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  • Articles  (118)
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  • Articles  (118)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of paleolimnology 4 (1990), S. 1-22 
    ISSN: 1573-0417
    Keywords: sulfate ; carbon ; nitrogen ; hydrogen ; organic matter ; enrichment factor ; lake sediments ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract This paper discusses the use of S as a paleolimnological tracer of limnetic sulfate concentration. A positive relationship (p〈0.05) was found between limnetic sulfate and sediment S concentrations for the Great Lakes, English Lakes, and lakes from the Adirondack and Northern New England regions. There is a positive correlation (p〈0.05) between C and S concentration in sediment across all regions studied. The importance of C in affecting S content in sediment was also examined by a series of cores taken at different water depths in Big Moose Lake (Adirondacks). There was a strong relationship between C and S among cores with sediment from deeper water having higher C and S concentrations (r 2=0.99). Sulfur from the shallower cores had greater concentrations of chromium-reducible S (pyrite), while cores from deeper waters had a greater proportion of organic S fractions including C-bonded S and ester sulfates. For assessing historical changes in S accumulation in sediments, enrichment factors were calculated for the PIRLA lakes. Pre-1900 net sediment accumulation rates of S were very similar across all regions. Sulfur enrichment was greatest in Adirondack sediment which had total post-1900 S accumulation of 1.1 to 7.4 times pre-1900 S accumulation. Sediment from Northern New England (NNE) generally had lower S concentration than Adirondack sediments and S enrichment factors ranged from 1.2 to 2.1. Sediment from the Northern Great Lakes States region had similar S concentration and distribution with depth to NNE sediment. In two Northern Florida lakes, sediment showed little variation in S concentration with depth, but in two other lakes from the same region, there was higher S concentration in deeper layers. Lakes which had the greatest enrichment factors also exhibited the most marked changes in C:S ratios. Ratios of C:N showed little variation (10.6 to 26.1) among the PIRLA lakes. A first order model indicated slow decomposition within these organic rich sediments. Elemental concentrations and ratios of sediment from a variety of lakes and reservoirs were complied. Maximum and minimum elemental ratios for all the data were 28 to 8.1 for C:N, 0.81 to 0.11 for C:H, and 675 to 12.5 for C:S, respectively. For the C:S ratios in all regions except the Great Lakes, the maximum ratio was less than 231. Both the maximum and minimum amount of N and H concentration of organic matter is related to biotic processes. The minimum concentration of S is regulated not only by nutrient demands but also by non-assimilatory processes. Sulfur incorporation into sediments is a function of a complex of factors, but limnetic sulfate concentration and organic matter content play a major role in regulating the S content of sediment. Further quantification of S incorporation pathways will aid in the paleolimnological interpretation of sediment S profiles. Such information is also important in assessing how S sediment pools will respond to decreases in limnetic sulfate concentration which may occur with decreases in inputs from acidic deposition.
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  • 2
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    Nutrient cycling in agroecosystems 21 (1990), S. 167-170 
    ISSN: 1573-0867
    Keywords: Mo ; interaction ; soybean ; deficiency ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Recent on-farm liming experiments showed that Mo deficiency in soybean [Glycine max (L.) Merr.] is widespread in northern Alabama. In contrast, a long-term, fertility-rotation experiment in the same area showed no response to Mo during 33 yr when Mo was added bienially to corn [Zea mays L.] in the rotation; however, soybean foliage had the chlorotic appearance of Mo deficiency. The objective of this study was to determine if Mo deficiency was being missed by comparing only two fertilizer treatments. Each rotation-fertilizer treatment plot was split into two, with one-half receiving MO at a 100 g ha−1 foliar rate after seedling emergence, while the other half received none. Yields were increased by Mo in 13 to 16 fertilizer treatments in 1985 and 15 out of 16 in 1986. Leaf-N concentrations and seed weight had comparable increased amounts by the Mo supplement. Without the Mo supplement, there was a response to lime but not to P, K, or a Mo-containing micronutrient mixture; with the Mo supplement, there was no response to liming, but a definite response to P and K (in addition to Mo). The lack of response to Mo when applied to corn in a 2-yr rotation over 33 yr led to the erroneous conclusion that these soils were not Mo deficient for soybean.
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  • 3
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    Nutrient cycling in agroecosystems 22 (1990), S. 71-78 
    ISSN: 1573-0867
    Keywords: Boron ; critical level ; grain ; nitrogen ; nodulation ; nutrition ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A two year field study on the effect of nitrogen N and boron B fertilization on the nodulation, mineral nutrition and grain yield of cowpea was carried out in the Nigerian savanna where fairly widespread B deficiency has been reported. Treatments consisted of four levels of N (0, 15, 30 and 60 kg/ha in 1986 and 0, 15, 30 and 45 kg/ha in 1987) and three levels of B (0, 1.5 and 3.0 kg/ha). Cowpea responded positively though nonsignificantly to N fertilization up to 30 kg N/ha. However, N had no effect on the N, P, K and B content of index leaves. Boron application consistently reduced grain yield. Like N, applied B had no effect on the N, P, K concentration of index leaves but increased B concentration highly significantly (P 〈 0.001). The critical level of B toxicity in index leaves was approximated to be 21pm under field condition. Application of N and B depressed nodulation.
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  • 4
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    Nutrient cycling in agroecosystems 23 (1990), S. 97-103 
    ISSN: 1573-0867
    Keywords: Carbon ; mineralization ; nitrogen ; organic fertilizer ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The C and N mineralization characteristics of two organic N fertilizers were determined in a soil-less incubation system at three temperature regimes. Protox (derived from activated sewage sludge) initially degraded more rapidly by microbial action compared with dried blood. However, dried blood released more CO2-C and inorganic N towards the end of the incubation periods. The rate of microbial degradation increased with temperature. Mineralization characteristics of protein-based N sources are discussed in relation to organic N nutrition of vegetable crops.
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  • 5
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    Nutrient cycling in agroecosystems 23 (1990), S. 105-112 
    ISSN: 1573-0867
    Keywords: Ammonium ; fertigation ; nitrate ; nitrogen ; trickle irrigation ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The movement and transformations of ammonium-, urea- and nitrate-N in the wetted volume of soil below the trickle emitter was studied in a field experiment following the fertigation of N as ammonium sulphate, urea and calcium nitrate. Effects on soil pH in the wetted volume were also investigated. During a fertigation cycle (emitter rate 2lh−1) applied ammonium was concentrated in the surface 10 cm of soil immediately below the emitter and little lateral movement occurred. In contrast, because of their greater mobility in the soil, fertigated urea and nitrate were more evenly distributed down the soil profile below the emitter and had moved laterally in the profile to 15 cm radius from the emitter. The conversion of applied N to nitrate-N was more rapid when urea rather than ammonium-N was applied suggesting that the accumulation of large amounts of ammonium below the emitter in the ammonium sulphate treatment probably retarded nitrification. Following their conversion to nitrate-N, both fertigated ammonium sulphate and urea caused acidification in the wetted soil volume. Acidification was confined to the surface 20 cm of soil in the ammonium sulphate treatment, however because of its greater mobility, fertigation with urea (2lh−1) resulted in acidification occurring down to a depth of 40 cm. Such subsoil acidity is likely to be very difficult to ameliorate. Increasing the trickle discharge rate from 2lh−1 to 4lh−1 reduced the downward movement of urea and encouraged its lateral spread in the surface soil. As a consequence, acidification was confined to the surface (0–20 cm) soil.
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  • 6
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    International journal of biometeorology 34 (1990), S. 42-48 
    ISSN: 1432-1254
    Keywords: Briths ; Humans ; Solar wind ; Geomagnetism ; Melatonin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Data obtained from the literature on the annual pattern of human conceptions and plasma melatonin at high latitudes indicated that simple annual rhythms do not exist. Instead, prominent semiannual rhythms are found, with equinoctial troughs and solsticial peaks. A prominent semiannual environmental event is the magnetic disturbance induced by the solar wind. The semiannual magnetic disturbances are worldwide, but most pronounced in the auroral zones where the corpuscular radiation enters the atmosphere. Magnetic indices that predominantly reflect these events were obtained from the literature and correlated with the melatonin and conception data. Significant and inverse correlations were found for Inuit conceptions and the melatonin data. The correlations obtained for 48 contiguous states of the United States indicated that only the extreme northern states exhibited this relationship. These data were compared with a previous correlational study in the United States which established that sunshine was correlated with conceptions in the middle latitude and southern states. An hypothesis of dual control by electromagnetic and magnetic energies is proposed: melatonin is a progonadal hormone in humans controlled by both factors, depending on their relative strength. Other studies are reviewed regarding the possible factors involved in determining the annual pattern of human conceptions. Demographic studies of geographic variation in temporal patterns of conceptions, with particular regard to variations of the magnetic fields on the earth's surface, may provide some insight into the efficacy of these different factors.
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  • 7
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    Journal of applied phycology 2 (1990), S. 183-185 
    ISSN: 1573-5176
    Keywords: seaweed ; Lessonia trabeculata ; Phaeophyta ; mannitol ; polysaccharides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract D-mannitol was the only low-molecular weight carbohydrate isolated from ethanolic extracts of Lessonia trabeculata blades. After sequential extraction with water, acid and alkali, laminaran, fucose-containing polysaccharides and alginic acid were also isolated. Fucose-containing polysaccharide from the acidic extract was separated into three fractions by ion exchange chromatography. Alginic acid was the major polysaccharide obtained in the sequential extraction.
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  • 8
    ISSN: 1573-5176
    Keywords: seaweed ; Agardhiella ; carrageenan ; phosphorus ; cultivation ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gas liquid chromatography, chemical analyses, and infrared and13C-NMR spectroscopies indicated that phycocolloids extracted fromAgardhiella subulata had a dominant ι-carrageenan feature with less deviant ι-carrageenan and υ-carrageenan. The presence of methylated galactose and a small contamination by xylose were registered. Unattached plants were cultivated for 4 weeks in tanks receiving seawater enriched with 53.5 µM nitrate and 0 to 20 µM phosphate (Pi) week−1. The growth was phosphorus (P)-limited up to a tissue P content of 0.14 ± 0.03% dry weight. Maximal specific growth rate and carrageenan content were observed with enrichments of 6 µM Pi and 3 µM Pi, respectively. Hence carrageenan production was promoted in the range of 3–6 µM Pi. Further Pi enrichment was useless. This phenomenon, observed with P nutrition, is comparable to the ‘Neish effect’ in nitrogen nutrition studies.
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  • 9
    ISSN: 1573-5036
    Keywords: disturbance ; fertilizer ; nitrogen ; nutrient enrichment ; phosphorus ; secondary succession ; species richness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of annual additions of mineral N and P (100 kg ha−1) on plant species composition and annual aboveground net primary production (ANPP) were investigated during the first three years following disturbance in a semi-arid ecosystem. Additions of N reduced richness of perennial plant species during years 2 and 3, while P reduced the number of perennial species only in year 3. From year 1 to year 2, annual and biennial species richness declined in all treatments while ANPP of annual species increased greatly. Added N increased ANPP of annual species while it decreased ANPP of most perennial species relative to the unfertilized control treatment. Community similarities were higher for the control and native vegetation than for other pairs of treatments using both species presence and plant production data. Nitrogen additions have retarded but not completely arrested secondary succession in this system.
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  • 10
    ISSN: 1573-5036
    Keywords: eucalypt ; foliar analysis ; legume ; nitrogen ; phosphorus ; plant nutrients ; plant analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The sensitivity of tissue nutrient concentrations to changes in plant age and the supply of P and N was compared between leaves and associated twigs in two forest species. In a young regrowth stand, tissues were sampled on three occasions from the mid-crown position of karri (Eucalyptus diversicolor F. Muell.) and Bossiaea laidlawiana Tovey and Morris, a major understorey legume. Leaves and twigs were also sampled from young plants of B. laidlawiana growing in a mature eucalypt stand to which P treatments had been applied. Nitrogen application increased N concentrations in twigs of karri and B. laidlawiana, but not in leaves. Phosphorus application increased P concentrations in both leaves and twigs of karri but the average increases were proportionally greater in twigs (65%) than in leaves (36%). Over the sampling period, P concentrations in leaves declined, while those in twigs were relatively stable. In B. laidlawiana, P supply also had a larger effect on P concentrations in twigs than in leaves. Addition of 200 kg P ha−1 increased average P concentrations in twigs by 109% in the regrowth stand and by 215% in the mature stand while the corresponding increases in leaves were only 11% and 27%. Concentrations of other nutrients in both species were also affected by N and P application, the most notable being a decline in the concentrations of the minor nutrients, Zn and Cu, with increased P supply. The increased N concentrations in twigs of karri, and the increased P concentrations in tissues of both species, were associated with responses of karri to added N and P, and of B. laidlawiana to added P. This indicates that tissue concentrations of N and P were generally below critical concentrations where N and P were not applied. The results show that for these species twigs may be a better tissue than leaves for diagnosing deficiencies or predicting N and P requirements. The ratio of P concentrations in twigs to P concentrations in leaves also increased with added P. It is suggested that this ratio may be a useful index if it reduces the variability caused by sampling position within the crown or genetic differences between plants.
