the growth response to temperature in polluted soils, one group in Cu-polluted soil, a second group in soil polluted with Zn and Cd, and a third group in soils polluted with Ni and Pb.
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    Biology and fertility of soils 23 (1996), S. 33-37 
    ISSN: 1432-0789
    Keywords: Key words Soil organic C ; Soil microbial biomass ; Crop residue decomposition ; Soil C balance ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil C balances were calculated in a field experiment started in 1956. Treatments include a fallow and soils receiving different N fertilizers or organic amendments. By assuming the absence of a priming effect, the degree of mineralization of crop residues and organic amendments was calculated. Crop residue mineralization was not affected by a more than 50% decrease in the size of the microbial biomass in soil fertilized with (NH4)2SO4, which had caused the pH of this soil to drop from 6.6 to 4.4. More C had accumulated per unit C input in peat- and sewage sludge-amended soils than in any of the other soils, suggesting that peat and sewage sludge were more resistant to microbial attack. Recalcitrance of substrate C was an adequate explanation for the low ratio of biomass C to soil C in the peat-amended soils, but not in the sewage sludge-amended soil. There was a close linear relationship (r=0.94) between the content of microbial biomass C in the soil measured in 1990 and cumulative C losses from the soil since 1956. Compared to the relationship between soil biomass C and soil organic C concentrations, the linear relationship between microbial C and cumulative C losses suggested that the significantly reduced biomass in the sewage sludge-amended soil was at least partially due to the presence of toxic substances (presumably elevated heavy metal concentrations) in this soil and was probably not affected by the somewhat low pH (5.3) in this soil.
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    Environmental geochemistry and health 18 (1996), S. 113-121 
    ISSN: 1573-2983
    Keywords: Heavy metals ; arsenic ; cadmium ; copper ; lead ; soils ; neutron activation analysis ; X-ray fluorescence atomic absorption spectrophotometry ; bauxite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract A regional survey of Jamaican surface soils has been conducted in which more than 200 samples were collected at a sample density of 1 per 64 km2 across the island and analysed for total concentrations of 31 elements by instrumental neutron activation analysis (INAA), energy dispersive X-ray fluorescence (EDXRF) analysis and atomic absorption spectrophotometry (AAS). The aim of the survey was to begin the construction of a high-precision geochemical database to provide information on elemental levels in soils for application to environmental studies, agriculture, and human and animal health. Results on the regional scale are presented for As, Cd, Cu, Hg and Pb. Although Jamaican surface soils are enriched in several heavy metals compared with world soil means and crustal abundances, lead is of particular importance at this stage because of its occurrence in residential areas. Except for Cu, the distribution maps of these elements are highly correlated with bauxite which in Jamaica is associated with white limestone geology and residualterra rossa soils.
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  • 76
    ISSN: 1573-515X
    Keywords: lacustrine sediment ; organic matter ; sedimentation rates ; recycling ; burial ; carbon ; nitrogen ; silicon ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The areal distribution of organic C contents, δ13C values, total N and P and biogenic Si contents in surficial sediments were used to study the distribution, origin and diagenetic transformations of sedimented biogenic debris in the eutrophic subalpine Lake Bled (Slovenia), which for most of the yearhas an anoxic hypolimnion. The influence of an allochthonous input, restricted to the western basin, was clearly traced by higher organic C and total N and P contents, higher δ13C values, and higher sedimentation rate in comparison to the eastern basin. The low δ13C values of sedimentary organic matter in the major part of the lake, lower than the δ13C values of different types of organic matter, suggest that this sedimentary organic matter is most probably the product of a microbial community and not a residue of primary production. The temporal variation of benthic diffusive fluxes of NH4, Si and PO4, derived from modelling the pore water profiles, was related to sedimentation of phytoplanktonic blooms, while the PO4 fluxes were also dependent on changing redox conditions at the sediment-water interface in the period of the winter-spring overtum. The removal of PO4 in pore waters is probably due to the adsorption of phosphate and precipitation of apatite and vivianite. The budget of C, N and P at the sediment-water interface revealed a high recycling efficiency (〉70%), also confirmed by the rather uniform (or only slightly decreasing) vertical profiles of organic C, total N and P in sediment cores and C/N and C/P ratios. The percentage of biogenic Si recycling is low (〈10%), suggesting its removal in sediments.
