Influence of Sediment Characteristics on Heavy Metal Toxicity in an Urban Marsh
by Carolyn S. Bentivegna, Joy-Elaine Alfano, Sean M. Bugel, and Katarzyna Czechowicz
Department of Biology, Seton Hall University, South Orange, NJ 07079
Remediation and protection of urban wetlands are gaining public support as the contribution of these wetlands to biodiversity, and their importance to local fisheries and wildlife, become better understood. When developing remediation strategies, it is important to consider the key parameters that influence availability and toxicity of contaminants to which plant and animal life are exposed. Kearny Marsh is an important component of the Hackensack Meadowlands, which, located as they are in one of the most populated metropolitan areas in the United States, have been subjected to urban encroachment. We undertook studies to determine what sediment and detritus characteristics might be influencing heavy metal toxicity in Kearny Marsh. Toxicity parameters included sediment grain size, percentage of total organic carbon (%TOC), SEM–AVS, and heavy metal concentrations in whole sediment and detritus. These parameters were correlated with ten-day survival and growth, under laboratory conditions, of the aquatic larvae of Chironomus riparius (midge fly) in order to determine what factors were having the most effect on toxicity. Data showed that both sediment and detritus were highly contaminated with heavy metals. High metal levels in detritus had a significantly negative effect on the survival and growth of Chironomus larvae. Conversely, high iron-to-metal ratios in both sediment and detritus were correlated with reduced toxicity. The %TOC in sediments was linked to larval growth in October but not in June. SEM–AVS and grain size were not good indicators of toxicity. We conclude that detritus and iron could prove to be important factors for controlling and remediating heavy metal toxicity in Kearny Marsh and other wetlands in highly urbanized areas.
Key words: Acid volatile sulfides; Chironomus; detritus; Hackensack Meadowlands; heavy metals; iron; remediation; sediment; total organic carbon; toxicity testing; wetland.