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  • 11
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    Plant and soil 123 (1990), S. 67-71 
    ISSN: 1573-5036
    Keywords: Dalbergia sissoo ; fertilization ; nitrification ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of added ammonium, phosphorus, potassium, and gypsum on net nitrogen mineralization was studied in soil beneath a six-year-old plantation of the N2-fixing tree Dalbergia sissoo in Pakistan. Soil with and without amendments was placed in polyethylene bags and incubated, buried in the soil, for 30 days. After that time the soil was analyzed and net ammonium and nitrate production and net nitrogen mineralization were calculated. The addition of ammonium stimulated nitrification indicating that the process was substrate limited. The inhibition of nitrification by Nitrapyrin showed that the process is autotrophic in these soils. Gypsum addition lowered soil pH from 8.0 to 7.2 and significantly stimulated ammonification, nitrification and net nitrogen mineralization. The addition of potassium more than tripled the soil K:Na ratio. Net ammonium and nitrate production and net nitrogen mineralization all increased in this treatment. The addition of phosphorus had no significant effect on soil nitrogen dynamics.
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  • 12
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    Plant and soil 127 (1990), S. 213-218 
    ISSN: 1573-5036
    Keywords: dry matter yield ; nickel ; nitrogen ; nutrient concentration ; wheat roots ; wheat tops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was conducted to study the effect of Ni on the growth and nutrients concentration in wheat (Triticum aestivum Cv. WH 291) in the presence and absence of applied N as urea. Responses to N application were observed up to 120 μg N g−1 soil. No response to Ni was observed in the dry matter yield of wheat tops (leaves + stem) in the absence of applied N while in the presence of applied N, significant yield increases were obtained at 12.5μg Ni g−1 soil. Nickel was not toxic to wheat up to 50μg Ni g−1 soil in the presence of 120μg N g−1 soil. Nitrogen and Ni concentration in wheat tops and roots increased with increasing levels of applied N and Ni, respectively. Applied Ni had an antagonistic effect on N concentration. Similarly, N reduced the Ni concentration in the wheat tissues. Positive growth responses to Ni were associated with 22 and 15μg Ni g−1 in wheat tops, in the presence of applied N at 60 and 120μg N g−1 soil, while Ni toxicity was associated with 63, 92.5 and 112.5μg Ni g−1 in wheat tops, in the absence and presence of applied N at 60 and 120μg N g−1 soil, respectively.
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  • 13
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    Plant and soil 128 (1990), S. 21-30 
    ISSN: 1573-5036
    Keywords: allocation ; clearcut ; mineralization ; nitrogen ; prescribed fire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Past and current work on biological processes related to nitrogen fluxes and cycling in natural and disturbed Mediterranean forest sites are discussed. In natural conditions, the main point reviewed is mineral nitrogen availability in the soil, and particularly the process of mineralization (ammonification, nitrification) in the field as well as nitrogen uptake by Pinus pinea. Some aspects of nitrogen translocation within the trees are also considered. Perturbation of the nitrogen status, and especially nitrogen mineralization, as a result of manipulation of forest sites are discussed by comparing both a holm oak coppice with a clearcut and a Pinus halepensis woodland before and after prescribed fire.
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  • 14
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    Plant and soil 125 (1990), S. 19-27 
    ISSN: 1573-5036
    Keywords: amino acid ; deficiency ; essentiality ; malate ; micronutrient ; nickel ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Barley (Hordeum vulgare L. cv. ‘Onda’) plants were grown in nutrient solutions supplied either 0 (no Ni added), 0.6, or 1.0 μM NiSO4. Plants supplied 0 μM Ni developed Ni deficiency symptoms; Ni deficiency resulted in the disruption of nitrogen metabolism, and affected the concentration of malate and various inorganic anions in roots, shoots, and grain of barley. The concentrations of 10 of the 11 soluble amino acids determined were 50–200% higher in 30-day-old shoots of plants supplied inadequate Ni levels than in shoots of Ni-supplied plants. The total concentration of all amino acids determined was higher in roots and grain of Ni-deficient plants. Concentrations of NO3 - and Cl- were also higher in Ni-deficient barley shoots than in Ni-sufficient barley shoots. In contrast, the concentration of alanine in shoots of Ni-deficient barley was reduced to one-third of the concentration in Ni-sufficient plants. The shoot concentrations of malate and SO4 2- were also depressed under Ni-deficient conditions. Total nitrogen concentration in grain, but not in shoots, of Ni-deficient plants was significantly increased over that found in Ni-adequate plants. Nickel deficiency results in marked disruptions of N metabolism, malate and amino acid concentrations in barley. These results are discussed in view of the possible roles of Ni in plants.
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  • 15
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    Plant and soil 125 (1990), S. 119-128 
    ISSN: 1573-5036
    Keywords: ammonia ; application method ; application rate ; environment ; grassland ; nitrogen ; slurry ; volatilization ; wind speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three experiments were conducted to examine the influence of slurry application rate, wind speed and applying slurry in narrow bands on ammonia (NH3) volatilization from cattle slurry surface-applied to grassland. The experiments were conducted in the field using a system of small wind tunnels to measure NH3 loss. There was an inverse relationship between slurry application rate and the proportion of NH4 +-N volatilized. From slurry applied at 20, 40, 60, 80, 100 and 120 m3 ha-1, the respective proportions of NH4 +-N lost by NH3 volatization in 6 days were 60, 56, 49, 40, 44 and 44%. The negative relationship was most pronounced in the first 24 hours after application when 57–77% of the total loss for 6 days occurred. Wind speed had a positive effect on NH3 volatilization, although the effect was small in relation to the total loss; increasing the wind speed from 0.5 to 3.0 m s-1 increased the total 5 day loss by a factor of 0.29. The effect of wind speed was also most pronounced in the first 24 hours when much of the NH3 loss took place. The effect of reducing the surface area of the applied slurry was examined by comparing NH3 volatilization from slurry broadcast across plots with that applied in narrow bands. Although the rate of NH3 volatilization was considerably smaller from the banded application immediately after the slurry was applied, the difference between the treatments progressively narrowed until 2 days after application, after which a higher rate was maintained from the banded slurry. After 5 days the total loss from the banded application was 83% of that from broadcast slurry.
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  • 16
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    Plant and soil 125 (1990), S. 109-117 
    ISSN: 1573-5036
    Keywords: ammonia ; environment ; grassland ; mechanical separation ; nitrogen ; slurry ; volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three experiments were conducted using a system of small wind tunnels to measure ammonia (NH3) volatilization from cattle slurry after surface application to land. In each experiment slurry was applied at a rate equivalent to 80 m3 ha-1, providing the equivalent of approximately 100 kg NH4 +-N ha-1. The first experiment compared NH3 volatilization from the liquid fraction obtained by mechanical separation of slurry with that from unseparated slurry. The total NH3 loss over six days from unseparated and separated slurry were very similar, being 38 and 35% respectively of the NH4 +-N applied. For the first five hours, the rate of NH3 loss was higher from the unseparated slurry, thereafter it was consistently lower. In the second experiment, slurry was ponded in a tray to examine whether impeded infiltration or changes in the NH4 + concentration or overall pH of the slurry influenced the rapid decline in rate soon after application that is characteristic of NH3 volatilization from animal slurries applied to land. It appeared, however, that other factors such as resistance to diffusion within the slurry and/or at the slurry surface were mostly responsible for the rapid decline in rate. In the third experiment, in which NH3 volatilization was measured from slurry applied to grassland or bare soil, the total loss from slurry applied to grassland was approximately 1.5 times that from slurry applied to bare soil.
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  • 17
    ISSN: 1573-5036
    Keywords: calcium ; copper ; desert ; ground water ; iron ; magnesium ; manganese ; nitrogen ; phosphorus ; Prosopis glandulosa ; rooting patterns ; sodium ; symbiotic nitrogen fixation ; trace metals ; water table ; water use efficiency ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mesquite plants (Prosopis glandulosa var. Torreyana) were grown in 2-m long columns 20 cm in diameter, and provided with a constant, stable ground water source 10 cm above the sealed base of the column. Ground water contained 0, 1 or 5 mM nitrate, or a mixed salt solution (1.4, 2.8, or 5.6 dS m-1) with the ionic ratios of ground water found in a field stand of Prosopis at Harper's Well (2.8 dS m-1). Water uptake in the highly salinized columns began to decrease relative to low salt columns when soil salinity probes 30 cm above the column base read approximately 28 dS m-1, a potential threshold for mesquite salt tolerance. Prosopis growth increased with increasing nitrate, and decreased with increasing salinity. Water use efficiency was little affected by treatment, averaging approximately 2 g dry matter L-1 water used. Most fine roots were recovered from a zone about 25 cm above the ground water surface where water content and aeration appeared to be optimal for root growth. Root-shoot ratio was little affected by nitrate, but increased slightly with increasing salinity. Plant tissue P concentrations tended to increase with increasing salinity and decrease with increasing N, approaching potentially deficient foliage concentrations at 5 mM nitrate. The whole-plant leaf samples increased in sodium concentration both with added salt and with added nitrate. Foliar manganese concentrations increased with increasing salt in the absence of nitrate. Concentrations of sodium in leaves were low (〈10 g kg-1), considering the high salt concentrations in the ground water. Prosopis appears to exclude sodium very effectively, especially from its younger leaves. Although Prosopis is highly salt tolerant, the degree to which it utilizes soil nitrate in place of biologically fixed N may lower its salinity tolerance and affect its nutrient relations in phreatic environments.
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  • 18
    ISSN: 1573-5036
    Keywords: grassland ; leaching ; leaf litter ; macro-organic matter ; mineralization ; nitrogen ; ploughing ; roots ; stubble
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The amounts of organic matter in the stubble, litter, root and soil macro-organic matter fractions of two swards of perennial ryegrass that had received normal applications of either fertilizer or cattle urine were, on average for the four fractions, about 3000, 500, 11,500 and 8,800 kg ha−1. The swards had been established 8 or 15 years previously and each was sampled at intervals over a period of about one year. The amounts of N contained in the four fractions were, on average, 68, 12, 249 and 240 kg ha−1, a total of 569 kg N ha−1. With other swards, increasing rates of application of fertilizer N were found to have little effect on the amounts of organic matter in stubble and roots. Concentrations of N in the organic matter of the stubble and roots, however, increased significantly with increasing rate of fertilizer application, though, with stubble, moderate rates of application had little effect. Assessments based on these data, together with other published information, indicate that the amount of N mineralized from the combined stubble, litter, root and macro-organic matter fractions during the first year after ploughing may range from about 40 kg to at least 360 kg N ha−1 depending on the age of the sward and its recent management. The amount mineralized is likely to increase with age of sward, with increasing rate of fertilizer N and with utilisation by grazing rather than cutting.
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  • 19
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    Plant and soil 123 (1990), S. 155-159 
    ISSN: 1573-5036
    Keywords: cultivars ; nitrogen ; roots ; tropic climate ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Due to the high price of fertilizer the input of N for grain maize production must be kept low in many parts of the world. Low input cultivars have been suggested to meet this requirement. Screening of a group of tropical cultivars revealed two high input, two low input and two intermediate cultivars with regard to N utilization. One of the causes of an interaction between genotype and N fertilization might be differences in root morphology. Screening for such differences at an early seedling stage would facilitate the selection for low input varieties. This hypothesis was tested by growing seedlings of the six varieties at different levels of N until the fourth leaf stage. There was no significant interaction between genotypes and N supply. At low and medium N supply, the total seedling biomass was the same but at low N a higher proportion of dry weight was found in the roots. Total biomass was reduced at high N. Low input and intermediate cultivars had higher shoot and root dry weights than did high input cultivars but no significant differences in root surface area were found. Root surface area was greatest at low N. Number and total length of seminal roots were significantly lower for high input varieties which, in combination with a relatively high root surface area, points to an intensive root type.
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  • 20
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    Plant and soil 124 (1990), S. 33-37 
    ISSN: 1573-5036
    Keywords: leaf area ; nitrogen ; mineral nutrition ; phosphorus ; photoperiod ; Triticum ; wheat ; spikelet initiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of N and P on the number of spikelets of spring wheat (Triticum aestivum L.), grown in nutrient solution, were studied under 8 h and 16 h photoperiods. The effect of P was apparent only at a high rate of N supply and the effects of N were increased significantly at a high rate of P supply. Increasing N supply increased the number of spikelets due to a promotion of the rate of spikelet initiation. It also increased the leaf-blade area and the dry matter weight of the plants at the stage of terminal spikelet initiation. These effects of N were much greater under the short photoperiod than under the long photoperiod. The practical significance of these findings for winter-grown wheat in temperate regions is pointed out.
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  • 21
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    Plant and soil 128 (1990), S. 97-101 
    ISSN: 1573-5036
    Keywords: calcium ; magnesium ; nitrogen ; nitrogen saturation ; Norway spruce ; nutritional imbalance ; Picea abies ; soil solution ; sulphur/nitrogen ratio ; tree nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Differences in nitrogen cycling and in the nutrition of trees are significantly coupled to the levels of nitrogen input and to the nitrate levels in the soil solution. Relatively high nitrogen supply can cause unbalanced nutrition on sites which contain either low or moderate amounts of other nutrients. This is indicated by low cation/nitrogen ratios in foliage and also by the S/N ratio falling temporarily below 0.030.
