Potential for Increased Mercury Accumulation in the Estuary Food Web

Davis, Jay A; Yee, Donald; Collins, Joshua N.; Schwarzbach, Steven E.; Luoma, Samuel N.

doi:10.15447/sfews.2003v1iss1art4

Cited by 32 publications

(22 citation statements)

References 64 publications

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“…One implication is that an increase or decrease in dissolved MeHg concentrations in the water column could affect the amount of MeHg accumulated by phytoplankton during blooms. In South Bay, there is potential to both increase dissolved MeHg from wetland restorations (Davis et al 2003) and to decrease it through regulatory actions, such as development of a Total Maximum Daily Load to restrict mercury loadings to the estuary (Conaway et al 2008). Accordingly, the link between dissolved concentrations and algal concentrations warrants further investigation.…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, Luengen et al (2007) found that concentrations of some metals (e.g., Mn, cobalt [Co], Zn, and Pb) increased as the spring 2003 bloom degraded, demonstrating that decay of the bloom also affected metal cycling. However, neither total Hg (Hg T ), which includes both inorganic and organic forms of mercury, nor MeHg has been previously measured during a South Bay bloom, despite the mercury pollution in the estuary (Thompson et al 2000;Davis et al 2003).…”

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confidence: 99%

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Role of phytoplankton in mercury cycling in the San Francisco Bay estuary

Luengen

Flegal

2009

Limnol. Oceanogr.

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To study the role of phytoplankton in mercury cycling, we measured methylmercury (MeHg) and total mercury (Hg T ) in surface waters during the spring 2003 phytoplankton bloom in San Francisco Bay. Conditions that described the peak of the bloom, the amount of sorbent, and decay of the bloom were summarized by principal component analysis (PCA). Multivariate analyses conducted with the PCA factors demonstrated that the bloom accounted for a significant (p 5 0.03) decrease in dissolved (,0.45 mm) MeHg. Dissolved MeHg was depleted to 0.026 pmol L 21 and was unaffected when chlorophyll a concentrations nearly tripled, indicating that bloom dilution could occur as a result of a limited amount of MeHg. The calculated algal MeHg concentration was 3-10 pmol g 21 (dry weight). As the bloom decayed, dissolved MeHg concentrations significantly (p 5 0.04) increased, likely due to MeHg remineralization from decaying phytoplankton and/or production in sediments. By creating suboxic conditions in surface sediments and stimulating microbial activity, decomposing phytoplankton could bolster MeHg production, a potential side effect of large blooms. Unlike dissolved MeHg, dissolved Hg T concentrations were not measurably altered by the bloom or decay factors. That difference corroborated previous culture studies in which phytoplankton actively accumulated MeHg, but not Hg T . As the bloom decayed, Hg T K d values significantly (p 5 0.012) increased, possibly because particles (i.e., phytoplankton) with low Hg T concentrations were lost from the water column. Based on the relationship between Hg T particulate concentrations and percent phytoplankton, the calculated algal Hg T concentration was ,0.5 nmol g 21 (dry weight).

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Role of phytoplankton in mercury cycling in the San Francisco Bay estuary

Luengen

Flegal

2009

Limnol. Oceanogr.

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“…Their widespread use and dispersion has left residues in soils and sediments of the Sacramento and San Joaquin River watersheds that are transported to the Bay mostly during large storm events. Similarly, many studies of methylmercury (MeHg) bioaccumu lation and effects have raised concern about mercury (Hg) contamination (Davis et al, 2003;Eagles-Smith et al, 2009;Greenfield and Jahn 2010;Gassel et al, 2011;Davis et al, 2011;Davis et al, 2012) and resulted in a fish consumption advisory for San Francisco Bay (OEHHA 2011).…”

Section: Introductionmentioning

confidence: 99%

Estimation of Contaminant Loads from the Sacramento‐San Joaquin River Delta to San Francisco Bay

David

Gluchowski²,

Leatherbarrow³

et al. 2015

Water Environment Research

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Contaminant concentrations from the Sacramento-San Joaquin River watershed were determined in water samples mainly during flood flows in an ongoing effort to describe contaminant loads entering San Francisco Bay, CA, USA. Calculated PCB and total mercury loads during the 6-year observation period ranged between 3.9 and 19 kg/yr and 61 and 410 kg/yr, respectively. Long-term average PCB loads were estimated at 7.7 kg/yr and total mercury loads were estimated at 200 kg/yr. Also monitored were PAHs, PBDEs (two years of data), and dioxins/furans (one year of data) with average loads of 392, 11, and 0.15/0.014 (OCDD/OCDF) kg/yr, respectively. Organochlorine pesticide loads were estimated at 9.9 kg/yr (DDT), 1.6 kg/yr (chlordane), and 2.2 kg/yr (dieldrin). Selenium loads were estimated at 16 300 kg/yr. With the exception of selenium, all average contaminant loads described in the present study were close to or below regulatory load allocations established for North San Francisco Bay.

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“…An intensive restoration program is underway to restore wetlands surrounding the Bay, including the conversion of thousands of hectares of historic salt ponds and other isolated habitats to wetlands (Goals Project, 1999;Grenier and Davis, 2010). MeHg production can be relatively high in nearshore managed ponds and wetland habitats due to differences in hydrology and redox conditions (Davis et al, 2003;Grenier and Davis, 2010;Heim et al, 2007;Miles and Ricca, 2010). Consequently, Hg monitoring in Bay biota is underway to evaluate potential short and long-term changes in MeHg exposure and bioaccumulation due to habitat restoration.…”

Section: Introductionmentioning

confidence: 99%