Mercury on a landscape scale—Balancing regional export with wildlife health

U.S. Geological Survey (USGS) | June 26th, 2018

The Cosumnes River watershed requires a 57–64 percent reduction in loads to meet the new Delta methylmercury (MeHg) total maximum daily load allocation, established by

The Cosumnes River watershed requires a 57–64 percent reduction in loads to meet the new Delta methylmercury (MeHg) total maximum daily load allocation, established by the Central Valley Regional Water Quality Control Board. Because there are no large point sources of MeHg in the watershed, the focus of MeHg load reductions will fall upon non-point sources, particularly the expansive wetlands considered to be a primary source of MeHg in the region. Few management practices have been implemented and tested in order to meet load reductions in managed wetlands, but recent efforts have shown promise. This project examines a treatment approach to reduce MeHg loads to the Sacramento-San Joaquin River Delta by creating open-water deep cells with a small footprint at the downstream end of wetlands to promote net demethylation of MeHg and to minimize MeHg and Hg loads exiting wetlands at the Cosumnes River Preserve. Specifically, the deep cells were were located immediately up gradient of the wetland’s outflow weir and were deep enough (75–91 centimeter depth) to be vegetation-free. The topographic and hydrologic structure of each treatment wetland was modified to include open-water deep cells so that the removal of aqueous MeHg might be enhanced through (1) particle settling, (2) photo-degradation, and (3) benthic microbial demethylation. These deep cells were, therefore, expected to clean MeHg from surface water prior to its discharge to the Cosumnes River and the downstream Delta.

Mercury Risks to Wildlife in California Lakes: Statewide Survey Finds Fish-Eating Birds at Risk in Many Lakes

U.S. Geological Survey (USGS) | May 22nd, 2015

Numerous water bodies in California are listed under the Clean Water Act as being impaired by mercury contamination. Mercury generally poses risks both to humans who co

Numerous water bodies in California are listed under the Clean Water Act as being impaired by mercury contamination. Mercury generally poses risks both to humans who consume fish from these water bodies and to wildlife species at the top of the aquatic food chain. The SWAMP has recently completed statewide surveys of contaminants in sport fish from California lakes, rivers, and coastal waters. These surveys generated information regarding potential human exposure to mercury, but did not include monitoring to assess risks to wildlife. This study was performed to address critical information gaps related to mercury risks to wildlife in California lakes. Western grebes and Clark’s grebes were chosen as the wildlife indicator species. These grebe species are widely distributed and breed in lakes throughout California, are piscivorous (fish-eaters) near the top of the lake food chain, and become flightless after they arrive at their summer locations. This makes them excellent indicators of lake-specific contaminant exposure. Mercury concentrations were measured in grebe blood at all of the lakes, and in grebe eggs where they could be collected. Mercury also was measured in the small fish species that grebes eat and in sport fish in order to determine whether correlations between fish and grebes could be used to estimate risk to grebes in cases where direct measurements of mercury in grebes are not available. Grebes, prey fish, and sport fish were sampled at 25 lakes throughout California (Figure 1) during the spring and summer of 2012 and 2013, seasons when breeding occurs and birds are vulnerable to mercury - induced impairment of reproduction. Mercury concentrations were measured in blood from 354 grebes at 25 lakes, 101 grebe eggs at 7 lakes, 505 prey fish from14 species at 25 lakes, and 230 sport fish from 5 species at 24 lakes. T he lakes included in the survey were selected to be a representative sampling spanning the entire state, a range of mercury contamination, and a variety of sizes, shapes, and elevations.

Mercury, Monomethyl Mercury, and Dissolved Organic Carbon Concentrations in Surface Water Entering and Exiting Constructed Wetlands Treated with Metal-Based Coagulants, Twitchell Island, California

U.S. Geological Survey (USGS) | August 30th, 2015

Coagulation with metal-based salts is a practice commonly employed by drinking-water utilities to decrease particle and dissolved organic carbon concentrations in water.

