Total levels and equilibrium-based phyto- and bioaccessibility of heavy metals as tools to assess sediment quality in recreational waterways

Author(s): Tsanangurayi Tongesayi, Ester Booth, Sade Stevens, Eric Winter

Deal Lake is one of themajor recreation sites in the state of NewJersey, and its vitality is restored by periodic dredging. The quality of the Lake’s sediments is extremely crucial for the health of its ecosystemand human health. Dredged sediments are often used for land reclamation and beach restoration, which potentially expose humans to chemical hazards. We assessed the quality of the Lake’s sediments by determining heavy metal(loid) concentrations, and the phytoaccessibility and bioaccessibility of the metals. A certified reference material, Ref1944, was used to validate the analytical measurement. Totalmetal levels ofAs, Cd, Cr, Pb and Zn were significantly higher than the National Oceanic and Atmospheric Administration’s Probable Effects Levels. Arsenic level was highest at the site closest to the Power and Light Plant, probably due to effluent from arsenic-containing wood preservatives, and was lowest at the site which had an overgrowth of weeds, probably due to uptake by weeds in place of phosphorus. Phytoaccessibility and bioaccessibility showed dependence on binding preferences and binding strengths. We proposed equilibrium-based availabilitymodels that depict the 24-hour phytoaccessibility and the 60-minute bioaccessibility as equilibrium concentrations. Uptake by cells shifts the equilibria towards dissolution, meaning that larger proportions of metals can become available than predicted.

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