METAL DISTRIBUTION AND BIOUPTAKE IN URBAN AND SUBURBAN INFLUENCED STREAMS AROUND HARTFORD, CT

Suburban and urban development contribute greatly to the increase of metal and organic carbon inputs primarily from stormwater runoff or wastewater treatment facilities into streams. Typically, sediment available metals correlate well with stream health as indicated by macroinvertebrate surveys. The question examined in this study is whether sediment derived metals or water column sources of metals enhance metal uptake due to dietary uptake of metals attached to periphyton by some macroinvertebrate species. Macroinvertebrates, periphyton, stream water, and sediment were sampled in areas of high and low canopy (e.g. high and low periphyton growth) upstream and downstream of major inputs in Roaring Brook (suburban), Glastonbury, CT, and Fenton River (low development) as a control site in Storrs, CT. Stream water Cu and most sediment Cu and Pb concentrations were significantly higher at the downstream sites than upstream. Sediment Pb, Cu, and Zn concentrations were 18, 8 and 14 µg/g, respectively downstream, 9, 5 and 8 µg/g, respectively, upstream and significantly lower in Fenton River. Periphyton concentrations of Zn and Cu were higher in downstream sites at about 50 and 25 µg/g at Roaring Brook compared to 90 and 15 µg/g, respectively in Fenton River. Average macroinvertebrate metal concentrations were similar at both sites, but individual organisms showed distinct differences, e.g. stonefly Cu and Zn concentrations were about 4-fold, and 3-fold higher, respectively in Roaring Brook compared to Fenton River, corresponding to the differences in sediment metal concentrations observed. Metal uptake by each organism likely reflects functional feeding group and metal sources at sites, but too few replicate organisms were available to assess correlations between sediment, water column or periphyton metal source and organism metal content.