Ignacio Rivera-Duarte

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Temporal and spatial measurements of the toxicity (EC50), chemical speciation, and complexation capacity (Cu-CC) of copper in waters from San Diego Bay suggest control of the Cu-CC over copper bioavailability. While spatial distributions of total copper (CuT) indicate an increase in concentration from the mouth toward the head of San Diego Bay, the(More)
This study compared the sensitivity of two rapid toxicity tests, QwikLite and Microtox, to seven metals and ammonia. Both of these tests measure a reduction in light production from bioluminescent microorganisms (dinoflagellates and marine bacteria, respectively) as a means of toxicity detection and are simple and inexpensive to conduct compared to many(More)
Bacterial abundance and production, free (uncomplexed) copper ion concentration, total dissolved copper concentration, dissolved organic carbon (DOC), total suspended solids (TSS), and chlorophyll a were measured over the course of 1 year in a series of 27 sample “Boxes” established within San Diego Bay. Water was collected through a trace metal-clean(More)
The use of measured volatile organic chemical (VOC) concentrations in indoor air to evaluate vapor intrusion is complicated by (i) indoor sources of the same VOCs and (ii) temporal variability in vapor intrusion. This study evaluated the efficacy of utilizing induced negative and positive building pressure conditions during a vapor intrusion investigation(More)
Dissolved and particulate metals (Ag, Cd, Co, Cu, Ni, and Zn) and nutrients (PO(4), NO(3), and H(4)SiO(4)) were measured in Todos Santos Bay (TSB) in August 2005. Two sources producing local gradients were identified: one from a dredge discharge area (DDA) and another south of the port and a creek. The average concentrations of dissolved Cd and Zn (1.3 and(More)
The Orion 94-29 Cu(II) jalpaite ion selective electrode (Cu-ISE) was used to measure both the concentration of the aqueous free Cu(II) ion ([Cu(II)aq]) and its changes due to additions of Cu, in artificial seawater (ASW) and in seawater from San Diego Bay, CA. The range of free copper ion (i.e., pCu, -log [Cu(II)aq]) determined in seawater samples from the(More)
Critical tissue copper (Cu) residues associated with adverse effects on embryo-larval development were determined for the Mediterranean mussel (Mytilus galloprovincialis) and purple sea urchin (Strongylocentrotus purpuratus) following laboratory exposure to Cu-spiked seawater collected from San Diego Bay, California, USA. Whole body(More)
Copper-based epoxy and ablative antifouling painted panels were exposed in natural seawater to evaluate environmental loading parameters. In situ loading factors including initial exposure, passive leaching, and surface refreshment were measured utilizing two protocols developed by the US Navy: the dome method and the in-water hull cleaning sampling method.(More)
Copper concentrations in parts of San Diego Bay (CA, USA) exceed ambient water quality criteria (WQC; currently 3.1 microg/L dissolved, U.S. Environmental Protection Agency [U.S. EPA]). In order to better understand the bioavailability of copper to water-column organisms in the bay, toxicity tests were performed with copper added to surface water collected(More)
Understanding biogeochemical cycling of trace metals in the ocean requires information about variability in metal concentrations and distribution over short, e.g., diel, time scales. Such variability and the factors that influence it are poorly characterized. To address this shortcoming, we measured trace metal concentrations in the total dissolved,(More)