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Treating soil solution samplers to prevent microbial removal of analytes
D L Lewis1, A P Simons, W B Moore
1Environmental Research Laboratory and Technology Applications, Inc., U.S. Environmental Protection Agency, Athens, Georgia 30613; Institute of Ecology, University of Georgia, Athens, Georgia 30602 ; Scientific Evaluation Section, Bureau of Pesticides, Department of Agriculture and Consumer Services, State of Florida, Tallahassee, Florida 32311 ; and Pesticide & Review Section, Department of Environmental Regulation, State of Florida, Tallahassee, Florida 32399.
Soil microbes in lysimeters significantly reduce pesticide concentrations. Treating samplers with biocides prevents microbial activity, ensuring accurate soil water monitoring for pesticides and other contaminants.
Area of Science:
- Environmental Chemistry
- Soil Science
- Microbiology
Background:
- Soil water sampling devices, known as lysimeters, are crucial for monitoring contaminants.
- Microbial colonization of lysimeters can alter the chemical composition of collected soil water.
- This microbial activity may lead to inaccurate assessments of organic and inorganic compounds in soil.
Purpose of the Study:
- To investigate the impact of soil microorganisms on the concentration of organic chemicals in lysimeters.
- To determine if chemical treatments can prevent microbial activity and improve the accuracy of soil water sampling.
- To assess the efficacy of biocides and bacteriostats in maintaining chemical integrity within lysimeters.
Main Methods:
- Lysimeters were deployed in soil to collect water samples.
- Concentrations of specific organic chemicals (pesticides, benzoate) were measured inside and outside lysimeters.
- Biocides (sodium hypochlorite) and bacteriostats (copper salt) were added to lysimeters to inhibit microbial activity.
- Field studies were conducted to validate the effectiveness of copper salt treatment.
Main Results:
- Soil microorganisms significantly reduced concentrations of biodegradable organic chemicals, with losses sometimes exceeding 99%.
- Addition of biocides or bacteriostats prevented microbial degradation, resulting in chemical concentrations inside lysimeters matching those outside.
- Copper salt treatment effectively prevented microbial activity in field studies.
Conclusions:
- Microbial colonization of lysimeters leads to substantial losses of certain organic chemicals.
- Chemically treating soil water samplers with biocides or bacteriostats can prevent microbial degradation.
- This treatment improves the accuracy of soil water data for various organic and inorganic analytes, including pesticides and nutrients.
