Identification of tire leachate toxicants and a risk assessment of water quality effects using tire reefs in canals

摘要

Cover is an important component of aquatic habitat and fisheries management. Fisheries biologists often try to improve habitats through the addition of natural and artificial material to improve cover diversity and complexity. Habitat-improvement programs range from submerging used Christmas trees to more complex programs using sophisticated artificial habitat modules. Used automobile tires have been employed in the large scale construction of reefs and fish attractors in marine environments and to a lesser extent in freshwater and have been recognized as a durable, inexpensive and long-lasting material which benefits fishery communities.Recent studies by the U.S. Bureau of Reclamation have quantified the importance of tire reefs to enhancing freshwater canal fisheries in the southwestern United States. These studies have demonstrated that fishes and aquatic macroinvertebrates are attracted to these structures, increasing species diversity, densities and biomass where reefs are placed in canals. Potential benefits to fishermen are great in the form of recreational fishing. However, the use of tire reefs in aquatic environments which have relatively small volumes compared to marine or reservoir environments has raised water quality concerns. Effects of tires on water quality have not typically been studied in the past because of the obvious presence of fishes and other aquatic organisms that make use of tire reefs; the implication being that tires are inert and non-toxic.Little information on effects of tires on water quality is contained in the literature. Stone et al. (1975) demonstrated that tire exposure had no detrimental effects on two species of marine fish while results of Kelloughu27s (1991) freshwater tests were inconclusive, but suggested that some factor in tire leachate was toxic to rainbow trout (Oncorhynchus mykiss). Nozaka et al. (1973) found no harmful substances leached from tire material soaked in fresh water.Because there are few data on toxicity associated with tires, this became the focus of our study. Toxicity Identification Evaluation (TIE) procedures developed by the EPA (1991) were used to evaluate water quality impacted by tires.