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  • 1
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    Snowpack chemistry, nitrate stable isotopes and net deposition fluxes from the largest ice-free region in Greenland
    PANGAEA
    In:  Supplement to: Curtis, Chris J; Kaiser, Jan; Marca, Alina; Anderson, N John; Simpson, Gavin; Jones, Vivienne; Whiteford, Erika (2018): Spatial variations in snowpack chemistry, isotopic composition of NO₃⁻ and nitrogen deposition from the ice sheet margin to the coast of western Greenland. Biogeosciences, 15(2), 529-550, https://doi.org/10.5194/bg-15-529-2018
    Details
    Publication Date: 2023-05-12
    Description: Snowpack chemistry, nitrate stable isotopes and net deposition fluxes for the largest ice-free region in Greenland 15 were investigated to determine whether there are spatial gradients from the ice sheet margin to the coast linked to a gradient in precipitation. Late-season snowpack was sampled in March 2011 at 8 locations within 3 lake catchments in each of 3 regions (ice sheet margin in the east, central area near Kelly Ville and the coastal zone to the west). At the coast, snowpack accumulation averaged 181 mm snow water equivalent (SWE), compared with 36 mm SWE by the ice sheet. Coastal snowpack showed significantly greater concentrations of marine salts (Na+, Cl-, other major cations), ammonium (regional means 1.4-2.7 µmol/l), total and non-sea salt sulfate (total 1.8-7.7, non-sea salt 1.0-1.8 µmol/l) than the two inland regions. Nitrate (1.5-2.4 µmol/l) showed significantly lower concentrations at the coast. Despite lower concentrations, higher precipitation at the coast results in a strong deposition gradient for NO3- as well as NH4+ and non-sea salt sulfate (nss-SO4^2-) increasing from the inland regions to the coast (lowest at Kelly Ville 6, 4 and 3; highest at coast 9, 17 and 11 mol/ha/yr of NO3-, NH4+ and nss-SO4^2- respectively). The d15N of snowpack NO3- shows a significant decrease from the ice sheet margin (-7.5 per mil) to the coast (-11.3 per mil). We attribute the spatial gradient of d15N in SW Greenland to post-deposition processing rather than differing sources because of 1) the climatic gradient from ice sheet margin to coast, 2) within catchment isotopic differences between terrestrial snowpack and lake-ice snowpack, and 3) similarities between fresh snow (rather than accumulated snowpack) at Kelly Ville and the coast. Hence the d15N of coastal snowpack is most representative of snowfall in SW Greenland, but after deposition the effects of photolysis, volatilization and sublimation lead 30 to enrichment of the remaining snowpack with the greatest effect in inland areas of low precipitation and high sublimation losses.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 2
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    Snow mass and depth determination from the largest ice-free region in Greenland (2018)
    PANGAEA
    Details
    Publication Date: 2023-01-13
    Keywords: Comment; DEPTH, ice/snow; ELEVATION; Greenland_Kelly-Ville; LATITUDE; Location; LONGITUDE; Mass; Sample comment; Sample ID; Site; SNOW; Snow/ice sample; Snow water equivalent; West Greenland
    Type: Dataset
    Format: text/tab-separated-values, 5783 data points
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  • 3
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    Snowpack chemistry and isotopes determination from the largest ice-free region in Greenland (2018)
    PANGAEA
    Details
    Publication Date: 2023-02-12
    Keywords: ALTITUDE; Ammonium; Calcium; Chloride; DATE/TIME; Greenland_Kelly-Ville; LATITUDE; Location; LONGITUDE; Magnesium; Nitrate; Nitrite; Phosphate; Potassium ion; Sample ID; Sample type; Site; SNOW; Snow/ice sample; Sodium ion; Sulfate; West Greenland; Δ17O, nitrate; δ15N; δ17O; δ18O
    Type: Dataset
    Format: text/tab-separated-values, 1290 data points
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  • 4
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    (Table 1) Radiocarbon dating of a lake sediment core, southern West Greenland (2008)
    PANGAEA
    In:  Supplement to: Anderson, N John; Brodersen, Klaus P; Ryves, David B; McGowan, Suzanne; Johansson, Liselotte S; Jeppesen, Erik; Leng, Melanie J (2008): Climate versus in-lake processes as controls on the development of community structure in a low-arctic lake (South-West greenland). Ecosystems, 11(2), 307-324, https://doi.org/10.1007/s10021-007-9123-y
    Details
    Publication Date: 2023-12-13
