Jill Mikucki 2015-01-28 tabular digitial data McMurdo Dry Valleys LTER McMurdo Dry Valleys LTER 10.6073/pasta/dc7b513f0ae8a640ef186df53ff02b6c https://mcm.lternet.edu/content/taylor-glacier-blood-falls-geomicrobiology Blood Falls, a subglacial discharge from the Taylor Glacier, Antarctica provides an example of the diverse physical and chemical habitats available for life in the polar desert of the McMurdo Dry Valleys. Geochemical analysis shows that Blood Falls outflow resembles concentrated seawater remnant from the Pliocene intrusion of marine waters combined with products of weathering. The result is an iron-rich, salty seep at the terminus of Taylor Glacier, which is subject to episodic releases into permanently ice-covered Lake Bonney. Blood Falls influences the geochemistry of Lake Bonney, and provides organic carbon and viable microbes to the lake system. Presented here is the first data on the geobiology of Blood Falls, and relate it to the evolutionary history of this unique environment. The novel geological evolution of this subglacial environment makes Blood Falls an important site for the study of metabolic strategies in subglacial environments, and the impact of subglacial efflux on associated lake ecosystems. The subglacial outflow of Blood Falls provides a surface feature where samples representative of the subglacial environment can be obtained. The presence of metabolically active, subglacial microbial communities could significantly affect biogeochemical cycling on glacial and interglacial timescales (Sharp et al., 1999). This ancient saline subglacial system also provides an important site for exobiological studies, as similar environments may exist under the Martian polar caps or subsurface terrain today. The goals of this study was to examine the microbiology of the site and couple these observations to it's in-situ geochemistry. 1999-09-01 2004-03-16 ground condition As needed Red River art Blood Falls ID: red_bfalls 162.268051147461 162.268051147461 -77.723335266113 -77.723335266113 [term:vocabulary] None <cntorg>McMurdo Dry Valleys LTER</cntorg> <onlink>http://mcmlter.org/</onlink> <span property="dc:title" content="McMurdo Dry Valleys LTER" class="rdf-meta element-hidden"></span> Name: Christine Foreman Role: associated researcher Name: W. Berry Lyons Role: associated researcher Name: Inigo San Gil Role: data manager Not Applicable Not Applicable Field and/or Lab Methods Sample Collection Samples were collected from subglacial outflow waters associated with Blood Falls discharge during austral summers from 1999-2003. Samples near the outlet of Blood Falls were collected for enumeration and bacterial activity in December of 2000 and 2001. A transect of samples (TransX) was collected in December (see Figure 1), 2002 to capture a profile of releases from Blood Falls into Lake Bonney, starting at the source of the outflow (Trans1) and out onto the moat ice surrounding the lake with increasing distance from the source (Trans2-5). Trans2 was collected from basal ice below the source, Trans3 was collected from waters at the shoreline where Blood Falls meets the moat ice, Trans4 was collected 5 m from the shoreline just below moat ice that melted and refroze daily, and Trans5 was collected under 0.4 m of moat ice approximately 70 m from the shoreline before the moat ice meets the permanent ice cover of Lake Bonney. Autoclaved metal spatulas were used to scrape ice samples into sterile plastic bags (Whirl-Pak) or sterile plastic conical tubes (Falcon). Subsequent manipulations were carried out aseptically in a positive flow hood. Subglacial flow water was collected in clean Nalgene bottles for geochemical analysis. All ice samples were melted slowly at 2-4 °C in sterile containers before analysis. Samples for analysis of dissolved organic carbon were collected in acid-washed, combusted (450 °C for &gt; 4h) amber glass bottles. Dissolved inorganic carbon samples were collected in gas tight glass serum