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Leewis MC, Berlemont R, Podgorski DC, Srinivas A, Zito P, Spencer RGM, McFarland J, Douglas TA, Conaway CH, Waldrop M, Mackelprang R. Life at the Frozen Limit: Microbial Carbon Metabolism Across a Late Pleistocene Permafrost Chronosequence. Front Microbiol 2020; 11:1753. [PMID: 32849382 PMCID: PMC7403407 DOI: 10.3389/fmicb.2020.01753] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 07/06/2020] [Indexed: 11/13/2022] Open
Abstract
Permafrost is an extreme habitat yet it hosts microbial populations that remain active over millennia. Using permafrost collected from a Pleistocene chronosequence (19 to 33 ka), we hypothesized that the functional genetic potential of microbial communities in permafrost would reflect microbial strategies to metabolize permafrost soluble organic matter (OM) in situ over geologic time. We also hypothesized that changes in the metagenome across the chronosequence would correlate with shifts in carbon chemistry, permafrost age, and paleoclimate at the time of permafrost formation. We combined high-resolution characterization of water-soluble OM by Fourier-transform ion-cyclotron-resonance mass spectrometry (FT-ICR MS), quantification of organic anions in permafrost water extracts, and metagenomic sequencing to better understand the relationships between the molecular-level composition of potentially bioavailable OM, the microbial community, and permafrost age. Both age and paleoclimate had marked effects on both the molecular composition of dissolved OM and the microbial community. The relative abundance of genes associated with hydrogenotrophic methanogenesis, carbohydrate active enzyme families, nominal oxidation state of carbon (NOSC), and number of identifiable molecular formulae significantly decreased with increasing age. In contrast, genes associated with fermentation of short chain fatty acids (SCFAs), the concentration of SCFAs and ammonium all significantly increased with age. We present a conceptual model of microbial metabolism in permafrost based on fermentation of OM and the buildup of organic acids that helps to explain the unique chemistry of ancient permafrost soils. These findings imply long-term in situ microbial turnover of ancient permafrost OM and that this pooled biolabile OM could prime ancient permafrost soils for a larger and more rapid microbial response to thaw compared to younger permafrost soils.
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Affiliation(s)
- Mary-Cathrine Leewis
- U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Menlo Park, CA, United States
| | - Renaud Berlemont
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA, United States
| | - David C Podgorski
- Pontchartrain Institute for Environmental Sciences, Department of Chemistry, University of New Orleans, New Orleans, LA, United States
| | - Archana Srinivas
- Department of Biology, California State University Northridge, Northridge, CA, United States
| | - Phoebe Zito
- Pontchartrain Institute for Environmental Sciences, Department of Chemistry, University of New Orleans, New Orleans, LA, United States
| | - Robert G M Spencer
- National High Magnetic Field Laboratory Geochemistry Group, Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL, United States
| | - Jack McFarland
- U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Menlo Park, CA, United States
| | - Thomas A Douglas
- U.S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK, United States
| | | | - Mark Waldrop
- U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Menlo Park, CA, United States
| | - Rachel Mackelprang
- Department of Biology, California State University Northridge, Northridge, CA, United States
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Mackelprang R, Burkert A, Haw M, Mahendrarajah T, Conaway CH, Douglas TA, Waldrop MP. Microbial survival strategies in ancient permafrost: insights from metagenomics. ISME J 2017; 11:2305-2318. [PMID: 28696425 PMCID: PMC5607373 DOI: 10.1038/ismej.2017.93] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 02/25/2017] [Accepted: 04/27/2017] [Indexed: 01/14/2023]
Abstract
In permafrost (perennially frozen ground) microbes survive oligotrophic conditions, sub-zero temperatures, low water availability and high salinity over millennia. Viable life exists in permafrost tens of thousands of years old but we know little about the metabolic and physiological adaptations to the challenges presented by life in frozen ground over geologic time. In this study we asked whether increasing age and the associated stressors drive adaptive changes in community composition and function. We conducted deep metagenomic and 16 S rRNA gene sequencing across a Pleistocene permafrost chronosequence from 19 000 to 33 000 years before present (kyr). We found that age markedly affected community composition and reduced diversity. Reconstruction of paleovegetation from metagenomic sequence suggests vegetation differences in the paleo record are not responsible for shifts in community composition and function. Rather, we observed shifts consistent with long-term survival strategies in extreme cryogenic environments. These include increased reliance on scavenging detrital biomass, horizontal gene transfer, chemotaxis, dormancy, environmental sensing and stress response. Our results identify traits that may enable survival in ancient cryoenvironments with no influx of energy or new materials.
