Little is known about the fate of oil spills in rivers. Hyporheic flows of water through river sediments exchange surface and groundwater and create upwelling and downwelling zones that are important for fish spawning and embryo development. Risk assessments of oil spills to rivers do not consider the potential for hyporheic flows to carry oil droplets into sediments and the potential for prolonged exposure of fish to trapped oil. This project assessed whether oil droplets in water flowing through gravel will be trapped and whether hydrocarbons partitioning from trapped oil droplets are bioavailable to fish. Columns packed with gravel were injected with oil-in-water dispersions prepared with light crude, medium crude, diluted bitumens, and heavy fuel oil to generate a series of oil droplet loadings. The concentrations of oil trapped in the gravel increased with oil loading and viscosity. When the columns were perfused with clean water, oil concentrations in column effluents decreased to the detection limit within the first week of water flow, with sporadically higher concentrations associated with oil droplet release. Despite the low concentrations of hydrocarbons measured in column effluent, hydrocarbons were bioavailable to juvenile rainbow trout (Oncorhynchus mykiss) for more than three weeks of water flow, as indicated by strong induction of liver ethoxyresorufin-o-deethylase activity. These findings indicate that ecological risk assessments and spill response should identify and protect areas in rivers sensitive to contaminant trapping.

人们对河流漏油的命运知之甚少。穿过河流沉积物的水的水流交换地表水和地下水，并形成上涌区和下涌区，这对于鱼类产卵和胚胎发育很重要。对河流溢油的风险评估未考虑过流将油滴带入沉积物中的潜在可能性，也未考虑鱼类长时间暴露于被困油中的可能性。该项目评估了流经砾石的水中的油滴是否会被捕获，以及从捕获的油滴中分离出来的碳氢化合物是否对鱼类具有生物利用性。填充砾石的塔中注入了由轻质原油，中质原油，稀释的沥青和重质燃油制备的水包油分散液，以产生一系列油滴载荷。砾石中捕获的油的浓度随油量和粘度的增加而增加。当用纯净水灌注色谱柱时，在水流的第一周内，色谱柱流出物中的油浓度降低到检测极限，并且油滴的释放会偶尔出现较高的浓度。尽管在柱子流出物中测得的烃浓度较低，但少年虹鳟鱼仍可生物利用烃（虹鳟）为三周以上的水流量，由肝的强诱导ethoxyresorufin-所示ö -deethylase活性。这些发现表明，生态风险评估和溢出反应应确定并保护河流中对污染物捕获敏感的区域。