Determining spatial distributions and temporal trends in trace metals in sediments and benthic organisms is common practice for monitoring environmental contamination. These data can be the basis for assessing metal exposure, the potential for adverse biological effects, and the response to regulatory or management actions (Suter, 2001). Another common method of environmental monitoring is to examine the community structure of sediment-dwelling benthic organisms (Simon, 2002). Spatial and temporal changes in community structure reflect the integrated response of resident species to environmental conditions, although the underlying cause(s) for the response may be difficult to identify and quantify. Together, measurements of metal exposure and biological response can provide a more complete view of anthropogenic disturbances and the associated effects on ecosystem health. Despite the complexities inherent in monitoring natural systems, the adopted approach has been effective in relating changes in near-field contamination to changes in reproductive activity of a clam (Hornberger and others, 2000) and in benthic community structure (Kennish, 1998). This study, with its basis in historical data, provides a rare multi-decadal context within which future environmental changes can be assessed.

Trace-metal concentrations in sediment and in the clam Macoma petalum (World Register of Marine Species, 2025; formerly reported as Limecola balthica and M. petalum), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat located 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, California. This report includes data collected by the U.S. Geological Survey (USGS) starting in January 2019. These data append to long-term datasets extending back to 1974. This dataset supports the City of Palo Alto’s Near-Field Receiving-Water Monitoring Program, initiated in 1994. This data release is presented as two datasets each on its own child page. The first child page contains clam tissue metals data, sediment metals data, percentage fine sediment, total organic carbon, and the salinity of the overlying water. The second child page contains clam reproduction and benthic community data. Please read the metadata file corresponding to each dataset for complete details.

Trace-metal concentrations in sediment and in the clam Limecola petalum (World Register of Marine Species, 2020; formerly reported as Macoma balthica and M. petalum), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat located 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, California. This report includes data collected by the U.S. Geological Survey (USGS) starting in January 2019. These data append to long-term datasets extending back to 1974. This dataset supports the City of Palo Alto’s Near-Field Receiving-Water Monitoring Program, initiated in 1994. This data release is presented as two datasets each on its own child page. The first child page contains clam tissue metals data, sediment metals data, percentage fine sediment, total organic carbon, and the salinity of the overlying water. The second child page contains clam reproduction and benthic community data. Please read the metadata file corresponding to each dataset for complete details.

This data release contains ten data tables and a data dictionary for the Technical Assistance Agreement (TAA) between the U.S. Geological Survey and the San Francisco Estuary Institute titled "Lower San Francisco Bay Bivalve Grazing Rates”. The data are provided in comma-delimited value spreadsheets as well as Microsoft Excel Worksheet formats.

This data release contains ten data tables and a data dictionary for the Technical Assistance Agreement (TAA) between the U.S. Geological Survey and the San Francisco Estuary Institute titled "Lower San Francisco Bay Bivalve Grazing Rates”. The data are provided in comma-delimited value spreadsheets as well as Microsoft Excel Worksheet formats.

This dataset contains information on benthic invertebrate community structure of samples collected from nearshore index monitoring stations within a Great Lake basin each year. The composition of benthic invertebrates (such as insects, worms, mussels, snails and crayfish) found in a sample is used as a biological indicator of trophic status and general environmental conditions to help understand ecosystem function, structure and change. Surveys are typically conducted in one of the Great Lakes basins each year. In most cases, five replicate samples (600 μm mesh, 9-inch ponar) were collected at each station. This dataset links with Sediment chemistry (Great Lakes nearshore areas) and Water chemistry (Great Lakes nearshore areas) datasets.

Sediment particles can strongly bind metals, effectively repartitioning them from solution to a solid phase. As a result, sediments may accumulate and retain metals released to an aquatic environment. Sediment cores provide a historical record of metal inputs that can reveal anthropogenic influences (Förstner and Wittmann, 1979). Specifically, studies of sediment cores in San Francisco Bay chronicled metal inputs and suggested that legacy contamination can remain a chronic source of metals to the system owing to sediment mixing and redistribution (Hornberger and others, 1999; Van Geen and Luoma, 1999). Metals in sediments also indicate exposure levels to benthic animals through contact with, and ingestion of, bottom sediments and suspended particulate materials. However, physical and geochemical conditions of the sediment affect the biological availability of the bound metals. Assimilation of bioavailable sediment-bound metal by digestive processes and the contribution of this source of metals relative to metals in the aqueous phase are difficult to predict from sediment concentrations alone. Thus, in order to better estimate bioavailable metal exposures, the tissues of organisms may be analyzed for trace metals (Phillips and Rainbow, 1993). Different species concentrate metals to different degrees. However, if one species is analyzed consistently, the results can be used to track temporal changes in trace-element exposures at a specified location. This data release includes the sediment and tissue metal data starting in January 2019 and is presented in 13 tables as comma-separated values (.CSV) files as follows: T1_Sediment_Summary as a summary of the fine sediment, silver, aluminum, chromium, copper, iron, mercury, nickel, selenium, zinc and total organic carbon in the sediment. T2_Sediment_Metals_ICPOES provides detailed silver, aluminum, chromium, copper, iron, mercury, nickel, selenium and zinc data collected by inductively coupled plasma-optical emission spectrophotometry (ICP-OES) T3_Sediment_Hg_Se reports detailed mercury and selenium data T4_TOC reports detailed total organic carbon data from the sediment T5_Tissue_Metals reports the silver, chromium, copper, nickel, and zinc data collected from clams with the size and mass of the collected clam tissue for each sample date. T6_Tissue_Hg_Se reports the mercury and selenium data collected from clam tissue collected by size fraction and collection date. T7_QA_ICPOES_Sediment_SRM reports the standard reference material run data for certified reference standards for sediment analyzed on the ICP-OES. T8_QA_ICPOES_Tissue_SRM reports the standard reference material run data collected for certified standards for biological tissues analyzed on the ICP-OES. T9_QA_Hg_ Se reports the standard reference materials run for mercury and selenium data T10_QA_Spike_Recovery reports the spike recovery runs for the ICP-OES T11_QA_ICPOES_Blanks reports the procedural blanks run on the ICP-OES T12_QA_MDL_MRL reports the annual method detection limits and method reporting limits for the listed analyte T13_QA_SRM_reference_values reports the reference values for each of the reported standard reference material included in this data release