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  • 22
    ISSN: 1573-5117
    Keywords: phytoplankton collapses ; hypertrophic ; nitrogen ; phosphorus ; sedimentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Short-term changes in phytoplankton and zooplankton biomass have occurred 1–3 times every summer for the past 5 years in the shallow and hypertrophic Lake Søbygård, Denmark. These changes markedly affected lake water characteristics as well as the sediment/water interaction. Thus during a collapse of the phytoplankton biomass in 1985, lasting for about 2 weeks, the lake water became almost anoxic, followed by rapid increase in nitrogen and phosphorus at rates of 100–400 mg N M−2 day−1 and 100–200 mg P m−1 day−1. Average external loading during this period was about 350 mg N m−2 day−1 and 5 mg P m−2 day−1, respectively. Due to high phytoplankton biomass and subsequently a high sedimentation and recycling of nutrients, gross release rates of phosphorus and nitrogen were several times higher than net release rates. The net summer sediment release of phosphorus was usually about 40 mg P m−2 day−1, corresponding to a 2–3 fold increase in the net phosphorus release during the collapse. The nitrogen and phosphorus increase during the collapse is considered to be due primarily to a decreased sedimentation because of low algal biomass. The nutrient interactions between sediment and lake water during phytoplankton collapse, therefore, were changed from being dominated by both a large input and a large sedimentation of nutrients to a dominance of only a large input. Nitrogen was derived from both the inlet and sediment, whereas phosphorus was preferentially derived from the sediment. Different temperature levels may be a main reason for the different release rates from year to year.
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  • 23
    ISSN: 1573-5117
    Keywords: submerged macrophyte ; Ceratophyllum demersum ; litter ; decomposition ; pyrolysis mass spectra ; residual mass ; carbon ; nitrogen ; phosphorus
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    Topics: Biology
    Notes: Abstract A study was made of decomposition ofCeratophyllum demersum litter over a 17-day period under controlled conditions of temperature and oxygen (5, 10 and 18 °C; aerobic and anaerobic) and over a 169-day period in the field (Lake Vechten, The Netherlands). Litter, water and sediment were sampled on the 0, 2, 4, 7 and 17th day under controlled conditions and on the 0, 17, 49, 127 and 169th day in the field. The litter was analyzed quantitatively for dry mass, ash, carbon, nitrogen, phosphorus and qualitatively of organic composition by pyrolysis mass spectrometry. The water was analyzed for the elemental concentrations of organic carbon (total and dissolved), nitrogen (total, ammonia and particulate) and phosphorus (total and orthophosphate) and for the concentrations of photosynthetic pigments and bacteria. The sediment was analyzed for the elemental concentrations of nitrogen, carbon and phosphorus, and for bacterial numbers. The pattern of litter mass loss fitted an exponential model fairly well. Mass decreased faster under controlled aerobic than under anaerobic conditions and the decrease was stimulated by increasing temperature, relatively more in the range of 5 to 10 °C (by 20%) than in the range of 10 of 18 °C (by 2%). The residual mass ranged from 73 to 43% of initial under controlled aerobic conditions and from 84 to 65% under anaerobic conditions after 17 days. It decreased far less in the field, to 38% of initial mass in the field after 169 days. The litter initially lost a carbohydrate fraction by leaching in all treatments. The protein content decreased initially as well but increased subsequently at increasing temperature stimulated under anaerobic conditions. The changes in organic composition were correlated with those in nitrogen but not with those in carbon and phosphorus contents. The organic composition of litter incubated in the field differed from that of litter incubated in the laboratory. The field residues contained less proteinaceous material than the laboratory residues. The changes in carbon, nitrogen and phosphorus concentrations in the litter showed different patterns. The carbon concentration generally increased, the nitrogen concentration initially dropped and increased subsequently, and the phosphorus concentration initially dropped and remained relatively constant subsequently. Chemical immobilization of the decomposition process may have occurred in the laboratory, but was unlikely in the field. Carbon, nitrogen and phosphorus left the litter initially largely in particulate form and were recovered in the water. The ratio dissolved: total nutrient concentration was lower under controlled aerobic than under anaerobic conditions. Increasing temperature stimulated bacterial use of dissolved organic carbon and nitrogen. A rapid nutrient flow occurred from macrophyte litter, via water to sediment. The phytoplankton biomass in the water was greatly stimulated by substances freed from the decomposing litter. Diatoms increased generally relatively more than green algae, predominating alternatively with green algae under aerobic conditions and continuously under anaerobic conditions. Bacterial numbers in the water initially increased, partly due to transgression of bacteria from the sediment-water interface to the water and partly due to an actual increase in community biomass. The bacteria returned largely to the sediment-water interface, stimulated by increasing temperature, as most of the substrate readily usable by them had left the litter in the litter-bag and was associated with the upper sediment layers. It is feasible that the annual die-off of theC. demersum population of Lake Vechten barely affects nutrient cycling in the lake, because the contribution to the nutrient pools of the lake when fully mixed is only small. However, small particles originating from decomposingC. demersum litter may influence the lake considerably by decreasing water transparency and serving as a food source for filter-feeders and detritivorous macrofauna.
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  • 24
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    Hydrobiologia 204-205 (1990), S. 25-33 
    ISSN: 1573-5117
    Keywords: Durvillaea ; Ecklonia ; harvesting ; New Zealand ; Pterocladia ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several species of algae have been commercially harvested in New Zealand, mainly for extraction of agar and alginates. In the past, the harvest was comprised mostly of shore-cast plants. There has been more recent interest, however, in harvesting attached plants of Pterocladia spp., Porphyra spp., Gracilaria sordida, Durvillaea spp., Macrocystis pyrifera, and Ecklonia radiata. The ecological effects of harvesting attached algae depend largely on the sizes of plants, the season of removal, the patch size of clearances, and the proximity and identity of mature plants. These have not been well-studied for seaweeds in New Zealand, but population and life history studies indicate that harvesting methods affect the continuity of algal resources, at least on a local scale, and are crucial factors in their management.
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  • 25
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    Hydrobiologia 202 (1990), S. 61-69 
    ISSN: 1573-5117
    Keywords: Gulls ; phosphorus ; nitrogen ; eutrophication ; excretion ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nutrient excretion rates and the annual contribution of P from the feces of the gullsLarus argentatus andL. marinus (and of N fromL. argentatus) to the nutrient budget of Gull Pond (Wellfleet), a soft water seepage lake, have been estimated. Intensive year-round gull counts by species were combined with determinations of defecation rate and the nutrient content of feces to quantitatively assess the P loading rates associated with regular gull use of this coastal pond on a seasonal and annual basis. Total P loading from gulls was estimated to be 52 kg yr−1, with 17 kg fromL. argentatus and 35 kg fromL. marinus, resulting from about 5.0 × 106 h yr−1 and 1.7 × 106 h yr−1 of pond use. This compares with P loading estimates of 67 kg yr−1 from upgradient septic systems, 2 kg yr−1 from precipitation and 3 kg yr−1 from unpolluted ground water. Fifty-six percent of annual gull P loading was associated with migratory activity in late fall. Estimated annual N loading byL. argentatus was 14 kg TKN, 206 g NO3-N, and 1.85 g g NH3-N.
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  • 26
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    Hydrobiologia 204-205 (1990), S. 225-231 
    ISSN: 1573-5117
    Keywords: brown algae ; growth ; Korea ; seaweed ; size distribution
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    Topics: Biology
    Notes: Abstract About fifty individuals of four dominant large brown algae were collected by random sampling at monthly intervals using SCUBA. Size frequencies of Sargassum confusum and S. horneri were concentrated mainly in the small size classes during the initial growth phase, but were more or less evenly distributed in most size classes during the fast growing phase. Undaria pinnatifida and Costaria costata showed the same tendency as Sargassum spp., that frequency distribution became even when the plants reached their maximum growth. The kelp species recorded their maximum lengths in March, whereas Sargassum spp. showed their peaks in early summer. The relationships between the length and weight in different growth phases appeared to be dependent on the phenology of each species.
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  • 27
    ISSN: 1573-5117
    Keywords: heated effluent ; Laminaria ; nuclear power plant ; Pterygophora ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Abundances of Laminaria setchellii and Pterygophora californica were determined three times per year for two years before startup of the Diablo Canyon Power Plant (DCPP) and thereafter for three years during which time the plant was in operation. The test site was situated at 3 m depth and was exposed almost continuously to heated effluent during plant operation. A control population was established about 60 m away from the test site and at an 8 m depth (i.e. lying below the heated plume). Abundances at both sites were relatively stable during the preoperational period. Abundances of Laminaria and Pterygophora declined, mortality increased, and recruitment ceased at the test site following plant operation and the discharge of heated effluent. In contrast, Laminaria abundance remained stable at the control site and a strong recruitment episode markedly increased Pterygophora densities during 1987, the final year of our study. Complete losses of Laminaria and Pterygophora were also observed in nearby shallow portions of Diablo Cove exposed to the thermal plume. Laminaria was more sensitive to heated effluent than Pterygophora. Adults of both species were more sensitive than juveniles.
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  • 28
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    Hydrobiologia 204-205 (1990), S. 275-280 
    ISSN: 1573-5117
    Keywords: breakwaters ; Ecklonia ; Eisenia ; Sargassum ; seaweed ; substrata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Coastal structures are constructed principally to protect the coast line. However, these structures also can act as artificial substrata for seaweeds. In particular, armor blocks, such as tetrapods, prove to be good algal substrata. Our field observations on the vegetation and standing crop of seaweed communities on armor blocks led us to the following conclusions: 1) Ecklonia cavacommunities grew on tetrapods that had been placed to coincide with the maturation period of E. cava. The communities have been maintained for more than four years. 2) The standing crop of seaweeds on an offshore breakwater composed of tetrapods placed seven years before was almost the same as that found under natural conditions. 3) Variations in roughened surfaces (pebbles or scores and grooves 3 or 46 mm wide) did not affect the growth of Sargassum spp. However, a greater number of Ecklonia stolonifera plants were observed attached to roughened surfaces compared to smooth surfaces.
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  • 29
    ISSN: 1573-5117
    Keywords: electrophoresis ; Porphyra ; seaweed ; systematics
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    Topics: Biology
    Notes: Abstract Traditional morphological features have formed the basis for distinguishing species of Porphyra. Among these features are number of cell layers, number of chloroplasts per cell, arrangement of reproductive structures on the thallus, and overall morphology. Chromosome number and chromosome morphology have helped corroborate some species identities. A survey of northeast Pacific species of Porphyra using starch gel electrophoresis of 15 soluble proteins has shown that electrophoretic banding patterns provide a reliable diagnostic tool for species identification. Data from starch gel electrophoresis are presented to confirm the identities of species formerly associated with the Porphyra perforata species-complex in British Columbia and northern Washington. Porphyra abbottae, P. fallax, P. kanakaensis, and P. torta are recognized as distinct species, and Porphyra sanjuanensis is synonymized with P. perforata.
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  • 30
    ISSN: 1573-5117
    Keywords: Iridaea ; harvesting strategies ; matrix model ; population growth ; seaweed
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    Topics: Biology
    Notes: Abstract Populations of Iridaea splendens at Brockton Point, Stanley Park, Vancouver, Canada were observed to alternate in dominance between the gametophytic phase in summer and tetrasporophytic phase in winter. The mechanism regulating this alternation is not clear. Using a matrix projection model to simulate population growth, we show that this alternation is possible if there are differential survival and recruitment rates of the two phases in summer and winter. Sensitivity and elasticity analyses indicate the relative importance of perennation vs. recruitment. Recruitment from tetrasporophytes and from gametophytes both contribute about 25% to the population growth. Perennation among gametophytes is more important than among tetrasporophytes. The implication of this is that if this population is to be harvested, more tetrasporophytes can be harvested than gametophytes without resulting in the depletion of the resource. This is simulated in the matrix model by comparing the relative effects on population growth of increasing the mortality rate of the perennation phase of tetrasporophyte and gametophyte by 50 to 75%, and increasing recruitment rate in either phase, from summer to winter or from winter to summer.
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  • 31
    ISSN: 1573-5117
    Keywords: Chondrus ; disturbance ; encrusting corallines ; Irish moss ; Phymatolithon ; seaweed ; substratum
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    Topics: Biology
    Notes: Abstract Field observations in sublittoral Prince Edward Island, Canada, indicated that on a friable sandstone substratum Chondrus crispus was more commonly associated with Phymatolithon sp. than with bare rock. Thus, a substantial proportion of the population of Irish moss along the coast of Prince Edward Island occurs on this encrusting coralline. These observation may be explained on the basis of the relative stability of the substratum in contrast to other studies in which sloughing of epithallial cells by species of both Phymatolithon and Lithothamnium has been reported to limit epiphytism by fleshy macrophytes.
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  • 32
    ISSN: 1573-5117
    Keywords: biogeography ; bloom ; Dominica ; North Carolina ; Polysiphonia breviarticulata ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polysiphonia breviarticulata, a species previously known only from the Adriatic, the Mediterranean, and the Canary Islands, is reported for the first time from the Western Atlantic in Dominica and North Carolina. In the latter region it has grown in bloom quantities as drifting, planktonic plants that are a nuisance on beaches and a serious impediment to fishermen whose nets become fouled with the plants.
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  • 33
    ISSN: 1573-5117
    Keywords: digester ; composting ; Europe ; methanization ; phycocolloid extraction ; residues ; seaweed ; stranded macroalgae ; Ulva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Proliferation of macroalgae is a world-wide problem with 50,000 m3 of drift Ulva harvested per year in Brittany and about 1.0 to 1.2 million tons growing in the Venice lagoon. This biomass may be treated by bioconversion (aerobic or anaerobic fermentation) to give useful products (gas, fertilizers or others) and to remove a source of environmental pollution. Such a treatment also may be applied to cultivated or harvested seaweds and to seaweed industry residues. Studies of seaweed methanization showed Laminaria an especially good substrate and Ulva a possible substrate. Research led to a defined way of treating drift algae, encompassing natural hydrolysis and pressing with methanization of the juices. The most advanced full-scale realization for algal biomass utilization is the C.A.T.-Quatre-Vaulx composting plant in Saint-Cast-Le-Guildo (Brittany, France). It produced from seaweed, wood and animal dung a biological quality compost that is competitive with the traditional market products.