Coagulation with metal-based salts is a practice commonly employed by drinking-water utilities to decrease particle and dissolved organic carbon concentrations in water. In addition to decreasing dissolved organic carbon concentrations, the effectiveness of iron- and aluminum-based coagulants for decreasing dissolved concentrations both of inorganic and monomethyl mercury in water was demonstrated in laboratory studies that used agricultural drainage water from the Sacramento–San Joaquin Delta of California. To test the effectiveness of this approach at the field scale, nine 15-by-40-meter wetland cells were constructed on Twitchell Island that received untreated water from island drainage canals (control) or drainage water treated with polyaluminum chloride or ferric sulfate coagulants. Surface-water samples were collected approximately monthly during November 2012–September 2013 from the inlets and outlets of the wetland cells and then analyzed by the U.S. Geological Survey for total concentrations of mercury and monomethyl mercury in filtered (less than 0.3 micrometers) and suspended-particulate fractions and for concentrations of dissolved organic carbon.

Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms: Biological responses to ocean acidification

Ecology Letters (Wiley) | August 16th, 2010

Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acid

Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups. We used meta-analytic techniques to explore the biological responses to ocean acidification, and found negative effects on survival, calcification, growth and reproduction. However, there was significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative responses than non-calcifying organisms across numerous response variables, with the exception ofcrustaceans, which calcify but were not negatively affected. Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate.Organisms using one of the more soluble forms of calcium carbonate (high-magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation was dependent on the taxonomic group. Our analyses suggest that the biological effects of ocean acidification are generally large and negative, but the variation in sensitivity amongst organisms has important implications for ecosystem responses.

Metals in Wildfire Suppressants

American Chemical Society (ACS) | October 30th, 2024

Methodology for Flow and Salinity Estimates in the Sacramento-San Joaquin Delta and Suisun Marsh

California Department of Water Resources (DWR) | June 15th, 2022

This is the 43rd annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by the Delta M

This is the 43rd annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by the Delta Modeling Section. This report is submitted annually to the State Water Resources Control Board pursuant to its Water Right Decision D-1485, Term 9, which is still active pursuant to its Water Right Decision D-1641, Term 8. This report documents progress in the development and enhancement of computer models for the Delta Modeling Section of the Bay-Delta Office. It also reports the latest findings of studies conducted as part of the program. This report was compiled under the direction of Nicky Sandhu, Program Manager for the Bay-Delta Evaluation Program.

Methodology for Flow and Salinity Estimates in the Sacramento-San Joaquin Delta and Suisun Marsh

California Department of Water Resources (DWR) | June 1st, 2017

This is the 38th annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by t

This is the 38th annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by the Delta Modeling Section. This report is submitted annually by the section to the State Water Resources Control Board pursuant to its Water Right Decision D-1485, Term 9, which is still active pursuant to its Water Right Decision D-1641, Term 8. This report documents progress in the development and enhancement of computer models for the Delta Modeling Section of the Bay-Delta Office. It also reports the latest findings of studies conducted as part of the program. This report was compiled under the direction of Tara Smith, Program Manager for the Bay-Delta Evaluation Program.

Methodology for Flow and Salinity Estimates in the Sacramento-San Joaquin Delta and Suisun Marsh

California Department of Water Resources (DWR) | December 1st, 2019

Various water resource management actions have been planned to protect and restore salmon populations for a healthy Sacramento-San Joaquin Delta (Delta) ecosystem. Curren