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Affiliation(s)
- Rachel Mackelprang
- Department of Biology, California State University Northridge, Northridge, CA, USA
| | - Alexander Burkert
- Department of Biology, California State University Northridge, Northridge, CA, USA
| | - Monica Haw
- US Geological Survey, Menlo Park, CA, USA
| | - Tara Mahendrarajah
- Department of Biology, California State University Northridge, Northridge, CA, USA
| | | | - Thomas A Douglas
- US Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK, USA
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Stoliker DL, Repert DA, Smith RL, Song B, LeBlanc DR, McCobb TD, Conaway CH, Hyun SP, Koh DC, Moon HS, Kent DB. Hydrologic Controls on Nitrogen Cycling Processes and Functional Gene Abundance in Sediments of a Groundwater Flow-Through Lake. Environ Sci Technol 2016; 50:3649-57. [PMID: 26967929 DOI: 10.1021/acs.est.5b06155] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient.
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Affiliation(s)
| | | | - Richard L Smith
- U.S. Geological Survey , Boulder, Colorado, 80303 United States
| | - Bongkeun Song
- Virginia Institute of Marine Science , Gloucester Point, Virginia, 23062 United States
| | - Denis R LeBlanc
- U.S. Geological Survey , Northborough, Massachusetts, 01532 United States
| | - Timothy D McCobb
- U.S. Geological Survey , Northborough, Massachusetts, 01532 United States
| | | | - Sung Pil Hyun
- Korea Institute of Geoscience and Mineral Resources , Daejeon, 34132 Republic of Korea
| | - Dong-Chan Koh
- Korea Institute of Geoscience and Mineral Resources , Daejeon, 34132 Republic of Korea
| | - Hee Sun Moon
- Korea Institute of Geoscience and Mineral Resources , Daejeon, 34132 Republic of Korea
| | - Douglas B Kent
- U.S. Geological Survey , Menlo Park, California, 94025 United States
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Conaway CH, Thomas B, Saad N, Thordsen JJ, Kharaka YK. Carbon isotope analysis of dissolved organic carbon in fresh and saline (NaCl) water via continuous flow cavity ring-down spectroscopy following wet chemical oxidation. Isotopes Environ Health Stud 2015; 51:344-358. [PMID: 25689734 DOI: 10.1080/10256016.2015.1009910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This work examines the performance and limitations of a wet chemical oxidation carbon analyser interfaced with a cavity ring-down spectrometer (WCO-CRDS) in a continuous flow (CF) configuration for measuring δ(13)C of dissolved organic carbon (δ(13)C-DOC) in natural water samples. Low-chloride matrix (<5 g Cl/L) DOC solutions were analysed with as little as 2.5 mg C/L in a 9 mL aliquot with a precision of 0.5 ‰. In high-chloride matrix (10-100 g Cl/L) DOC solutions, bias towards lighter δ(13)C-DOC was observed because of incomplete oxidation despite using high-concentration oxidant, extended reaction time, or post-wet chemical oxidation gas-phase combustion. However, through a combination of dilution, chloride removal, and increasing the oxidant:sample ratio, high-salinity samples with sufficient DOC (>22.5 µg C/aliquot) may be analysed. The WCO-CRDS approach requires more total carbon (µg C/aliquot) than conventional CF-isotope ratio mass spectrometer, but is nonetheless applicable to a wide range of DOC concentration and water types, including brackish water, produced water, and basinal brines.
