|Smith Jr, Sammie|
Submitted to: Archives of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2009
Publication Date: 6/26/2009
Citation: Moore, M.T., Kroger, R., Cooper, C.M., Smith Jr, S. 2009. Ability of four emergent macrophytes to remediate permethrin in mesocosm experiments. Archives of Environmental Contamination and Toxicology. 57: 282-288. Interpretive Summary: Pesticides in runoff from farm fields can contaminate rivers, lakes, and streams. Management practices which incorporate the use of vegetation in sorbing contaminants from runoff are being studied in greater detail in the scientific community. This study examined the efficiency of permethrin (pyrethroid insecticide) removal by four common aquatic plants species. Although no individual plant species was more effective at permethrin mitigation relative to unplanted controls, over 80% of the measured permethrin mass was associated with vegetation in the Sparganium americanum mesocosms. Mitigation of agricultural runoff through vegetated buffer systems, such as drainage ditches, provides a new tool for farmers and landowners in the quest for improving the Nation’s aquatic resources.
Technical Abstract: Increased focus is being placed on the ability of natural vegetation to mitigate potential harmful effects of agricultural runoff, especially pyrethroid insecticides. Replicate 379 L Rubbermaid® tubs [1.25 m (l) x 0.6 m (w) x 0.8 m (h)] were planted with individual species of cutgrass (Leersia oryzoides), cattails (Typha latifolia), bur-reed (Sparganium americanum), and powdery alligator-flag (Thalia dealbata), all common wetland macrophytes found in the Mississippi Delta, USA agricultural region. Permethrin enriched water (target concentration 5 µg L-1) was pumped in at a 4 h hydraulic retention time at one end of the tub and discharged at the far end. Water samples were collected from discharge at 1 h intervals for 12 h and analyzed for permethrin concentrations. Permethrin removal rates were compared for the four different plant treatments and non-vegetated sediment-water controls. Results indicated that no particular single plant species was more effective at removing permethrin in water relative to unplanted controls. Overall mass reductions (from inflow to outflow) for cis-permethrin ranged from 67±6% in T. latifolia to 71±2% in L. oryzoides. Trans-permethrin overall mass reductions ranged from 76±4% in S. americanum to 82±2% in the unplanted control. Sediment and plant samples collected at the study conclusion indicated that 77-95% of measured permethrin mass was associated with sediment for mesocosms planted with L. oryzoides, T. latifolia, and T. dealbata. Conversely, mesocosms planted with S. americanum had 83% of measured mass associated with the plant material. Specific plant-pesticide retention studies can lead to improved planning for best management practices and remediation techniques such as constructed wetlands or vegetated agricultural drainage ditches.