Pesticide management for better water quality
McGinley, John
McGinley, John
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Publication Date
2023-07-31
Type
Thesis
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Abstract
The growth of the global population has forced the intensification of agricultural practices in order to achieve increased crop yields and production rates. This has been accomplished by elevated pesticide usage. While this intensified pesticide application has been beneficial in preventing diseases in agricultural crops, it has also amplified the contact of these compounds with air, soil and aquatic environments. This has resulted in an increased risk of human health issues, including neurological, respiratory and carcinogenic effects. Several physical, chemical, and biological treatment approaches have been employed to remove pesticides from aqueous solutions. One of the most extensively used remediation methods of pesticides is adsorption onto low-cost agricultural and industrial materials, which is simple and cost-effective. However, further investigations on readily available low-cost adsorbents are required. Therefore, the aims of this thesis were to (1) review the prevalence of pesticides, including legacy pesticides, in European waterways (2) develop a tool to help farmers assess the potential risk of pesticide transmission to waterways (3) assess low-cost agricultural and industrial materials as herbicide adsorbents for the removal of commonly used herbicides in Ireland, and (4) evaluate their potential in field-scale studies. This study found that legacy pesticides are still being detected in European surface water and groundwater at concentrations exceeding the maximum allowable concentration of 100 ng.l-1. Current remediation methods employed at drinking water facilities do not completely remove pesticides. There is still a need for remediation of existing contamination arising from legacy pesticides and ongoing pesticide use. New and emerging remediation methods for legacy pesticides include metal organic frameworks, nanoparticles, and membrane technologies. One of the many problems facing the farming community is being able to assess the potential risk of loss of pesticides to waterways. The screening tool, developed in this study, allows farmers and end-users to estimate the potential risk of applying various pesticides to different soil textures. A remediation technology was developed beginning with batch adsorption studies and progressing to trials for in situ treatment of herbicides in streams. The batch adsorption studies showed that granulated activated carbon (GAC) was the best medium for the removal of five commonly used herbicides in Irish agriculture, with >95% removal. The adsorption kinetic studies showed that the majority of the adsorption was completed within 18 h, while the adsorption isotherm process followed the Freundlich model, verifying multilayer adsorption. The in situ remediation trials involved both filter bag and filter pipe interventions at two agricultural catchment areas and an urban recreational setting. These trials showed that the filter pipes reduced the herbicide concentrations more efficiently than the filter bags, with a 48% reduction in detections observed for the filter pipes compared to 13% for the filter bags. The main findings of this thesis are that (1) legacy pesticides, including some which have been removed from the market for over 20 years, are still being detected throughout Europe at levels exceeding the maximum allowable concentration of 100 ng.l-1, (2) the remediation system, tested at both batch and field scale, is the first such system that has been demonstrated to be capable of removal of a range of herbicides from an environmental setting. This research, while supporting the European “Farm to Fork” strategy, highlights not only the issues of legacy pesticides and their remediation, but also demonstrates that small in situ remediation systems are feasible approaches to the problem of pesticide contamination of waterways.
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Publisher
NUI Galway