Fuller Neil, Anzalone Sara E, Huff Hartz Kara E, Whitledge Gregory W, Acuña Shawn, Magnuson Jason T, Schlenk Daniel, Lydy Michael J
Center for Fisheries, Aquaculture, and Aquatic Sciences, Department of Zoology, Southern Illinois University, Carbondale, Illinois, 62901, USA.
Metropolitan Water District of Southern California, Sacramento, CA, 95814, USA.
Chemosphere. 2022 Jul;298:134174. doi: 10.1016/j.chemosphere.2022.134174. Epub 2022 Mar 8.
The Sacramento River watershed, California, provides important rearing and migratory habitat for several species of conservation concern. Studies have suggested significant benefits for juvenile fish rearing in floodplain habitats of the watershed compared to the mainstem Sacramento River. However, the potential for contaminant exposure in each of these two habitats is poorly understood. Consequently, the present study aimed to determine the distribution and occurrence of bioavailable pesticides within two known salmon habitats using a suite of approaches including exhaustive chemical extraction, single-point Tenax extraction (SPTE) and ex situ passive sampling. Sediment samples were collected from sites within both habitats twice annually in 2019 and 2020, with inundation of the floodplain and high flows for both areas in 2019 and low flow conditions observed in 2020. Sediment characteristics including total organic carbon, black carbon and particle size distribution were determined to elucidate the influence of physical characteristics on pesticide distribution. Using exhaustive extractions, significantly greater sediment concentrations of organochlorines were observed in the floodplain compared to the Sacramento River in both years, with bioaccessible organochlorine concentrations also significantly greater in the floodplain (ANOVA, p < 0.05). Using both SPTEs and exhaustive extractions, significantly fewer pesticides were detected across both sites under low flow conditions as compared to high flow conditions (Poisson regression, p < 0.05). Sediment characteristics including percent fines and black carbon had significant positive relationships with total and bioaccessible pyrethroid and organochlorine concentrations. Fewer analytes were detected using low-density polyethylene (LDPE) passive samplers as compared to SPTEs, suggesting greater sensitivity of the Tenax technique for bioavailability assessments. These findings suggest that threatened juvenile fish populations rearing on the floodplain may have greater exposure to organochlorines than fish inhabiting adjacent riverine habitats, and that pesticide exposure of resident biota may be exacerbated during high-flow conditions.
加利福尼亚州的萨克拉门托河流域为几种受保护物种提供了重要的育幼和洄游栖息地。研究表明，与萨克拉门托河干流相比，该流域洪泛区栖息地对幼鱼育幼有显著益处。然而，人们对这两种栖息地中污染物暴露的可能性了解甚少。因此，本研究旨在通过一系列方法，包括彻底化学萃取、单点Tenax萃取（SPTE）和异地被动采样，来确定两种已知鲑鱼栖息地中生物可利用农药的分布和存在情况。2019年和2020年每年两次从两种栖息地的地点采集沉积物样本，2019年两个区域均出现洪泛区淹没和高流量情况，2020年观察到低流量情况。测定了沉积物特征，包括总有机碳、黑碳和粒度分布，以阐明物理特征对农药分布的影响。通过彻底萃取，在这两年中，与萨克拉门托河相比，洪泛区沉积物中有机氯的浓度显著更高，洪泛区中生物可及有机氯浓度也显著更高（方差分析，p < 0.05）。使用SPTE和彻底萃取方法，与高流量条件相比，在低流量条件下两个地点检测到的农药显著更少（泊松回归，p < 0.05）。沉积物特征，包括细粒百分比和黑碳，与拟除虫菊酯和有机氯的总量及生物可及浓度呈显著正相关。与SPTE相比，使用低密度聚乙烯（LDPE）被动采样器检测到的分析物更少，这表明Tenax技术在生物可利用性评估方面具有更高的灵敏度。这些发现表明，在洪泛区育幼的受威胁幼鱼种群可能比栖息在相邻河流栖息地的鱼类接触更多的有机氯，并且在高流量条件下，当地生物群的农药暴露可能会加剧。