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  • 77
    ISSN: 1573-515X
    Keywords: continental shelf ; estuaries ; mass balance ; nitrogen ; North Atlantic ; nutrient budget ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Five large rivers that discharge on the western North Atlantic continental shelf carry about 45% of the nitrogen (N) and 70% of the phosphorus (P) that others estimate to be the total flux of these elements from the entire North Atlantic watershed, including North, Central and South America, Europe, and Northwest Africa. We estimate that 61 · 109 moles y−1 of N and 20 · 109 moles y−1 of P from the large rivers are buried with sediments in their deltas, and that an equal amount of N and P from the large rivers is lost to the shelf through burial of river sediments that are deposited directly on the continental slope. The effective transport of active N and P from land to the shelf through the very large rivers is thus reduced to 292 · 109 moles y−1 of N and 13 · 109 moles y−1 of P. The remaining riverine fluxes from land must pass through estuaries. An analysis of annual total N and total P budgets for various estuaries around the North Atlantic revealed that the net fractional transport of these nutrients through estuaries to the continental shelf is inversely correlated with the log mean residence time of water in the system. This is consistent with numerous observations of nutrient retention and loss in temperate lakes. Denitrification is the major process responsible for removing N in most estuaries, and the fraction of total N input that is denitrified appears to be directly proportional to the log mean water residence time. In general, we estimate that estuarine processes retain and remove 30–65% of the total N and 10–55% of the total P that would otherwise pass into the coastal ocean. The resulting transport through estuaries to the shelf amounts to 172–335 · 109 moles y−1 of N and 11–19 · 109 moles y−1 of P. These values are similar to the effective contribution from the large rivers that discharge directly on the shelf. For the North Atlantic shelf as a whole, N fluxes from major rivers and estuaries exceed atmospheric deposition by a factor of 3.5–4.7, but this varies widely among regions of the shelf. For example, on the U.S. Atlantic shelf and on the northwest European shelf, atmospheric deposition of N may exceed estuarine exports. Denitrification in shelf sediments exceeds the combined N input from land and atmosphere by a factor of 1.4–2.2. This deficit must be met by a flux of N from the deeper ocean. Burial of organic matter fixed on the shelf removes only a small fraction of the total N and P input (2–12% of N from land and atmosphere; 1–17% of P), but it may be a significant loss for P in the North Sea and some other regions. The removal of N and P in fisheries landings is very small. The gross exchange of N and P between the shelf and the open ocean is much larger than inputs from land and, for the North Atlantic shelf as a whole, it may be much larger than the N and P removed through denitrification, burial, and fisheries. Overall, the North Atlantic continental shelf appears to remove some 700–950· 109 moles of N each year from the deep ocean and to transport somewhere between 18 and 30 · 109 moles of P to the open sea. If the N and P associated with riverine sediments deposited on the continental slope are included in the total balance, the net flux of N to the shelf is reduced by 60 · 109 moles y−1 and the P flux to the ocean is increased by 20 · 109 moles y−1. These conclusions are quite tentative, however, because of large uncertainties in our estimates of some important terms in the shelf mass balance.
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  • 78
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    Biogeochemistry 35 (1996), S. 419-432 
    ISSN: 1573-515X
    Keywords: phosphorus ; sequential extraction ; soils ; riparian forest ; seasonal pattern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract This study addresses the temporal distribution of forms of phosphorus in the soil of a temporarily flooded riparian forest of the valley of the river Garonne (Southwest of France). A sequential extraction for forms of phosphorus of increasing chemical stability was used. During the study period (13 months), the forest was flooded a few days during March and May. In winter, resin-Pi concentration was high (26 μg g−1) in comparison to spring values (〈9 μg g−1). NaHCO3-Po, NaHCO3-Pi or NaOH-Pi concentrations increased during winter (up to 74, 124 and 78 μg g−1 respectively) and decreased significantly during spring (32, 44 and 32 μg g−1 respectively). This pattern was attributed to simultaneous mineralization and plant uptake during the growing season and to the flood events (erosional processes and P-release). During summer and fall, resin-Pi concentration increased significantly (up to 26 μg g−1 in October). NaHCO3-Po concentrations remained low during spring and summer (〈33 μg g−1), and increased significantly in fall (〉45 μg g−1 NaHCO3-Pi or NaOH-Pi increased in late spring or summer (90 μg g−1 and 68 μg g−1 respectively). Increasing concentrations of the labile forms during late spring or summer were ascribed to the warm temperature and soil dryness that limited plant growth. HCl-Pi increased regularly after the floods (174 μg g−1 before the flood events to 254 μg g−1 after the floods). Residual P presented a similar pattern i.e. 214 μg g−1 and 279 μg g−1 respectively before and after the flood events. This pattern was attributed to a progressive incorporation of flood deposits to the soil.
