Year

2001

Degree Name

Master of Environmental Science (Hons.)

Department

Department of Environmental Science

Abstract

The seagrass Zostera capricorni was evaluated as a possible biomonitor of metal contamination in coastal waters. Metal concentrations in Z capricorni leaves and rhizomes were analyzed for correlations with porewater and sediment concentrations from 7 locations within Lake Illawarra, a 35 km2 lagoon located south of Wollongong, NSW (Australia). Concentrations of As, Cd, Cu, M n , Pb, and Z n in seagrass tissues collected near to an industrial complex including a steelworks and copper smelter, and adjacent to a former power station, were significantly higher than concentrations in seagrass collected from the lake entrance. Variations in metal concentrations were also observed between seagrass leaves and rhizomes. The majority of metals was accumulated to higher concentrations in leaves than in rhizomes. Arsenic concentrations were highest in rhizomes. Lead and nickel were not accumulated to high concentrations in most tissue samples from Lake Illawarra, although differences in ambient lead concentrations were reflected in some groups of leaf samples. Manganese concentrations in both leaves and rhizomes exhibited significant correlations with manganese concentrations in Lake Illawarra porewaters. Other metals were below detection limits (ICP-MS) in porewaters. The concentrations of arsenic, copper, nickel, lead and zinc in seagrass tissues exhibited negative or positive correlations with the percentage of silt and clay in sediments, but spatial variations of metals in Z capricorni were more influenced by proximity to industrial sources than by sediment grainsize. Multi-dimensional scaling of all seagrass leaf metal concentrations indicated that seasonal factors may exert a greater influence on the relative uptake of metals by seagrass than do localized factors such as metal sources and sediment grain size. Z. capricorni was found to fit the general requirements for a biomonitor of metal contamination in sediments.

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