Pesticide Risk Mitigation by Vegetated Treatment Systems: A Meta-Analysis

Abstract

Pesticides entering agricultural surface waters threaten water quality and aquatic communities. Recently, vegetated treatment systems (VTSs) (e.g., constructed wetlands and vegetated ditches) have been proposed as pesticide risk mitigation measures. However, little is known about the effectiveness of VTSs in controlling nonpoint source pesticide pollution and factors relevant for pesticide retention within these systems. Here, we conducted a meta-analysis on pesticide mitigation by VTSs using data from the scientific literature and the European LIFE ArtWET project. Overall, VTSs effectively reduced pesticide exposure levels (i.e., the majority of pesticide retention performances was >70%). A multiple linear regression analysis of 188 retention performance cases identified the two pesticide properties, organic carbon sorption coefficient value and water-phase 50% dissipation time, as well as the VTS characteristics overall plant coverage and hydraulic retention time for targeting high efficacy of pesticide retention. The application of a Tier I risk assessment (EU Uniform Principle) revealed a higher toxicity reduction for hydrophobic and nonpersistent insecticides compared with less sorptive and not readily degradable herbicides and fungicides. Overall, nearly half (48.5%) of all pesticide field concentrations ( = 130) failed Tier I standard risk assessment at the inlet of VTSs, and 29.2% of all outlet concentrations exceeded conservative acute threshold levels. We conclude that VTSs are a suitable and effective risk mitigation strategy for agricultural nonpoint source pesticide pollution of surface waters. Further research is needed to improve their overall efficacy in retaining pesticides.

Organic chemicals jeopardize the health of freshwater ecosystems on the continental scale

“…Hence, management tools such as land sparing, i.e., high-intensity agriculture in defined areas to spare land for conservation in other parts, appear to be less plausible for freshwater biodiversity conservation than land sharing through extensive agriculture (22). Control of diffuse sources of pollution from agriculture remains a challenging task but can, for example, be achieved by implementing riparian buffer strips (especially edge of field), grassed paths, or vegetated treatment systems (23,24). Risk from other chemicals of concern relates mainly to point source pollution (e.g., input of waste water from households or industry), implying the requirement of optimized treatment technologies (e.g., ozonation; ref.…”

Managing ditches for agroecological engineering of landscape. A review

“…The pesticide molecules are classified from top to bottom by decreasing hydrophobicity in Table 3. Qualitative evaluation of pesticide retention by mean of retention indices has been proposed by Margoum et al (2003): Pesticide retention within ditches mainly results not only from sorption processes (Elsaesser et al 2013;Stehle et al 2011) but also from the processes of degradation, plant uptake, or sedimentation of loaded particles. The ditch characteristics influencing the occurrence and intensity of these processes are described hereafter.…”

“…Sorption processes are deemed to be the main mechanisms of pesticide retention buffering both surface and leaching fluxes within ditches (Dousset et al 2010;Elsaesser et al 2013;Stehle et al 2011). Indeed, several components of ditches, including soil, sediments, vegetation, and litter, can provide efficient sorption sites for pesticides (Lagacherie et al 2006;Margoum et al 2006;Vallée et al 2014;Wan et al 2006).…”

“…The sorption mechanisms of polar or polarizable pesticides are highly related to the pH, the clay content of sediments, and the cation exchange capacity (CEC) (Brown et al 2004;Ulén et al 2013;Vallée et al 2014). Furthermore, at the ditch scale, the chemical retention time expressing the potential pesticide-substrate contact time, the water level, and ditch bottom shape significantly impact all of the sorption processes (Boutron et al 2011;Elsaesser et al 2013;Garon-Boucher 2003;Stehle et al 2011). …”

Microbial Community Assessment in Wetlands for Water Pollution Control: Past, Present, and Future Outlook

“…It is through these diverse and iterative sets of different conditions, in which wastewater passes through, that TWs are thought to have exceptional and sometimes surprising water treatment potential [8]. For example, CWs have shown promise for the removal of pesticides [17] and emerging contaminants, including antibiotics, pharmaceuticals and personal care products [18].…”