Contaminant loading limits for a major north temperate river system: A benthic ecorisk assessment approach

摘要

Sediment quality guidelines (SQGs) and an ecological risk assessment approach were used to calculate heavy metal loading limits for the Columbia River, the second largest river system in the contiguous United States. The SQG-risk assessment approach used was more restrictive than receiving water quality criteria for controlling point source discharges of particle-seeking contaminants. Based on conservative sediment quality guides (SQGs) and site-specific water-to-sediment transfer coefficients, an upper drainage basin loading of soluble lead (or the equivalent of a mixture of particle-seeking contaminants) of < 4 kg/yr per m(3)/sec of river flow (about 10 metric tons/yr) is proposed as a long-term protection goal for the Columbia River. Proposed benthic habitat/ecological health indicators for this large lotic ecosystem include: 1) in-stream spawning returns and hatching success of chinook salmon (Oncorhynchus tshawaytscha) in the Hanford Reach, 2) aquatic insect diversity, 3) presence or survival of freshwater bivalves (e.g., Corbiculae fluminae and Anodonta oregonensis) and 4) benthic amphipod densities (Corophium salmonis) in the lower river and estuary. References: 57