Question:What are other ways to assess soil contamination, besides directly measuring contaminant concentrations?

by bhamster | February 05, 2021 19:05 | #25605


This builds off a question that@abbykinchy asked during the soil research area review kick-off call and one of the current challenges identified on the soil contamination wiki.

Typical analytical techniques that soil testing labs use to measure heavy metals and organic contaminants in soil samples can get expensive. Maybe as a complementary or screening step, what kinds of methods and indicators could offer proxies for soil contamination?



8 Comments

Bioassays?

This uses biological (living) organisms, like plants or animals, to measure toxicity in a test sample. For example, soil contaminants can affect an organism’s growth in a predictable way, so measuring and comparing growth in organisms exposed to different samples can indicate the presence of toxic compounds.

I’ve found some resources on this topic and will start collecting them on a wiki page here. This Environmental Inquiry page is a great place to start for now.

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Biosensors?

Going a more bionic route, biosensors combine biological material with electronic components to detect contaminants. I saw them mentioned while browsing this Hackteria forum (thanks @dusjagr!). Here’s a book on biosensors that’s focused on water monitoring but mentions soil occasionally: Biosensors for Determination of Heavy Metals in Waters

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A wet chemical test like "heavy metals". This initially was done with hydrogen sulfide, so all the different kinds of metal salts were metal sulfides. Heavy metal sulfides ( such as lead sulfide) are dark colored and show up easily in solution. There are variations on the test that don't use hydrogen sulfide, but they usually are still sulfur based and stinky.

Another weird approach. Their are already a number of inexpensive water tests available on amazon. These tests are labeled as heavy metal, although they may not cover the whole range. The range of elements covered needs further investigation. But the cost is inexpensive and they should already be validated. They would need modified for soil.


These ideas are fantastic. Thanks so much @Ag8n! I read about this lead screening procedure that uses sodium rhodizonate as a color indicator, as it makes a purple precipitate with lead (Landes et al. 2019). Is that similar to what you're describing above with heavy metal sulfides?

Also, searching online for "DIY heavy metal wet chemical test" turned up this: a commercial heavy metal detection kit meant for detecting poison in food and drinks. Yowza. But I wonder if it would work on soil extracts?

Bring on the weird.

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Satellites- a quick search found a couple of articles. A more extensive search would surely find more.

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Some of the commercial water kits claim they work on soil. But... The lab I worked at tested clay and other fillers. It can be a pain. Working with moderately strong acids, for example. Then with clay, much filtering. And then ashing was required in some samples. Soil could include these same steps. Some of the water kits claimed they could test soil, but none mentioned these steps. Some kits are based on new tech and may not need these steps. But you see my caution.

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@gfedorke Tagging you into this thread that might align with your interests!

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