vials. Samples collected for bacterial enumeration were treated with formalin (2% final concentration) to prevent a change in bacterial numbers during storage (~ 2 weeks) before counting Geochemistry The pH was measured with a calibrated Beckman Φ12 pH meter. Eh was measured using a Hach ORP combination electrode (Hach Company, Loveland, CO) connected to a Beckman Φ12 digital voltmeter, with corrections for the reference electrode made in accordance with the ORP electrode instruction manual. Dissolved oxygen (DO) was determined by Winkler titration (Standard Methods, 1992). Dissolved inorganic carbon (DIC) was measured by infrared gas analysis on acid sparged samples. Dissolved organic carbon (DOC) was measured on filtered (25mm Whatman GF/F), acidified (HCl to pH~2-3) samples with a Shimadzu 5000 TOC analyzer. Nitrate (NO3-) and nitrite (NO2-) concentrations in water samples were measured with a Lachat autoanalyzer according to Standard Methods (1992). Nitrite levels were determined by diazotization, with sulfanilamide, and then coupled with a diamine to produce a pink dye, analyzed spectrophometrically on a Lachat autoanalyzer. Nitrate was reduced to nitrite by passing the sample through a copperized cadmium column and analyzing for nitrite, as above, giving a nitrate plus nitrite concentration. The nitrate concentration was determined by subtracting the nitrite concentration from the total (nitrate + nitrite) concentration. Ammonium (NH4+) concentrations were measured separately by reaction with alkaline phenol followed by sodium hypochlorite, forming indophenol blue. Sodium nitroprusside was added to enhance sensitivity and the sample was analyzed spectrophometrically on a Lachat autoanalyzer. Dissolved inorganic nitrogen (DIN) was reported as the summation of nitrate, nitrite and ammonium (DIN = NO3-+ NO2-+ NH4+). Soluble reactive phosphorus (SRP) was determined on 10 ml samples with the antimony- molybdate method (Standard Methods, 1992), absorbance was read in a 10 cm cell with a Beckman DU-640 spectrophotometer. Chlorophyll-a (CHL) was extracted into 90% acetone for 24 h at &lt;0 °C in the dark from particles collected on a Whatman GF/F filter, and the subsequent concentration was determined fluorometrically Conductivity was measured at 1-meter depth intervals in the west lobe of Lake Bonney using a Seabird SBE-25 conductivity temperature depth (CTD) sensor (Sea-Bird Electronics, Inc., Bellevue, Washington). Salinity was calculated using the UNESCO salinity algorithm available in the Seabird data acquisition software package (Sea-Bird Electronics, 1998). Modifications for the high salinity concentrations found below the halocline of Lake Bonney are described in Spigel and Priscu (1996). Total iron was determined using the ferrozine assay (Fulton et al., 2004). Microbial Activity Heterotrophic bacterial activity was measured using 3H-thymidine (20 nM) and 3H-leucine (20 nM) incorporation according to the methods described in Takacs and Priscu (1998). Formalin (5% final concentration)-treated replicates served as killed controls. Samples were incubated in the dark at 0-1 °C. Incubation was terminated by the addition of cold trichloroacetic acid (TCA) to a final concentration of 5%. The effect of temperature on the productivity of the natural bacterial assemblages from Blood Falls outflow was determined by incubating triplicate samples (10 mL) with 10 nM 3H-leucine for 24 h at varying temperatures using the methods described above. Doubling rates were calculated from the 3H-leucine incorporation data. Culture work Samples were collected for culture work during the austral summers (October – January) between 2001 and 2004 (Table 4.1). Outflow was collected directly into 74 mL serum vials by submerging the vials in the flow and crimp sealing them with a butyl rubber stopper with no head space. Serum vials were kept in the dark below 4 °C until return to McMurdo Station for incubation in selective media (approx 5-10 