Minnow Environmental, Georgetown, Ontario, Canada.
Environ Toxicol Chem. 2012 Mar;31(3):672-80. doi: 10.1002/etc.1730. Epub 2012 Feb 6.
Previous studies conducted in the Elk River watershed showed that selenium concentrations are higher in aquatic biota in lentic compared to lotic habitats of the system having similar water selenium concentrations. Studies have also shown that water selenium concentrations have increased over time (10% per year) and recent annual average concentrations have ranged up to 0.044 mg/L in areas downstream from mine discharges. For the present study, trophic transfer of selenium was characterized in lotic versus lentic habitats using concentrations measured in field-collected samples and assuming a three-step food chain of water to the base of the food web (biofilm), to benthic invertebrates, and then to westslope cutthroat trout (WCT) ovaries. Food chain models were developed for each habitat type (lotic and lentic) by combining linear regression equations for the three transfer relationships, allowing for prediction of fish ovary concentrations from water concentrations. Greater accumulation of selenium in lentic areas was mostly attributable to greater uptake at the base of the food chain compared to lotic areas. Enrichment/trophic transfer factors for selenium at all levels of the lotic and lentic food chains decreased and then became near constant as exposure concentrations increased. The lotic model predicted little increase in WCT ovary selenium concentrations over an eightfold increase in water concentrations (0.005-0.040 mg/L), accounting for the lack of observed increase in within-area fish tissue concentrations over time despite increasing trends in water concentrations.
先前在麋鹿河流域进行的研究表明,在系统的静水生境中,硒浓度高于流水生境,尽管这些静水和流水生境的水硒浓度相似。研究还表明,水硒浓度随时间增加(每年约增加 10%),在矿场排放物下游地区,最近的年平均浓度高达 0.044 毫克/升。在本研究中,采用现场采集样本中测量的浓度,通过假设从水到食物网基础(生物膜)、底栖无脊椎动物,再到西坡小口黑鲈(WCT)卵巢的三步食物链,来描述硒在流水生境和静水生境中的营养转移。通过结合三个传递关系的线性回归方程,为每个生境类型(流水和静水)开发了食物链模型,允许从水浓度预测鱼类卵巢浓度。静水区域中硒的积累量较大,主要归因于食物链基础的吸收量大于流水区域。随着暴露浓度的增加,硒在流水和静水食物链各级的富集/营养转移系数减小,然后变得接近常数。该流水模型预测,在水浓度增加八倍的情况下,WCT 卵巢硒浓度的增加很小(约 0.005-0.040 毫克/升),这解释了尽管水浓度呈上升趋势,但在一段时间内,鱼类组织浓度在区域内没有观察到增加的现象。