A review of total dissolved copper and its chemical speciation in San Francisco Bay, California.

Following basin-wide contamination from industrial emissions and urban development, total dissolved copper concentrations in some regions of San Francisco Bay have exceeded national and state guidelines for water quality. In the face of dramatic improvements in wastewater treatment and point source control, persisting elevated dissolved copper concentrations in the Bay have prompted multiple studies and extensive monitoring of this estuary since 1989. Statistical analyses of monitoring data show that total dissolved copper concentrations have declined in the North (by 17%) and South (29%) San Francisco Bay as well as in the Southern Sloughs (44%) from 1993 to 2001. Concentrations remain elevated in the farthest reaches of the Bay (Delta and Estuary Interface), and in the Central Bay. Dissolved copper concentrations throughout the Bay have also been positively correlated (r = 0.632, P < 0.0005, n = 598) with dissolved organic matter, supporting results from complimentary chemical speciation studies which indicate that high-affinity copper-binding organic ligands dominate the chemical speciation of dissolved copper in the Bay. These organic ligands typically bind > 99.9% of the dissolved copper, effectively buffering the system against small changes in dissolved copper concentrations, and maintaining free Cu(2+) concentrations well below the toxicity threshold of ambient aquatic microorganisms. In response to these findings, site-specific water quality criteria for dissolved copper concentrations are now being developed by the Regional Water Quality Board to provide a more appropriate standard for copper toxicity in the Bay-one based on its chemical speciation and bioavailability.

Isotopic evidence of the persistent dominance of blood lead concentrations by previous gasoline lead emissions in Yerevan, Armenia.

Recent (1999) blood lead (PbB) isotopic compositions (n=17) of males and females in Yerevan, Armenia, indicate that previous emissions of leaded gasoline still dominate the populace's PbB concentrations 2 years after the country's apparent de facto elimination of leaded gasoline in Armenia. The range of PbB isotopic compositions overlaps those of air and near-road surface soils in Yerevan, and the averages of those isotopic compositions in blood (208Pb/207Pb=2.442; 206Pb/207Pb=1.158) and near-road soils (208Pb/207Pb=2.442; 206Pb/207Pb=1.157) are indistinguishable. Using a proxy for historic leaded-gasoline emissions in Armenia, these analyses suggest that leaded gasoline was, is, and will continue to be via the resuspension of lead-bound soils contaminated by previous depositions from leaded-gasoline emissions, a relatively important source of industrial lead in both Yerevan's atmosphere and its populace. However, the level of lead contamination in the Armenian populace, based on the PbB geometric mean of 4.0microg/dL (n=49) measured in this initial survey, appears to be much lower than recently proposed by the Armenian Ministry of Nature Protection.