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Although a variety of analytical techniques have been developed to characterize metal speciation, few have been used successfully in the complicated matrices encountered in wastewater effluents and surface runoff. In this study, competitive ligand equilibrium-cathodic stripping voltammetry (CLE-CSV) and chelating resin column partitioninggraphite furnace atomic absorption spectroscopy (CRCP-GFAAS) are used to determine the speciation of Cu and Ni in point and non-point pollutant sources discharging into South San Francisco Bay. As expected, most of the dissolved Cu and Ni in wastewater effluents and surface runoff are complexed. Moderately strong metal-complexing ligands, which likely consist of activated sludge biopolymers and humic substances, are responsible for the complexation of only about 20% of the Ni and 5-50% of the Cu. The remaining Cu and Ni is complexed by ligands with apparent stability constants comparable to those of synthetic chelating agents. Strongly complexed Cu is present at concentrations below 40 nM and accounts for 5-60% of the Cu discharged by these sources. Strongly complexed Ni is present at concentrations ranging from approximately 10 to 100 nM and accounts for >75% of the Ni discharged by wastewater treatment plants and approximately 25% of the Ni in surface runoff. Strong Ni complexes, which are not removed during wastewater treatment, are extremely stable in seawater. The existence of strong metal-complexing ligands in wastewater effluent and, to a lesser degree, in surface runoff must be accounted for when evaluating metal treatability and biogeochemistry.

The fungicides Ziram and Maneb (class dithiocarbamate) are organic Zn and Mn complexes in which the trace metal is chelated to organic dithiocarbamate ligands. The resulting organic metal complex is small, neutrally charged, and lipophilic in character. Short-term uptake experiments using a coastal diatom demonstrated that these lipophilic organic Zn and Mn complexes diffuse across the lipid bilayer that constitutes the plasma membrane. In addition, Cu 2ϩ and Pb 2ϩ ions in seawater solution undergo exchange reactions with Zn and Mn and form lipophilic organic Cu and Pb complexes that also diffuse across the plasma membrane and into the cytosol of the cell. Intracellularly, these trace metals are thought to dissociate from the transport ligand and complex intracellular ligands. Based on these results, the presence of dithiocarbamate fungicides in surface water can inadvertantly enhance the passive uptake of a variety of toxic heavy metals from the water into microorganisms.

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The 1983 mass mortality of the sea urchin Diadema antillarum remains one of the most severe die-offs ever recorded in the Caribbean. Before 1983, the herbivore D. antillarum was pervasive on coral reefs in the region. Nine months after first detection of the mass mortality, 95% of the urchins had perished, and algal cover of coral increased between 100% and 250%. A water-borne pathogen was hypothesized as the causative agent, but it was never isolated. To date, surface current patterns have been used exclusively to explain both the cause and the distribution patterns of the mortality event. Using archived satellite images, we re-examined the water-borne pathogen hypothesis and investigated whether other mechanisms could also account for the dissemination pattern in some areas. In addition, archived satellite images were utilized to detect changes in coral reef reflectance. For infections in the Gulf of Mexico and Bermuda, satellite images confirm that surface currents are likely responsible for the distribution of the pathogen. For infections in the eastern Caribbean (Curacao, U.S. Virgin Islands, Barbados), however, another mechanism, possibly ballast water exchange, must be considered because the surface current and infection patterns do not coincide. Changes in coral reflectance were detectable from Landsat thermatic mapping data before and after the mass mortality and correspond to the change in algal cover. Results from our study demonstrate the potential of satellite images for use in determining connectivity between regions of the Caribbean and in detecting changes in coral reef cover.Utilización de Percepción Remota para Reanalizar la Mortandad Masiva de Diadema antillarum de 1983-1984 Resumen: El evento de mortandad masiva de 1983-1984 del erizo de mar Diadema antillarum se mantiene como uno de los eventos de mortandad masiva más severos de que se tengan registros en el Caribe. Antes de 1983, el hervíboro D. antillarum , abundaba en los arrecifes de coral de la región. Nueve meses después de la detección de la mortandad masiva, 95% de los erizos fallecieron y la cobertura de algas sobre el coral se incrementó entre 100 y 250%. Se estableció la hipótesis de que el agente causante fue un patógeno de origen acuático, pero nunca fue aislado. A la fecha, los patrones de corrientes superficiales han sido usados exclusivamente para explicar tanto el agente causal como los patrones de distribución de la mortandad. Utilizando imágenes de archivo de satélite, re-examinamos la hipótesis del agente de origen acuático e investigamos si otros mecanismos podrían también ser considerados en los patrones de diseminación de algunas áreas. Para infecciones del Golfo de México y Bermudas, las imágenes de satélite confirman que las corrientes superficiales son los responsables más probables de la distribución del patógeno. Sin embargo, para infecciones en el Este del Caribe (Curacao, U.S., Islas Virginia, Barbados), otro mecanismo, posiblemente el cambio de agua de lastre, podría ser considerado debido a que las corrient...