days). Media included R2A agar (Difco), Marine agar (Bacto) and thiosulfate-oxidizing agar (15%). Media are described in detail in Appendix C. Outflow sample (100 μl) was removed from the sealed serum vials with a 1 ml syringe, inoculated onto agar plates (15 g L-1), spread with a sterile cotton swab and incubated at 2-4o C until colonies appeared (about 3-4 weeks). Enrichments for autotrophic microbes were done in selective medium using the Hungate method (Hungate, 1969). Enrichments for iron-reduction were prepared by inoculating 0.5 ml of outflow collected as described above, into 4.5 ml mineral media that was prepared under CO2 gas and supplemented with Fe-OOH sludge (2 ml L-1), (Lovley and Phillips, 1986) and pressurized with H2 gas (30 psi), to a 0.7 M NaCl final concentration. Samples were serially diluted three times to a 10-3 extinction. DNA ExtractionSamples for environmental DNA extraction were collected directly from Blood Falls outflow during the 1999-00 austral summer (Table 4.1). Samples (1L) were kept chilled (below 4 °C) and filtered immediately upon returning to the field camp (~ 4 h). Cells were collected onto a 90 mm membrane filter, placed in a sterile plastic bag; heat sealed and stored at -20° C until extraction. Filters were cut into pieces using flame sterilized scissors and tweezers and then processed according to the manufacturer’s protocol (Mo Bio Laboratories, Inc. UltraClean Soil DNA Isolation Kit). The alternative protocol for maximum yields was followed. DNA extraction on a single isolated colony from each pure culture used the same methodology described above. 16S rDNA Clone Library ConstructionThe microbial 16S rDNA genes were amplified from extracted DNA using oligonucleotide primers 4F and 9F with 1492R (Table 4.2). Primers were purchased from Macromolecular Resources (Colorado State University). The 50-μl PCR reaction contained 5 μl DNA template, dNTPs nucleotide mix (Fisher Scientific, 200μM final concentration), bovine serum albumin (BSA) (0.5 μg/ μl), 0.5 μM final concentration of each primer, 10x Taq Buffer (1.5 mM Mg2+), 5x TaqMaster (a proprietary PCR enchancer, Eppendorf), and 1.25 units of Taq DNA polymerase (Eppendorf MasterTaq Kit). The reaction mixture was PCR amplified in an Eppendorf Mastercycler Gradient Thermal Cycler under conditions that included 15 sec of denaturation at 95o C, 45 sec of annealing at 55o C, and 1.5 min of primer extension at 72o C. These steps were repeated for 30 cycles. PCR products were purified using the QIAquick PCR purification kit (Qiagen) to remove primers, nucleotides, polymerases and salts. Purified PCR products were cloned using the pGEM-T Easy Vector System cloning kit with the pGEM-T Easy vector (Promega) according to the manufacturer’s protocol. Instrumentation:Beckman 12 pH meter Hach ORP combination electrode connected to a Beckman 12 digital voltmeter Shimadzu 5000 TOC analyzer Lachat autoanalyzer Beckman DU-640 spectrophotometer Seabird SBE-25 conductivity temperature depth (CTD) sensor Sample Collection Samples were collected from subglacial outflow waters associated with Blood Falls discharge during austral summers from 1999-2003. Samples near the outlet of Blood Falls were collected for enumeration and bacterial activity in December of 2000 and 2001. A transect of samples (TransX) was collected in December (see Figure 1), 2002 to capture a profile of releases from Blood Falls into Lake Bonney, starting at the source of the outflow (Trans1) and out onto the moat ice surrounding the lake with increasing distance from the source (Trans2-5). Trans2 was collected from basal ice below the source, Trans3 was collected from waters at the shoreline where Blood Falls meets the moat ice, Trans4 was collected 5 m from the shoreline just below moat ice that melted and refroze daily, and Trans5 was collected under 0.4 m of moat ice approximately 70 m from the shoreline before the moat ice meets the permanent ice cover of Lake Bonney. Autoclaved