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  • 79
    ISSN: 1573-515X
    Keywords: fertilizer study ; Hawaii ; montane tropical forest ; nitrogen ; phosphorus ; primary succession
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We applied fertilizers in a 23complete factorial design to determine the effects of nutrient amendments on plant growth in Hawaiian montane forests growing on two different volcanic substrates: ‘a‘ā and pāhoehoe lava. Both sites were about 140 years old and their overstories were nearly monospecific stands of Metrosideros polymorpha. Fertilizer applications included N, P, a mixture of essential macro- and micronutrients excepting P and N, and all combinations thereof in each of four blocks. Additions of nutrients other than N or P had no significant effects on measured plant-growth variables. In contrast, additions of either N or P significantly increased tree height growth, diameter increments, biomass growth, and height growth of the understory fern Dicranopteris linearis in both sites. The effect of N was greater than that of P. Greatest growth rates occurred in plots receiving both N and P, and signficant N*P interactions occurred in several cases, suggesting a synergistic effect between these two elements. Plant growth on these young, poorly weathered, basaltic lavas is colimited by N and P availability. Growth in a similar-aged stand growing on a mixture of volcanic ash and cinders is N but not P limited, indicating that the texture of the parent material influences nutrient-availability patterns during early primary succession.
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  • 80
    ISSN: 1573-515X
    Keywords: anthropogenic ; atmospheric deposition ; eutrophication ; fertilizer ; nitrogen ; nitrogen budget ; nitrogen fixation ; N:P ratio ; phosphorus ; pristine ; rivers ; temperate ; tropical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We present estimates of total nitrogen and total phosphorus fluxes in rivers to the North Atlantic Ocean from 14 regions in North America, South America, Europe, and Africa which collectively comprise the drainage basins to the North Atlantic. The Amazon basin dominates the overall phosphorus flux and has the highest phosphorus flux per area. The total nitrogen flux from the Amazon is also large, contributing 3.3 Tg yr−1 out of a total for the entire North Atlantic region of 13.1 Tg yr−1 . On a per area basis, however, the largest nitrogen fluxes are found in the highly disturbed watersheds around the North Sea, in northwestern Europe, and in the northeastern U.S., all of which have riverine nitrogen fluxes greater than 1,000 kg N km−2 yr−1. Non-point sources of nitrogen dominate riverine fluxes to the coast in all regions. River fluxes of total nitrogen from the temperate regions of the North Atlantic basin are correlated with population density, as has been observed previously for fluxes of nitrate in the world's major rivers. However, more striking is a strong linear correlation between river fluxes of total nitrogen and the sum of anthropogenically-derived nitrogen inputs to the temperate regions (fertilizer application, human-induced increases in atmospheric deposition of oxidized forms of nitrogen, fixation by leguminous crops, and the import/export of nitrogen in agricultural products). On average, regional nitrogen fluxes in rivers are only 25% of these anthropogenically derived nitrogen inputs. Denitrification in wetlands and aquatic ecosystems is probably the dominant sink, with storage in forests perhaps also of importance. Storage of nitrogen in groundwater, although of importance in some localities, is a very small sink for nitrogen inputs in all regions. Agricultural sources of nitrogen dominate inputs in many regions, particularly the Mississippi basin and the North Sea drainages. Deposition of oxidized nitrogen, primarily of industrial origin, is the major control over river nitrogen export in some regions such as the northeastern U.S. Using data from relatively pristine areas as an index of change, we estimate that riverine nitrogen fluxes in many of the temperate regions have increased from pre-industrial times by 2 to 20 fold, although some regions such as northern Canada are relatively unchanged. Fluxes from the most disturbed region, the North Sea drainages, have increased by 6 to 20 fold. Fluxes from the Amazon basin are also at least 2 to 5 fold greater than estimated fluxes from undisturbed temperate-zone regions, despite low population density and low inputs of anthropogenic nitrogen to the region. This suggests that natural riverine nitrogen fluxes in the tropics may be significantly greater than in the temperate zone. However, deforestation may be contributing to the tropical fluxes. In either case, projected increases in fertilizer use and atmospheric deposition in the coming decades are likely to cause dramatic increases in nitrogen loading to many tropical river systems.