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  • 34
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    Hydrobiologia 204-205 (1990), S. 367-373 
    ISSN: 1573-5117
    Keywords: culture ; Gracilaria ; model ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The agarophyte red seaweed Gracilaria conferta was used as a model plant to study the relationship between growth and environmental factors. This species was cultured in small outdoor tanks with continuous seawater supply during three years. Seaweeds were kept under constant density by weekly thinning and were also pulse-fed weekly with nitrogen and phosphate. Water temperature and underwater irradiance increase had opposite effects on the weekly growth rate in two seasons: negative in summer and positive in non-summer. Therefore, a dichotomic separation between summer (June–August) and non-summer (September–May) seasons was utilized in the proposed linear model. The linear model, of the analysis of covariance type, accounted for an explained percentage of total variation (R2) of 0.567, with significant coefficients of all variables included. A standardized model showed that season was the dominant variable, with its coefficient being twice that of temperature in summer, and zero in the non-summer season. Water temperature affected the growth rate twice as much as irradiance, and epiphytes showed a significant negative effect on growth only in the summer. This model aids in the prediction of growth on a seasonal basis under local conditions.
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  • 35
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    Hydrobiologia 204-205 (1990), S. 173-178 
    ISSN: 1573-5117
    Keywords: Gracilariaceae ; Rhodophyta ; seaweed ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A key to the genera of the Gracilariaceae is provided along with a short diagnosis for each genus. Features of the mature cystocarp and spermatangial configurations that separate genera are illustrated.
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  • 36
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    Hydrobiologia 204-205 (1990), S. 197-203 
    ISSN: 1573-5117
    Keywords: acid waste ; biomass ; pollution ; recolonization ; recovery ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Titanium dioxide wastes are suspected to be toxic to rocky shore communities in an estuary in southeast Norway. An experimental project lasting two years examined whether titanium dioxide wastes affected recolonization by rocky shore organisms. The experiments were performed in situ in six tanks (each with 9 m3 brackish water) at two different levels of salinity. Three different concentrations of industrial waste water were used. The growth season in 1986 was dry and sunny compared to 1987, causing reduction of growth on exposed granite chips compared to controls. At the two highest waste concentrations in the tanks, Fucus serratus was observed with necrotic tissue both years, and in 1986 benthic diatoms were scarce.
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  • 37
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    Hydrobiologia 204-205 (1990), S. 219-223 
    ISSN: 1573-5117
    Keywords: dissemination ; Gracilaria verrucosa ; Rhodophyta ; seaweed ; sexual reproduction ; spermatia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dissemination and viability of Gracilaria verrucosa spermatia were tested. Crosses were performed among three males and three females from Cape Gris Nez, northern France. Laboratory experiments show that spermatia have a mean fertile life of about five hours. Field studies show that spermatia are dispersed by stream and tidal currents and that fertilization can occur at least 80 m from a population.
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  • 38
    ISSN: 1573-5117
    Keywords: age ; Ecklonia stolonifera ; holdfast size ; Laminariales ; Phaeophyta ; seaweed
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    Topics: Biology
    Notes: Abstract Ecklonia stolonifera is distributed along the coast facing the Sea of Japan. The size of various parts of the shoot (blade length and width and stipe length and diameter) and the age were determined at Ooma, Aomori Prefecture. The smaller the holdfast, the higher the percentage of one-year-old shoots. Holdfasts 10 cm in diameter seemed to be three years old, whereas holdfasts 40 cm in diameter seemed to be five or more years old. Zoosporangial sori were observed on blades three or more years old. Ecklonia stolonifera holdfast diameter expands only vegetatively by stoloniferous rhizoids. Zoospores, formed on shoots three or more years old, serve for the formation of new populations.
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  • 39
    ISSN: 1573-5117
    Keywords: buoyant weight ; Corallinaceae ; growth rate ; Lithothamnion corallioides ; maerl ; seaweed
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    Topics: Biology
    Notes: Abstract Lithothamnion corallioides Crouan et Crouan (Rhodophyta, Corallinales) is the main constituent of the maerl beds of the Bay of Brest (Atlantic coast of western Brittany). Its growth rate was measured monthly in situ during one year. Growth rates were obtained by an adaptation of the buoyant weight technique. The highest daily growth rate was observed in July and reached 0.26 % d−1 (S.D. = 0.06), when expressed as the increase of calcium carbonate weight. The average daily growth rate was 0.12% d−1 (S.D. = 0.04) for a period of 275 days (summer and autumn 1988, winter 1989). Using this preliminary data, the calcium carbonate accretion rate can be estimated provisionally: 876 g m−2 year−1, a rate much lower than that of tropical reef coralline algae, but higher than that of Lithophyllum incrustans, the well known temperate European reef-builder.
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  • 40
    ISSN: 1573-5117
    Keywords: Ecklonia cava ; Phaeophyta ; photosynthesis ; respiration ; seaweed ; zoosporangial sori
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic rates were compared between Ecklonia cava bladelets with and without zoosporangial sori sampled from the subtidal zone (about 5 m deep) in Nabeta Bay, Shimoda, Japan. Photosynthetic rates of bladelets were lower in the sorus portion than in the non-sorus portion on the basis of area, dry weight and chlorophyll a. Respiration rates were higher in the sorus portion than in the non-sorus portion on the basis of area and chlorophyll a, whereas they were almost the same on a dry weight basis. The differences were mainly due to a large difference in dry weight per unit bladelet area between the sorus and the non-sorus portion. Light compensation points were higher in the sorus portion than in the non-sorus portion.
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  • 41
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    Hydrobiologia 204-205 (1990), S. 499-503 
    ISSN: 1573-5117
    Keywords: ammonium effect ; carrageenan ; fertilizer application ; gel strength ; growth rate ; Kappaphycus alvarezii ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Kappaphycus alvarezii, cultured in a region deficient in nitrogen with intermittent application of 10 mM ammonium at three-day intervals for 1 hour, attained a daily growth rate of 4.6%, which was considered to be the optimum growth rate. Under such conditions, the C/N ratio was 29 with a carrageenan content of 58% and gel strength of 45–70 g cm−2. Gel strength of carrageenan was high when nitrogen content was high and vice versa.
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  • 42
    ISSN: 1573-5117
    Keywords: agar yield ; calcium ; gel strength ; Gracilaria ; seaweed
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    Topics: Biology
    Notes: Abstract Studies were carried out on the seasonal variation in yield and gel strength of agar from Gacilaria domingensis with and without the addition of calcium chloride. Extraction was done with and without treatment with 1% hydrochloric acid. The results showed an increase in yield and gel strength when an alkaline solution of calcium was used, but the gel strength was low. For commercial use, Gracilaria domingensis should be mixed with better quality Gracilaria species because of its low gel strength.
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  • 43
    ISSN: 1573-5117
    Keywords: Cystocloniaceae ; iota-carrageenan ; IR spectra ; Phyllophoraceae ; Rhodophyceae ; seaweed ; tank culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carrageenans extracted under alkaline conditions were studied in some Rhodophyceae from the Normandy coast. Among these, four species yielding iota-carrageenan were studied throughout a whole year: Calliblepharis ciliata, Calliblepharis jubata, Cystoclonium purpureum and Gymnogongrus crenulatus. Carrageenan content varied with season, being maximal at the end of spring and minimal in autumn, and was positively correlated with the growth of these algae. A culture of Cystoclonium purpureum was initiated and, without trying to optimize growth conditions, yielded a mean production of 50 g fresh wt m−2 d−1 in 36 weeks of continuous tank culture.
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  • 44
    ISSN: 1573-5117
    Keywords: 13C NMR spectroscopy ; Cryptonemiales ; IR ; Kallymeniaceae ; phycocolloid ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The red alga Kallymenia reniformis (Rhodophyta, Cryptonemiales), collected on the west coast of Brittany, contained 13% ash, 5.6% crude protein and 38.7% soluble carbohydrate (on percent dry wt). The phycocolloid extract (38 % dried wt) was investigated using chemical and spectroscopic (IR and 13C NMR) methods. Preliminary results show that this polysaccharide belongs to the lambda-carrageenan family.
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  • 45
    ISSN: 1573-5117
    Keywords: gel state ; NMR spectroscopy ; phycocolloids ; seaweed ; solid state
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    Topics: Biology
    Notes: Abstract Both solid state (CP-MAS) and gel state (using standard solution state conditions) 13C NMR spectroscopy have been used to characterize a range of red algae that produce either agar or carrageenan. These techniques allow rapid determination of phycocolloid type within the algal tissue before extensive and time-consuming extractions and fractionations are carried out. The gel state technique can be used on living or dried material. Gel state spectra give high resolution and, because of the expectation that they will be correlated with the extractable phycocolloid, provide promise of a powerful technique for screening potentially useful red algae.
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  • 46
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    Hydrobiologia 204-205 (1990), S. 609-614 
    ISSN: 1573-5117
    Keywords: carrageenan ; Gigartinaceae ; Hypneaceae ; infrared analysis ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Infrared analyses of the carrageenan in ten species (representing four genera) of Gigartinaceae and one species of Hypneaceae in different reproductive phases from the northwestern coast of Baja California were studied. Cystocarpic samples of the Gigartinaceae presented varying degrees of a к/ι ‘hybrid’. The degree of hybridization was determined based on the ratio between the peak absorbances at 805/845 cm−1. A high correlation was observed between the 805/845 cm−1 and 805/970 cm−1 ratios. Tetrasporic samples of Gigartina leptorhynchos, Iridaea splendens, Rhodoglossum affine and R. roseum, presented a λ-carrageenan profile, whereas Gigartina tepida, G. exasperata, G. harveyana, G. canaliculata and G. spinosa presented a ε-carrageenan. The tetrasporic sample of Hypnea valentiae showed a κ-carrageenan with a very low degree of hybridization.
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  • 47
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    Hydrobiologia 204-205 (1990), S. 637-643 
    ISSN: 1573-5117
    Keywords: Nothogenia fastigiata ; seaweed ; sulfated galactans
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    Topics: Biology
    Notes: Abstract Fractionation of the cetrimide salts of the sulfated polysaccharides of Nothogenia fastigiata led to the isolation of a complex galactan sulfate. This product showed compositional and molecular weight heterodispersion together with composition-, temperature-, time-, and conformation-dependent molecular associations. In this sense, the behavior of the galactan sulfate is similar to that of the mannan sulfate previously isolated from the same seaweed.
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  • 48
    ISSN: 1573-5117
    Keywords: agar composition ; Curdiea coriacea ; Curdiea flabellata ; Gracilaria truncata ; Gracilariaceae ; Melanthalia abscissa ; polysaccharide ; seaweed
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    Notes: Abstract Polysaccharide extracts from four New Zealand members of the Gracilariaceae have been characterized by 13C-NMR spectroscopy and GLC analysis of alditol acetate derivatives prepared using a new double hydrolysis-reduction procedure. All were based on variously substituted repeating disaccharide units of agarobiose and ≤ 20% of its ‘precursor’ containing l-galactose-6-sulfate. Gracilaria truncata yielded a firm gelling agar with 67% methylation on the 6-position of the d-galactose residues. The other extracts belong to a new class of agar molecules having methylation on both the 6-position of the d-galactose units and the 2-position of the l-sugar units. The Curdiea coriacea polysaccharide displayed this double methylation almost completely (≥ 96 %); the alkali-modified polymer thus had only two free hydroxy-groups per disaccharide repeat unit, yet still gave a firm gel. The Curdiea flabellata and Melanthalia abscissa extracts had this double methylation pattern but to a lesser extent, and additional xylosyl branch units on up to 18% of the repeating disaccharide units.
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  • 49
    ISSN: 1573-5117
    Keywords: nitrogen ; phosphorus ; bluegill ; plankton ; mesocosm
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    Notes: Abstract We conducted an outdoor mesocosm experiment of factorial design consisting of three levels of nutrient supply (no nutrient addition and additions of nitrogen and phosphorus in ratios of 10:1 and 45:1) cross-classified with two levels of bluegill (Lepomis macrochirus) (presence and absence). Nutrient supply significantly affected total phosphorus (TP), total nitrogen (TN), TN: TP ratio, turbidity, Secchi depth, phytoplankton chlorophyll, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers. The presence of bluegill significantly increased TP, turbidity, diatoms, unicellular green algae, colonial blue-green algae, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers, and decreased Secchi depth, cladocerans, cyclopoid copepodids, copepod nauplii and chironomid tube densities. Nutrient supply and fish effects were not independent of each other as shown by significant nutrient × fish interaction effects for TP, Secchi depth, filamentous blue-green algae, periphyton chlorophyll, Asplanchna and non-predatory rotifers.