metal spatulas were used to scrape ice samples into sterile plastic bags (Whirl-Pak) or sterile plastic conical tubes (Falcon). Subsequent manipulations were carried out aseptically in a positive flow hood. Subglacial flow water was collected in clean Nalgene bottles for geochemical analysis. All ice samples were melted slowly at 2-4 °C in sterile containers before analysis. Samples for analysis of dissolved organic carbon were collected in acid-washed, combusted (450 °C for > 4h) amber glass bottles. Dissolved inorganic carbon samples were collected in gas tight glass serum vials. Samples collected for bacterial enumeration were treated with formalin (2% final concentration) to prevent a change in bacterial numbers during storage (~ 2 weeks) before counting Geochemistry The pH was measured with a calibrated Beckman Φ12 pH meter. Eh was measured using a Hach ORP combination electrode (Hach Company, Loveland, CO) connected to a Beckman Φ12 digital voltmeter, with corrections for the reference electrode made in accordance with the ORP electrode instruction manual. Dissolved oxygen (DO) was determined by Winkler titration (Standard Methods, 1992). Dissolved inorganic carbon (DIC) was measured by infrared gas analysis on acid sparged samples. Dissolved organic carbon (DOC) was measured on filtered (25mm Whatman GF/F), acidified (HCl to pH~2-3) samples with a Shimadzu 5000 TOC analyzer. Nitrate (NO3-) and nitrite (NO2-) concentrations in water samples were measured with a Lachat autoanalyzer according to Standard Methods (1992). Nitrite levels were determined by diazotization, with sulfanilamide, and then coupled with a diamine to produce a pink dye, analyzed spectrophometrically on a Lachat autoanalyzer. Nitrate was reduced to nitrite by passing the sample through a copperized cadmium column and analyzing for nitrite, as above, giving a nitrate plus nitrite concentration. The nitrate concentration was determined by subtracting the nitrite concentration from the total (nitrate + nitrite) concentration. Ammonium (NH4+) concentrations were measured separately by reaction with alkaline phenol followed by sodium hypochlorite, forming indophenol blue. Sodium nitroprusside was added to enhance sensitivity and the sample was analyzed spectrophometrically on a Lachat autoanalyzer. Dissolved inorganic nitrogen (DIN) was reported as the summation of nitrate, nitrite and ammonium (DIN = NO3-+ NO2-+ NH4+). Soluble reactive phosphorus (SRP) was determined on 10 ml samples with the antimony- molybdate method (Standard Methods, 1992), absorbance was read in a 10 cm cell with a Beckman DU-640 spectrophotometer. Chlorophyll-a (CHL) was extracted into 90% acetone for 24 h at <0 °C in the dark from particles collected on a Whatman GF/F filter, and the subsequent concentration was determined fluorometrically Conductivity was measured at 1-meter depth intervals in the west lobe of Lake Bonney using a Seabird SBE-25 conductivity temperature depth (CTD) sensor (Sea-Bird Electronics, Inc., Bellevue, Washington). Salinity was calculated using the UNESCO salinity algorithm available in the Seabird data acquisition software package (Sea-Bird Electronics, 1998). Modifications for the high salinity concentrations found below the halocline of Lake Bonney are described in Spigel and Priscu (1996). Total iron was determined using the ferrozine assay (Fulton et al., 2004). Microbial Activity Heterotrophic bacterial activity was measured using 3H-thymidine (20 nM) and 3H-leucine (20 nM) incorporation according to the methods described in Takacs and Priscu (1998). Formalin (5% final concentration)-treated replicates served as killed controls. Samples were incubated in the dark at 0-1 °C. Incubation was terminated by the addition of cold trichloroacetic acid (TCA) to a final concentration of 5%. The effect of temperature on the productivity of the natural bacterial assemblages from Blood Falls outflow was determined by incubating triplicate samples (10 mL) with 