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  • 81
    ISSN: 1573-2983
    Keywords: Zinc ; copper ; manganese ; iron ; lead ; cadmium ; nickel ; phosphorus ; limestone ; fertilizer ; sewage sludge compost
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract Previous research has demonstrated that many urban soils are enriched in Pb, Cd and Zn. Culture of vegetable crops in these soils could allow transfer of potentially toxic metals to foods. ‘Tanya’ lettuce (Lactuca sativa L.) was grown in pots of five urban garden soils and one control agricultural soil to assess the effect of urban-soil metal enrichment, and the effect of soil amendments, on heavy metal uptake by garden vegetables. The amendments included NPK fertilizer, limestone, Ca(H2PO4)2, and two rates of limed sewage sludge compost. Soil Cd ranged from 0.08 to 9.6 mg kg−1; soil Zn from 38 to 3490 mg kg−1; and soil Pb from 12 to 5210 mg kg−1. Lettuce yield on the urban garden soils was as great as or greater than that on the control soil. Lettuce Cd, Zn and Pb concentrations increased from 0.65, 23, and 2.2 mg kg−1 dry matter in the control soil to as high as 3.53, 422 and 37.0 mg kg−1 on the metal-rich urban garden soils. Adding limestone or limed sewage sludge compost raised soil pH and significantly reduced lettuce Cd and Zn, while phosphate fertilizer lowered soil pH and had little effect on Zn but increased Cd concentration in lettuce. Urban garden soils caused a significant increase in lettuce leaf Pb concentration, especially on the highest Pb soil. Adding NPK fertilizer, phosphate, or sludge compost to two high Pb soils lowered lettuce Pb concentration, but adding limestone generally did not. On normally fertilized soils, Pb uptake by lettuce was not exceptionally high until soil Pb substantially exceeded 500 mg kg−1. Comparing garden vegetables and soil as potential sources of Pb risk to children, it is clear that the risk is greater through ingestion of soil or dust than through ingestion of garden vegetables grown on the soil. Urban dwellers should obtain soil metal analyses before selecting garden locations to reduce Pb risk to their children.
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  • 82
    ISSN: 1572-8854
    Keywords: Octahedral ; phosphorus ; chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound [P(tpp)Cl2]+Cl− crystallizes in the space group P21/n witha=10.701(2),b=24.860(2),c=14.799(2), β=94.24(2)°,Z=4. The phosphorus atom has an octahedral coordination geometry formed by the four nitrogen atoms (Np) of the porphyrinato group and the two chloride ions. The average phosphorus-chloride distance is 2.150(1) Å, with phosphorus situated 0.006 Å below the porphyrin ring.
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  • 83
    ISSN: 1432-0789
    Keywords: Bioavailability ; CO2−C evolution ; Heavy metals ; Microbial biomass C ; Metabolic quotient ; Soil incubation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this work we studied the influence of Pb, Zn, and Tl on microbial biomass survival and activity during a laboratory incubation of soil. In comparison to uncontaminated soil, the microbial biomass C decreased sharply in soil contaminated with Zn and Tl, whereas the addition of Pb did not have any significant inhibitory effect on the level of microbial biomass C. Zn displayed the greatest biocidal effect, confirmed by the measurement of the death rate quotient (q D). The microbial activity, measured as CO2 evolution, increased significantly in contaminated soils, emphasizing the need of living organisms to expend more energy to survive. The greater demand for energy by microorganisms in order to cope with the toxicity of pollutants was also confirmed by measurement of the metabolic quotient (q CO2). In order to determine whether soil microorganisms affect the bioavailability of these metals through their mobilization and release, we studied the relationships between available Pb, Zn, and Tl, and microbial biomass C. The water-soluble fraction of Tl, available Tl, and Zn, and microbial biomass C were related significantly, but not Pb.
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  • 84
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    Biology and fertility of soils 20 (1995), S. 253-259 
    ISSN: 1432-0789
    Keywords: Heavy metals ; Microbial biomass ; Soil respiration ; Soil organic C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Chemical characteristics and some parameters related to biological components were determined in 16 soils from a fairly homogeneous area in the north of Italy, contaminated with different levels of heavy metals. Correlation analysis of the parameters studied showed close positive relationships among the metals and with the organic C content in the soils studied. Negative relationships were observed among the heavy metals, soil respiration, and the ratio between evolved CO2−C and microbial biomass C per unit time (specific respiratory activity). This was ascribed to an adverse heavy metal effect on the soil microflora, which appeared to increase the accumulation of organic matter as the heavy metal content increased, probably because the biomass was less effective in mineralising soil organic matter under these conditions.
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  • 85
    ISSN: 1573-0417
    Keywords: diatoms ; eutrophication ; lake management ; paleolimnology ; British Columbia ; lakes ; phosphorus ; training sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Eighteen lakes were added to a published training set of 46 British Columbia (BC) lakes in order to expand the original range of total phosphorus (TP) concentrations. Canonical correspondence analysis (CCA) was used to analyze the relationship between diatom assemblages and environmental variables. Specific conductivity and [TP] each explained significant (P≤0.05) directions of variance in the distribution of the diatoms. The relationship between diatom assemblages and [TP] was sufficiently strong to warrant the development of a weighted-averaging (WA) regression and calibration model that can be used to infer past trophic status from fossil diatom assemblages. The relationship between observed and inferred [TP] was not improved by the addition of more eutrophic lakes, however the [TP] range and the number of taxa used in the transfer function are now superior to the original model. Diatom species assemblages changed very little in lakes with TP concentrations greater than 85 µg 1−1, so we document the development of a model containing lakes with TP≤85 µg 1−1. The updated model uses 59 training lakes and covers a range of species optima from 6 to 41.9 µg 1−1 TP, and a total of 150 diatom taxa. The updated inference model provided a more realistic reconstruction of the anthropogenic history of a highly eutrophic BC lake. The model can now be used to infer past nutrient conditions in other BC lakes in order to assess changes in trophic status.
