9597dica English utf8 dataset McMurdo Dry Valleys LTER http://mcmlter.org/ 2014-11-12 ISO 19115-2 Geographic Information - North American Profile Metadata - Data with Biological Extensions ISO 19115-2:2009(E) Human Disturbances Effects on Chlorophyll-A 2014-11-12 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 Concerns over environmental disturbance in the McMurdo Dry Valleys are increasing with increasing foot traffic from tourists and scientist. The effect of pedestrian disturbance was monitored by comparing the species composition, depth distribution and soil properties between adjacent high-, low- and no- traffic sites. This study began in the austral summer 1995/1996. Name: John "Jeb" E. Barrett Role: field crew Name: Byron J. Adams Role: field crew Name: Denise Steigerwald Role: data manager Name: Inigo San Gil Role: data manager completed McMurdo Dry Valleys LTER http://mcmlter.org/ unknown Metadata completed in 2016 - San Gil. This file was created by Mark St. John on 9 Nov 1998, using raw data from the Excel workbook '9512dica.raw'. The file format was suggested by the LTER data manager, to conform with the relational database structure. disturbance population dynamics theme LTER Core Areas English This is the plot for the Biotic Effects Experiment at Lake Hoare  162.876007080078 162.876007080078 -77.635002136230 -77.635002136230 1995-12-07 https://mcm.lternet.edu/sites/default/files/9597dica.csv 9597dica eng; US McMurdo Dry Valleys LTER 9597dica 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 DATE_TIME Date on which sample was gathered 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/9597dica.csv dataset   Soils were sampled from three areas: heavy traffic (H), light traffic(L) and control (C) where soils had not been walked upon. Samples were taken for chlorophyll a analysis as follows: Soil was collected to 1 cm depth with a clean 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 +5C 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 in to 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 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 4mL 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, in to 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 in to 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 (ug/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 ug/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 ug 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