Nitrate-rich inland waters of the Ross Ice Shelf region, Antarctica
Abstract: Nutrient and major ion concentrations were measured in surface water samples from lakes, ponds and streams at sites 30-320 km south of McMurdo Sound: the Darwin Glacier region (79.7-8O.O0S), Pyramid Trough in the southern Dry Valleys (78.2"S), and the McMurdo Ice Shelf ablation zone (...
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| Format: | Text |
| Language: | English |
| Published: |
1994
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1075.4454 http://www.cen.ulaval.ca/warwickvincent/PDFfiles/88.pdf |
| Summary: | Abstract: Nutrient and major ion concentrations were measured in surface water samples from lakes, ponds and streams at sites 30-320 km south of McMurdo Sound: the Darwin Glacier region (79.7-8O.O0S), Pyramid Trough in the southern Dry Valleys (78.2"S), and the McMurdo Ice Shelf ablation zone (77.8-78.4"s). These aquatic environments ranged from dilute meltwaters (conductivity < 0.05 mS cm-l) to concentrated brines (> 50 mS cm-I). The lowest nitrate concentrations were recorded at the sites closest to the seasonally open waters of the Ross Sea. Muchhighervalues(100-142000mgNO~-N~3)wererecordedat sitesfurthersouth. Theseobservationssupport the hypothesis that NO; precipitation over Antarctica is of stratospheric rather than coastal marine origin. The nitrogen-rich waters contained chloride and nitrate in the ratio 5.45 g C1 : 1 g N (C.V. = 8.4%) which is within therange forAntarcticsnow, and indicativeofnitrate enrichment by freeze concentrationprocesses. Cyanobacterial mats were conspicuous elements of the biota across the full range of salinities, and were usually dominated by oscillatoriacean species. Nitrogen-fixing cyanobacteria and diatoms were also represented in these benthic microbial communities at the more northern sites, but were absent from all samples from the Darwin Glacier region. |
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