    Description: The dominant processes determining biological structure in lakes at millennial timescales are complex. In this study, we used a multi-proxy approach to determine the relative importance of in-lake versus indirect processes on the Holocene development of an oligotrophic lake in SW Greenland (66.99°N, 50.97°W). A 14C and 210Pb-dated sediment core covering approximately 8500 years BP was analyzed for organic-inorganic carbon content, pigments, diatoms, chironomids, cladocerans, and stable isotopes (d13C, d18O). Relationships among the different proxies and a number of independent controlling variables (Holocene temperature, an isotope-inferred cooling period, and immigration of Betula nana into the catchment) were explored using redundancy analysis (RDA) independent of time. The main ecological trajectories in the lake biota were captured by ordination first axis sample scores (18-32% variance explained). The importance of the arrival of Betula (ca. 6500 years BP) into the catchment was indicated by a series of partial-constrained ordinations, uniquely explaining 12-17% of the variance in chironomids and up to 9% in pigments. Climate influences on lake biota were strongest during a short-lived cooling period (identified by altered stable isotopes) early in the development of the lake when all proxies changed rapidly, although only chironomids had a unique component (8% in a partial-RDA) explained by the cooling event. Holocene climate explained less variance than either catchment changes or biotic relationships. The sediment record at this site indicates the importance of catchment factors for lake development, the complexity of community trends even in relatively simple systems (invertebrates are the top predators in the lake) and the challenges of deriving palaeoclimate inferences from sediment records in low-Arctic freshwater lakes.
    Keywords: Age, 14C AMS; Age, 14C calibrated, CALIB (Stuiver & Reimer, 1993); Age, dated; Age, dated material; Age, dated standard deviation; Age, maximum/old; Age, minimum/young; Calendar age; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Greenland; International Polar Year (2007-2008); IPY; Lake_SS2; RUSC; Russian corer; Sample ID; δ13C
    Type: Dataset
    Format: text/tab-separated-values, 40 data points
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  • 5
    Electronic Resource
    Electronic Resource
    Validation of a diatom–phosphorus calibration set for Sweden (2001)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. A weighted averaging (WA) regression and calibration model for diatoms and total phosphorus (TP) was developed from a dataset of 45 surface-sediment samples from Swedish lakes. Jack-knifed error statistics were comparable with those for similar diatom–TP datasets: r2jack=0.47, root mean squared error of prediction (RMSEP)=0.24 log10μg TP L–1 and mean bias=–0.002 log10 μg TP L–1 for the simple WA model; r2jack=0.36, RMSEP=0.27 log10 μg TP L–1 and mean bias=0.017 log10 μg TP L–1 for WA with tolerance downweighting.2. The model was used to estimate TP concentrations for the Ekoln basin of Lake Mälaren using a 210Pb-dated sediment core record. Highly eutrophic conditions developed in the basin in the 1960s as a result of nutrient inputs from cultivated land and the city of Uppsala. A reduction in the supply of phosphorus from sewage outlets in the late 1960s resulted in less eutrophic conditions.3. The model results indicated levels of 50–60 μg TP L–1 prior to 1900. The rapid eutrophication of the lake basin after the 1950s and the subsequent recovery were evident from the diatom data.4. Diatom-inferred TP (DI–TP) values were validated by comparison with monitored data for the period 1966–95. The diatom model tended to underestimate TP at high levels (〉 80 μg L–1) but overestimate at lower concentrations.5. A good agreement was observed between the trends in TP concentration and the DI–TP concentration and the timing of the maximum was well reflected by the diatom-based reconstruction. A significant correlation (r2=0.69, P 〈 0.01) was found between DI–TP and measured TP at this site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00732.x
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  • 6
    Electronic Resource
    Electronic Resource
    Phosphorus dynamics in Danish lakes and the implications for diatom ecology and palaeoecology (2002)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 47 (2002), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY 1. Seasonal phosphorus variability may be considerable in eutrophic lakes and patterns are influenced by internal, as well as external, nutrient loading. The strong seasonality of planktonic diatoms, with main growth periods in the spring and also in the autumn in meso- to eutrophic lakes, means that the measure of total phosphorus (TP) that is most relevant for diatom ecology may not be adequately assessed by single or few measurements during the year.2. The diatom species assemblage of surface sediments can be used to infer in-lake nutrient concentrations. Weighted averaging (WA) and weighted averaging