You are here:
SEDIMENT TOXICOLOGY TESTING, ISSUES AND METHODS
Citation:
Burton Jr, G. A., D. L. Denton, K T. Ho, AND S. Ireland. SEDIMENT TOXICOLOGY TESTING, ISSUES AND METHODS. Second Edition, Chapter 5, D. Hoffman, D. Rattner, G.A. Burton and J. Cairns (ed.), Handbook of Ecotoxicology. Lewis Publishers: CRC Press Company, Boca Raton, FL, , 111-150, (2003).
Description:
The significant role that sediments play in aquatic ecosystems is well known. They serve as both a sink and a source of organic and inorganic materials, where critical cycling processes for organic matter and the critical elements (e.g., C, N, P, and S). The majority of decomposition of allocthonous and autochthonous inputs occur in the sediment. Since most chemicals of anthropogenic origin (e.g., pesticides, polycyclic aromatic hydrocarbons (PAHs), and chlorinated hydrocarbons) tend to sorb to sediments and organic materials, they also end up concentrating in the sediment. Sediment contamination can have many detrimental effects on an ecosystem, some of which are evident and others more discrete or unknown. For example, benthic invertebrate communities can be totally lost or converted from sensitive to pollution-tolerant species. These tolerant species process a variety of materials, and their metabolic products may also be different. These differences mean that ecosystem functions, such as energy flow, productivity, and decomposition processes, may be significantly altered.
Loss of any biological community in the ecosystem can indirectly affect other components of the system. For example, if the benthic community is significantly changed, nitrogen cycling may be altered such that forms of nitrogen necessary for key phytoplankton species are lost and the phytoplankton are replaced with blue-green algae (cyanobacteria) capable of nitrogen fixation. The production of neuro- and hepatotoxins by the blue-green algae may then affect herbivorous fish and consumers of the water such as cattle and humans. Other effects from sediment contamination are direct, as observed in the Great Lakes, where top predator fish have become highly contaminated from consuming bottom feeding fish and benthic invertebrates that are laden with sediment-associated pollutants such as PAHs, mercury, and pesticides. Effects on ecosystem processes have been very dramatic in areas affected by both acid precipitation and acid mine drainage. However, in most areas receiving pollutant loadings the effects are difficult to observe and require use of a variety of assessment tools such as benthic macroinvertebrate community analyses, chemical testing, quantification of habitat characteristics, and toxicity testing (Figure 5.1).