Avian ecological risk potential in an urbanized estuary: Lower Hackensack River, New Jersey, USA.

As part of a comprehensive ecological risk assessment on a broad range of species, the potential for adverse effects in birds was evaluated at a chromate ore processing residue disposal site, Study Area 7, located at the confluence of the Lower Hackensack River, Passaic River, and Upper Newark Bay. Although detection of elevated concentrations of total chromium in sediment prompted the study, it was also necessary to consider potential risks related to other chemicals present in elevated concentrations due to widespread anthropogenic activities in Upper Newark Bay and its watershed. U.S. Army Corps of Engineers' TrophicTrace software was used to predict exposure to avian receptors using measured concentrations of chemicals in sediment, measured concentrations of chemicals in benthic invertebrates, and measured site physicochemical parameters. The TrophicTrace model was improved as part of the Study Area 7 ecological risk assessment to account for (1) incidental ingestion of sediment by dabbling and diving birds, (2) area use factors for spatial overlap of wide-ranging fish species and piscivorous birds, (3) spatially-explicit utilization of the site by birds with a variety of foraging strategies, and (4) temporal patterns of site utilization by migratory species. The ecological risk assessment demonstrated that chromium in sediment does not pose unacceptable hazards to avian receptors. Potentially unacceptable hazards were indicated for several organic chemicals (i.e., pesticides, polychlorinated biphenyls, and dioxins/furans), with hazard quotients highest for Upper Newark Bay reference conditions, reflecting potential widespread chemical impacts to the estuary. The modifications to TrophicTrace conducted for this assessment may be prudent and applicable for improving the accuracy and realism of other assessments involving avian receptors exposed to chemicals via contaminated sediment and transfer through the food web.

Geochemical stability of chromium in sediments from the lower Hackensack River, New Jersey.

Elevated levels of chromium, partly attributable to historical disposal of chromite ore processing residue, are present in sediment along the eastern shore of the lower Hackensack River near the confluence with Newark Bay. Due to anaerobic conditions in the sediment, the chromium is in the form of Cr(III), which poses no unacceptable risks to human health or to the river ecology. However, as water quality conditions have improved since the 1970s, aerobic conditions have become increasingly prevalent in the overlying water column. If these conditions result in oxidation of Cr(III) to Cr(VI), either under quiescent conditions or during severe weather or anthropogenic scouring events, the potential for adverse ecological effects due to biological exposures to Cr(VI) is possible, though the reaction kinetics associated with oxidation of Cr(III) to Cr(VI) are unfavorable. To investigate the stability of Cr(III) in Hackensack River sediments exposed to oxic conditions, sediment suspension and oxidation experiments and intertidal sediment exposure experiments that exposed the sediments to oxic conditions were conducted. Results revealed no detectable concentrations of Cr(VI), and thus no measurable potential for total chromium oxidation to Cr(VI). Furthermore, total chromium released from sediment to elutriate water in the oxidation and suspension experiments ranged from below detection (<0.01 mg/L) to 0.18 mg/L, below the freshwater National Recommended Water Quality Criteria (NRWQC) of 0.57 mg/L for Cr(III). These results support conclusions of a stable, in situ geochemical environment in sediments in the lower Hackensack River with respect to chromium. Results showed that chemicals other than Cr(VI), including copper, lead, mercury, zinc, and PCBs, were released at levels that may pose a potential for adverse ecological effects.

Using a Sediment Quality Triad approach to evaluate benthic toxicity in the Lower Hackensack River, New Jersey.

A Sediment Quality Triad (SQT) study consisting of chemical characterization in sediment, sediment toxicity and bioaccumulation testing, and benthic community assessments was performed in the Lower Hackensack River, New Jersey. Chemistry data in sediment and porewater were evaluated based on the equilibrium partitioning approach and other published information to investigate the potential for chemical effects on benthic organisms and communities. Relationships were supported by laboratory toxicity and bioaccumulation experiments to characterize chemical effects and bioavailability. Benthic community results were evaluated using a regional, multimetric benthic index of biotic integrity and four heterogeneity indices. Evidence of slight benthic community impairment was observed in five of nine sediment sample stations. Severe lethal toxicity to amphipods (Leptocheirus plumulosus) occurred in four of these five stations. Although elevated total chromium concentrations in sediment (as high as 1900 mg/kg) were the rationale for conducting the investigation, toxicity was strongly associated with concentrations of polycyclic aromatic hydrocarbons (PAHs) rather than total chromium. PAH toxic units (SigmaPAH TU) in sediment and SigmaPAH concentrations in laboratory organisms from the bioaccumulation experiment showed a clear dose-response relationship with toxicity, with 0% survival observed in sediments in which SigmaPAH TU > 1-2 and SigmaPAH concentrations in Macoma nasuta were >2 micromol/g, lipid weight. Metals detected in sediment and porewater, with the possible exception of copper, did not correlate with either toxicity or levels in tissue, likely because acid-volatile sulfide levels exceeded concentrations of simultaneous extracted metals at all sample locations. The study reinforces the value of using multiple lines of evidence approaches such as the SQT and the importance of augmenting chemical and biological analyses with modeling and/or other approaches to evaluate chemical bioavailability and toxicity of sediments.