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  • 86
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    Environmental geology 26 (1995), S. 199-210 
    ISSN: 1432-0495
    Keywords: Coastal lagoon ; Chilka Lake ; Sediment ; Heavy metals ; Chemical fractionation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Chilka lake, the largest coastal lagoon of Asia is one of the most dynamic ecosystems along the Indian coast. Historically the lagoon has undergone a considerable reduction in surface area due, in part, to input from natural processes but mostly due to human activities. The purpose of this investigation is to document the heavy metals' affinity for specific geochemical phases in the recently deposited sediments in the lagoon. Thirty-three samples were collected and analyzed for different geochemical phases of Fe, Mn, Cu, Cr, Ni, Pb, and Zn utilizing a sequential extraction scheme. In the nonlithogenous fraction, the exchangeable fraction was not geochemically significant, having 〈2% of the total metal concentration for all the elements. However, the carbonate fraction contained the following percentages of the total concentration: 〈1% Fe, 13% Mn, 6% Cu, 4% Cr, 8% Ni, 13% Pb, and 12% Zn, suggesting the detrital origin of the sediments. Reducible and organic matter-bound fractions were the significant phases in the nonlithogenous fraction, containing 9% Fe, 16% Mn, 15% Cu, 16% Cr, 16% Ni, 14% Pb, and 14% Zn in the former and 4% Fe, 3% Mn, 17% Cu, 3% Cr, 14% Ni, 15% Pb, and 14% Zn in the latter. The phenomenon has been attributed to the scavenging affinity of Fe-Mn oxides and affinity for sorption into organic matter of the lagoon sediments. The lithogenous, residual fraction generally considered as a guide for natural background values was determined to contain 87% Fe, 67% Mn, 61% Cu, 77% Cr, 61.3% Ni, 56% Pb, and 60% Zn of the total concentrations.
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  • 87
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    Environmental geology 25 (1995), S. 114-118 
    ISSN: 1432-0495
    Keywords: Plants ; Heavy metals ; Biogeochemical prospecting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The distribution of Zn, Cd, Pb, and Cu, in plants growing in mineralized and sterile areas of Tuscany has been studied to verify if and to what extent metalaccumulating species represent evidence of geochemical anomalies in soils. Samples of leaves and twigs from trees were collected, and analyzed by means of differential pulse anodic stripping voltammetry (DPASV). Hollies, brambles, and Holm oaks in particular were considered in the mineralized area of Bottino, and the special aptitude of hollies in concentrating Cd with respect to the other metals has been verified. Cadmium has been previously recognized as a pathfinder for zinc ore bodies; the results of this investigation appear to point out the relevance of holly as a bioindicator of geochemical zinc anomalies. Lower metal concentration characterizes the same species from other mineralized and sterile zones, with the exception of the urbanized area of Florence, where relatively higher Zn concentrations in hollies appear to be due to atmospheric pollution.
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  • 88
    ISSN: 1573-515X
    Keywords: budget ; carbon ; mass balance ; Narragansett Bay ; nitrogen ; nutrients ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Narragansett Bay is a relatively well-mixed, high salinity coastal embayment and estuary complex in southern New England (USA). Much of the shoreline is urban and the watershed is densely developed. We have combined our data on C, N, and P inputs to this system, on C, N, and P accumulation in the sediments, and on denitrification with extensive work by others to develop approximate annual mass balances for these elements. The results show that primary production within the bay is the major source of organic carbon (4 times greater than other sources), that land drainage and upstream sewage and fertilizer are the major sources of N, and that landward flowing bottom water from offshore may be a major source of dissolved inorganic phosphorus. Most of the nutrients entering the bay arrive in dissolved inorganic form, though DON is a significant component of the N carried by the rivers. About 40% of the DIN in the rivers is in the form of ammonia. Sedimentation rates are low in most of Narragansett Bay, and it appears that less than 20% of the total annual input of each of these elements is retained within the system. A very small amount of C, N, and P is removed in fisheries landings, denitrification in the sediments removes perhaps 10–25% of the N input, and most of the carbon fixed in the system is respired within it. Stoichiometric calculations suggest that some 10–20% of the organic matter formed in the bay is exported to offshore and that Narragansett Bay is an autotrophic system. Most of the N and P that enters the bay is, however, exported to offshore waters in dissolved inorganic form. This assessment of the overall biogeochemical behavior of C, N, and P in the bay is consistent with more rigorously constrained mass balances obtained using large living models or mesocosms of the bay at the Marine Ecosystem Research Laboratory (MERL).
