Soil Apatite Grain Weathering Metrics from Taylor Valley, Antarctica

Summary

Abstract: 

Mineral apatite is the ultimate source of the essential nutrient phosphorus to the soil ecosystem. In order to assess the biogeochemical weathering of apatite grains in the dry, basic soils of the McMurdo Dry Valleys, we collected nine surface soil samples from the Fryxell and Bonney Basins of Taylor Valley. After separating more than 50 individual soil apatite grains from each sample, we used scanning electron microscopy to quantify the morphology and surface etching of apatite grains to determine the degree of weathering. We developed three metrics to quantify the degree of weathering: aspect ratio, percent crystal faces, and a qualitative pitting index. This dataset contains the raw data from analyzing the morphology of more than 600 grains using the software ImageJ. Samples were collected during January 2013. The samples from the Bonney Basin (LB) were collected 21 Jan 2013, and the samples from the Fryxell Basin (LF) were collected 18 January 2013. Samples were processed and analyzed 2014-2016.

Date Range: 

Friday, January 18, 2013 to Monday, January 21, 2013

...or query the data clicking the:

Variables: 

DATASET_CODE
  • Label: Dataset code
  • Definition: DATASET_CODE
  • Type: Nominal
  • Missing values: None specified
BASIN
  • Label: Basin
  • Definition: Identifies the region where the sample was collected; either Fryxell Basin or Bonney Basin
  • Type: Nominal
  • Missing values: None specified
MOISTURE_LEVEL
  • Label: Soil Moisture Level
  • Definition: Identifies the moisture level of the soil sample; either dry or saturated. Dry samples are from outside of stream channels, while saturated samples are from the hyporheic zone.
  • Type: Nominal
  • Missing values: None specified
SAMPLE_ID
  • Label: Sample ID
  • Definition: Unique sample identifier. LB=Lake Bonney; LF=Lake Fryxell; D=dry; W=wet
  • Type: Nominal
  • Missing values: None specified
LATITUDE
  • Label: Latitude
  • Definition: Latitude in decimal degrees.
  • Type: Nominal
  • Missing values: None specified
LONGITUDE
  • Label: Longitude
  • Definition: Longitude in decimal degrees.
  • Type: Nominal
  • Missing values: None specified
GRAIN_ID
  • Label: Grain ID
  • Definition: Unique grain identifier. P=phosphorus. We separated more than 50 apatite grains from each sample.
  • Type: Nominal
  • Missing values: None specified
PITTING_INDEX
  • Label: Pitting Index
  • Definition: A qualitative index of how chemically altered the apatite grain was. Our pitting index ranges from 1 (grains with few to no etch pits) to 4 (grains with etch pits covering the entire grain surface).
  • Type: Nominal
  • Missing values: None specified
ASPECT_RATIO
  • Label: Aspect Ratio
  • Definition: The length of the long axis of the grain divided by the length of the short axis, giving a measure of how elongated grains are. An aspect ratio of 1 is a perfectly round grain.
  • Type: Nominal
  • Missing values: None specified
PERCENT_CRYSTAL_FACES
  • Label: Percent Crystal Faces
  • Definition: The percent of the total visible grain area that was a recognizable crystal face.
  • Type: Nominal
  • Missing values: None specified

Data set ID: 

261
People

Owner/Creator: 

Contact: 

Additional Project roles: 

Associated Researcher
Associated Researcher
Associated Researcher
Associated Researcher
Data Manager