Contamination of a soft-water stream ecosystem in southwest Virginia by highway-generated heavy metals

Abstract

Study of two sections of a stream associated with highways of different traffic densities and a third section used as a reference area demonstrated that concentrations of lead, nickel, cadmium, and zinc in sediments, benthic macroinvertebrates, and fish were highly correlated to the amount of traffic associated with the respective sampling site.

Highest sediment concentrations of lead, nickel, and zinc occurred in spring, most likely due to accumulation and subsequent runoff in snow. Accumulation of these metals in invertebrates and fish is probably a more· time-dependent process. Concentrations in these organisms were related to physiological and ecological factors as well as the relative availability of each metal at each study site.

The major physiological factor influencing accumulation of heavy metals in stream organisms seemed to be the relative amount of tissue with a high affinity for these metals in each organism. The major ecological factor influencing accumulation of heavy metals seemed to be the relative amount of sediment association characteristic of each species. Invertebrates contained the highest levels of each metal, followed by bottom-oriented fish with a small proportion of muscle, while species of fish with a large percentage of muscle inhabiting the upper water column contained the lowest concentrations.

Biomagnification of these four metals was not demonstrated. Significant bioaccumulation of lead, nickel, and cadmium in bone; and cadmium in the kidneys of fish was found to occur. Major biological uptake of lead, nickel, cadmium, and zinc in these organisms was via water and/ or sediment-water interaction.