Mobility of pesticides in water, sediment, plants and soils, including soil columns

Understanding mobility of pesticides is an important part of environmental toxicology and chemistry. Pesticides need to be mobile enough to allow them to be transported to the site of action. On the other hand, pesticides that are too mobile will rapidly dissipate once applied to the target area and contaminate water and sediment. Many factors can affect the mobility of pesticides in soil and water including soil characteristics, pesticide properties, and timing of application.

Picture of a soil column experiment. The packed soil column is placed vertically in a formulated insecticide which moves up the column through capillary action, to determine how far a pesticides will travel in soil.Research in the lab has primarily focused on the transport of herbicides and their metabolites through soil profiles and into groundwater and surface water bodies. Recent research has focused on testing various formulations for their ability to increase the mobility of insecticides. Using formulations to increase mobility is essential for ensuring that insecticides are capable of moving through the soil to reach the habitats of ground-dwelling insect pest such as termites.


Some relevant publications:

Zhao, S., J.B. Belden, J.H. Cink, and J.R. Coats. 2010. Mobility of five termiticides in soil columns. Chapter in Proceedings of the 2010 NCUE. NCUE, Portland, OR, pp 169-174

Arthur, E.L., P.J. Rice, P.J. Rice, T.A. Anderson, and J.R. Coats.  1998.  Mobility and degradation of pesticides and their degradates in intact soil columns, Chapter 7 in Environmental Behavior of Pesticides:  The Lysimeter Concept.  F. Führ, J. Plimmer, R. Hance, and J. Nelson, eds.  American Chemical Society, Washington, D.C. pp. 88-114.

Kruger , E.L., B.  Zhu, and J.R. Coats. 1996. Relative mobilities of atrazine, five atrazine degradates, metolachlor, and simazine in soils of Iowa.  Environ. Toxicol. Chem. 15: 691-695.

Kruger, E.L., P.J. Rice, J.Anhalt, T.A. Anderson, and J.R. Coats. 1996. Use of undisturbed soil columns under controlled conditions to study the fate of [14C]deethylatrazine, J. Agric. Food Chem. 44: 114-1149.

Somasundaram, L., J.R. Coats, V.M. Shanbhag, and K.D. Racke. 1991. Mobility of pesticides and their hydrolysis metabolites in soil. Environ. Toxicol. Chem. 10: 185-194.

Fate of transgenic insecticides in soil and water, including insecticidal Bt protein toxins and vaccines

In recent years, transgenic crops have increased significantly in their usage in agriculture. Many of these crops produce insecticidal Bt proteins that target specific insect pests. As with conventional chemicals, it is important to know the fate of these insecticidal Bt proteins in the environment. The fate data is used in the risk assessment process to determine potential exposure of the insecticidal Bt proteins to non-target organisms.

Picture of a typical ELISA plate.Prior work in the lab has focused on the fate of some of these insecticidal Bt proteins in aquatic and soil microcosm. Current work in the lab aims to improve detection of these insecticidal Bt proteins in environmental samples with enzyme-linked immunosorbent assays (ELISAs), to ensure that only intact, bioactive proteins are being detected.

Double-stranded RNA (dsRNA) is the future of transgenic insecticides. Double-stranded RNA kills insects by inducing RNA interference (RNAi) pathways to inhibit gene expression. The lab plans to being studying the fate of these dsRNA molecules in aquatic environments.


Some relevant publications:

Prihoda, K, and J.R. Coats. 2008. Fate of Bacillus thuringiensis (Bt) Cry3Bb1 protein in a soil microcosm. Chemosphere 73: 1102-1107.

Prihoda, K., and J.R. Coats. 2008. Aquatic fate and effects of Bacillus thuringiensis Cry3Bb1 protein: Toward risk assessment. Environ. Toxicol. Chem. 27: 793-798.

Kosaki, Hirofumi, Jeffrey. D. Wolt, Kan Wang, and Joel Coats. 2008. Subacute effects of maize-expressed vaccine protein, Escherichia coli heat-labile enterotoxin subunit B (LTB), on the springtail, Folsomia candida and the earthworm, Eisenia fetida. J. Agric. Food Chem. 56: 11342-11347.

Clark, B.W., K.R. Prihoda, and J.R. Coats. 2006. Subacute effects of transgenic Cry1Ab Bacillus thuringiensis corn litter on the isopods Trachelipus rathkii and Armadillidium nasatum. Environ. Toxicol. Chem. 25(10): 2653-2661.

Clark, B.W., T.A. Phillips, and J.R. Coats. 2005. Environmental fate and effects of Bacillus thuringiensis (Bt) proteins from transgenic crops: a review. J. Agric. Food Chem. 53(12):  4643-4653.

