Transformation and Sorption of Fipronil in Urban Stream Sediments

Abstract

Fipronil is an urban-use insecticide, and the increased use has led to its frequent detections in urban streams. Most studies on the environmental fate of fipronil so far have focused on soils, and little is known about its behavior in sediment-water systems. In this study, we investigated the transformation and sorption of fipronil in urban stream sediments from California, incubated under facultative and anaerobic conditions. Degradation of fipronil in sediments generally followed exponential decay kinetics, and the first-order half-lives of fipronil were only 4.6-18.5 days in anaerobic sediments. The persistence of fipronil under facultative conditions was considerably longer, with half-lives from 25 to 91 days. Sterilization generally decreased the dissipation of fipronil, indicating that microbial activity was an important factor in fipronil transformations in sediments. Under facultative conditions, fipronil sulfide and sulfone were observed, while only fipronil sulfide was detected in anaerobic samples. The sorption coefficient K d consistently increased with organic carbon contents of sediments. In the same sediment, K d usually also increased with contact time, suggesting decreased availability for aged residues. Results from this study showed that the stability of fipronil in sediments depends closely on the oxygen status and that due to the readily conversion of fipronil to the sulfone and sulfide metabolites, the overall risk assessment of fipronil in surface aquatic systems should take into consideration fipronil as well as its metabolites.

Analysis, occurrence, and toxic potential of pyrethroids, and fipronil in sediments from an urban estuary

“…The spatial pattern of fipronil contamination also coincided with pyrethroids, with the highest P FIP occurring at correlated with sediment fines (R s ¼ 0.79; p < 0.01; n ¼ 12), but was not correlated with TOC (R s ¼ 0.31; p < 0.2; n ¼ 18). In the absence of usage data to assess occurrence and persistence, the lower hydrophobicity and sediment-water partition coefficients for fipronil and its degradates compared with pyrethroids [32][33][34] can explain these trends.…”

Insecticides in sediment cores from a rural and a suburban area in South China: A reflection of shift in application patterns

“…Pesticides may reach surface water through various pathways, such as atmospheric deposition, surface runoff, and sewage drainage (Lin et al, 2008;Jiang and Gan, 2012). As a consequence, pesticide pollution in aquatic ecosystems has gained worldwide awareness because of their ubiquity in the environment and potential risk to aquatic organisms and human health (Beketov et al, 2013;Malaj et al, 2014).…”

Survival, Growth, and Body Residues of Hyalella azteca (Saussure) Exposed to Fipronil Contaminated Sediments from Non-Vegetated and Vegetated Microcosms

“…According to NASS (2008), from 2001 to 2005 approximately 30,000 kg year -1 of fipronil was used on agricultural crops in the US for pest management. As a result, there is a high probability for fipronil and metabolite run-off from agricultural land, entering waterways and mobilizing to sediments (Gunasekara et al 2007) where these compounds can be moderately persistant (Lin et al 2008). Within waterways such as drainage ditches, wetlands, or sediment retention ponds, the presence of emergent aquatic plants such as Typha latifolia L. and Thallia dealbata Fraser ex Roscoe could be useful in mitigating fipronil and metabolite contamination of water and sediment (Kröger and Moore 2008).…”

“…Within waterways such as drainage ditches, wetlands, or sediment retention ponds, the presence of emergent aquatic plants such as Typha latifolia L. and Thallia dealbata Fraser ex Roscoe could be useful in mitigating fipronil and metabolite contamination of water and sediment (Kröger and Moore 2008). However, due to the paucity of published data regarding fipronil and metabolite contamination, bioavailability and risk to benthic aquatic biota in waterway sediments (Gunasekara et al 2007;Lin et al 2008;Maul et al 2008) the effects of fipronil and metabolite sediment contamination on sedimentassociated aquatic organisms is in need of assessment. This study assessed chronic 28-days effects of fipronil and metabolite contaminated sediments from non-vegetated and T. dealbata vegetated wetland microcosms on Hyalella azteca during wet and dry exposures.…”