Effect-Directed Analysis of Toxicants in Sediment with Combined Passive Dosing and in Vivo Toxicity Testing

Abstract

Identifying key toxicants in sediment is a great challenge, particularly if nontarget toxicants are involved. To identify the contaminants responsible for sediment toxicity to Chironomus dilutus in Guangzhou reach of the Pearl River in South China, passive dosing and in vivo toxicity testing were incorporated into effect-directed analysis (EDA) to account for bioavailability. Fractionation of sediment extracts was performed with gel permeation chromatography and reverse phase liquid chromatography sequentially. Polydimethylsiloxane served as passive dosing matrix for midge bioassays. The fractions showing abnormal enzymatic response were subject to a nontarget analysis, which screened out 15 candidate toxicants. The concentrations of the screened contaminants (log-based organic carbon normalized) in sediments of 10 sites were compared to sediment toxicity (10 and 20 day mortality and 10 day enzymatic response) to C. dilutus using correlation analyses. The results suggested that oxidative stress induced by cypermethrin, dimethomorph, pebulate and thenylchlor may have in part caused the observed toxicity to C. dilutus. The present study shows that EDA procedures coupled with passive dosing and in vivo toxicity testing can be effective in identifying sediment-bound toxicants, which may pose high risk to benthic organisms but are not routinely monitored and/or regulated. The findings of the present study highlight the importance of incorporating environmentally relevant approaches in assessing sediment heavily impacted by a multitude of contaminants, which is often the case in many developing countries.

Accelerated Passive Dosing of Hydrophobic Complex Mixtures–Controlling the Level and Composition in Aquatic Tests

“…Lastly, passive dosing is increasingly used for setting and maintaining HOC exposure in aquatic tests. In passive dosing, a biocompatible polymer such as silicone is loaded with the test substance and then used as dominant partitioning donor to establish and control freely dissolved HOC concentrations in an aqueous medium. ,− This approach has been used in many types of toxicity studies, − bioaccumulation studies, , biodegradation studies, − and binding and sorption studies − and for solubility measurements. , Passive dosing has so far primarily been used for research on single compounds and simple mixtures and more recently for research on defined composed mixtures of more than 30 chemicals . For complex mixtures, passive dosing has only been used to dose crude oil and fuel oil into water near the saturation limit. − Table provides a comparison of the three dosing methods (solvent spiking, WAF, and passive dosing) based on their underlying principles.…”

Extended Virtual Screening Strategies To Link Antiandrogenic Activities and Detected Organic Contaminants in Soils

“…Thus, an alternative method, effect-directed analysis (EDA) that combines chemical and biological characterization has been established to fill the gap in cause–effect relationships between the compounds present and biological effects . EDA has been widely used to identify key toxicants in various environmental matrices including waters, sediments, − soils, and drinking water . Key processes in EDA usually include toxicity evaluation of environmental samples, stepwise fractionation of toxic samples, and structure elucidation of toxicants.…”

Effect-directed analysis in environment research: current status and future challenges

“…体内生物效应测试 是最早应用到EDA中的生物评价方法, 能够反映污染 物的生态毒理学效应. 常见的模式生物包括藻类 [83,84] , 浮游动物及小型昆虫(水蚤 [23] 、水生寡毛虫 [60] 、摇 蚊 [85] 、跳虫 [86] ), 小型动物(新西兰泥螺 [87] 、淡水蜗 牛 [73] 、钩虾 [88] )和鱼类 [24,89~91] 等.…”