Coupling Ecological Restoration with Bioremediation to Target Dioxin Mineralization, Metal and Hydrocarbon Removal in the Passaic River
Paul S. Mankiewicz and Todd McDonnell
The Gaia Institute, 440 City Island Avenue, Bronx, NY 10464, 718.885.1906, paul.mankiewicz@gaia-inst.org
Industry has developed along waterways because of ready access to transportation, power, and waste disposal. Rivers provided a seemingly endless means of pollutant dilution, and large water bodies seemed to offer a near infinite sink for industrial wastes. Many industrial facilities were built on marshes, mudflats, shellfish beds and reefs, destroying the most active available natural filter in the process. This doubly flawed approach governed the practice of certain industries even after the creation of pollutants that are not readily removed by natural processes, including dioxins and PCBs.
The Passaic River is the prime example of these two errors: sediments - contaminated from years of dioxin discharged into the estuary by Diamond Shamrock - industrial effluents, combined sewer discharge, wastewater discharge, and the highest density of population and transportation infrastructure in the most populous state in the union are coupled with the near elimination of marsh, mudflat, and shellfish habitat. A reversal of this dual track to degradation will likely require a new and dynamic approach to mitigation and restoration in the Passaic River.
Contaminant problems in the Passaic River present unique opportunities for both mitigation and green-port development. Research over the past two decades has produced a body of knowledge demonstrating hydrocarbon, metal, nitrogen, and carbon removal capacities in enriched wetland and sediment column systems. Chemicals of concern already impact environmental quality and, in the event of large storms, are potentially subject to remobilization in the Passaic. On-site treatment may provide the safest option available.
Salt-marsh ecosystems, which are natural pollutant removal systems, can be used to restore the Passaic River and increase biogeochemical processing of carbon, nitrogen, and metals in the sediment and water column. The limited penetration of marsh root systems together with deep sediment contamination from the Diamond Shamrock facility, make marsh restoration alone inadequate to remediate contamination at depth. However, adding a significant carbon source in the absence of oxygen can establish necessary anaerobic conditions to support biogeochemical activities under which dioxin dechlorination occurs.
This project aims to create a carbon rich sediment column with significant concentrations of co-factors capable of removing dioxin. The full range of redox potentials and electron acceptors is to be achieved by adding a carbon source to the sediment column, and capping the in-situ biogeochemical reactor with saltmarsh. Natural attenuation, if it occurs in Passaic River sediments for dioxins, does not appear to take place at rates capable of providing significant human and ecological health protection. For this reason, contaminated sediments will need to be enriched with carbon, nutrients, and catalytic surface-active agents in order to induce enhanced rates of breakdown.