Wednesday, December 17, 2014

Lab Work

Now that we’ve collected soil samples, we need to extract and identify the organisms living in the soil. We also need to measure the chemistry of the soil to understand the organisms’ habitat. For the past few days, we’ve been working quite a lot in the lab.
We first preserve part of the soil to measure the bacteria and fungi back at home in the U.S. We separate some of the soil into a vial and add a solution that preserves the bacteria and fungi. These vials will be sent home and analyzed there. We will use microscopes to count the number of bacterial and fungal cells in each sample, and we will find out what species they are using their DNA.

From another portion of soil, we extract the nematodes that live in the water around the soil particles. This is done by wrapping the soil in a tissue and placing it on a rack that’s submerged in water. The nematodes float out of the soil into the water, then drop to the bottom of the dish. We’ll collect the nematodes from the bottom of the dish and look at them under a microscope to identify them. Other animals also live in the water around soil particles, such as Tardigrades and rotifers, which we may find in these samples.
We also extract larger invertebrates from the soil. These are removed from the soil using two methods. One of the methods uses heat created by a light bulb. We place soil or moss on a funnel and attach a light bulb. (You can buy official versions, but we made our own out of drink cans, gauze, and Christmas lights!) We gradually turn up the dimmer switch over a few days, which heats and dries the soil. The organisms try to move deeper in the soil to stay cool, which makes them fall down through the funnel into our vial. So far, we have found a lot of mites and springtails in these samples.
We also plan to measure the chemistry of the soil. We want to know how much nutrients are available in the soil (like nitrogen, phosphorus, and carbon). We want to know the pH of the soil and how salty it is. All of these are important for the organisms living in the soil. If it’s too salty, too acidic, or if nutrients are too low, they may not be able to survive. We expect to find that the different types of growth on the soil (moss, lichen, algae, etc.) house different communities of organisms because they create different soil chemistry.

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