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Conaway CH, Storlazzi CD, Draut AE, Swarzenski PW. Short-term variability of 7Be atmospheric deposition and watershed response in a Pacific coastal stream, Monterey Bay, California, USA. J Environ Radioact 2013; 120:94-103. [PMID: 23474944 DOI: 10.1016/j.jenvrad.2013.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 01/30/2013] [Accepted: 02/07/2013] [Indexed: 06/01/2023]
Abstract
Beryllium-7 is a powerful and commonly used tracer for environmental processes such as watershed sediment provenance, soil erosion, fluvial and nearshore sediment cycling, and atmospheric fallout. However, few studies have quantified temporal or spatial variability of (7)Be accumulation from atmospheric fallout, and parameters that would better define the uses and limitations of this geochemical tracer. We investigated the abundance and variability of (7)Be in atmospheric deposition in both rain events and dry periods, and in stream surface-water samples collected over a ten-month interval at sites near northern Monterey Bay (37°N, 122°W) on the central California coast, a region characterized by a rainy winters, dry summers, and small mountainous streams with flashy hydrology. The range of (7)Be activity in rainwater samples from the main sampling site was 1.3-4.4 Bq L(-1), with a mean (±standard deviation) of 2.2 ± 0.9 Bq L(-1), and a volume-weighted average of 2.0 Bq L(-1). The range of wet atmospheric deposition was 18-188 Bq m(-2) per rain event, with a mean of 72 ± 53 Bq m(-2). Dry deposition fluxes of (7)Be ranged from less than 0.01 up to 0.45 Bq m(-2) d(-1), with an estimated dry season deposition of 7 Bq m(-2) month(-1). Annualized (7)Be atmospheric deposition was approximately 1900 Bq m(-2) yr(-1), with most deposition via rainwater (>95%) and little via dry deposition. Overall, these activities and deposition fluxes are similar to values found in other coastal locations with comparable latitude and Mediterranean-type climate. Particulate (7)Be values in the surface water of the San Lorenzo River in Santa Cruz, California, ranged from <0.01 Bq g(-1) to 0.6 Bq g(-1), with a median activity of 0.26 Bq g(-1). A large storm event in January 2010 characterized by prolonged flooding resulted in the entrainment of (7)Be-depleted sediment, presumably from substantial erosion in the watershed. There were too few particulate (7)Be data over the storm to accurately model a (7)Be load, but the results suggest enhanced watershed export of (7)Be from small, mountainous river systems compared to other watershed types.
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6
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Ganguli PM, Conaway CH, Swarzenski PW, Izbicki JA, Flegal AR. Mercury speciation and transport via submarine groundwater discharge at a southern California coastal lagoon system. Environ Sci Technol 2012; 46:1480-1488. [PMID: 22283682 DOI: 10.1021/es202783u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We measured total mercury (Hg(T)) and monomethylmercury (MMHg) concentrations in coastal groundwater and seawater over a range of tidal conditions near Malibu Lagoon, California, and used (222)Rn-derived estimates of submarine groundwater discharge (SGD) to assess the flux of mercury species to nearshore seawater. We infer a groundwater-seawater mixing scenario based on salinity and temperature trends and suggest that increased groundwater discharge to the ocean during low tide transported mercury offshore. Unfiltered Hg(T) (U-Hg(T)) concentrations in groundwater (2.2-5.9 pM) and seawater (3.3-5.2 pM) decreased during a falling tide, with groundwater U-Hg(T) concentrations typically lower than seawater concentrations. Despite the low Hg(T) in groundwater, bioaccumulative MMHg was produced in onshore sediment as evidenced by elevated MMHg concentrations in groundwater (0.2-1 pM) relative to seawater (∼0.1 pM) throughout most of the tidal cycle. During low tide, groundwater appeared to transport MMHg to the coast, resulting in a 5-fold increase in seawater MMHg (from 0.1 to 0.5 pM). Similarly, filtered Hg(T) (F-Hg(T)) concentrations in seawater increased approximately 7-fold during low tide (from 0.5 to 3.6 pM). These elevated seawater F-Hg(T) concentrations exceeded those in filtered and unfiltered groundwater during low tide, but were similar to seawater U-Hg(T) concentrations, suggesting that enhanced SGD altered mercury partitioning and/or solubilization dynamics in coastal waters. Finally, we estimate that the SGD Hg(T) and MMHg fluxes to seawater were 0.41 and 0.15 nmol m(-2) d(-1), respectively - comparable in magnitude to atmospheric and benthic fluxes in similar environments.
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Affiliation(s)
- P M Ganguli
- Earth and Planetary Sciences, University of California, Santa Cruz, California, United States.