Phytoremediation of pesticides in water and soil

Extensive pesticide use over several decades has resulted in the contamination of soils and water bodies. Pesticides can either these ecosystems either by intentional application, or incidentally by spray drift, surface water runoff, or spills. These pesticides may have a variety of detrimental effects on aquatic and terrestrial organisms, and could lead to disruption of the ecosystem. Cleaning up contaminated sites by conventional methods, such as excavation and storage off-site, can be expensive and not practical for areas with only minor contamination issues. In the last several decades, in situ methods of remediation, such as bioremediation and phytoremediation, have gained traction as low-cost, alternative clean-up methods.

Picture of a switchgrass column typically used in a phytoremediation experiment.Much of the phytoremediation work in this lab has focused on using prairie grasses native to Iowa, such as big blue stem and switchgrass, to help remove herbicides like atrazine and metolachlor from contaminated soils and water bodies. Typical studies involve the plants being exposed to field-collected soils from contaminated sites, or simulated surface water runoff spiked with pesticides. Concentrations of the pesticides are monitored over time to determine the effect that the grasses have on the dissipation, movement, and bioavailability of the pesticides. Radiolabeled pesticides have been used to track uptake and metabolism of the pesticides in greater detail, allowing for mass balance studies to determine the distribution of the pesticides and their metabolites within plant tissues.


Some relevant publications:

Albright, V.C., III, I.J. Murphy, J.A. Anderson, J.R. Coats. 2013. Fate of atrazine in switchgrass-soil column system. Chemosphere 90(6): 1847-1853.

Murphy, I.J. and J.R. Coats. 2011. The capacity of switchgrass (Panicum virgatum) to degrade atrazine in a phytoremediation setting. Environ. Toxicol. Chem. 30: 715-722.

Henderson, K.L., J.B. Belden and J.R. Coats. 2007. Mass balance of metolachlor in a grassed phytoremediation system. Environ. Sci. Technol. 41: 4084-4089

Arthur, E.L., P.J. Rice, P.J. Rice, T.A. Anderson, S.M. Baladi,   K.L.D. Henderson, and J.R. Coats. 2005. Phytoremediation – An overview. Crit. Rev. Plant Sci. 24: 109-122.

Belden, J.B., T.A. Phillips, and J.R. Coats. 2004. Effect of prairie grass on the dissipation, movement, and bioavailability of selected herbicides in prepared soil columns. Environ. Toxicol. Chem. 23: 125-132.

Degradation, persistence, mobility and bioavailability of veterinary pharmaceuticals in soil, water and sediment

Veterinary pharmaceuticals have emerged in recent years as a contaminant of concern in the environment. While not applied to soil and water bodies directly, veterinary pharmaceuticals enter the ecosystem after being excreted by grazing livestock or by the spreading of manue on agricultural fields as fertilizer. As with other chemicals, veterinary pharmaceuticals may have detrimental effects on aquatic and terrestrial organisms, particularly on bacteria where they may contribute to the development of antibiotic resistance.

Picture of a high performance liquid chromatography machine typically used for detection of veterinary pharmaceuticals.Research in the lab has primarily focused on three veterinary antibiotics: erythromycin, sulfamethazine, and tylosin. Understanding the degradation, persistence, mobility, and bioavailability of these veterinary antibiotics is important for determining any adverse effects they may have on the ecosystem. Other research in the lab has focused on improving the methods used to detect these veterinary antibiotics in environmental samples.


Some relevant publications:

Carstens, K.L., A.D. Gross, T.B. Moorman, J.R. Coats. 2013. Sorption and photodegradation processes govern distribution and fate of sulfamethazine in freshwater–sediment microcosms. Environ. Sci. Technol. 47(19): 10877-10883

Jessick, A.M., T.B. Moorman, J.R. Coats. 2011. Optimization of analytical methods to improve detection of erythromycin from water and sediment. J. Environ. Sci. Health, Part B 46(8): 735-740

Henderson, K.L., and J.R. Coats, Editors.2009. Veterinary Pharmaceuticals in the Environment. American Chemical Society, Washington, D.C. 247 pp.

Hu, D., and J.R. Coats. 2009. Laboratory evaluation of mobility and sorption for the veterinary antibiotic, tylosin, in agricultural soil. J. Environ. Monit.11: 1634-1638.

Hu, D., B. Fulton, K.L. Henderson, and J.R. Coats. 2008. Identification of tylosin photoreaction products and comparison of ELISA and HPLC methods for their detection in water. Environ. Sci. Technol. 42: 2982-87.