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  • 89
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    Journal of atmospheric chemistry 20 (1995), S. 179-212 
    ISSN: 1573-0662
    Keywords: Heavy metals ; concentration ; deposition ; North Sea ; troposphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A literature review of the atmospheric concentration rates and dry and wet deposition fluxes of particulate Cd, Cr, Cu, Pb and Zn to the North Sea and adjacent areas is given. The results of direct measurements of dry and wet deposition fluxes are compared to indirect estimates and to modelling values. This work points out the large uncertainties in results of different studies on atmospheric input of trace elements into the North Sea. The current knowledge about the dependence of the deposition velocity upon the particle size and about the processes controlling wet deposition fluxes, and the quality and completeness of the emission data are still inadequate for describing the environmental cycle and impact of heavy metals in the North Sea.
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  • 90
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    Biogeochemistry 29 (1995), S. 223-235 
    ISSN: 1573-515X
    Keywords: chronosequence ; montane tropical forest ; nitrogen ; nutrient limitation ; phosphorus ; productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We tested the hypothesis that P was the nutrient limiting net primary production of a nativeMetrosideros polymorpha forest on a highly weathered montane tropical soil in Hawaii. A factorial experiment used all combinations of three fertilizer treatments: nitrogen (N), phosphorus (P) and a mix of other essential nutrients (OE), consisting primarily of mineral derived cations and excluding N and P. P addition, but not N or OE, increased leaf area index within 12 months, foliar P concentration measured at 18 months, and stem diameter increment within 18 months. Stem growth at 18 months was even greater when trees fertilized with P also received the OE treatment. N and P additions increased leaf litterfall and N and P in combination further increased litterfall. The sequence of responses suggests that increased available P promoted an increase in photosynthetic area which led to increased wood production. P was the essential element most limiting to primary production on old volcanic soil in contrast to the N limitation found on young volcanic soils.
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  • 91
    ISSN: 1432-0789
    Keywords: Earthworms ; Soil microfauna ; Decomposition ; Cotton strip ; Heavy metals ; Enchytraeids ; Nematodes ; Pasture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Contamination of grazed pasture gave 0–5 cm soil contents of 19–835 mg kg-1 Cu, 47–739 mg kg-1 Cr, and 12–790 mg kg-1 As. Soil Cu, Cr, As contents were correlated and declined with depth to 30 cm. In plots with medium and high contamination buried cotton strips retained most of their original tensile strength, indicating repression of decomposition processes.Lumbricus rubellus andAporrectodea rosea were absent in plots with medium and high contamination; there was no evidence of heavy metal accumulation in earthworm tissue; soil bulk density was greater in the absence of lumbricids. Enchytraeids and nematodes were most abundant with low contamination. Nematode diversity was greater with low (0–5 cm) or medium (5–10 cm) contamination than in control plots or those with high contamination; the proportion of predators increased with contamination. Basal soil respiration was less sensitive than substrate-induced respiration to contamination. Although contamination reduced the nitrification rate, all mineral N was found as NO inf3 sup- after 14 days. Sulphatase was the enzyme activity most sensitive to high contamination. Whereas contamination by 100 mg kg-1 of Cu, Cr, and As caused little depression of soil biological activity, there was some supperssion at 400 mg kg-1 and at 800 mg kg-1 normal processes were inhibited and herbage production was negligible. No single measurement adequately indicated the need for site remediation.
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  • 92
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
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  • 93
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    Environmental geology 23 (1994), S. 156-165 
    ISSN: 1432-0495
    Keywords: Pore solution ; Supergene alteration ; Acid mine drainage ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The study of supergene processes (i.e., secondary processes running in ore deposits and driven by thermodynamic nonequilibrium between ore-and rock-forming minerals and natural waters, gasses, etc.) is important in order to understand the migration of heavy metals from ore into their adjacent surroundings. The contamination of the local environment can be characterized by the composition of pore waters. The Pb-Zn-Cu ore deposits of Zlaté Hory (Czech Republic) have been chosen for a detailed study of pore solutions. A simple model has been created to describe the evolution of supergene processes in the ore deposits. This model is based on the determination of chemical composition of pore solutions. The dilution of pore solutions of such mineral deposits results in acid mine drainage. Pore solutions can have, during specific stages of their evolution, relatively high concentrations of Cu (0.09 mol/kg), Zn (0.1 mol/kg), SO4 (0.8 mol/kg) and an extremely low pH (1.38). The supergene alteration of pyrite is the most important process determining the character of pore water. This reaction causes significant acidification and is a leading source of acid mine drainage. The leached zone originates from the interaction of pyrite and limonite. Increased concentrations of heavy metals and sulfates occur in pore waters. The dynamic composition of pore waters within ore deposits undergoing the supergene process can be used to distinguish: (1) three main zoneslimonite, transition, and primary zone and (2) two areas—an area with the highest intensity of weathering processes and an area of weathering initiation. In these areas the rate of sulfide oxidation is higher as a result of low pH. From the study of these zones and areas we can further our knowledge of ore body, pore solution, acid mine drainage, and contamination of the local environment.
