dpca94 English utf8 dataset McMurdo Dry Valleys LTER http://mcmlter.org/ 2014-11-11 ISO 19115-2 Geographic Information - North American Profile Metadata - Data with Biological Extensions ISO 19115-2:2009(E) Soil Depth Effects on Chlorophyll-a Concentrations 2014-11-11 publication Diana Wall Colorado State University http://www.colostate.edu Johnson Hall 107 Fort Collins CO 80523 US Diana.Wall@colostate.edu http://wp.natsci.colostate.edu/walllab/ pointOfContact Ross Virginia Dartmouth College http://dartmouth.edu/ (603) 646-0192 Hinman Box 6182 Hanover NH 03755 US ross.a.virginia@dartmouth.edu http://sites.dartmouth.edu/ravirginia/ pointOfContact documentDigital Investigation of the effect of soil depth on soil biota and properties was part of the McMurdo Dry Valleys Long Term Ecological Research (LTER) project. Chlorophyll-a concentrations from soil samples collected for organism extraction and identification was monitored at various soil depths in Taylor Valley in order to accomplish this. Samples were taken on 21-Nov-1994 and 26-Dec-1994. Name: Inigo San Gil Role: data manager Name: Denise Steigerwald Role: data manager completed McMurdo Dry Valleys LTER http://mcmlter.org/ unknown This file was created by Mark St. John on 13-Oct-1998, using raw data from the Excel workbooks '9411dpca.raw' and '9412dpca.raw'. The file format was suggested by the LTER data manager, to conform with the relational database structure. On 19 Oct 1998, these files were submitted to Denise Steigerwald, the MCM LTER data manager, located at INSTAAR, University of Colorado.                            Upon arrival at INSTAAR, the data manager combined the 2 data files, removed columns for latitude and longitude, and updated the location names to match those provided in the "soil measurement locations" file (from which latitude and longitude can be found). The resulting file was reformatted to present in ascii, comma delimited text and MS-DOS text (table layout) on the MCM LTER web site. Both of these files are linked to this web page above.     In 2016, data and metadata was enhanced for findability by inclusion in DEIMS. San Gil. population dynamics theme LTER Core Areas English Long Term Manipulation Experiment at South Side of Lake Hoare LTM 162.882125854492 162.882125854492 -77.632965087891 -77.632965087891 ground condition 1994-11-21 1994-12-26 https://mcm.lternet.edu/sites/default/files/dpca94.csv dpca94 eng; US McMurdo Dry Valleys LTER dpca94 Data Source Definition : Comma delimited spreadsheet containing the dpca94 data described here Record Delimiter : \n Number of Header Lines : 1 Number of Footer Lines : 0 Orientation : Column Quote Character : "Field Delimiter : , false LOCATION Name of area where measurement was made. In this case, the depth experimenting site at the south side of Lake Hoare. DATE_TIME Date on which sample was gathered in this case, only two dates in Nov/dec 1994 Date Time Format: mm/dd/yyyy SAMPLE # Sample ID CHL-A (uG/G SOIL) Chlorophyll a concentration found in soil COMMENTS Helpful hints about the sample FILE NAME Name of file in which data was stored DBF https://mcm.lternet.edu/sites/default/files/dpca94.csv dataset Samples were taken for chlorophyll a analysis as follows: Sampling bags were prepared with one plastic vial and clean plastic teaspoon per sample. Centers of 8 polygons were found and labelled "A" to "H". Samples were taken from within the 10 cm diameter circular area of each plot. The location of the sampling was recorded each year so that areas were not re-sampled. Soil was collected to 1 cm depth with the plastic spoon, excluding rocks with a diameter >5 mm. About 4 teaspoons of soil were placed into the vial, keeping the vial out of the light in a closed hand. The soil samples were stored in a light-tight bag, in a cooler for transportation. On return to the laboratory (within 8 hours of sampling), the soils were stored at +5 degrees C until further processing. Extraction of chlorophyll from the soil. All procedures were carried out in the dark or very low irradiance to avoid degradation of the chlorophyll. The soil samples were mixed thoroughly in the vials, and a sample of approximately 5 g was weighed out into a 50 mL plastic centrifuge tube with a screw-top cap. 10 mL of a 50:50 DMSO/90% acetone solution was added to each sample and they were mixed thoroughly on a bench-top Vortex mixer for about 5 seconds. The vials were placed in a -4 degrees C constant temperature room, in the dark, and left for 12-18 hours. Determination of chlorophyll-a concentration. This was determined fluorometrically using a Turner model 111 fluorometer. A calibration using a known concentration of chlorophyll was carried out prior to sample analysis. The machine was blanked using a 50:50 DMSO/90% acetone solution. Each vial was mixed thoroughly, then centrifuged for 5 minutes at about 1800 RPM. A sample of approximately 4 mL of the DMSO/acetone solution was taken from the top of the sample with a pipette, being careful not to get any soil particles in the solution. The sample was placed in a cuvette, into the fluorometer and the fluorescence was recorded. This was done fairly quickly in order to prevent light from breaking down the chlorophyll. This measurement is called Fo, the initial fluorescence. After taking this reading, 0.1 mL of 1N HCl was added directly to the cuvette and the cuvette was gently agitated. After 20 seconds, the fluorescence was re-measured. (During this step, the acid converts the chlorophyll to phaeophytin by releasing a magnesium ion in an acidic environment). This measurement is called Fa, the fluorescence after acidification. The solution was discarded into a waste container, and the cuvette rinsed 3 times with DMSO/90% acetone solution before proceeding with the next sample. Calculation of chlorophyll concentration. The calibration curve that was constructed for the fluorometer had the following equation: [chlorophyll (microg/L) = (Fo-Fa)-0.4254)/2.2385]. The Fo and Fa figures were put in to this equation to calculate chlorophyll concentration. Subsequently, this figure was divided by 1000 to convert to microg/mL. Next, this is multiplied by 10 as the soil was extracted in 10mL of DMSO/90% acetone. Finally, this is divided by the fresh weight of the soil in g to give the concentration in microg chlorophyll per g fresh weight of soil. If the extract was diluted prior to reading on the fluorometer, the dilution factor (noted in the comments column) was applied at the end of the equation. Metadata Access Constraints: none Metadata Use Constraints: none annually McMurdo Dry Valleys LTER http://mcmlter.org/ pointOfContact