Center Update: Pesticide Phytoremediation

— Written By

Evaluation of Various Riparian, Aquatic, And Wetland Species For Phytoremediation Of Pesticides

 PI: Fred Yelverton; Student: Alayne McKnight

 Synthetic pesticides are commonly used throughout various sectors of agriculture. While much research has concluded off-target pesticide movement is limited in some situations, it occurs and the ultimate sink for pesticides is soil and water. Pesticides may enter ecosystems by intentional application to an area or incidentally by spray drift, runoff, and lateral subsurface flow, among other means. These pesticides may have detrimental off-target effects on various aquatics and terrestrial organisms. Further, land managers must be mindful of potential off-target and adverse effects when using pesticides to ensure environmental sustainability. As part of comprehensive land management plans, identifying species and associated best management practices to remediate pesticides that are transported off-target need to be devised to serve as an in-situ remediation for stormwater basins, retention ponds and vegetated buffer zones or riparian strips.

OBJECTIVES

  1. Evaluate the pesticide phytoremediation potential of various terrestrial and riparian plant species. Research to date has shown various plant species can effectively remove pesticides from aquatic and wetland systems; however, research has not evaluated terrestrial and riparian species. Experiments will expose plants to select pesticides and degradation, uptake, and degradation will be monitored over time allowing for mass balance over time within plant tissues and soil.
  2. Evaluate the pesticide phytoremediation potential of various aquatic and wetland plant species. Research to date has shown various plant species can effectively remove pesticides from aquatic and wetland systems; however, uptake, degradation and persistence varies widely with compounds and plant species over time. Similar to objective one, plants will be exposed to select pesticides and degradation, uptake, and degradation will be monitored and mass balance within plant tissues, water and soil will be conducted.

Pesticides can move off-target due to many factors including improper application or unpredictable rainfall events, resulting in contamination of sensitive water bodies and causing adverse effects on inhabiting species. Through best management practices, such as the implementation of vegetative buffer strips, off-target movement of pesticides can be decreased, and compound degradation can be increased via phytoremediation. In this study, blueflag iris (Iris versicolor), broomsedge (Andropogon virginicus) and switchgrass (Panicum virgatum) were planted in soil treated with one of three commonly used pesticides, namely atrazine (herbicide), azoxystrobin (fungicide) or imidacloprid (insecticide). Treated non-planted pots and non-treated planted pots were included as controls. At 28, 56 and 112 days after treatment (DAT), plants were destructively harvested and analyzed for pesticide residue in soil and above-ground and below-ground vegetation using high-performance liquid chromatography (HPLC). Relative to the amount of pesticide found in planted pots compared to non-planted pots, I. versicolor was found to reduce greater atrazine in soil compared to non-planted pots at 112 DAT by 58.7%. I. versicolor was also the most capable of reducing azoxystrobin, by 86.9% compared to non-planted pots, from the soil at 112 DAT. At the same sampling time, I. versicolor and P. virgatum reduced greater imidacloprid from soil by 62.5% and 64.3% compared to non-planted pots, respectively. This information supports the recommendation for establishment of diverse plant species for optimization of phytoremediation capacities.

Azoxystrobin (strobilurin fungicide) and imidacloprid (neonicotinoid insecticide) have been detected in surface waters near treated agricultural, urban, and mixed landscapes. The hazards of pesticide runoff can be prevented through best management practices, including the establishment of diverse wetland plant barriers that can phytoremediate the chemicals in which they come into contact with. In this study, the wetland plant species softrush (Juncus effuses), pickerelweed (Pontederia cordata), and arrowhead (Sagittaria latifolia) were planted in sandy soil containers that were then placed in azoxystrobin or imidacloprid treated water. Every week for 2 months, water samples were collected for pesticide residue analysis using high-performance liquid chromatography (HPLC). At 14, 28, and 56 days after initiation, plants were destructively harvested and analyzed for pesticide residue in soil, above-ground vegetation, and below-ground vegetation. Results from this study report P. cordata reduced greater azoxystrobin (51.7% reduction compared to treated non-planted containers) compared to J. effuses and S. latifolia (24.9% and 28.7% reduction from non-planted containers) at 56 days. However, S. latifolia reduced greater imidacloprid (79.3% reduction compared to non-planted containers) compared to J. effuses and P. cordata (36.0% and 37.1% reduction from non-planted containers) at 56 days.

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Written By

Grady Miller, N.C. Cooperative ExtensionDr. Grady MillerProfessor Call Dr. Grady Email Dr. Grady Crop & Soil Sciences
NC State Extension, NC State University
Posted on Dec 17, 2020
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