10 nM 3H-leucine for 24 h at varying temperatures using the methods described above. Doubling rates were calculated from the 3H-leucine incorporation data.Culture work Samples were collected for culture work during the austral summers (October – January) between 2001 and 2004 (Table 4.1). Outflow was collected directly into 74 mL serum vials by submerging the vials in the flow and crimp sealing them with a butyl rubber stopper with no head space. Serum vials were kept in the dark below 4 °C until return to McMurdo Station for incubation in selective media (approx 5-10 days). Media included R2A agar (Difco), Marine agar (Bacto) and thiosulfate-oxidizing agar (15%). Media are described in detail in Appendix C. Outflow sample (100 μl) was removed from the sealed serum vials with a 1 ml syringe, inoculated onto agar plates (15 g L-1), spread with a sterile cotton swab and incubated at 2-4o C until colonies appeared (about 3-4 weeks). Enrichments for autotrophic microbes were done in selective medium using the Hungate method (Hungate, 1969). Enrichments for iron-reduction were prepared by inoculating 0.5 ml of outflow collected as described above, into 4.5 ml mineral media that was prepared under CO2 gas and supplemented with Fe-OOH sludge (2 ml L-1), (Lovley and Phillips, 1986) and pressurized with H2 gas (30 psi), to a 0.7 M NaCl final concentration. Samples were serially diluted three times to a 10-3 extinction.DNA ExtractionSamples for environmental DNA extraction were collected directly from Blood Falls outflow during the 1999-00 austral summer (Table 4.1). Samples (1L) were kept chilled (below 4 °C) and filtered immediately upon returning to the field camp (~ 4 h). Cells were collected onto a 90 mm membrane filter, placed in a sterile plastic bag; heat sealed and stored at -20° C until extraction. Filters were cut into pieces using flame sterilized scissors and tweezers and then processed according to the manufacturer’s protocol (Mo Bio Laboratories, Inc. UltraClean Soil DNA Isolation Kit). The alternative protocol for maximum yields was followed. DNA extraction on a single isolated colony from each pure culture used the same methodology described above.16S rDNA Clone Library ConstructionThe microbial 16S rDNA genes were amplified from extracted DNA using oligonucleotide primers 4F and 9F with 1492R (Table 4.2). Primers were purchased from Macromolecular Resources (Colorado State University). The 50-μl PCR reaction contained 5 μl DNA template, dNTPs nucleotide mix (Fisher Scientific, 200μM final concentration), bovine serum albumin (BSA) (0.5 μg/ μl), 0.5 μM final concentration of each primer, 10x Taq Buffer (1.5 mM Mg2+), 5x TaqMaster (a proprietary PCR enchancer, Eppendorf), and 1.25 units of Taq DNA polymerase (Eppendorf MasterTaq Kit). The reaction mixture was PCR amplified in an Eppendorf Mastercycler Gradient Thermal Cycler under conditions that included 15 sec of denaturation at 95o C, 45 sec of annealing at 55o C, and 1.5 min of primer extension at 72o C. These steps were repeated for 30 cycles. PCR products were purified using the QIAquick PCR purification kit (Qiagen) to remove primers, nucleotides, polymerases and salts. Purified PCR products were cloned using the pGEM-T Easy Vector System cloning kit with the pGEM-T Easy vector (Promega) according to the manufacturer’s protocol. unknown biogeo_data_bloodfalls Bloodfalls Geomicrobiology Summary: Samples were collected from subglacial outflow waters associated with Blood Falls discharge during austral summers from 1999-2003. Samples near the outlet of Blood Falls were collected for enumeration and bacterial activity in December of 2000 and 2001. A transect of samples (TransX) was collected in December (see Figure 1), 2002 to capture a profile of releases from Blood Falls into Lake Bonney, starting at the source of the outflow (Trans1) and out onto the moat ice surrounding the lake with increasing distance from the source (Trans2-5). Trans2 was collected from