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7
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Gallon C, Ranville MA, Conaway CH, Landing WM, Buck CS, Morton PL, Flegal AR. Asian industrial lead inputs to the North Pacific evidenced by lead concentrations and isotopic compositions in surface waters and aerosols. Environ Sci Technol 2011; 45:9874-9882. [PMID: 22007971 DOI: 10.1021/es2020428] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent trends of atmospheric lead deposition to the North Pacific were investigated with analyses of lead in aerosols and surface waters collected on the fourth Intergovernmental Oceanographic Commission Contaminant Baseline Survey from May to June, 2002. Lead concentrations of the aerosols varied by 2 orders of magnitude (0.1-26.4 pmol/m(3)) due in part to variations in dust deposition during the cruise. The ranges in lead aerosol enrichment factors relative to iron (1-119) and aluminum (3-168) were similar, evidencing the transport of Asian industrial lead aerosols across the North Pacific. The oceanic deposition of some of those aerosols was substantiated by the gradient of lead concentrations of North Pacific waters, which varied 3-fold (32.7-103.5 pmol/kg), were highest along with the Asian margin of the basin, and decreased eastward. The hypothesized predominance of Asian industrial lead inputs to the North Pacific was further corroborated by the lead isotopic composition of ocean surface waters ((206)Pb/(207)Pb = 1.157-1.169; (208)Pb/(206)Pb = 2.093-2.118), which fell within the range of isotopic ratios reported in Asian aerosols that are primarily attributed to Chinese industrial lead emissions.
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Affiliation(s)
- Céline Gallon
- Institute of Marine Sciences, 1156 High Street, University of California-Santa Cruz, Santa Cruz, California 95064, United States.
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8
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David N, McKee LJ, Black FJ, Flegal AR, Conaway CH, Schoellhamer DH, Ganju NK. Mercury concentrations and loads in a large river system tributary to San Francisco Bay, California, U.S.A. Environ Toxicol Chem 2009; 28:2091-2100. [PMID: 19499967 DOI: 10.1897/08-482.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Accepted: 05/11/2009] [Indexed: 05/27/2023]
Abstract
In order to estimate total mercury (HgT) loads entering San Francisco Bay, U.S.A., via the Sacramento-San Joaquin River system, unfiltered water samples were collected between January 2002 and January 2006 during high flow events and analyzed for HgT. Unfiltered HgT concentrations ranged from 3.2 to 75 ng/L and showed a strong correlation (r2 = 0.8, p < 0.001, n=78) to suspended sediment concentrations (SSC). During infrequent large floods, HgT concentrations relative to SSC were approximately twice as high as observed during smaller floods. This difference indicates the transport of more Hg-contaminated particles during high discharge events. Daily HgT loads in the Sacramento-San Joaquin River at Mallard Island ranged from below the limit of detection to 35 kg. Annual HgT loads varied from 61 +/- 22 kg (n=5) in water year (WY) 2002 to 470 +/- 170 kg (n=25) in WY 2006. The data collected will assist in understanding the long-term recovery of San Francisco Bay from Hg contamination and in implementing the Hg total maximum daily load, the long-term cleanup plan for Hg in the Bay.
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Affiliation(s)
- Nicole David
- San Francisco Estuary Institute, 7770 Pardee Lane, Oakland, California 94621, USA.
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Black FJ, Conaway CH, Flegal AR. Stability of dimethyl mercury in seawater and its conversion to monomethyl mercury. Environ Sci Technol 2009; 43:4056-4062. [PMID: 19569330 DOI: 10.1021/es9001218] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Dimethyl mercury (DMHg) is commonly detected in the world's oceans, but little is known about the mechanisms responsible for DMHg degradation in natural waters or the products of this degradation. Similarly, the potential for the conversion of DMHg to monomethyl mercury (MMHg) under the acidic conditions commonly used to preserve samples for MMHg analysis has not been fully addressed. We provide evidence suggesting that DMHg in natural seawater is not readily photodegraded by sunlight as previously thought. Other experiments demonstrated that DMHg in seawater is, however, readily decomposed under acidic conditions, with MMHg as the predominant product. This facile conversion of DMHg to MMHg at low pH both necessitates an alternative preservation method to acidification for samples to be analyzed for MMHg when DMHg is present, and requires that data from previous studies of MMHg in seawater employing sample acidification be revisited in instances where appreciable DMHg concentrations were possible.
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Affiliation(s)
- Frank J Black
- WIGS Laboratory, Department of Environmental Toxicology, University of California, Santa Cruz, California 95064, USA.