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  • 50
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    Hydrobiologia 202 (1990), S. 61-69 
    ISSN: 1573-5117
    Keywords: Gulls ; phosphorus ; nitrogen ; eutrophication ; excretion ; nutrients
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    Notes: Abstract Nutrient excretion rates and the annual contribution of P from the feces of the gulls Larus argentatus and L. marinus (and of N from L. argentatus) to the nutrient budget of Gull Pond (Wellfleet), a soft water seepage lake, have been estimated. Intensive year-round gull counts by species were combined with determinations of defecation rate and the nutrient content of feces to quantitatively assess the P loading rates associated with regular gull use of this coastal pond on a seasonal and annual basis. Total P loading from gulls was estimated to be 52 kg yr−1, with 17 kg from L. argentatus and 35 kg from L. marinus, resulting from about 5.0 × 106 h yr−1 and 1.7 × 106 h yr−1 of pond use. This compares with P loading estimates of 67 kg yr−1 from upgradient septic systems, 2 kg yr−1 from precipitation and 3 kg yr−1 from unpolluted ground water. Fifty-six percent of annual gull P loading was associated with migratory activity in late fall. Estimated annual N loading by L. argentatus was 14 kg TKN, 206 g NO3-N, and 1.85 g g NH3-N.
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  • 51
    ISSN: 1573-5117
    Keywords: Eucheuma uncinatum ; harvesting ; Macrocystis pyrifera ; recruitment ; seaweed ; survivorship
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    Notes: Abstract The ecological effects of harvesting were investigated for two species, the giant kelp Macrocystis pyrifera and Eucheuma uncinatum, by using harvest records and aerial surveys that show yield changes and by using studies of recruitment, survivorship and community interactions. There were no ecological effects found for M. pyrifera harvested with contemporary methods, and there are no recommendations for changing current management practices for this species. It is recommended that E. uncinatum, which on occasion produces commercially significant standing crops, not be harvested unless special precautions are taken to leave some plants for regeneration of the harvested populations.
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  • 52
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    Hydrobiologia 204-205 (1990), S. 17-24 
    ISSN: 1573-5117
    Keywords: Ascophyllum ; Chondrus ; dragrakes ; ecological impact ; harvesting ; Laminaria ; seaweed
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    Topics: Biology
    Notes: Abstract The ecological impact of marine plant harvesting is related to the intensity of exploitation, the harvesting technique, and the vulnerability of the species or habitat to perturbation. In eastern Canada information was available on four levels of impact: long-term changes in the target species and direct loss or damage to non-target species, direct or indirect impact on the habitat or community, indirect effects of changes in habitat or community structure, and trophic level impact. Near monoculture stands of Chondrus crispus have associated with them up to 36 animals species and 19 major species of algae that are vulnerable to removal as by-catch. Indirect effects of changes in macrophyte cover were not observed in fish species utilization of Ascophyllum nodosum beds on rising tides. Subtidal areas devoid of all macrophyte cover had lower levels of the preferred foods for Homarus americanus than kelp-covered areas; however, barren grounds are not created by macrophyte exploitation rates of 20% to 80% in eastern Canada. Long-term harvesting has altered the population structure and population ecology of C. crispus and A. nodosum in some areas. In general both target species and associated communities are resistant to perturbation.
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  • 53
    ISSN: 1573-5117
    Keywords: Gigartina ; polymorphy ; Rhodophyta ; seaweed ; South Africa ; wave exposure
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    Topics: Biology
    Notes: Abstract Gametophytes from lower intertidal populations of the South African rhodophyte Gigartina radula, collected from sites subjected to different conditions of wave exposure, were compared with respect to various morphological, physiological and population attributes. A multivariate analysis of 13 variables revealed that variation in most parameters does not correlate directly with the wave exposure gradient. A clear pattern of response is revealed that suggests that environmental stresses occur at both the exposed and the sheltered sites although they are more extreme at the exposed sites. A number of important variables, notably photosynthetic production, showed maximum values in plants from semi-exposed sites.
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  • 54
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    Hydrobiologia 204-205 (1990), S. 65-71 
    ISSN: 1573-5117
    Keywords: absorption cross section ; light ; photon growth yield ; seaweed
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    Topics: Biology
    Notes: Abstract The ecological significance of photoadaptation and photoacclimation is at best inferential. This is attributed to two factors: 1) The dimensions of light absorption by multicellular tissues are inadequately described by theory, which is confounded by the interaction of polychromatic light fields with different light harvesting pigment-protein systems, the package effect, heterogeneous absorption and multiple scatter. 2) The practice of extrapolating light utilization for growth from physiological scale measurements, i.e. photosynthesis-incident light curves. Needed are parameters designed to yield the relation of light absorption properties (a function of LHPPs and tissue anatomy) to light utilization efficiency. The parameters, absorption cross section normalized to carbon (aC) and photon growth yield (PGY), the growth analog of quantum yield, are demonstrated here.
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  • 55
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    Hydrobiologia 204-205 (1990), S. 89-98 
    ISSN: 1573-5117
    Keywords: seaweed ; cultivation ; nori ; Porphyra ; Washington ; British Columbia
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    Notes: Abstract The cultivation of the red alga Porphyra in North America to produce the edible product ‘nori’ is now in its tenth year of development. Cultivation technology has been transferred and modified from Japan and Korea. Early efforts by the Washington State Department of Natural Resources indicated that cultivation is biologically feasible and could be economically viable. Commercial production has begun in Washington, U.S.A. and in British Columbia, Canada. Early products are of high quality. Constraints to more rapid development are institutional — obtaining necessary permits for use of water areas and financing is difficult.
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  • 56
    ISSN: 1573-5117
    Keywords: Laminaria ; molecular biology ; seaweed ; taxonomy
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    Notes: Abstract High levels of phenotypic variation in kelp species necessitate the use of taxonomic markers that are independent of morphology. Restriction fragment length polymorphism (RFLP) analysis of nuclear DNA can provide such markers. In this paper we present the results of an RFLP analysis of cytoplasmic ribosomal DNA (rDNA) in three Laminaria species (L. agardhii, L. digitata, L. groenlandica). Comparison of the restriction maps of the nontranscribed spacer (NTS) in the rDNAs suggests that this method should be useful for the differentiation of these taxa. These results are discussed, as are the applications of RFLP mapping to the identification of field-collected, morphologically variable plants.
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  • 57
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    Hydrobiologia 204-205 (1990), S. 119-124 
    ISSN: 1573-5117
    Keywords: Ahnfeltia ; Gymnogongrus ; life history ; Phyllophora ; Phyllophoraceae ; Rhodophyta ; seaweed ; taxonomy
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    Notes: Abstract The Phyllophoraceae Rabenhorst (Gigartinales) is a family that shows a great diversity of life history patterns. The three largest phyllophoroid genera, Ahnfeltia, Gymnogongrus and Phyllophora, all commercial sources of phycocolloids, show the greatest range of life history. Information from life history studies has been of significance to classification of the Phyllophoraceae at the family, generic and specific levels. In the tetrasporophyte of Ahnfeltia plicata, previously known as Porphyrodiscus simulans, tetrasporangia are zonate and borne terminally in small superficial sori in contrast to the chains of cruciate tetrasporangia characteristic of the Phyllophoraceae. A study of reproduction and life history in the type species, A. plicata, from the Atlantic concluded that the unique carposporophyte development, in conjunction with the most primitive pit-plug structure known in the Florideophycidae, justified the proposal of a new family Ahnfeltiaceae Maggs et Pueschel in the Ahnfeltiales Maggs et Pueschel. Most Pacific species of Ahnfeltia are instead phyllophoracean and closely related to Gymnogongrus. Gymnogongrus griffithsiae, the type species, forms tetrasporoblasts whereas the majority form internal cystocarps and have heteromorphic life histories. Proposals to divide the genus by life history type require further detailed morphological and ontogenetic studies of G. griffithsiae. Phyllophora species exhibit at least three different types of life history, tetrasporoblastic, isomorphic and heteromorphic, and this genus could likewise be split along these lines. At the specific level, intraspecific life history variability appears to be related to morphological variation in some species of Gymnogongrus.
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  • 58
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    Hydrobiologia 204-205 (1990), S. 293-299 
    ISSN: 1573-5117
    Keywords: biogeography ; Ecklonia ; Gigartina ; Gracilaria ; Laminaria ; Namibia ; Porphyra ; seaweed ; Suhria
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    Notes: Abstract Of the 1500 km coast of Namibia, only 80 km is predominantly rocky, the remaining 1420 km being sandy with only minor rocky outcrops. At present two species are utilized, Gracilaria verrucosa for agar and Laminaria schinzii for human consumption. Other potentially utilizable seaweeds occurring on the coast are Ecklonia maxima for alginates, Suhria vittata for agar, Gigartina radula, G. stiriata and Aeodes orbitosa for carrageenans and Porphyra capensis for human consumption. Laminaria schinzii also can be used for alginate production. Due to the diamond-mining areas around the 80 km rocky area at Luderitz (26° 39′ S), only 20 km are accessible; hence, at present the seaweeds are being exploited almost to their full potential. The species currently not being utilized could be used, however, to support the industry that already exists at Luderitz. To increase production, access to the diamond areas would have to be gained or a cultivation program initiated.
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  • 59
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    Hydrobiologia 204-205 (1990), S. 317-323 
    ISSN: 1573-5117
    Keywords: Chondrus crispus ; harvest method ; Irish moss ; net primary productivity ; outplants ; seaweed ; wild harvest
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    Topics: Biology
    Notes: Abstract Western Prince Edward Island Irish moss (Chondrus crispus) has been intensively dragraked since 1966. As well, most unattached fronds removed by wave surge, ice, etc. are brought to shore by waves and currents, where they are harvested eagerly. Accurate annual fishing yields were recorded between 1966 and 1981 inclusive. Given that herbivore densities are reduced, likely due to the intensive raking, and that mean annual bycatch (non-Irish moss seaweeds) (23.4 %) and commercial bed sizes (873 ha) were known, the fishing yields thus were considered a unique database from which to calculate net primary production (NPP). Factors used to convert from wet to dry wt (DW), and from dry wt to carbon were 0.22 an 0.31, respectively. Calculated mean annual NPP values were as follows: 2.101 ± 0.654 t (DW) ha−1 y−1; 210.1 g DW m−2 yr−1 and 63.0 g C m−2 yr−1. These values are much lower than those calculated for northwest Atlantic kelp and rockweed but similar to that determined for northeast Atlantic Gracilaria verrucosa. The interannual variability pattern for NPP was similar for both the wild Irish moss harvest and that of experimental Chondrus crispus outplants placed in one of the 14 commercial beds.
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  • 60
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    Hydrobiologia 204-205 (1990), S. 15-16 
    ISSN: 1573-5117
    Keywords: community ; disturbance ; harvesting ; population ; recruitment ; seaweed ; stability
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  • 61
    ISSN: 1573-5117
    Keywords: bioassay ; Chlorophyta ; functional-form ; Halimeda ; nutrients ; productivity ; seaweed ; Udotea
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    Topics: Biology
    Notes: Abstract Members of the green algal order Bryopsidales (= Caulerpales) are important calcifying agents of tropical reefs and comprise two fundamentally different life-form groups: (1) epilithic species with limited attachment structures and (2) psammophytic forms that have extensive subterranean rhizoidal systems. Because the shallow-water habitats of the former have relatively low nitrogen (N) to phosphorus (Pi) ratios compared to the pore waters of the sedimentary carbonate-rich substrata in which the latter are anchored, we hypothesized that epilithic forms should tend to be relatively more limited by N, while psammophytic species should tend to show Pi limitation. In partial support of the hypothesis, light-saturated net photosynthesis (Pmax) in the epilithic forms, Halimeda opuntia, H. lacrimosa and H. copiosa, tended to be enhanced by N, while Pi was inhibitory or had no effect. In contrast, the psammophytic forms, Udotea sp., U. conglutinata, H. monde, H. tuna and H. simulans, tended to be stimulated more by Pi, whereas N had little effect. The utility of a bioassay to assess macroalgal nutrient limitation, based on a physiological response (net Pmax) to short-term nutrient pulses, is demonstrated.
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  • 62
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    Hydrobiologia 204-205 (1990), S. 99-104 
    ISSN: 1573-5117
    Keywords: AIDS ; antiviral ; herpes ; red algae ; seaweed ; sulfated polysaccharide
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    Topics: Biology
    Notes: Abstract It is possible that heparin-like sulfated polysaccharides from red algae, or fractions thereof, might be found to be low-cost, broad-spectrum antiviral agents. The prevailing view among virologists has been that sulfated polysaccharides inhibit viral action by acting only at the surfaces of cells. This perception now is changing with the finding that both the herpes virus (containing DNA) and human immunodeficiency virus (containing RNA) are inhibited by sulfated polysaccharides that act within the cell as well as external to it. Aqueous extracts of many red algae are active against retroviruses. Carrageenan, a common cell wall polysaccharide from red algae, is co-internalized into infected cells with the Herpes simplex virus (HSV), inhibiting the virus. Carrageenan also interferes with fusion (syncytium formation) between cells infected with the human immunodeficiency virus (HIV) and inhibits the specific retroviral enzyme reverse transcriptase.
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  • 63
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    Hydrobiologia 203 (1990), S. 93-97 
    ISSN: 1573-5117
    Keywords: sediments ; nitrogen ; phosphorus ; nutrient limitation ; photosynthesis
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    Notes: Abstract A diffusion enrichment technique is presented which allows for chemical enrichment of soft surficial and shallow subsurface sediments and subsequent measurement of O2 production. The sediment is enriched by inserting a perforated tube containing dialysis tubing filled with a nutrient/agar mixture. O2 production by surficial sediment is measured using an inverted, translucent, polyethylene chamber over the sediment. The inside of the chamber contains a collapsible bag connected to the water outside the chamber. When water overlying the sediment is withdrawn from a sampling port, it is displaced with water from outside the chamber, thus preventing contamination of water samples with pore water from below. The technique was tested by enriching near-shore sediments in a large oligotrophic lake with inorganic N and P. NHinf4/p+ additions significantly stimulated benthic primary production as measured by 02 production, whereas enrichment with POinf4/3- had no effect.
