Linkage of Bioaccumulation and Biological Effects to Changes in Pollutant Loads in South San Francisco Bay

Abstract

The developed world has invested billions of dollars in waste treatment since the 1970s; however, changes in ecological or biological responses are rarely associated with reductions in metal pollutants. Here we present a novel, 23-yr time series of environmental change from a San Francisco Bay mudflat located 1 km from the discharge of a suburban domestic sewage treatment plant. Samples of surface sediment, the bioindicator Macoma balthica, and metals loading data were used to establish links between discharge, bioaccumulation, and effects. Mean annual Ag concentrations in M. balthica were 106 μg/g in 1978 and 3.67 μg/g in 1998. Concentrations of Cu declined from 287 μg/g in 1980 to a minimum of 24 μg/g in 1991. Declining Cu bioaccumulation was strongly correlated with decreasing Cu loads from the plant between 1977 and 1998. Relationships with bioaccumulation and total annual precipitation suggested that inputs from nonpoint sources were most important in controlling Zn bioavailability during the same period. Ecoepidemiological criteria were used to associate failed gamete production in M. balthica to a metals-enriched environment. Reproduction persistently failed between the mid-1970s and mid-1980s; it recovered after metal contamination declined. Other potential environmental causes such as food availability, sediment chemistry, or seasonal salinity fluctuations were not related to the timing of the change in reproductive capability. The results establish an associative link, suggesting that it is important to further investigate the chemical interference of Cu and/or Ag with invertebrate reproduction at relatively moderate levels of environmental contamination.

Kinetic modeling of Ag, Cd and Co bioaccumulation in the clam Macoma balthica: quantifying dietary and dissolved sources

“…Macoma balthica were collected in June 1999 from an exposed mudflat near the Palo Alto Baylands, California, in south San Francisco Bay, where this population of clams has been monitored for metal concentrations for over 25 yr (Hornberger et al 2000). Clams were fed a continuous supply of the diatom Thalassiosira pseudonana and were acclimated to experimental conditions (12°C, salinity 25) for 10 d prior to experiments.…”

“…With more focus on understanding the interplay between animal behavior and metal exposures, it may be possible to constrain more tightly the model parameters for specific populations of animals living in specific environmental conditions. This study focused on a population of Macoma balthica in south San Francisco Bay at a site that has been continuously monitored for 30 yr (Hornberger et al 2000). In experiments using clams collected from this location, many of the parameters in the model have been determined for Ag, Cd, and Co over a range of environmental conditions (Reinfelder et al 1997.…”

Analysis of engineered nanomaterials in complex matrices (environment and biota): General considerations and conceptual case studies

“…Although the concentrations of Ag in wastewater in the United States, as evidenced by discharges in urban wastewater facilities, has significantly decreased from 1989 to 2007, potential releases resulting from manufacturing and using commercial engineered AgNP products may result in future increases of total Ag present in wastewater [84,85]. Past and current sources of Ag contamination in wastewater include photographic facilities, smelters, mines, and urban wastes.…”

Subcellular controls of silver biokinetics in the green mussel Perna viridis from two hydrographic zones

“…Although the Ag concentration is often low in the environment, dietary exposure to Ag at environmentally realistic concentrations may cause toxicity to marine bivalves (Hornberger et al 2000). In Hong Kong, Ag is one of the major metal contaminants, especially in marine sediments, due to the significant input of industrial activities.…”