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10
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Conaway CH, Black FJ, Gault-Ringold M, Pennington JT, Chavez FP, Flegal AR. Dimethylmercury in coastal upwelling waters, Monterey Bay, California. Environ Sci Technol 2009; 43:1305-1309. [PMID: 19350895 DOI: 10.1021/es802705t] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Depth profiles of dimethylmercury (DMHg) concentration were determined at nearshore to offshore sites in Monterey Bay, California. The onset of spring upwelling in the bay was accompanied by increases in DMHg concentrations. Profiles show DMHg increasing gradually with depth in fall and winter from <0.03 pM at the surface to 0.5 pM at 200 m. During the spring, DMHg concentrations increased between 30 and 100 m, first within Monterey Bay, then offshore. This change was accompanied by an increase in DMHg concentrations in the surface water DMHg between fall/winter (<0.03 pM) and spring (0.06-0.29 pM). Microbial activity associated with the remineralization of sinking organic matter produced by the high primary production in the bay may result in the relatively high DMHg in subsurface water in the bay, which when upwelled may facilitate the incorporation of organomercury into biota. As a result, productive coastal upwelling areas may represent an important source of methylated mercury to surface waters, and thus be an important source of mercury to marine ecosystems.
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Affiliation(s)
- Christopher H Conaway
- Department of Microbiology and Environmental Toxicology, University of California at Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA.
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Abstract
This review presents some of the published and other important literature on mercury contamination in San Francisco Estuary. Studies on human consumption of contaminated sportfish and on detecting ecological impacts of this contamination in wetland areas validate concerns regarding mercury's toxicity in this system. Mining, industrial, and environmental uses of mercury have occurred for more than a century, resulting in its large historic and continuing transport to the estuary. Consequently, there is a widespread distribution in the estuary, but more work is needed to show its relative chemical and biological availability from these sources. The uptake of mercury in the estuary has been shown in phytoplankton, but studies on biomagnification in local food webs have yet to draw a clear path to impairment in sportfish and waterbirds. In light of these concerns of impairment and the need for further information, large restoration activities planned for the estuary will require new technical approaches to solve important management questions, such as the location of key areas of methylmercury production.
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Affiliation(s)
- Christopher H Conaway
- Department of Environmental Toxicology, University of California, Santa Cruz, CA 95064, USA
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Flegal AR, Davis JA, Connor MS, Conaway CH. Sources, transport, fate, and toxicity of pollutants in the San Francisco Bay estuary. Environ Res 2007; 105:1-4. [PMID: 17692310 DOI: 10.1016/j.envres.2007.05.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Accepted: 05/25/2007] [Indexed: 05/16/2023]
Affiliation(s)
- A Russell Flegal
- Environmental Toxicology, WIGS, University of California, Santa Cruz, CA 95064, USA
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Conaway CH, Ross JRM, Looker R, Mason RP, Flegal AR. Decadal mercury trends in San Francisco Estuary sediments. Environ Res 2007; 105:53-66. [PMID: 17161835 DOI: 10.1016/j.envres.2006.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 10/17/2006] [Accepted: 10/20/2006] [Indexed: 05/12/2023]
Abstract
Monitoring sediment quality and total mercury concentrations over the period 1993-2001 at 26 stations in San Francisco Estuary has shown the seasonal cycling of mercury sediment concentrations, as well as a significant (P < 0.05) decrease in those concentrations at eight stations across the estuary. This decrease in sediment mercury concentrations is attributed to the transport of relatively cleaner sediment to the estuary from the Sacramento River and San Joaquin River watersheds. Despite the decreases observed in some parts of the estuary, no corresponding trend has been found in concurrent studies on sport fish and bivalves in the estuary.
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Affiliation(s)
- Christopher H Conaway
- Department of Environmental Toxicology, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
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Flegal AR, Conaway CH, Scelfo GM, Hibdon SA, Sañudo-Wilhelmy SA. A review of factors influencing measurements of decadal variations in metal contamination in San Francisco Bay, California. Ecotoxicology 2005; 14:645-60. [PMID: 16215699 DOI: 10.1007/s10646-005-0016-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/06/2004] [Indexed: 05/04/2023]
Abstract
This review summarizes some of the principal results of systematic measurements of trace metal concentrations throughout San Francisco Bay that began in 1989, and that have yielded insights on the factors controlling temporal and spatial variations of those concentrations on seasonal to decadal time scales. Pronounced seasonal variation in some metal concentrations is associated with gradients in the system's hydrology and the diagenetic remobilization of metals from benthic sediments. Additional temporal variation is associated with interannual differences in hydrologic flushing (e.g., ENSO cycles) and episodic storm events. While intra- and inter-annual variabilities complicate assessments of long-term variations in metal concentrations, recent analyses using stable lead isotopic composition distributions and time-series models have deconvoluted decadal changes in lead and silver concentrations in the estuary. Decadal variations in concentrations of other contaminant metals (e.g., mercury) are now being characterized, as well as projections of future concentrations of other metals of concern (e.g., copper). These historic assessments and projections of trace metal variations attest to the importance of long-term, systematic monitoring programs to quantify past and future impacts on water quality in San Francisco Bay and other complex estuarine systems.
