Impact on brown trout (Salmo trutta) by trace element species in streams draining shooting ranges

Summary

The use of small arms ammunition causes signicant deposits of lead (Pb), copper (Cu), antimony (Sb) and zinc (Zn) in shooting ranges. Deposited metals may be mobilised and transported into aquatic systems and thus be a potential risk to aquatic organisms. Fish are commonly used to study biological effects of aquatic metal contamination, as they are keystone species in the aquatic compartment of the ecosystem. In the present study, 3 different shooting ranges in Norway were investigated. Water samples were collected at different seasons, and in two of the sites frequent sampling were performed during a period of 3 weeks. To obtain information on specie distribution, water samples for determination of metals, were fractioned in situ according to size and charge properties. Size fractionation was performed using membrane filter and ultrafiltration (hollow fibre, nominal cut of 10KDa), while charge fractionation was performed using ion exchange chromatography. In one of the shooting ranges, brown trout were exposed to the contaminated stream to study uptake and effects of the studied metals. Blood samples were measured for plasma sodium (Na), plasma chloride (Cl-), hemoglobin (Hb) and glucose. In addition, hepatic and gill tissue burdens of metals, blood _d-aminolevulinic acid dehydrase (ALA-D) and hepatic levls of metallothionein (MT), total glutathione (tGSH) and oxidized glutathione (GSSG) were measured to determine toxic stress to the fish In conclusion, Pb was mainly present as particles and colloids, Cu mainly as colloids and Zn and Sb as low molecular mass (LMM) forms. Fish exposed to the contaminated water accumulated metals on gills and liver, and significant changes in physiology, ALA-D, MT and GSSG were identified.