Highly Contaminated Sediments from the Gowanus Canal (New York) Superfund Site: An Environmental Forensic Approach

The 2.5 km long Gowanus Canal (Brooklyn, NY, USA) is a severely contaminated urban waterway dating from the mid-nineteenth century, listed as a US Environmental Protection Agency (USEPA) Superfund site since 2010. Applying an environmental forensics approach to the extensive USEPA data set, we detect systematic variations in parent PAH ring number distributions in the canal sediments, as well as an extraordinary enrichment in organic carbon. We subjected a supplemental sample set to a more detailed analysis by quantitative pyrolysis-GC-MS, Rock-Eval pyrolysis, and organic petrology. With these sensitive methods, we can confirm the alkyl-PAH fingerprint of coal tar (a legacy of former manufactured gas plants along the canal), the presence of coal (bituminous and anthracite) and coal combustion products, and the steroid and fatty acid signatures of raw sewage effluent. The latter compels us to emphasize the urgency of controlling the continuing input from combined sewer overflow events following rainstorms, besides remediating the legacy coal tar contamination that provoked its Superfund designation. As an addition to the environmental forensic toolbox, for complexly-contaminated sites we recommend a rapid Rock-Eval (or equivalent) bulk pyrolysis pre-screening of numerous core and surface samples from the suspect locale, followed by pyrolysis-GC-MS for molecular-level screening of a representative sub-set.