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  • 64
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    Hydrobiologia 204-205 (1990), S. 331-338 
    ISSN: 1573-5117
    Keywords: biology ; phenology ; Philippines ; Sargassum ; seaweed ; standing crop
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    Topics: Biology
    Notes: Abstract The seasonality of standing crop of a Sargassum bed was investigated by conducting monthly sampling from February 1988 to July 1989. Environmental parameters of water movement, salinity, number of daytime minus tides, and water temperature were also measured. An intra-annual pattern of variation in standing crop of Sargassum crassifolium, S. cristaefolium, S. oligocystum, and S. polycystum was observed. Standing crop was generally lowest in February, March, April, or May, and highest in November through January. Sargassum accounted for about 35 to 85% of the monthly algal standing crop of the bed, and the observed variation in overall standing crop of the bed generally reflected the standing crop of Sargassum. The seasonality of the standing crops of the associated algal divisions also followed an annual cycle, but their maximum and minimum standing crops did not coincide with those of Sargassum. Individually, as well as collectively, the standing crops of the Sargassum spp. were poorly correlated with the environmental factors observed.
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  • 65
    ISSN: 1573-5117
    Keywords: Chile ; culture ; growth ; Laminariales ; Lessonia ; seaweed ; sporophytes
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    Topics: Biology
    Notes: Abstract Lessonia trabeculata is one of the major kelps found along the northern coast of Chile. In addition to its ecological and economic importance, L. trabeculata may be severely affected by environmental disturbances such as El Níño, which during 1982–1983 cleared wide areas along the coast of Peru and Chile. The main goal of this work was to mass culture L. trabeculata and to observe the growth of sporophytes obtained in the laboratory and cultured in the sea. Juvenile sporophytes obtained in the laboratory were attached between 1 and 6 m in depth. The linear growth rate, as blade elongation, was recorded weekly for seven months. No significant differences (p 〈 0.05) were found in sporophyte blade linear growth at different depths. The best elongation growth rate was 7.5 ± 1.6 mm d−1 at 3 m during March. This preliminary work suggests that L. trabeculata follows an annual growth cycle similar to that of other Laminariales with a high rate of blade elongation during the summer and decreasing towards autumn. This species can be considered a potential candidate for aquaculture to increase the availability of raw material and aid in repopulation of overexploited areas.
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  • 66
    ISSN: 1573-5117
    Keywords: distribution ; Gelidium ; red algae ; seaweed
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    Topics: Biology
    Notes: Abstract Two species of Gelidium, provisionally referred to as G. pusillum and G. latifolium, are included in the Scandinavian flora and reach their northern limit of distribution on the Norwegian west coast. Small frond sizes due to adverse growth conditions, extreme phenotypic variability and lack of sexual reproduction make identification of specimens very difficult. Both species were isolated into unialgal culture and were compared with cultured strains referable to G. pusillum from Ireland and France. Temperature and salinity requirements and tolerance ranges were determined and discussed in view of distribution along the Norwegian coast. Little or no growth occurs below 9 °C, corresponding to a northern summer growth limit. On the Norwegian Skagerrak coast, low winter temperature rather than reduced salinity is the limiting factor.
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    Hydrobiologia 204-205 (1990), S. 389-395 
    ISSN: 1573-5117
    Keywords: aquaculture ; genetics ; hybrid ; monoecious ; mutants ; seaweed ; selection ; sterility
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    Topics: Biology
    Notes: Abstract Sporelings of the monoecious red alga Gelidium vagum were placed into 4500 individual cultures after treatment with the chemical mutagen nitrosoguanidine and raised to sexual maturity to search for reproductive mutants. Isolates undergoing normal self-fertilization were discarded, leaving approximately 250 self-sterile plants and mutants with abnormal reproduction or reproductive structures. Self-sterile mutants were tested further in crosses to a fertile green marker stock. From the results, many mutants appeared to be either male-sterile, female-sterile or unable to form carposporophytes. Although sufficient data on the inheritance pattern of the self-sterile mutants are available for only a few of the isolates, some apparently stable sterility mutations with simple Mendelian transmission were identified. Preliminary testing of one of the male-sterile mutations confirmed that it effectively eliminated self-fertilization and facilitated the formation of hybrid plants in crosses.
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  • 68
    ISSN: 1573-5117
    Keywords: autodiploidization ; Boergesenia forbesii ; diplohaplont ; life cycle ; seaweed ; Siphonocladales ; Valonia fastigiata ; Valonia utricularis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Life history studies were carried out with isolates of Boergesenia forbesii (from Western Australia), Valonia fastigiata (Hawaii) and V. utricularis (Canary Islands, Mediterranean Sea) cultivated under laboratory conditions. Ploidy levels of nuclei were identified by micro spectrophotometric DNA content measurements after Feulgen staining. Fundamentally, the life history in both genera is diplohaplontic. Autodiploidization phenomena have been observed favoring the diploid generation. In contrast to other genera of the Siphonocladales s. str. producing biflagellate diploid zoospores (e.g. Ernodesmis, Boodlea), Valonia develops haploid and diploid zoospores with four flagella. No diploid zoospores were observed in Boergesenia.
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  • 69
    ISSN: 1573-5117
    Keywords: conchocelis ; conchospores ; photoperiod ; Porphyra ; reproduction ; seaweed
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    Notes: Abstract The leafy thalli of species of the marine red algal genus Porphyra grow rapidly but persist for a relatively short time on rocky intertidal or subtidal substrata or as epiphytes on other marine plants. In most species, the large, short-lived leafy thalli alternate with small, presumably perennial, filamentous ‘conchocelis’ plants. Depending on the species of northeastern Pacific Porphyra, photoperiod and temperature are important regulators of conchospore formation and release. Data from laboratory studies of conchospore formation and release in five Washington species of Porphyra (P. abottae, P. nereocystis, P. perforata, P. pseudolanceolata and P. torta) indicate that conchospores are most likely to be released at a time that precedes the appearance of the leafy thalli in the field.
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    Hydrobiologia 204-205 (1990), S. 287-292 
    ISSN: 1573-5117
    Keywords: dry biomass ; Fucus ; Gelidium ; harvest ; Irish moss ; Laminaria ; seaweed ; Spain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Commercial seaweeds in Spain are harvested on the north and northwest coasts. They are mainly agarophytes and carrageenophytes (Gelidium spp. and some ‘Irish moss’-like species, respectively), although some Phaeophyceae species (Fucus spp. and Laminaria spp.) are also exploited for alginates. No industrial seaweed cultivation is carried out in Spain at present. Spain's total commercial seaweed harvest can be estimated at 6,528 ± 2,076 t dry wt year−1. Gelidium spp. are by far the most harvested, attaining 5,135 ± 1,761 t dry wt y−1. To date, Spain's commercial seaweed harvest is low compared with that of other countries, but data on field standing crops and productivities of commercial taxa suggest that harvesting could be increased greatly.
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    Hydrobiologia 204-205 (1990), S. 325-330 
    ISSN: 1573-5117
    Keywords: decline and recovery of a resource ; Gracilaria harvesting and processing ; product utilization ; seaweed ; socio-economic impact
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    Topics: Biology
    Notes: Abstract Since World War II the greater Saldanha Bay lagoon system, South Africa, has been an important Gracilaria producer. Two agar factories, built in the 1960's, used Gracilaria from Saldanha Bay as their raw material. In the early 1970's the industry was destroyed as a result of dredging and marine construction operations to establish a harbor in the bay for loading ore. These environmental changes destroyed stocks and prevented the previously significant beachings of the seaweed from occurring. After a few years of no or very low commercial production, the resource slowly started to recover. The size of Gracilaria drifts increased over the following eight years to approximately one-third of the original output. This trend seems to continue. Although the stocks and resultant drifts are unlikely to recover fully to their original quantity, current production is already sufficient to ensure re-establishment of a seaweed industry in Saldanha Bay. This could have considerable socio-economic impact on the area.
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  • 72
    ISSN: 1573-5117
    Keywords: Agardhiella subulata ; plant growth regulator ; seaweed ; tissue culture
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    Notes: Abstract We examined whether auxins and cytokinins, either singly or in combination, stimulate cell division in tissue cultures of a red seaweed. Our experimental model consisted of filamentous and callus-like growths that developed from cross-sectional discs cut from young branches of Agardhiella subulata. Plant growth regulators were added to the medium to give combinations of an auxin with a cytokinin over a range of concentrations (1 µg L−1 −10 mg L−1). Several mixtures of auxins and cytokinins, as well as some single auxins, cytokinins and phenolics, stimulated cell division and growth in the tissue cultures beyond that of controls. The treatments that were effective included: phenylacetic acid/zeatin; phenylacetic acid/6-benzylaminopurine; α-naphthaleneacetic acid/zeatin; 2,4,5-trichlorophenoxyacetic acid/6-benzylaminopurine; and indoleacetic acid/kinetin. High concentrations of cytokinins (i.e. 10 mg L−1) inhibited the regeneration of plants in some of the cell cultures. These results provide further evidence that growth regulators can be used for the tissue culture of seaweeds and for the study of developmental phenomena in these plants.
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  • 73
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    Keywords: nitrogen ; phosphate ; phytoplankton ; Mediterranean lagoon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A network of 63 stations was used on four occasions (June 1986, October 1986, February 1987, and May 1987) to study the spatio-temporal distribution of inorganic nutrients in Thau Lagoon (‘l'étang de Thau’), which covers 7500 hectares on the French Mediterranean coast. Three environmental factors, revealed by multiple regression models, govern the distributions observed. Allochthonous inputs from the watershed enrich the environment with nitrogen and phosphorus compounds in the winter and autumn. Internal sources are essentially localized in the shellfish breeding zone of the lagoon. In the summer, shellfish excretions and the rapid remineralization of organic deposits produce ammonium ions. Uptake by phytoplankton has a much larger impact on the seasonal variation of inorganic nitrogen than on that of phosphorus; the latter is present in excess in the lagoon waters. Thus, nitrogen appears to be the primary limiting nutrient for the development of the chorophyllous biomass.
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  • 74
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    Hydrobiologia 204-205 (1990), S. 397-400 
    ISSN: 1573-5117
    Keywords: carpospores ; degree of self-fertilization ; F1 conchocelis ; genetic marker ; pigmentation mutant ; Porphyra yezoensis ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Crosses between genotypically distinct thalli of the monoecious species Porphyra yezoensis were carried out using immature thallus fragments from green- and red-type color mutants and also wild-type thalli. As the genes governing the mutants are monogenic, recessive to the wild-type, and belong to the same linkage group, the degree of self-fertilization could be estimated based on the pigmentation of the resultant diploid conchocelis. The degree of self-fertilization in the cross between the green-type and the wild-type was 48.5–55.0%, and in the cross between the red-type and the wild-type was 45.1–56.5%. In the cross between the green- and red-type mutants, the degree of self-fertilization was 46.0–54.5% when the green-type was the female parent, and was 44.8–55.6% when the red-type was the female parent.
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  • 75
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    Hydrobiologia 204-205 (1990), S. 461-466 
    ISSN: 1573-5117
    Keywords: Brazil ; culture ; Laminaria ; photon flux density ; seaweed ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Laminaria abyssalis occurs in deep water in tropical latitudes of the Brazilian coast (19° 23′ S, 38° 28′ W to 22° 54′ S, 42° 13′ 09″ W). Its life cycle has been completed in the laboratory in seven months using different conditions of light and temperature. The gametophytic stage required for growth the low photon flux density of 1.2 ± 0.3 µmol m−2 s−1 and 18 °C, while the juvenile and adult sporophytes needed 15 µmol m−2 s−1 and 18 °C. The sporophytes became fertile at 23 °C. Our results showed that light and temperature are the main factors regulating the growth and life history of this species under the culture conditions tested.
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  • 76
    ISSN: 1573-5117
    Keywords: cell wall ; fibrillar component ; Gracilaria verrucosa ; protoplast ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cell wall of Gracilaria verrucosa is composed of two fractions: a matrix made of agar and a skeleton whose composition is unknown. This fibrillar part was isolated using both physical and chemical techniques. Total hydrolysis followed by gas-liquid chromatography allowed us to establish the sugar composition. Enzymatic degradations were carried out with cellulases, xylanases, agarases and pectinases. Efficiencies of the enzymatic digestions were monitored by both chemical analysis and electron microscopy. Pectinases had no effect. The fibrillar part was composed mainly of a cellulosic network that was unmasked by the xylanase action and degraded after cellulase digestion. The results suggest that a cocktail composed of agarases and cellulases can be used successfully to prepare protoplasts from Gracilaria verrucosa.