partial least squares (WAPLS) regression and calibration models for diatoms and annual mean TP were developed for a 29-site data set of Danish lakes based on (a) all diatom species and (b) planktonic species only. Jack-knifed error statistics were: 〈inlineGraphic alt="inline image" href="urn:x-wiley:00465070:FWB938:FWB_938_mu1" location="equation/FWB_938_mu1.gif"/〉=0.37, root mean squared error of prediction (RMSEP)=0.28 log10μg TP L−1 and mean bias=0.04 log10μg TP L−1 for the WAPLS 2-component model based on all species; 〈inlineGraphic alt="inline image" href="urn:x-wiley:00465070:FWB938:FWB_938_mu2" location="equation/FWB_938_mu2.gif"/〉=0.23, RMSEP= 0.32log10μg TP L−1 and mean bias=0.07 log10μg TP L−1 for the WA model with tolerance downweighting based on planktonic species only. These are comparable with similar, published data sets.3. A subset of 23 sites was used to develop models based on seasonal TP measurements. Mean spring TP concentrations gave only slightly improved RMSEP values for models based on all species and plankton-only (0.24 log10μg TP L−1 and 0.29 log10μg TP L−1, respectively).4. Weighted averaging models derive environmental optima, for individual species, which are not necessarily of ecological relevance. However, good water chemistry data are required to model species' responses adequately and to develop calibration data sets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2002.00938.x
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  • 7
    Electronic Resource
    Electronic Resource
    Distribution of chironomids (Diptera) in low arctic West Greenland lakes: trophic conditions, temperature and environmental reconstruction (2002)
    Oxford UK : Blackwell Science Ltd
    Freshwater biology 47 (2002), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Surface sediment samples of subfossil chironomid head capsules from 47 lakes in southern West Greenland were analysed using multivariate numerical methods in order to explore the relationship between chironomid assemblages and selected environmental variables. The study lakes are located along a climate gradient ranging from coastal maritime conditions near the Davis Strait to a continental climate near the margin of the Greenland ice sheet.2. High-resolution surface water temperatures were measured through the summer season using automatic data loggers in 21 of the study lakes. The mean July surface water temperature (1999) ranged from 7.3 to 16.5 °C in the data set.3. In all lakes, a total of 24 chironomid taxa were recorded; Micropsectra, Psectrocladius, Chironomus and Procladius were the dominant genera. There was a strong correlation between the trophic variables [total nitrogen and total phosphorus (TN, TP)] and temperature, and in redundancy analysis (RDA) the three variables explained almost equal significant amounts of variation in the chironomid data (19.8–22.3%). However, temperature lost significant explanatory power when the effect of TN was partialled out in RDA.4. The lakes were classified using two-way indicator species analysis (TWINSPAN) into eight groups defined by temperature, trophic variables, salinity (conductivity) and lake-morphometric data. Fourteen chironomid taxa showed significant differences in percentage abundances among groups, with Heterotrissocladius, Micropsectra, Ablabesmyia and Chironomus as the most robust group-indicator taxa. Forward selection of taxa in multiple discriminant analysis was used to fit chironomid assemblages into lake groups. Using only eight taxa, 95% of lakes were correctly classified at a second TWINSPAN division level (four groups) and 85% of lakes at a third division level (eight groups).5. This study showed that there is considerable potential in using subfossil chironomid head capsules as paleoenvironmental indicators in both short- and long-term (down-core) studies of lake ontogeny and palaeoclimate conditions in West Greenland. However, because of the strong correlation between temperature and trophic variables, a quantitative reconstruction of lake- and habitat-type is recommended, in combination with direct reconstruction of single variables such as temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2002.00831.x
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  • 8
    Electronic Resource
    Electronic Resource
    Chironomid stratigraphy in the shallow and eutrophic Lake Søbygaard, Denmark: chironomid–macrophyte co-occurrence (2001)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 46 (2001), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. A sediment core from the shallow, hypertrophic Lake Søbygaard (mean depth ∼1 m; [TP] 310 μg P L−1) was analysed for subfossil remains to reconstruct chironomid community changes in relation to the succession and disappearance of aquatic macrophytes. 
