Uptake and Translocation of Heavy Metals in Salt Marsh Sediments by Spartina patens

Abstract

The Hackensack Meadowlands is a coastal marsh system in northeastern New Jersey, located approximately 10 km west of New York City. Within the Meadowlands, twelve destructed or degraded estuarine wetland sites are currently part of ecological restoration projects that are in various phases of development from planning to completion (http:// www.meadowlands.state.nj.us/naturalresources/wetlands/ Wetlands.cfm). A completed restoration site is Harrier Meadow (North Arlington, NJ) where mitigation work included the creation of channels, impoundments, low marsh habitat and upland habitat islands. Important salt marsh plant species such as salt-meadow grass (Spartina patens), and spike grass (Distichlis spicata) dominate portions of the marsh. The sediments of Harrier Meadow contain heavy metals at concentrations that are below regulatory action limits (e.g., cadmium (Cd) 0–1 ppm; chromium (Cr) 10–18 ppm; copper (Cu) 13–60 ppm; nickel (Ni) 7–15 ppm; lead (Pb) 0–87 ppm; zinc (Zn) 28–94 ppm) (http:// www.meri.njmeadowlands.gov/ecorisk/), but above those typically found in uncontaminated environments (van Driel et al. 1995; Swaileh et al. 2004). Since Spartina species have been shown to take up heavy metals into roots and translocate them into aboveground parts (see Weis and Weis (2004) for review), we had investigated the fate and the effects of selected heavy metals (i.e., Cd, Cr, Cu, Ni, Pb, and Zn) in sediment cores that were densely covered with Spartina patens in a recent short-term study (Suntornvongsagul et al. 2007). Since levels of metals taken up and translocated had been shown to vary depending on the metal concentration in the substrate (Vogel-Mikus et al. 2005), and to be affected by the presence of other metals (McKenna et al. 1993; Podar et al. 2004), half of these cores were artificially amended with Ni in order to increase its availability, and to assess potential effects on uptake of other metals. Ni was chosen since it was the most accumulated metal in shoots from a mixture containing Cd(II), Cu(II), Ni(II) and Zn(II) in identical concentrations (Peralta-Videa et al. 2002), and was assumed to persist in hydrated form in pore water. We demonstrated that Ni-amendment had no significant effect on the fate of other metals in sediments, however, observed increased root-uptake of certain metals. Although translocation of Ni into shoots reflected the 10-fold higher concentrations in sediments and roots in Ni-amended cores, metal translocation into shoots was generally small for all metals (Suntornvongsagul et al. 2007). The goal of the current study was to extend the observations beyond the first growing season, and to assess whether Ni-amendment had effects on metal uptake and translocation after three growing seasons.