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  • 94
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    Environmental geology 24 (1994), S. 223-232 
    ISSN: 1432-0495
    Keywords: Sediments ; Heavy metals ; Estuary ; River Weser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Studies of heavy metal concentrations in porewaters and in sediments from the Weser Estuary, Germany, indicate that the depth distribution of Mn, Cd, and Cu in the solid phase is predominantly influenced by the subsurface redox regime, while Ni shows only moderate alteration. Based on solid-phase heavy metal data from eight locations in the study area, linear regressions of Fe, Mn, Cu, Ni, and Cd on Al allowed differences between the initial metal concentration and the concentration preserved in the sediments to be predicted. We calculate that, due to early diagenetic processes, Mn is enriched to 145 percent, while Cu and Cd are depleted to 71 percent and 46 percent, respectively, of the initial metal concentration in the near-surface sediment. Maximum depletion of Cd (84 percent), Cu (68 percent), Mn (54 percent), and Ni (24 percent) concentrations in the sediment, observed at a restricted area downcore, indicate the importance of post-depositional processes to metal preservation in the sediment. Without knowledge of the quantitative effects of diagenetic reactions on the preservation of metal concentrations in sediments, the depth distribution of metals in sediment cores may be misinterpreted as the effect of human activities.
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  • 95
    ISSN: 1432-0495
    Keywords: Sequential extraction ; Diagenesis ; Estuary ; Sediment ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The early diagenetic environment of intertidal sandy sediments (sands) and muddy sediments (muds) is described and compared from two cores taken from an unpolluted part of the Manukau Harbour, New Zealand. Extraction techniques characterized the form of the trace elements (Fe, Mn, S, C, Pb, Zn, Cu) at different depths in the sediment. Dissolved forms of Fe, Mn, and S were measured in interstitial water. Nonresidual metal concentrations, humic acid, FeS, and FeS2 are an order of magnitude higher in the muds than in the sands because of dilution by unreactive sand particles. Muds contain a larger proportion of metals in the mobile fractions; exchangeable (Mn), carbonate (Mn, Fe, Zn), and easily-reducible oxide (Fe, Mn, Zn, Pb). This is due to greater surface area (for Mn adsorption); the favorable conditions for MnCO3, FeCO3, and FeS precipitation; and higher concentrations of easily reducible iron oxide and humic acid. Therefore, compared to the sands, muds are more important as reservoirs for toxic metals, both in terms of quantity and availability. At either site there was very little difference between the forms of Zn, Pb or Cu identified by sequential extraction as sediments changed from oxic to anoxic conditions. One reason for this is that the amounts and proportions of some of the important components that bind metals, viz., amorphous iron hydrous oxides, humic acids, and FeS2, do not change much. Other components that do change with redox conditions, for example, manganese phases and FeS, are only minor components of the sediment. Redox conditions, then, have relatively little effect on trace-metal partitioning in the sediment matrix of these unpolluted sediments.
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  • 96
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
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  • 97
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 23 (1994), S. 264-270 
    ISSN: 1432-0495
    Keywords: Fly ash ; Sequential extraction ; Heavy metals ; Voltammetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The mobility of Cd, Co, Cu, Ni, Pb, Sb, and Zn from six different coal-fired power plant fly ashes that show a wide compositional range was examined using a sequential extraction procedure in order to assess their mobility when these wastes are ponded or landfilled. The extraction sequence was as follows: (1) water extractable, (2) cation exchangeable (CH3COONH4 at pH 7), (3) surface oxide-bound cations (CH3COONH4 at pH 5), (4) Fe oxide-bound cations (HONH3Cl), and (5) residual (HF, HCl, HNO3, 2∶1∶1). The heavy metal contents in the extraction solutions were determined by anodic (Cd, Cu, Pb, Sb, and Zn) and cathodic (Ni and Co) stripping voltammetry. The results reveal differences in the total contents of the selected trace elements among the fly ash samples, which must be related to differences in coal composition and combustion technology. The extractable fraction under natural conditions ranges from 1.5 to 36.4 percent of the total element content. Cadmium, Co, Cu, and Zn show the highest extractable fraction (10.8–18.9 percent on average). Cadmium is the most easily water-extractable element, while Co, Cu, and Zn increase their mobility as the severity of the extraction increases. Cobalt, Ni, Pb, and Zn are mainly associated with the surface oxide-bound and Fe oxide-bound fractions. Nickel, Pb, and Sb have low mobility potentials (5.3–6.6 percent as extractable fraction), but Sb presents a relatively high water-extractable fraction.
