Nutrients, Trace Metals, Polycyclic Aromatic Hydrocarbons, and Pesticides in Urban Streams of the Tampa Bay Watershed, Florida.

Human alterations of natural landscapes have resulted in degradation of tributaries, streams, and rivers in urbanized and rapidly urbanizing regions.  A variety of water quality problems including eutrophication of natural waters, microbial and toxics contamination, and harmful algal blooms plague coastal water bodies of Florida.  The human population has been increasing steadily in the coastal areas along the Gulf Coast of Florida, Alabama, Louisiana, Mississippi, and Texas.  For example, during 1960–2000, population in coastal counties of these five states increased by >100% from 8 to over 17 million.  This increase in human population has transformed the natural or agricultural dominated landscape to urban watersheds, with associated increases in impervious surfaces (rooftops, roads, parking lots) that have in turn increased the runoff of polluted water to urban streams.  The objective of this study was to determine the impact of historic land use conversion on stream sediment contamination in selected urbanized and rapidly urbanizing areas of the Tampa Bay Watershed.  We collected sediment and water samples from nine streams that drain different land uses ranging from <5% to >60% urban land. Sediments were analyzed for nutrients (nitrogen, phosphorus), 16 trace metals, 14 polycyclic aromatic hydrocarbons (PAHs), and organo-chlorine pesticides.  This presentation will compare and contrast the influence of urbanization on inorganic and organic contaminants, with a discussion of likely sources of these contaminants in urban streams.  This knowledge is fundamental to 1) understand the complex biogeochemical processes and pathways governing the fate and transport of contaminants in urban environments and 2) develop best management practices to reduce the delivery of harmful contaminants from urban watersheds to environmentally sensitive coastal water bodies.