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  • 77
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    Hydrobiologia 204-205 (1990), S. 545-549 
    ISSN: 1573-5117
    Keywords: agar ; cystocarpic ; Gelidium rex ; seaweed ; tetrasporic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gelidium rex grows in the rocky intertidal of central Chile. Extraction of vegetative G. rex with water at 95 °C yielded 17.9% of agar with a gel strength value of 590 g cm−2. The gel strength increased up to 1272 g cm−2 when the alga was treated with alkali prior to extraction. Cystocarpic and tetrasporic thalli of G. rex were extracted with distilled water at 95 °C, affording soluble polysaccharides in 36.0% and 15.7% yield respectively. Polysaccharides of both life history phases were fractionated by chromatography on DEAE Sephadex. Elution with distilled water gave fractions devoid of sulfate; the fraction from cystocarpic plants contained 45.5% of 3,6-anhydrogalactose whereas the neutral fraction from tetrasporic plants contained 40.0% of 3,6-anhydrogalactose. Further elution with 0.1, 0.4, 0.8 and 1.5 molar aqueous solutions of KCl afforded four fractions for each polysaccharide. Chemical analysis of these fractions showed that the agars from cystocarpic and tetrasporic Gelidium rex are mixtures of related polysaccharides that range from neutral polymers to highly sulfated galactans.
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  • 78
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    Hydrobiologia 204-205 (1990), S. 577-584 
    ISSN: 1573-5117
    Keywords: antitumor ; Ehrlich carcinoma ; lipids ; Meth-A fibrosarcoma ; polysaccharides ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Powdered tissue from 46 species of air-dried marine algae (four green, 21 brown and 21 red algae) were screened for antitumor activity. Significant activity against Ehrlich carcinoma was found in the brown algae Scytosiphon lomentaria (69.8% inhibition), Lessonia nigrescens (60.0%), Laminaria japonica (57.6%), Sargassum ringgoldianum (46.5%), the red algae Porphyra yezoensis (53.2%) and Eucheuma gelatinae (52.1%) and the green alga Enteromorpha prolifera (51.7%). Five brown and four red algae showed appreciable antitumor activity against Meth-A fibrosarcoma. To identify specific molecules with antitumor activity, 15 kinds of polysaccharide preparations of seaweed origin and 24 kinds of lipid fractions extracted from various seaweeds were tested. Appreciable inhibition of Ehrlich carcinoma was found for fucoidan preparations from Undaria pinnatifida and Sargassum ringgoldianum, for carrageenans and for porphyran. Several glycolipid and phospholipid fractions from brown and red algae were effective against Meth-A fibrosarcoma.
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  • 79
    ISSN: 1573-5117
    Keywords: agar ; cell wall ; electron microscopy ; Gracilaria ; seaweed ; steam explosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ultrastructural (SEM, TEM) and cytochemical organization of the skeletal and matrix polysaccharides of fresh and steam exploded Gracilaria verrucosa thalli were compared to chemical analyses of the agar extracted after this treatment. Upon steam explosion, surface microfractures appeared in limited areas of the cortex. SEM preparations indicated that apical and medullary regions were the most affected, resulting in detachment of adjacent cells. In TEM sections, the cuticle of the surface layer exhibited deeply altered zones with a spongy appearance. In the cytoplasm starch grains were disrupted. The skeletal component of the immediate cell wall was maintained with a different organization of the microfibrils and was positive to periodic acid-thiosemicarbazide-silver proteinate. The intercellular matrix contained granules and fibrils and lacked a ruthenium red reaction. These results are consistent with lower sulfate-ester and higher glucose contents detected in agars extracted using steam explosion.
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  • 80
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    Hydrobiologia 204-205 (1990), S. 615-620 
    ISSN: 1573-5117
    Keywords: agaroid ; Chondria macrocarpa ; polysaccharide ; Rhodophyta ; seaweed ; xylogalactan sulfate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A structure is proposed for the complex xylogalactan sulfate from Chondria macrocarpa. The hot-water extract of C. macrocarpa was desulfated or alkali-treated and Smith degraded. Constituent sugars and their substitution patterns were identified using a modified Hakamori methylation procedure suited to sulfated polysaccharides and a double hydrolysis-reduction protocol that yielded derivatives from all of the sugar residues, including the labile 3,6-anhydrogalactosyl residues. The polymer has an agar-type backbone of alternating 3-linked \-d- and 4-linked α-L-galactopyranosyl units. The d-residues are partially sulfated on O-2 (50%) and O-6 (20–30%). About 40% of the l-residues are present as the 3,6-anhydride and 25% as its ‘precursor’ l-galactose 6-sulfate. A significant proportion of the remaining l-galactosyl residues have both a d-xylopyranosyl substituent on O-3 and a sulfate ester on O-6 and are stable to alkali.
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  • 81
    ISSN: 1573-5117
    Keywords: arachidonic acid derivatives ; caribbean ; eicosanoids ; eicosapentaenoic acid derivatives ; Oregon ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Red marine algae are shown in this work to be a rich source of eicosanoid-type natural products. This is the first isolation of several of these mammalian arachidonic acid metabolites from any marine or terrestrial plant source (12-HETE, 12-HEPE, 6(E)-LTB4, hepoxilin B3). A few of these represent truly novel substances never previously isolated from nature [12(R), 13(S)-diHETE]. Inherent in these seaweed natural product structures is evidence for a highly evolved lipoxygenase-type metabolism that matches or exceeds the complexity of comparable metabolic routes in mammalian systems. As these compounds are produced by algae in relatively large quantities (0.1–5.0% of crude lipid extracts), these plants could be important commercial resources for these expensive and rare biochemicals. Further, we suggest that this metabolism is important to physiological processes in red algae that are completely unknown at present. For example, it is possible that they act in an exocrine sense to coordinate reproductive events, a hypothesis under current investigation through culture studies.
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  • 82
    ISSN: 1573-5117
    Keywords: agar ; carrageenan ; Eucheuma denticulatum ; Gelidium madagascariense ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several species of red algae known to contain agar or carrageenan are abundant on the southeast and southwest coasts of Madagascar. The agarophyte Gelidium madagascariense, collected in the Fort Dauphin area, has been exported on a small scale to Japan for several years. FT-IR and GLC analysis show that it contains an agar polymer, of which the methylated fraction contains predominantly 6-O-methyl galactose and traces of 4-O-methyl galactose. Eucheuma denticulatum grows profusely on the coral reefs in the Tulear area. FT-IR and GLC analysis show that it contains iota-carrageenan, with no methyl-derivative contaminants. The 3,6-anhydro-galactose content was found to be rather low, suggesting a possible contamination with deviant iota. The economic potential of other sources of phycocolloids, as well as the possibility of farming different species of Eucheuma in the Tulear area, is discussed.
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  • 83
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    Biogeochemistry 10 (1990), S. 67-79 
    ISSN: 1573-515X
    Keywords: deserts ; ecosystem ; nitrogen ; nutrient cycling ; soils ; southwestern United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A lower limit for nitrogen loss from desert ecosystems in the southwestern United States was estimated by comparing nitrogen inputs to the amount of nitrogen stored in desert soils and vegetation. Atmospheric input of nitrogen for the last 10 000 years was conservatively estimated to be 2.99 kg N/m2. The amount of nitrogen stored in desert soils was calculated to be 0.604 kg N/m3 using extant data from 212 profiles located in Arizona, California, Nevada, and Utah. The average amount of nitrogen stored in desert vegetation is approximately 0.036 kg N/m2. Desert conditions have existed in the southwestern United States throughout the last 10 000 years. Under such conditions, vertical leaching of nitrogen below a depth of 1 m is small (ca. 0.028 kg N/m2 over 10 000 years) and streamflow losses of nitrogen from the desert landscape are negligible. Thus, the discrepancy found between nitrogen input and storage represents the amount of nitrogen lost to the atmosphere during the last 10 000 years. Loss of nitrogen to the atmosphere was calculated to be 2.32 kg N/m2, which is 77% of the atmospheric inputs. Processes resulting in nitrogen loss to the atmosphere from desert ecosystems include wind erosion, ammonia volatilization, nitrification, and denitrification. Our analysis cannot assess the relative importance of these processes, but each is worthy of future research efforts.
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  • 84
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    Biogeochemistry 11 (1990), S. 1-22 
    ISSN: 1573-515X
    Keywords: disturbance ; ecosystems ; forests ; indirect interactions ; landscape ecology ; Minnesota ; nitrogen ; nutrient cycling ; path analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Path analysis was used to determine the importance of long-term disturbance regime and the relative importances of correlations among vegetation patterns, disturbance history, and nitrogen (N) mineralization in old-growth forests of northwestern Minnesota. Leaf biomass (estimated by allometric equations), fire history (from fire scars on Pinus resinosa trees), and N mineralization rates (estimated from incubationsin situ) were determined from sample plots dominated by Betula papyrifera, Populus tremuloides, andP. grandidentata a mixture ofAcer saccharumandTilia americana, or Quercus borealis andOstrya virginiana. Results showed that topographic and soil-moisture controls on N mineralization, vegetation patterns, and disturbance are substantially stronger than is suggested by direct correlation. Indirect interactions among ecosystem variables played in important role. These interactions probably include the tendency for species that cycle large amounts of N to colonize more mesic sites that burned rarely in the past. Soil moisture was correlated both directly with N mineralization and indirectly, through its effects on vegetation pattern, and thus, litter quality. Although disturbance regime also depended on topography, the strengths of relationships between disturbance regime and other variables were relatively weak. These dependencies suggested that long-term fire regime is probably more a consequence than a cause for vegetation and fertility patterns. Topography, through its effects on soil moisture and microclimate, is an overriding influence on ecosystem properties, which in turn influence fire regime.
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  • 85
    ISSN: 1573-515X
    Keywords: cumulative ; flow ; GIS ; landscape ; lead ; nitrogen ; phosphorus ; suspended solids ; watershed ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A method was developed to evaluate the cumulative effect of wetland mosaics in the landscape on stream water quality and quantity in the nine-county region surrounding Minneapolis—St. Paul, Minnesota. A Geographic Information System (GIS) was used to record and measure 33 watershed variables derived from historical aerial photos. These watershed variables were then reduced to eight principal components which explained 86% of the variance. Relationships between stream water quality variables and the three wetland-related principal components were explored through stepwise multiple regression analysis. The proximity of wetlands to the sampling station was related to principal component two, which was associated with decreased annual concentrations of inorganic suspended solids, fecal coliform, nitrates, specific conductivity, flow-weighted NH4 flow-weighted total P, and a decreased proportion of phosphorus in dissolved form(p 〈 0.05). Wetland extent was related to decreased specific conductivity, chloride, and lead concentrations. The wetland-related principal components were also associated with the seasonal export of organic matter, organic nitrogen, and orthophosphate. Relationships between water quality and wetlands components were different for time-weighted averages as compared to flow-weighted averages. This suggests that wetlands were more effective in removing suspended solids, total phosphorus, and ammonia during high flow periods but were more effective in removing nitrates during low flow periods.
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    Biogeochemistry 11 (1990), S. 23-43 
    ISSN: 1573-515X
    Keywords: acid precipitation ; ammonium ; mass balance ; nitrate ; nitrogen ; retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The relative contribution of HN03 to precipitation acidity in eastern Canada has increased in recent years leading to some concern that the relative importance of NO− 3 deposition in acidification of terrestrial and aquatic ecosystems may increase. To gauge the extent of this impact, annual mass balances for N0− 3 and NH+ 4 were calculated for several forested catchments and lakes in Ontario. Retention of NH+ 4 (R NH4) by forested catchments was consistently high compared to retention of NO3 − (R NO3) which was highly variable. Retention of inorganic nitrogen was influenced by catchment grade and areal water discharge. In lakes, the reciprocals of retention of N0− 3 and NH+ 4 were linearly related to the ratio of lake mean depth to water residence time (z/τ; equal to areal water discharge), and retention did not appear to be a function of degree of acidification of the lakes. Net N consumption-based acidification of lakes, defined as the ratio of annual NH; mass to N0− 3 mass consumption, was negatively correlated with /τ and N consumption-related acidification was most likely to occur when − was 〈 1.5 m yr−1. If retention mechanisms are unaffected by changes in deposition, changes in deposition will still result in changes in surface water concentrations although the changes will be of similar proportions. Therefore, ‘NO− 3 saturation’ should not be defined by concentrations alone, but should be defined as decreasing long-term, average NO− 3 retention in streams and lakes in response to long-term increases in NO− 3 deposition. Analysis o f survey data will be facilitated by grouping lakes and catchments according to similar characteristics.
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  • 87
    ISSN: 1573-515X
    Keywords: nitrogen ; snow ; flux
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    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Increased emissions of nitrogen compounds to the atmosphere by human activities have been well documented. However, in order to better quantify these anthropogenic emissions, better knowledge of natural emissions rates must be known. In addition, variation in natural emissions through time should be documented. In this note we present data collected and/or analyzed by us for NO3 − in recent snow from remote regions of the world. We also summarize existing data sets from other remote regions. This is done to establish a better understanding of NO3 − deposition rates in these regions as well as to add more information to our global understanding of NO3 − deposition.
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  • 88
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    Plant cell, tissue and organ culture 21 (1990), S. 185-189 
    ISSN: 1573-5044
    Keywords: ammonium nitrate ; Malus ; nitrogen ; potassium nitrate ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of some macronutrients, especially NH4NO3 and KNO3, on root development of microcuttings from 3 apple scion cultivars is discussed. A reduction of the level of NH4NO3 in the medium from full strength to 1/4 strength significantly increased the percentage rooting of ‘Gala’ and ‘Royal Gala’, but not ‘Jonagold’. Further reduction of NH4NO3 level from 1/4 strength to zero significantly reduced the percentage of rooting in ‘Gala’ but not ‘Royal Gala’. ‘Jonagold’ rooted best at zero concentration NH4NO3. Without NH4NO3, rooting percentages were as high as 100% for all 3 cultivars when KNO3 was provided at full strength. The results show that adventitious roots can be induced on apple scion cultivars by media manipulation.