2. Species composition in the 1.10 m core indicates a succession from a ‘naturally’ eutrophic state to a hypertrophic state during recent centuries. Radiometric dating (210Pb) of the uppermost 20 cm of the sediment core (∼1932–93) indicates that sediment accumulation rate had doubled in recent decades. 
3. Changes in chironomid assemblages were in close agreement with changes in both diatoms and macrophyte remains in the same core. Distinct changes in chironomid communities reflect the eutrophication process and macrophyte succession through Chara, Ceratophyllum and Potamogeton dominance to the present state, with complete loss of submerged vegetation and dominance by phytoplankton. 
4. The co-occurrence and relationship between aquatic macrophyte diversity and recent subfossil chironomid assemblages were assessed from an additional 25 Danish lakes. There was good agreement between the macrophyte and chironomid-based lake groupings. Overall, a significant difference (P〈0.001) was found in chironomid assemblages among lakes in different macrophyte classes. In a pair-wise comparison, the poorly buffered mesotrophic lakes and the alkaline eutrophic lakes had significantly different chironomid assemblages. 
5. Chironomid taxa commonly reported to be associated with macrophytes (Cricotopus, Endochironomus and Glyptotendipes) were shown also to be indicators of highly productive lakes lacking abundant submerged vegetation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2001.00652.x
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  • 9
    Electronic Resource
    Electronic Resource
    Variability of diatom-inferred phosphorus profiles in a small lake basin and its implications for histories of lake eutrophication (1998)
    Springer
    Journal of paleolimnology 20 (1998), S. 47-55 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; spatial variability ; canonical correspondence analysis ; lake eutrophication ; transfer functions ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatom analyses were undertaken of sediment cores covering a range of water depths in a small eutrophic lake (Lough Augher, Co. Tyrone, N. Ireland). The significance of between-core variability in diatom relative frequency stratigraphy was assessed by Canonical Correspondence Analysis (CCA) where the ordination axes were constrained to external environmental variables (sediment depth, core location coordinates, water depth, effective fetch, distance-from-shore and distance-from-inflow). After the removal of the effect of sediment age by partialling it out, the resultant first two axes from the partial-CCA were significantly correlated with water depth and distance-from-shore, indicating non-uniform diatom stratigraphies across the lake. Despite this variability, all cores show the same succession of species and, therefore, record the eutrophication of the lake. Diatom-inferred total phosphorus (DI-TP) was inferred for six cores using weighted averaging regression and calibration. Apart from considerable differences of DI-TP in surficial sediment samples, there was good between-core repeatability of DI-TP profiles. These data support the use of DI-TP for establishing background nutrient concentrations for lakes, and associated implications for lake restoration schemes using single cores. Comparisons of DI-TP profiles and total diatom accumulation rate data for the individual cores indicate that diatom production peaked prior to the maximum TP concentrations in the lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007923813511
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  • 10
    Electronic Resource
    Electronic Resource
    Learning from the past: Diatoms as palaeoecological indicators of changes in marine environments (1992)
    Springer
    Aquatic ecology 26 (1992), S. 19-30 
    Details
    ISSN: 1573-5125
    Keywords: palaeoecology ; diatoms ; North Sea ; The Netherlands ; transfer functions ; weighted averaging ; coastal changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The North Sea is seriously threatened by a variety of pollution sources. Terrestrially derived effluents are causing extensive environmental damage and changes to ecosystems of both the offshore and coastal waters. Coastal and estuarine communities are being lost to reclamation projects, and there is the future threat of rising sea level associaed with global warming. The spatial and temporal extent of recent anthropogenic changes are largely unknown due to the paucity of background information. The possible role of palaeoecological methodology in providing ‘reference levels’ against which current status can be compared, and their importance for restoration and policy decisions, are presented. The usefulness of diatoms as environmental indicators is illustrated. The extent of natural and anthropogenic changes on coastal habitats are demonstrated by reference to the Holocene evolution of the coastline of The Netherlands. Possible profitable areas for further research are outlined,e.g. a diatom nutrient calibration data set for shallow marine embayments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02298025
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