Various water resource management actions have been planned to protect and restore salmon populations for a healthy Sacramento-San Joaquin Delta (Delta) ecosystem. Currently, evaluating the effectiveness of these actions relies on field studies and/or expert opinion. Field studies can be costly and may not provide a comprehensive assessment for a range of applications because of limited study areas, durations, and river conditions. Expert opinion, although valuable, may under- or over-emphasize the importance of certain project components.  To supplement field studies and provide a quantitative assessment tool, the California Department of Water Resources (DWR), in collaboration with the United States Geological Survey (USGS), developed an ecological modeling tool, ECO-PTM. ECO-PTM is an individual-based juvenile salmon migration model that is based on a random-walk particle-tracking method with fish-like behaviors attached to the particles. The behavioral parameters are estimated from acoustic telemetry tag data of juvenile late-fall Chinook salmon (Tag Data) from various field studies (Perry et al. 2018). A stochastic optimization tool, Particle Swarm Optimization, is used to calibrate the swimming behavior parameters. ECO-PTM can simulate juvenile salmonid migration timing, routing, and survival.  This chapter describes ECO-PTM and its behavioral modules, and the model performance and applications to assist water resource management planning, assessment, and decision-making related to juvenile salmonid survival outcomes. 

Methods of Analysis—Determination of Pesticides in Filtered Water and Suspended Sediment using Liquid Chromatography- and Gas Chromatography-Tandem Mass Spectrometry

U.S. Geological Survey (USGS) | January 31st, 2024

The widespread application of pesticides in agricultural and urban areas leads to their presence in surface waters. Presence of these biologically active chemicals in en

The widespread application of pesticides in agricultural and urban areas leads to their presence in surface waters. Presence of these biologically active chemicals in environmental waters potentially has adverse effects on nontarget organisms. To better understand the environmental fate of these contaminants, a robust method to capture chemicals with wide-ranging physicochemical properties has been developed. The method was developed by the U.S. Geological Survey’s Organic Chemistry Research Laboratory to monitor pesticides, pesticide degradates, and other agrochemicals in environmental surface waters throughout the country. The analysis involves a multiresidue method to determine 183 pesticides and pesticide degradates in filtered water samples and 178 pesticides and pesticide degradates in paired suspended sediment samples. After the filtration of whole water, contaminants are individually measured in the filtered water and the collected suspended sediment. Filtered water is extracted via solid-phase extraction, whereas suspended sediment is extracted using an ultrasonication, solid-liquid extraction. Samples are analyzed by liquid chromatography-tandem mass spectrometry using an electrospray ionization source in positive and negative modes and analyzed by gas chromatography-tandem mass spectrometry using an advanced electron ionization source in positive mode. Instrument parameters were optimized for the highest sensitivity, and at least two transitions (quantifier and qualifier) were monitored for each analyte. Recoveries in test filtered water (n=9; 183 analytes) from the American River, California, and suspended sediment (n=9; 178 analytes) samples fortified at 15 nanograms per liter (ng/L) ranged from 70.1 to 121.0 and 71.1 to 117.0 percent in water and suspended sediment filter samples, respectively.

Microbial Water Quality at Minimally Human-Impacted Reference Beaches in Northern California

San Francisco Estuary Institute (SFEI) | September 3rd, 2018

All of the coastal reference beaches that have been used by the State of California for quantifying “natural loads” of fecal indicator bacteria have been in Southern

All of the coastal reference beaches that have been used by the State of California for quantifying “natural loads” of fecal indicator bacteria have been in Southern California. None has been in the northern and central coastal regions of the State. To fill this information gap, this study assessed bacteria concentrations at coastal reference beaches in Northern California, investigated possible factors influencing the bacteria concentrations, and evaluated how these concentrations compare to results from the Southern California reference beaches. Reference beaches were defined as open beaches with breaking waves that receive runoff from undeveloped watersheds. The study beaches were selected to represent a variety of geographical conditions and watershed sizes in Northern California. Five reference beaches were sampled between January 2016 and September 2017 for a total of 25‐30 sampling events, including 10 wet weather events, 10 winter dry events, and 10 summer dry events. The number of samples collected was admittedly small for characterizing variable bacteria concentrations but was deemed sufficient for providing initial information relevant to management questions. At each beach, samples were collected from an ocean site in the surf zone and from a freshwater site in the watershed draining to the beach. Samples were analyzed for total coliform, fecal coliform, Escherichia coli (E. coli), enterococci (ocean sites only), as well as a human‐specific genetic marker (human Bacteroides HF183).