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1. Dissolved organic carbon (DOC) concentration was determined for a range of lakes of varying conductivity (30–4000 μS cm−1) in the low Arctic of SW Greenland. DOC concentration range from <1 to >100 mg C L−1, occasionally approaching 200 mg C L−1 in meromictic, oligosaline lakes. DOC concentration was strongly related to [log10] conductivity and total nitrogen. 2. Peak DOC concentrations (>80 mg L−1) occur in lakes located approximately 50 km from the present ice sheet margin, a zone of low effective precipitation; evaporative concentration is the first-order control on DOC concentration. Lakes at the coast and closer to the ice margin had lower DOC concentrations (<20 mg C L−1). Local factors, notably the presence or absence of an outflow and catchment morphometry, resulted in considerable variability in concentration (20–100 mg C L−1) within the area of maximum concentration around 51°W. 3. Despite their high DOC concentration, these lakes are essentially colourless. Dissolved organic matter (DOM) absorption ( a375) was low in most lakes (<10 m−1) with maximum values (approximately 20 m−1) occurring in one humic-stained lake in the area. Absorption values corrected for DOC concentration ( ) were very low (<0.6 m2 g−1 C) for all lakes apart from those at the coast, perhaps reflecting greater allochthonous inputs at these sites. 4. S, the spectral slope coefficient, ranged from 16 to 27 μm−1 and was weakly correlated with DOC concentration. Both a375 and S showed similar distribution patterns along the sampling gradient as did DOC, with maximum values at approximately 51°W. High and low S may indicate fresher, more rapidly flushed, systems with less degraded DOM or greater inputs from their catchments. 5. The lakes closer to the head of the fjord with higher conductivity, had low (<0.2 m2 g−1 C) and high S (>21 μm−1) and this may reflect increasingly longer lake water residence times, greater DOM age and photochemical degradation. [ABSTRACT FROM AUTHOR]

We analyzed the relationship between chrysophyte cyst assemblages in surface sediment samples and limnological and geographical variables for 70 lakes located along Søndre Strømfjord in southwest Greenland. Over 247 stomatocysts were identified and of these, 153 were sufficiently abundant for use in statistical analyses. Eight stomatocysts were considered to be new and are described formally. Canonical correspondence analysis indicated that conductivity was the dominant variable explaining cyst distribution, reflecting the large conductivity gradient in lake water chemistry in this area. High conductivity lakes had distinctive cyst assemblages with lower diversity than low alkalinity lakes, where assemblages were similar to alpine soft-water lakes elsewhere. The high conductivity lakes, however, had similar cysts to other saline lakes elsewhere in the arctic. Additionally, pH, calcium, maximum depth, longitude, sulfate, total phosphorus, and altitude all explained significant amounts of variability of cyst assemblages. Longitude was the only geographical variable that explained cyst variability independently of other variables (i.e. had a unique effect), which suggests that the climatic gradient from the coast to the head of the fjord has a structuring effect on cyst assemblages. Conductivity (weighted-averaging partial least squares, r2=0.917; root mean square error=0.142; r2jack=0.861, root mean square error of prediction=0.191) and pH inference models (weighted averaging, r2=0.924; root mean square error=0.158; r2jack=0.826, root mean square error of prediction=0.240) were developed. For the pH model, high conductivity lakes (>800 μS20·cm−1) were removed. Both models are statistically robust and could be applied to lakes in west Greenland to reconstruct conductivity and/or pH. Such paleolimnological reconstructions provide the means of acquiring long-term data for use in the evaluation of, for example, regional paleoclimatic models. [ABSTRACT FROM AUTHOR]

Physical and chemical profiles of a shallow (c. 12-m-deep) subsaline (total dissolved solids 2.3–2.8 g l-1) closed-basin lake in the continental area of southwestern Greenland are described for the first time. Watercolumn data for every 5th consecutive day between April 20 and October 6, 2001, and continuous recordings of lake water level and meteorological conditions are used to infer controls on contemporary lake functioning, sediment formation and climate–lake interactions. Limnological observations demonstrate the importance of lake-ice formation and its role in haline convection and the development of meromixis. Observed lake cycling suggest that the lake at present is in a state of near-meromixis where stagnant bottom waters de-stratify through deep penetration of weak haline convective cells by the end of June. From this study, the primary reasons the shallow Greenlandic low salinity lakes develop meromixis are: (i) lack of an outflow (ii) meltwater dilution and chemical stratification of surface waters, (iii) insubstantial wind mixing, (iv) a weak winter thermohaline convective cell forced by cryoconcentration, and (v) biogeochemically enhanced solute concentrations near the sediment bed. Throughout the open water period the hydrological balance is dominated by evaporative losses. Lake surface water conductivities change from 2110 to 2890 μS cm-1 due to the combined effects of open water evaporation, meltwater dilution, diffusive exchanges over the seasonal pycnocline, and boundary mixing. Freeze-out of salts and resulting deep haline convection increase overall water column salinity during winter. Owing to deep convective mixing, plant nutrients are relatively high in the upper watercolumn with a dominant internal source of phosphorous. Extreme productivity pulses of phytoplankton are observed as soon as sub-ice radiation levels increase and directly after ice-out when sufficient wind mixing can support an intense monospecific diatom bloom of Diatoma spp. leading to the rapid depletion of dissolved silica. [ABSTRACT FROM AUTHOR]