Methods

Sampling locations within each harbor were selected to provide spatial coverage of the harbor and to collect a variety of sediment types.  Sample stations are located both proximate to and away from known wastewater discharge points.  Sediment at each sampling location was collected using a ponar grab sampler.  Each sediment sample was examined in the field for texture (approximate grain size), color and for the presence of large natural or anthropogenic particles (shell fragments, pieces of coal, etc.).  A portion of each grab sample was placed into a labeled gallon zip-lock plastic bag and placed in a cooler for return to the laboratory.  A second portion of the sediment grab sample was placed in a separate gallon zip-lock plastic bag for particle size analysis and loss on ignition (LOI).
In the laboratory, any overlying water in the zip-lock bags was carefully decanted and the sediment sample was thoroughly mixed in the bag.  A portion of the sediment sample was removed and placed into a 600 ml glass beaker and oven-dried at 90°C for 24-48 hours.  The remaining sediment sample was stored frozen in gallon zip-lock storage bags.  Dried sediment samples were then disaggregated using a mortar and pestle and stored in labeled plastic twirl bags.  A portion of the dried sediment (1.0 ± 0.001 g) was weighed into 30 ml glass beakers and digested using a hydrogen peroxide-nitric acid (H2O2-HNO3) sediment metal extraction technique according to US EPA Method 3050a (US EPA, 1986).  The filtered digest solutions were analyzed for Fe, Cu, Zn, Ni, and Pb using air-acetylene flame atomic absorption spectrophotometry (PerkinElmer Zeeman 8100).  All glassware will be acid-rinsed prior to use to prevent contamination.  An estuarine sediment reference material (NIST 2702 estuarine sediment) was analyzed for metals to check the accuracy and precision of the analytical techniques.  Sediment organic matter content was determined on oven-dried sediment from weight loss on ignition (LOI) at 550°C in a muffle furnace.