Bioaccumulation of sediment-associated contaminants in freshwater organisms
This report provides information on a laboratory method to assess the ability of freshwater mayflies, worms and minnows to absorb contaminants in sediment, and the impact on its survival and growth.
This laboratory method is primarily for scientists and regulators who need to measure the risk of contaminated sediments on aquatic organisms and fish-eating birds and mammals.
Executive summary
Methods are described to measure the ability of polluting materials (contaminants) from sediment and water to move into the tissues of three different freshwater organisms, a mayfly (Hexagenia spp), an aquatic worm (Lumbriculus variegatus) and a minnow (Pimephales promelas), over a period of 28 days. Our goal was to create a cost effective laboratory method to use with sediments containing different pollutants. Results from this method can be used to:
- Evaluate whether contaminants move from the sediment into test organisms
- Evaluate the likelihood that harmful effects may occur to aquatic organisms after exposure to the sediment.
- Allow scientists and regulators to measure the risk of these contaminants in a natural ecosystem
This method may be used for testing with previously untested contaminants, for monitoring programs, or to answer research questions. It has been proven effective for measuring the effects of pollutants such as PCBs (Polychlorinated biphenyls), Metals, Mercury, Arsenic, PAHs (Polyaromatic Hydrocarbons - substances related to oil products) and PFOS (Perfluorooctanesulfonic acid – substances related to teflon, scotchguard and firefighting foams).
The ratio of organic matter in the sediment to the weight of the organism after it has been dried in an oven is held constant for every test. The main endpoint in this test is the concentration of the contaminants in the organism at the end of the test, but the survival percentage, fat content and change in body weight is also measured. This method primarily describes how to determine the concentration of contaminants in the whole body, including the gut, of organisms, but there is also guidance on how to determine the concentration of contaminants in the whole body, excluding the gut.
Several different laboratories across the continent performed this method to ensure that this method is suitable for the intended use to measure the movement of contaminants from sediment and water into the tissue of organisms. This method has been used by many labs in North America and has been proven to provide reliable and consistent results.