Sediment particles can strongly bind metals, effectively repartitioning them from solution to a solid phase. As a result, sediments may accumulate and retain metals released to an aquatic environment. Sediment cores provide a historical record of metal inputs that can reveal anthropogenic influences (Förstner and Wittmann, 1979). Specifically, studies of sediment cores in San Francisco Bay chronicled metal inputs and suggested that legacy contamination can remain a chronic source of metals to the system owing to sediment mixing and redistribution (Hornberger and others, 1999; Van Geen and Luoma, 1999). Metals in sediments also indicate exposure levels to benthic animals through contact with, and ingestion of, bottom sediments and suspended particulate materials. However, physical and geochemical conditions of the sediment affect the biological availability of the bound metals. Assimilation of bioavailable sediment-bound metal by digestive processes and the contribution of this source of metals relative to metals in the aqueous phase are difficult to predict from sediment concentrations alone. Thus, in order to better estimate bioavailable metal exposures, the tissues of organisms may be analyzed for trace metals (Phillips and Rainbow, 1993). Different species concentrate metals to different degrees. However, if one species is analyzed consistently, the results can be used to track temporal changes in trace-element exposures at a specified location. This data release includes the sediment and tissue metal data starting in January 2019 and is presented in 13 tables as comma-separated values (.CSV) files as follows: T1_Sediment_Summary as a summary of the fine sediment, silver, aluminum, chromium, copper, iron, mercury, nickel, selenium, zinc and total organic carbon in the sediment. T2_Sediment_Metals_ICPOES provides detailed silver, aluminum, chromium, copper, iron, mercury, nickel, selenium and zinc data collected by inductively coupled plasma-optical emission spectrophotometry (ICP-OES) T3_Sediment_Hg_Se reports detailed mercury and selenium data T4_TOC reports detailed total organic carbon data from the sediment T5_Tissue_Metals reports the silver, chromium, copper, nickel, and zinc data collected from clams with the size and mass of the collected clam tissue for each sample date. T6_Tissue_Hg_Se reports the mercury and selenium data collected from clam tissue collected by size fraction and collection date. T7_QA_ICPOES_Sediment_SRM reports the standard reference material run data for certified reference standards for sediment analyzed on the ICP-OES. T8_QA_ICPOES_Tissue_SRM reports the standard reference material run data collected for certified standards for biological tissues analyzed on the ICP-OES. T9_QA_Hg_ Se reports the standard reference materials run for mercury and selenium data T10_QA_Spike_Recovery reports the spike recovery runs for the ICP-OES T11_QA_ICPOES_Blanks reports the procedural blanks run on the ICP-OES T12_QA_MDL_MRL reports the annual method detection limits and method reporting limits for the listed analyte T13_QA_SRM_reference_values reports the reference values for each of the reported standard reference material included in this data release

Between 1900 and 1932, a copper (Cu) mine operated near Gay, Michigan, along the shore of Lake Superior, discharged approximately 22.8 million metric tons of waste material known as ‘stamp sands’ (SS) to a nearby beach. This pile of SS has migrated via wind and rain along the beaches in northern Grand Traverse Bay and into Buffalo Reef, an important spawning area for Lake Trout and Lake Whitefish. During their first summer, these newly spawned fish consume benthic invertebrates and zooplankton in nearby beach habitats. SS contain elevated concentrations of metals (especially Cu) that are toxic to many invertebrate taxa, and studies have observed very few benthic taxa in areas with very high SS. Here, we sampled the invertebrate community from four beaches: one near Buffalo Reef with very high SS, one in southern Grand Traverse Bay with moderate SS, one in the nearby Little Traverse Bay with very little SS and a beach ~58 km away with no SS (Big Bay). We also re-sampled the benthos at some sites that had been sampled as part of an earlier study. Both benthic invertebrates (in August 2021) and zooplankton (in June and July 2021) were sampled along the transects at these four beaches. Sediment samples were collected at the same time as the benthic invertebrate sampling and used to quantify SS and 12 metals at each site (including Cu).