Abstract:
Between December 2012 and March 2013, snow measurements were conducted in 3 snow pits at both Gourlay Snowfield and Tuva Glacier, Signy Island, to determine the primary and bacterial production within the snowpacks. Sites are denoted 'TX' and 'GY', where 'X' and 'Y' are numbers representing one of nine snowpits in a grid at Tuva and Gourlay respectively. Snow samples of the 'top' layer were taken from the surface snow layer at a depth of 0 to 20 cm from the surface; snow samples of the middle 'mid' layer were taken from 20 cm to the bottom of the snow pit; and samples from the 'ice' layer were taken from the superimposed ice at the bottom of the snow pit. Snow samples of the top and middle layer only were used for primary production, whilst bacterial production also included the lower ice layer. Samples collected from the pits were processed at Signy Station laboratory before being transported to the UK for further analysis.
Funding was provided by the NERC grants NE/H014446/1 and NE/H014802/1.
Keywords:
Bacterial production, Glacier, Primary production, Signy Island, Snow, Superimposed ice
| Access Constraints: | Requests for data can be made via the UK Polar Data Centre (UK PDC) at BAS. |
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| Use Constraints: | This data is governed by the NERC data policy http://www.nerc.ac.uk/research/sites/data/policy/ and supplied under Open Government Licence v.3 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ |
| Creation Date: | 2017-08-08 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
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| Parameters: |
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| Personnel: | |
| Name | UK PDC |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Dr Pete Convey |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Andy Hodson |
| Role(s) | Investigator |
| Organisation | University of Sheffield |
| Name | Dr David Pearce |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Dr Marie Sabacka |
| Role(s) | Technical Contact |
| Organisation | University of Bristol |
| Parent Dataset: | N/A |
| Reference: | Publication in progress. | |
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| Quality: | ||
| Lineage: | The selected pits formed a diagonal in the direction of the melt. Snow samples of top and middle layer were collected from these three pits and melted overnight. 150 ml of melted snow was added to B.O.D. borosilicate bottles to which 7.7 uCi (284.9 kBq) of 14C bicarbonate was added. 5 replicates for each sample: 3 clear bottles (live), 1 bottle dark bottle that did not allow any light penetration (dark) and a bottle to which 5% of filtered buffered parafolmaldehyde was added (kill). Microorganisms in the 'kill' bottle were killed with formaldehyde prior to the addition of the 14C isotope. Bottles were in clear plastic trays filled with snow and added onto the surface of the pit (TOP) or buried at the bottom of the pit (MID). Samples were incubated for 24 hours. Low light condition was ensured when handling the samples by using a shelter to cover from sunlight. Isotope was added just prior to experiment on site. The trays with vials were attached to snow stakes with ropes to ensure no movement. The experiment was conducted at the beginning of the season (December) and at the end of the season (March). At the end of the incubation, samples were put into a dark box and immediately transferred to the Signy laboratory (up to 1 hour). Afterwards, samples were filtered in darkened lab under low pressure (<7 psi) onto 25 mm GFF filters (combusted at 450°C for 5 hours) that were carefully positioned at the bottom of clean glass scintillation vials. 0.5 ml of 3N HCl was added to each vial and samples were dried in a fume hood at 60°C for up to 8 hours. Scintillation vials containing dried filters were transported to Sheffield University at room temperature. In the laboratory, 10 ml of scintillation cocktail was added to each sample and run on Scintillation counter. Disintegration per minute (dpm) was calculated on scintillation counter and recalculated to uptake of carbon in .micro grams (ug) of Carbon per litre (l) per day (d). Bacterial production uptake was measured using leucine uptake incubation following modified version of method described by Smith et al. (1992). Briefly: snow and ice were collected into autoclaved and acid-washed 1 L amber HDPE bottles. Samples were melted overnight at +4°C. 1.5 ml of snow or ice melted was added to a 2 mL plastic centrifuge tubes (autoclaved). Five replicates per sample: three live controls and two kill controls. Each sample contained 4.4 µCi (162.8 kBq) of tritiated leucine, wiith final concentration of 20nM leucine per sample. Kill controls were killed with 100 µl of 100% cold trichloroacetic acid (TCA) prior to the addition of 3H isotope (final concentration %). Tray with vials was covered in aluminium foil in order to prevent light penetration and was placed at the same site of sampling and incubated for 24 hours. The experiment was stopped by addition of 100 µl of 100% TCA. Samples were kept at +4 C and in the dark prior and during transportation to the laboratory in Sheffield. 1.5 mL of scintillation cocktail (Monophase®) was added to each sample. Disintegration per minute (dpm) was calculated on scintillation counter and recalculated to uptake of carbon in .micro grams (ug) of Carbon per litre (l) per day (d). |
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| Temporal Coverage: | |
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| Start Date | 2012-12-01 |
| End Date | 2013-03-31 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -60.726 |
| Northernmost | -60.709 |
| Longitude | |
| Westernmost | -45.644 |
| Easternmost | -45.607 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Location: | |
| Location | Antarctica |
| Detailed Location | Gourlay Snowfield and Tuva Glacier, Signy Island |
| Data Collection: | Instrumentation used: Scintillation counter |
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| Data Storage: | Data is in Excel format and is approximately 14KB. |
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