How we sample

Tomorrow, we're scheduled to go out into the field to do our last sampling for the season. I figured I should explain what we do when we sample.

I took some pictures of Byron collecting a sample at the LTM plots at the south side of Lake Hoare so I'll explain it below the pictures.

The first step is to use a spoon to scrape the very top layer of dirt into an amber vial. This sample is used to measure levels of  chlorophyll A. The measurement tells us how much photosynthesis is occurring in that plot.

Next, we use a small scoop to dig out some of the soil. We try to take the top 10 centimeters of soil which ends up being about 3 scoops. This is the sample that we will end up processing to count nematodes, tardigrades, rotifers, etc. The soil biogeochemists also take a portion of the sample to run their analysis.

Byron wanted to make sure that I got a picture of the whirling action! The bags we use are called Whirl-Paks. We remove the air from the top of the bag then roll the top of the bag down until it is flush against the sample. The last step is to use the built-in twist tie to close the bag.

The finished product! These pictures were taking while sampling the LTM plots at the south side of Lake Hoare. Matterhorn is in the background.

We like to have a minimum of three people for each sampling trip. One person has a map of the plots and directs two samplers to the various plots. The plots are arranged on a grid but none of them are labeled so you need to have a map to figure out the various treatments (Labels don't hold up under the harsh conditions of the Dry Valleys. The LTM plots were actually labeled with metal tags originally but most of the tags are either missing or sandblasted so the engraved words are unrecognizable.). We prelabel all of the vials and bags so that we can get the sampling done quickly in the field.

After we finish sampling, we sometimes have treatments to apply to the plots. You might remember I explained that we water the BEE plots by adding 5.6 liters of water. There are other plots where we add liquid carbon, nitrogen, and phosphorous. I wasn't involved with those plots though because a different team went to those sites.

That's it! The last step is to call the helicopter up to come pick us up and to stick all of the samples in a refrigerator set at 4 degrees Celsius.