With the surge of urbanization and industrialization, the Raritan River, and particularly its 15-mile long lower portion, has experienced profound contamination over the last 100 years. More than 15 EPA designated Superfund Sites are present in the Raritan watershed, and exceptionally high concentrations of toxic heavy metals such as cadmium, copper, lead, and mercury have been observed in Raritan Bay sediments. These metal contaminants pose significant environmental threats to the local ecosystem, the water supply, and the community living along the Lower Raritan River. However, only a few studies reported the heavy metal distribution along the Lower Raritan River and their extent of accumulation in the river biota. The objective of this study was to develop a better understanding of the temporal variability and spatial distribution of toxic heavy metals (Arsenic, Chromium, Cadmium and Lead) in surface water, sediment, and biota in the regional ecosystem of the Lower Raritan River. In this study, Dr. Kaixuan Bu and Joe Roccanova from the Department of Marine and Coastal Sciences (DMCS) partnered with Dr. Jeffra Schaefer and Dr. Philip Sontag from the Department of Environmental Science (DES). The study was partially funded through a Rutgers Raritan River Consortium mini-grant.
In April 2018, the team conducted the first field trip aboard the R/V Rutgers and collected surface water and sediment samples at six sampling sites along the Lower Raritan River (Fig. 1). During this trip, two classes of undergraduate students attending the Analytical Environmental Chemistry Lab Course participated in the sampling; they learned metal-free sampling techniques and analytical principles for metal analyses of different sample types (Fig. 2). Two more sampling trips were conducted in late May and early August, to determine how riverine heavy metal distribution and bioaccumulation change over time, and to identify their potential sources within the river’s watershed. Surface water, zooplankton, and sediment samples were collected during these two trips.
Water collection was done in triplicate at each site off the boat, and heavy metals were analyzed as dissolved form and particulate form. Zooplankton samples and predominantly copepods (Fig. 3) were collected by dragging a 200 μm collection net behind the vessel for 5-10 minutes at each sampling site. Sediments were collected using an Ekman sediment sampler, however we were unable to collect sediment samples from every site. All analytical tasks have been performed at Rutgers Inorganic Analytical Lab in DMCS. Currently, the team is further analyzing and interpreting the data results and will soon present a more detailed account of their findings to the Raritan River community.
Dr. Bu presented preliminary results of this research as well as a poster at the 10th Annual Sustainable Raritan River Conference and Awards Ceremony on June 8, 2018. Follow these links to view his presentation titled, Temporal Heavy Metal Distribution and Bioaccumulation in the Lower Raritan and to see the associated poster.
Image credits: Google map provided by Kaixuan Bu; Students collecting Raritan surface water during the April Sampling trip by Kaixuan Bu; Zooplankton samples, dominated by copepods (Acartia tonsa), collected during August trip by Kaixuan Bu.