basal ice below the source, Trans3 was collected from waters at the shoreline where Blood Falls meets the moat ice, Trans4 was collected 5 m from the shoreline just below moat ice that melted and refroze daily, and Trans5 was collected under 0.4 m of moat ice approximately 70 m from the shoreline before the moat ice meets the permanent ice cover of Lake Bonney. Sample Location Sample Location The data provider Sample Location pH pH The data provider pH DO (µM O2) Dissolved oxygen (DO) was determined by Winkler titration. The data provider molarity Eh (mV) Conductivity was measured at 1-meter depth intervals in the west lobe of Lake Bonney using a Seabird SBE-25 conductivity temperature depth (CTD) sensor (Sea-Bird Electronics, Inc., Bellevue, Washington). The data provider millivolt DIC (µM) Dissolved inorganic carbon (DIC) was measured by infrared gas analysis on acid sparged samples. The data provider molarity DIN (µM) Dissolved inorganic nitrogen (DIN) was reported as the summation of nitrate, nitrite and ammonium (DIN = NO3-+ NO2-+ NH4+). The data provider molarity SRP (µM) Soluble reactive phosphorus (SRP) was determined on 10 ml samples with the antimony-molybdate method (Standard Methods, 1992), absorbance was read in a 10 cm cell with a Beckman DU-640 spectrophotometer. The data provider molarity DIN:SRP The ratio of DIN to SRP. Useful for looking a phosphorus deficiency. The data provider molarity DOC (µM C) Dissolved organic carbon (DOC) was measured on filtered (25mm Whatman GF/F), acidified (HCl to pH~2-3) samples with a Shimadzu 5000 TOC analyzer. The data provider molarity CHL (µg per L) Chlorophyll-a (CHL) was extracted into 90% acetone for 24 h at <0 °C in the dark from particles collected on a Whatman GF/F filter, and the subsequent concentration was determined fluorometrically. The data provider microgramsPerLiter Bacteria (10^4 cells per mL) Environmental (in situ) cell abundance as determined on 0.2 μm-filtered samples. The data provider cellsPERmL McMurdo Dry Valleys LTER The data distributor shall not be liable for innacuracies in the content http 1 0 \n 1 column , https://mcm.lternet.edu/sites/default/files/data/biogeo_data_bloodfalls.csv None bio_activ_data_bloodfalls Bloodsfalls Microbial Activity Summary: Bacteria at the source of Blood Falls incorporated thymidine into TCA-insoluble products at an average rate of 1.5 x 10-3 nM d-1. There was considerable variation between the samples, with rates ranging from 0.4 to 3.0 x 10-3 nM d-1 (SD = 1.1 x 10-3). Thymidine incorporation experiments were used to compute cell doubling times ranging from 37 to 54 days at 0 °C. The effect of temperature on leucine incorporation was determined at 0 °C, 5 °C, 10 °C, 15 °C, 20 °C and 30 °C . The activation energy (Ea) over the range of temperatures tested, and the Q10 for metabolic activity between 0 and 20 °C were 8764 kcal mol-1 and 1.74, respectively. DATASET_CODE Code to designate the table name The data provider Code to designate the table name Date Date the sample was collected. The data provider calendar date/time MM/DD/YYYY gregorian calendar Temperature Temperature in C The data provider celsius 3H-labeld Thymidine incorporation Nanomol per doubling time of incorporated 3H-labeld Thymidine The data provider nM d-1 x 10-3 3H-labeld Leucine incorporation Nanomol per doubling time of incorporated 3H-labeld Leucine The data provider nM d-1 Doubling time Doubling time, in whole numbers. The data provider dimensionless McMurdo Dry Valleys LTER The data distributor shall not be liable for innacuracies in the content http 1 0 \n 1 column , https://mcm.lternet.edu/sites/default/files/bio_activ_data_bloodfalls.csv None subglacial_geochem_bloodfalls Bloodfalls Subglacial Release Geochemistry Summary: The chemistry of Blood Falls was first sampled by Hamilton et al. in 1958 and again by Black et al. in 1962 (Hamilton et al., 1962 and Black et al., 1965). However, in these studies, the researchers sampled the salt precipitates, or the salt cone that formed around the terminus of the Taylor Glacier, they did not sample true, unaltered outflow. Keys (1979) collected the first detailed chemical data in 1978 on what he described as a discharge of saline icing at Blood Falls.