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Affiliation(s)
- A Russell Flegal
- WIGS Laboratory Department of Environmental Toxicology, University of California at Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
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Cooney MM, Conaway CH, Mefford IN. Epinephrine, norepinephrine and dopamine concentrations in amphibian brain. Comp Biochem Physiol C Comp Pharmacol Toxicol 1985; 82:395-7. [PMID: 2866911 DOI: 10.1016/0742-8413(85)90180-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The whole brain concentrations of epinephrine, norepinephrine and dopamine in North American amphibians, orders Caudata and Salientia, are reported. Epinephrine is the major catecholamine in the Salientia while norepinephrine and epinephrine concentrations are roughly equivalent in suborders of Caudata. Relative regional concentrations are similar to other classes (mammals, reptiles and birds) although the absolute concentration of epinephrine is considerably higher in amphibians than in most other species.
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Abstract
Homosexual activity among adult females in a heterosexual group of rhesus monkeys (Macaca mulatta) is documented and discussed. The mounter was usually in the follicular stage of the menstrual cycle and the mountee was in the ovulatory period. Activity during the luteal phase was low for all animals. Female mounting did not appear to be a preparation or substitute for heterosexual activity. Ritualized solicitation patterns among the females were intense and varied, strongly resembling those for heterosexual pairs. Dominance, partner preference, sexual stimulation, reproductive state, individual characteristics, and past experience are discussed in the framework of multiple factors influencing the homosexual relationship.
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Abstract
Oocytes obtained from antral follicles of adult and adolescent rhesus monkeys during the annual breeding season extruded polar bodies in vitro at significantly higher rates (50--60%) than oocytes from animals of similar age during the non-breeding season ((20--30%) or from infant and prepubertal females at any time of the year (20--30%). The proportion of oocytes degenerating in culture was greatest in groups where maturation was highest.
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Kerber WT, Conaway CH, Smith DM. The duration of gestation in the squirrel monkey (Saimiri sciureus). Lab Anim Sci 1977; 27:700-2. [PMID: 413002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A restricted mating period was used to determine the duration of gestation in the squirrel monkey (Saimiri sciureus) of Colombian-Brazilian origin. Ten pregnancies were observed. The length of the gestation period was found to range from 141 to 154 days with a mean of 146.9 +/- 3.28 SD, a median of 146.5, and a modal length of 146.
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Chaffee RR, Roberts JC, Conaway CH, Sorenson MW. Comparative effects of temperature exposure on mass and oxidative enzyme activity of brown fat in insectivores, tupaiads and primates. Lipids 1970; 5:23-9. [PMID: 4313859 DOI: 10.1007/bf02531089] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Dryden GL, Bauman TR, Conaway CH, Anderson RR. Thyroid hormone secretion rate and biological half-life (t one half) of L-thyroxine-131 I in the musk shrew (Suncus murinus). Gen Comp Endocrinol 1969; 12:536-40. [PMID: 4181507 DOI: 10.1016/0016-6480(69)90171-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Chaffee RR, Kaufman WC, Kratochvil CH, Sorenson MW, Conaway CH, Middleton CC. Comparative chemical thermoregulation in cold- and heat-acclimated rodents, insectivores, protoprimates, and primates. Fed Proc 1969; 28:1029-34. [PMID: 4977406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Richmond M, Conaway CH. Management, breeding, and reproductive performance of the vole, Microtus ochrogaster, in a laboratory colony. Lab Anim Care 1969; 19:80-7. [PMID: 4237324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Sorenson MW, Conaway CH. The social and reproductive behavior of Tupaia montana in captivity. J Mammal 1968; 49:502-12. [PMID: 5670809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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