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  • 89
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    Biogeochemistry 9 (1990), S. 117-134 
    ISSN: 1573-515X
    Keywords: nitrogen ; Mediterranean ; natural versus anthropogenic atmospheric nitrogen ; atmospheric input ; riverine input ; marine ecosystems ; primary production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Bulk inorganic nitrogen deposition was monitored over a period of 3 years at the Bavella Pass (Corsica, France). Annual fluxes range between 126 and 150μmol.m−2.d-−1, increasing slightly with annual rainfall. Natural background average concentrations of rain water and associated fluxes were estimated from a classification of rain events into ‘natural’ (Oceanic and Saharan), polluted and composite. Long range transport of incoming polluted air masses increases the atmospheric wet nitrogen input by at least a factor of 1.6 in this Mediterranean area. Extrapolation of atmospheric dissolved inorganic nitrogen input to the Western Mediterranean leads to fluxes of 80 to l00μmol.m−2.d-−1. This atmospheric input is in the same order of magnitude as the inorganic nitrogen riverine input. As a consequence, the nitrogen budget for the Mediterranean has had to be reassessed. Atmospheric wet inorganic nitrogen input is of noticeable importance to marine Mediterranean ecosystems, representing on average 10 to 25% of new production in the Western Basin, with values of up to 60% in oligotrophic zones.
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    Ecological research 5 (1990), S. 111-130 
    ISSN: 1440-1703
    Keywords: Big woody materials ; Decomposition rate ; Foothill diperocarp forest ; nitrogen ; turnover time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dynamics of aboveground big woody organs over 10 cm diameter was studied at a mature foothill dipterocarp forest in West Sumatra. The biomass of big woody organs was estimated to be 519 m3 ha−1 or 408 metric ton ha−1 by means of a pipe model theory. The diameter distribution showed a convex curve and the mode was found at a diameter of about 20 cm. The standing mass of big dead woody litter on the forest floor was 116 m3 ha−1, which accounted for 22% by voume or 9.5% by weight of the biomass of living organs respectively. Thedbh observation with two 1-ha plots for 4 yr and 5 yr respectively revealed that the average net production rate was 9.5 ton ha−1 yr−1. The death rate (7.9 ton ha−1 yr−1) accounted for 83% of the net production rate and was nearly equivalent to the decay rate (7.5 ha−1 yr−1) of dead wood on the forest floor. The balance between the death and decay rates was confirmed for each diameter class. Average turnover periods for big woody organs and dead woody litter were estimated to be 43 and 8.1 yr, respectively. Standing masses of live anddead woody materials accumulated in the study forest were approximately equal to those obtained in a mature tropical lowland rainforest, whereas the flow rates were lower, being only 70% of the corresponding values.
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    Nutrient cycling in agroecosystems 22 (1990), S. 29-35 
    ISSN: 1573-0867
    Keywords: Zinc ; nitrogen ; interaction ; limed ; unlimed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A green house experiment was conducted to study the interaction effect of Zn and N in wheat (S-308). Zinc was applied as ZnSO4.7H2O at 0, 5, 10 and 20 mg per kg, and nitrogen as urea at 0, 75 and 150 mg per kg. In the absence of added N and lime 5 mg Zn per kg increased the grain, straw and root weight, but the application of either N (75 and 150 mg per kg) or lime (4000 mg CaCO3 per kg), 10 mg Zn per kg responded significantly. However, when N and lime were added together, 20 mg Zn per kg increased the grain, straw and root weight significantly. Irrespective of Zn and N, the grain, straw and root weights were higher in limed that in unlimed soils. The application of N increased the Zn concentration in wheat tops and roots in unlimed soils, and decreased it in limed soils. However, because of an increase in wheat yield, the uptake of Zn by wheat tops and roots also increased with N application both in limed and unlimed soils. The addition of Zn to 10 mg per kg, increased the N concentration in the absence of N, but in the presence of N, the addition of Zn to 20 mg per kg decreased the N concentration in wheat tops and roots. The applied Zn to 10 mg per kg in unlimed soils and to 20 mg per kg in limed soils increased the N uptake by wheat tops and roots, respectively. The Zn concentration was higher in absence of lime than in its presence while a reverse trend was true for N concentration.
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  • 92
    ISSN: 1573-0867
    Keywords: Potatoes ; nitrogen ; foliar sprays ; urea ; 15N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of the timing of N fertilizer application on the uptake and partitioning of N within the crop and the yield of tubers has been studied in two experiments. In 1985 either none, 8 or 12 g N m−2 was applied and in 1986 none, 12 or 18 g N m−2. Fertilizer N was applied either at planting, around the time of tuber initiation or half at planting and the remainder in four foliar sprays of urea during tuber bulking.15N-labelled fertilizer was applied to measure the recovery of fertilizer N in the crops. There was an apparent pre-emergence loss of nitrate from the soil when N was applied at planting in 1986, thereby reducing the efficiency of fertilizer use. Applying the N at tuber initiation delayed and reduced the accumulation of N in the canopy compared with crops receiving all their fertilizer at planting. Foliar sprays of urea slightly increased both tuber yields and tuber N contents when compared to a single application at planting. The proportion of the fertilizer N recovered in the crop was little affected by the rate of N application, but a greater proportion of foliar-applied N was recovered than N broadcast at planting, due partly to pre-emergence losses of nitrate in 1986. It is suggested that late applications of N was foliar sprays can be of benefit to crops with a long growing season and reduce environmental losses of N.
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    Nutrient cycling in agroecosystems 21 (1990), S. 171-177 
    ISSN: 1573-0867
    Keywords: Bermudagrass ; nitrogen ; model ; nutrient uptake ; forages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Equations were developed to estimate concentration of nitrogen for bermudagrass forage [Cynodon dactylon, (L.) Pers.] as related to applied nitrogen level and harvest interval. Data from six field studies were used in the analysis. Estimates of N concentration in forage obtained with these equations agreed with data from other studies with fertilizer and waste application to bermudagrass (correlation coefficient of 0.94). Concentration of nitrogen decreased linearly with harvest interval (up to 6 weeks) and increased exponentially with nitrogen level. These equations should provide relevant information for crop production and environmental quality.
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  • 94
    ISSN: 1572-9567
    Keywords: Burnett apparatus ; compressibility factor ; density ; ethane ; methane ; mixtures ; nitrogen ; refractive index ; Z-meter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The European Gas Research Group (GERG; Groupe Européen de Recherches Gazières) initiated a round-robin test of six Z-meters manufactured by Desgranges et Huot, a Burnett apparatus, and an interferometric device to back up the pVT data of the Z-meters. Two gas mixtures were measured. One mixture contained 49.7 mol% of methane and 50.3 mol% of nitrogen; the second mixture 81.3 mol% of methane, 16.4 mol% of ethane, and 2.3 mol% of propane. The test temperatures were mainly 280 and 300 K for the first mixture and 290 and 320 K for the second mixture. The maximum pressures were 8 MPa for Z-meters and 12 MPa for the Burnett apparatus and the grating interferometer. The experimental compressibility factors Z of the six Z-meters are generally in agreement within ±0.05%. The agreement with the reference data from the Burnett apparatus and the refractive index measurements is also within ± 0.05%. Only two isotherms of the binary mixtures differ by about 0.1% from the other data. Recent natural gas measurements show substantially the same results.
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    International journal of thermophysics 11 (1990), S. 201-211 
    ISSN: 1572-9567
    Keywords: enthalpy ; heat capacity ; high temperatures ; nitrogen ; virial coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Calculations of the second virial coefficients and their derivatives for the Hulburt-Hirschfelder (HH) and other accurate interaction potentials are used to determine the thermodynamic properties of nitrogen at high temperatures. Unlike the usual methods employing partition functions, which are most accurate at low temperatures where the energy levels are precisely known, the virial coefficient method depends on integrating over potential energy functions which provide a useful description of energies even near the top of the potential well, a region where the vibrational-rotational energy levels are not readily accessible. This makes this method particularly useful for predicting high-temperature properties outside the range of laboratory measurements and beyond the useful limits of the partition function approach. In the present work, we use the virial coefficient method to predict the heat capacities and enthalpies of nitrogen up to 25,000 K.
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    International journal of thermophysics 11 (1990), S. 597-601 
    ISSN: 1572-9567
    Keywords: measurement techniques ; nitrogen ; parallel-plate apparatus ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A parallel-plate apparatus is suited for accurate measurements of the thermal conductivity coefficient of fluids over a wide range of densities. This is illustrated by measurements of the thermal conductivity coefficient of nitrogen at a temperature of 308.15 K and at pressures up to 20.1 MPa with an accuracy of 0.5%. The agreement with a recent correlation based on accurate measurements by other authors is satisfactory.
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  • 97
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 11 (1990), S. 897-910 
    ISSN: 1572-9567
    Keywords: binary mixtures ; carbon dioxide ; cylindrical resonator ; electrostatic transducers ; ethane ; gas ; isotherm ; methane ; mixtures ; multicomponent ; mixtures ; natural gas ; nitrogen ; propane ; sound speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A description of a fixed-path length acoustic resonator which uses electrostatic transducers for sound generation and detection is given. Also, a summary of the measurements on 13 binary and 4 multicomponent gas mixtures of natural gas components is given. Data were obtained at pressures to 10 MPa for five isotherms at 25 K increments from 250 to 350 K. The binary mixtures are primarily methane-rich, with either ethane, nitrogen, carbon dioxide, or propane as the second constituent. The multicomponent mixture compositions represent four naturally occurring natural gas mixtures.
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  • 98
    Electronic Resource
    Electronic Resource
    Springer
    Biodegradation 10 (1990), S. 309-328 
    ISSN: 1572-9729
    Keywords: estuaries ; groundwater ; nitrogen ; nitrogen cycle ; nitrogen loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We examined the importance of nitrogen inputs from groundwater and runoff in a small coastal marine cove on Cape Cod, MA, USA. We evaluated groundwater inputs by three different methods: a water budget, assuming discharge equals recharge; direct measurements of discharge using bell jars; and a budget of water and salt at the mouth of the Cove over several tidal cycles. The lowest estimates were obtained by using a water budget and the highest estimates were obtained using a budget of water and salt at the Cove mouth. Overall there was more than a five fold difference in the freshwater inputs calculated by using these methods. Nitrogen in groundwater appears to be largely derived from on site septic systems. Average nitrate concentrations were highest in the region where building density was greatest. Nitrate in groundwater appeared to behave conservatively in sandy sediments where groundwater flow rates were high (〉 11/m2/h), indicating that denitrification was not substantially reducing external nitrogen loading to the Cove. Nitrogen inputs from groundwater were approximately 300 mmol-N/m3/y of Cove water. Road runoff contributed an additional 60 mmol/m3/y. Total nitrogen inputs from groundwater and road runoff to this cove were similar in magnitude to river dominated estuaries in urbanized areas in the United States.
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  • 99
    ISSN: 1573-5087
    Keywords: Lemna gibba ; cytokinins ; isopentenyladenosine ; zeatinriboside ; abscisic acid ; nitrogen ; phosphorus ; relative growth rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relationship between endogenous cytokinin content and relative growth rate (RGR) was studied in cultures of Lemna gibba L. G3 supplied with daily doses of mineral nutrients that were increased exponentially over time. At the optimal level of nutrient supply the RGR was 30–35% day-1. The RGR was regulated by adjusting the rate of nitrogen supply, or it was restricted by addition of 0.5 μM abscisic acid (ABA). Another approach used to investigate the specific roles of nitrogen (N) and phosphorus (P), was to transfer optimally growing plants to media without N or P but otherwise complete. The plants were harvested at regular intervals for determination of the RGR and levels of cytokinins of the isopentenyladenosine (iPA) and zeatinriboside (ZR) types with an enzyme-linked immunosorbent assay (ELISA). Levels of both iPA- and ZR-type cytokinins decreased when nitrogen was applied to cultures in growth limiting amounts. The cytokinin levels decreased more rapidly than the RGR when either N or P was lacking in the medium, suggesting an early influence of nutrient availability on cytokinin levels which in turn may induce adaptive response by the plant. RGR retardation induced by ABA did not affect cytokinin levels during the first 4 days of the treatment, and the later effects were small. The experiments gave no indication that ABA is involved in the adaptation response of Lemna plants to nutritional stress.
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  • 100
    ISSN: 1573-5117
    Keywords: phytoplankton ; primary production ; phosphorus ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Lake Erken climatic factors such as duration of ice cover, snow-depth and insolation govern the phytoplankton development and the species composition during the spring, with significant variations from year to year. Generally the small diatom, Stephanodiscus hantzschii var. pusillus creates a conspicuous peak at ice-break. In some years motile dinoflagellates start to develop under the ice already in early March, which results in a much longer spring bloom. The highest biomasses were recorded in 1954–1955 with values up to 11 mg 1−1 of fresh weight. The chlorophyll a concentrations have at most reached an epilimnetic average of 30 µg 1−1. The primary production reached a maximum value of 2200 mg C m−2 d−1 in 1955 and the average production for two months during the spring varied from 30 to 64 mg C m−3 d−1. Concerning nutrients, phosphorus was shown to be the limiting nutrient at the end of the spring bloom. This fact was confirmed by orthophosphate concentrations, algal surplus phosphorus content and alkaline phosphatase activity, as well as estimations of inorganic N : P and C : P ratios and nutrient enrichment experiments
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