†Since the inception of the McMurdo LTER in 1992, flow from Blood Falls has been sampled routinely, providing over a decade of chemical data (data available in this site). It is clear from these geochemical data that the source water of Blood Falls is marine in origin (Lyons et al., 1998, 1999) and that the release of ancient subglacial fluid is episodic in nature resulting in complex and dynamic chemistry of waters sampled at Blood Falls (Lyons et al., 2005). Collection Date Collection Date The data provider calendar date/time MM/DD/YYYY gregorian calendar Temperature Temperature The data provider celsius pH pH as measured with a calibrated Beckman 12 pH meter The data provider dimensionless DOC (µM) Dissolved organic carbon (DOC) was measured on filtered (25 mm Whatman GF/F) acidified samples with a Shimadzu 5000 TOC analyzer. The data provider molarity DIC (mM) Dissolved inorganic carbon (DIC) was measured by infrared gas analysis on acid sparged samples. The data provider molarity DO (mM) Dissolved oxygen (DO) was determined by Winkler titration. The data provider molarity Cells (1x10^5) Cell counts of 10mL outflow samples The data provider counts %live Percentage live cells in outflow samples The data provider percent Cl- (mM) Cl- concentration The data provider molarity SO4 2- (mM) SO4 2- The data provider molarity SO4:Cl The ratio of SO4 to Cl The data provider molarity McMurdo Dry Valleys LTER The data distributor shall not be liable for innacuracies in the content http 1 0 \n 1 column , https://mcm.lternet.edu/sites/default/files/subglacial_geochem_bloodfalls.csv None bloodfalls_transect_biogeo Bloodfalls Geomicrobiology Transect Data Sample Sample The data provider Sample pH pH The data provider pH Cell density Cell density The data provider cells per mL CFUs R2A Count of colony forming units on R2A media. The data provider count CFUs Mar Count of colony forming units on Mar media. The data provider count Fe (µM) Fe (µM) The data provider molarity Chl--a (µg/L) Chlorophyll- a (CHL) was extracted into 90% acetone for 24 h at <0 °C in the dark from particles collected on a Whatman GF/F filter, and the subsequent concentration was determined fluorometrically. The data provider molarity DIC (mM) Dissolved inorganic carbon (DIC)as measured by infrared gas analysis on acid sparged samples. The data provider molarity DO (µM) Dissolved oxygen (DO) was determined by Winkler titration. The data provider molarity DOC (µM) Dissolved organic carbon (DOC) was measure on filtered (Whatman GF/F) and acidified samples with a Shimadzu 5000 TOC analyzer. The data provider molarity DIN (µM) DIN The data provider microMoles Na (mM) Sodium concentration as measured according to the protocol of Welch et al. (1996). The data provider milliMoles Cl (mM) Chloride concentration as measured according to the protocol of Welch et al. (1996). The data provider milliMoles SO42- (mM) Sulfate concentration as measured according to the protocol of Welch et al. (1996). The data provider milliMoles Ca2+ (mM) Calcium concentration as measured according to the protocol of Welch et al. (1996). The data provider milliMoles Richness Richness calculated from the 16S rRNA clone library. The data provider milliMoles McMurdo Dry Valleys LTER The data distributor shall not be liable for innacuracies in the content http 1 0 \n 1 column , https://mcm.lternet.edu/sites/default/files/bloodfalls_transect_biogeo.csv None 2015-01-28 2015-01-28 McMurdo Dry Valleys LTER http://mcmlter.org/ Biological Data Profile of the Content Standards for Digital Geospatial Metadata devised by the Federal Geographic Data Committee. Drupal Ecological information Management Systems, version D7, Biological Data Profile module