MP1 New Approaches to Determining Soil and Sediment Exposures
256 Portland Ballroom
1:20 PM - 4:40 PM, Monday
() Bio-assay of soil metals mobilized by salt marsh plants.
Green, P.1, Norris, A.1, Fan, T.1, 2, Vines, C.3, Cherr, G.3, Higashi, R.1, 1 University of California, Davis, CA, USA2 University of Louisville, Louisville, KY, USA3 Bodega Marine Laboratory, Bodega Bay, CA, USA
ABSTRACT- Vascular plants can profoundly alter bioavailability of sediment toxic metals through currently under-considered bio-conduits of transport. Described is a combined chemical-biological approach to toxic metal bioavailability assessment from coastal soils, in two steps. First, salts exuded by two species of estuarine marsh grasses, Distichlis spicata (salt grass) and Spartina sp. (cord grass), are simply and rapidly sampled then analyzed by ICP-MS. Second, toxicity of the salts are assayed with sea urchin embryos which exhibit abnormal development and are highly sensitive to environmental contaminants. We have also used the metals alone of the leaf exudates to survey several coastal marshes in California. Metals eluted from rhizospheric soil associated with the plant were analyzed in parallel. The two sets of data revealed dramatic variations in element bioavailability to plants. Moreover, we conducted experiments with Spartina in sand culture with added Cd, with the goal of understanding the process physiologically. We have experimentally exposed Spartina to levels of Cd representative of levels found in coastal California salt marshes. Leaf exudates were collected at three time points during the six week Cd exposure. The bioavailability and ecotoxicity of the exuded metals was investigated using an ecologically sensitive, model organism: the sea urchin. The ecological threads between land and sea are connected: the ability of Spartina to mobilize metals within the rhizosphere negatively impact the development of sea urchins.
Key words: metals, wetlands, plants, soil