Degradation and leaching potential of pesticides in biobed systems

• Published in: Pest management science Vol. 60; no. 7; pp. 645 - 654
• Main Authors: Fogg, P, Boxall, A.B.A, Walker, A, Jukes, A
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.07.2004; Wiley; Wiley Subscription Services, Inc
• Subjects: biobeds; Biodegradation, Environmental; Biological and medical sciences; Biomass; chemical degradation; Contamination; degradation; drinking water; farm ponds; Fundamental and applied biological sciences. Psychology; Leaching; leaching potential; pesticide residues; Pesticide Residues - metabolism; pesticide waste; Pesticides; Pesticides - metabolism; Phytopathology. Animal pests. Plant and forest protection; Soil - analysis; soil pollution; water management; Water Movements; Water Pollutants, Chemical - metabolism; Water pollution; Biodegradation; Microbial activity; leaching potential; biobeds; water management; Pesticides; Washing; degradation; Spatial scale; Microbial biomass; Leaching; pesticide waste; Humidity; Water content; Rain water; Water pollution; Wastes; Drying
• ISSN: 1526-498X; 1526-4998
• DOI: 10.1002/ps.826

Biobeds provide a potential solution to pesticide contamination of surface waters arising from the farmyard. Previous work has shown that biobeds can effectively treat spills and splashes of pesticide. This study investigated the potential for biobeds to treat much larger volumes and amounts of pesticide waste not only arising from spills but also from washing processes. Two systems were assessed using a range of pesticides at the semi-field scale, ie a lined biobed system and an unlined system. Studies using the lined biobeds demonstrated that water management was crucial, with biobeds needing to be covered to exclude rain-water. Once covered, the top of the biobed became hydrophobic, restricting moisture loss and resulting in saturated conditions at depth. The drying out of the top layer coincided with a measured decrease in microbial biomass in the treated biobeds. Applied pesticides were effectively retained within the 0-5 cm layer. Whilst all pesticides tested degraded, low moisture content and microbial activity meant degradation rates were low. Studies using unlined biobeds showed that only the most mobile pesticides leached, and for these >99% was removed by the system, with a significant proportion degraded within 9 months. Peak concentrations of the two most mobile pesticides did however exceeded the limits that are likely to be required by regulatory bodies. However, it is thought that these limits could be reached by optimisation of the system.