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  • 98
    ISSN: 1432-0789
    Keywords: Municipal waste compost ; Calcareous soil ; Heavy metals ; Enzyme activities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A 3-year field experiment on a calcareous Fluventic Xerochrept planted with corn (Zea mays L.) was carried out to evaluate the effects of amending the soil with high and low rates of composted municipal waste on soil enzyme activities (alkaline phosphomonoesterase, phosphodiesterase, arylsulphatase, dehydrogenase, and l-asparaginase). These enzyme activities all increased when compost was added at rates of up to 90 t ha-1, and the phosphatases continued to show a linear increase with compost rates of up to 270 t ha-1. The addition of mineral fertilizer increased enzyme activities in unamended soil, and masked the stimulating effect of compost on the amended soils. Heavy metals did not affect soil enzyme activities up to a compost addition of at least three times the amount specified by Italian law.
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  • 99
    ISSN: 1432-0789
    Keywords: Heavy metals ; Microbial biomass ; Respiration ; Enzymes ; Denitrification ; Dimethyl sulphoxide reduction ; Nematodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microbial properties and nematode abundance were measured along a gradient of increasing Cu, Cr, and As concentrations (50–1300 mg Cr kg-1) in the top 5 cm of a pasture soil contaminated by runoff of preserving liquor from an adjacent timber-treatment plant. Microbial biomass C and N were significantly (P〈0.05) lower in contaminated than uncontaminated soils. The amount of microbial biomass C as a percentage of total organic C declined significantly (r 2 value with Cr 0.726*) with increasing contamination, and the ratio of respired C to biomass C was significantly (P〈0.05) higher with contamination. Substrate-induced respiration, microbial biomass P, and denitrification declined (r2 value with Cr 0.601, 0.833*, and 0.709*, respectively) with increasing contamination. Increasing contamination had no effect on prokaryote substrate-induced respiration but eukaryote: eukaryote substrate-induced respiration declined significantly (r 2 value with Cr 0.722*). Accordingly, the ratio of prokaryote substrate-induced respiration increased significantly (r 2 value with Cr 0.799*) with contamination. There was a significant (r 2 value with Cr 0.872*) hyperbolic relationship between sulphatase activity and contamination, with activity declining by approximately 80% at 〉1000 mg Cr kg-1. Increasing contamination had no effect on basal respiration, dimethyl sulphoxide reduction, and phosphatase, urease, and invertase activities. Numbers of plant-associated nematodes declined significantly (r 2 value with Cr 0.780*) with contamination. On a percentage basis, plant-feeding nematodes predominated in less contaminated soils, whereas bacterial-feeding and predatory nematodes predominated in heavily contaminated soils. The use of the fumigation—incubation procedure for measurement of microbial biomass C in heavy-metal contaminated soils is discussed.
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  • 100
    ISSN: 1432-0789
    Keywords: Heavy metals ; Microbial activity ; Microbial diversity ; Sensitivity-resistance index ; Biomonitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A sensitivity-resistance index was developed, and proved to be a very sensitive biomonitor of soil pollution with heavy metals. The index was developed by a step-by-step approach. Ultimately, the bacterial soil microflora was divided into three groups, senstivive, tolerant, and resistant microflora. Zn and Cd sensitivity was defined as no growth occurring in the presence of 5 and 0.5 mg l-1 of these metals, respectively, while resistance was defined as distinct growth in the presence of 50 and 16 mg l-1, respectively. The sensitivity: resistance ratio of a referent clay soil (0.57 mg Cd kg-1 and 140 mg Zn kg-1) was 0.53, but for polluted (6 mg Cd kg-1 + 670 mg Zn kg-1) clay soil, the ratio was 0.24. For a referent (0.06 mg Cd kg-1 + 12 mg Zn kg-1) sandy soil the sensitivity: resistance ratio was 1.50 whereas polluted (2.3 mg Cd kg-1 + 252 mg Zn kg-1) sandy soil had a ratio 0.19. The ecological value of the sensitivity-resistance lies in its capacity to reflect potential deradation of aromatic compounds. It has been shown repeatedly that sensitive bacteria grow significantly better on a range of selected aromatic compounds. It has been speculated that resistance fo heavy metals may reduce the bioremediation capacity of soil towards chlorinated aromatics and polyaromatic hydrocarbons.
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