This data release provides the measurement of anthropogenic metals and other elements in sediments of a core obtained off San Francisquito Creek in South San Francisco Bay.

This data release provides 210Pb and 137Cs measurements in sediments of a core obtained off San Francisquito Creek in South San Francisco Bay.

Elemental chemistry and weight percent of the less than 0.063 mm fine sediment fraction are reported for surface sediments from shoals, the ebb tide delta, local tributaries, and inland rivers that carry sediment to San Francisco Bay, California.

Elemental chemistry and weight percent of the less than 0.063 mm fine sediment fraction are reported for surface sediments from shoals, the ebb tide delta, local tributaries, and inland rivers that carry sediment to San Francisco Bay, California.

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

This data release provides radiocarbon measurements from a core obtained off San Francisquito Creek in South San Francisco Bay.

This data release provides radiocarbon measurements from a core obtained off San Francisquito Creek in South San Francisco Bay.

The Hamilton Wetland Restoration Project (HWRP) is a joint venture between the US Army Corps of Engineers (USACE; San Francisco District) and the California State Coastal Conservancy. The site is located on the property of the former Hamilton Army Airfield in Novato, California, along the western edge of San Pablo Bay, which is part of northern San Francisco Bay. The initial stages of wetland restoration, which included dredged sediment reuse, took place during 2009–2011. From 2011 until April 2014, the site was maintained as partially flooded through a temporary one-way culvert that allowed bay water onto the site. On April 25th, 2014, the outboard levee towards the north-eastern corner of the site was breached to restore tidal connectivity from the bay to the restoration area. The anticipated period for complete site restoration and marsh evolution is 10–15 years. During this period an active wetland vegetation replanting program was established by the USACE to augment the natural seeding by native plants. The various habitats on the restoration site include open-water sub-tidal, mudflats, emergent marsh, grassland, and upland transition zone. San Francisco Bay is contaminated with legacy mercury (Hg) from historic use in mining areas throughout the watershed, as well as from contemporary atmospheric and point-source inputs. Since wetlands are known to be particularly effective zones for the production of toxic methylmercury (MeHg) from inorganic Hg(II), the National Environmental Policy Act (NEPA) and California Environmental Quality Act (CEQA) documentation associated with the HWRP restoration identified MeHg production as a potentially significant impact of restoring the site to wetland habitat. As part of the USACE Monitoring and Adaptive Management plan (MAMP) for the restoration, the USACE was directed by the Regional Water Quality Control Board (RWQCB) and the San Francisco Bay Conservation and Development Commission (BCDC) to assess MeHg concentrations at the HWRP site. To fulfill this requirement, the USACE entered into an agreement with the U.S. Geological Survey (USGS) to conduct a multi-year and multi-phase investigation of mercury in biota (fish), water, and sediment at the HWRP site. The Sample and Analysis Plan (SAP) covers a period of 13 years and is divided into three phases. Phase 1 included the monitoring of sediment and water pre-breach [2013] and post-breach [2014], and the monitoring of fish pre-breach [2013 only]. Phase 2 covers the three-year period 2014-2016 (near-term post-breach). Phase 3 covers the nine-year period from 2017-2025 (long-term post-breach). Field sampling occurred once per year during a two-week window from mid to late June. A reference site, (Sonoma Baylands) managed by the U.S. Fish and Wildlife Service, was similarly sampled coincident with the HWRP site throughout the study. During the first year of study (2013, pre-breach), an additional reference site was sampled (China Camp) but was subsequently dropped. This data release summarizes the result to date for surface water and bed sediment. Fish data are not included. The list of surface water constituents include: filter-passing total mercury (THg) and methylmercury (MeHg); particulate THg, MeHg and divalent reactive mercury (RHg, operationally defined); particulate organic carbon (POC) along with the carbon-13 isotopic composition (δ 13C-POC); particulate nitrogen (PN) along with the nitrogen-15 isotopic composition (δ 15N-PN); total suspended solids (TSS); chlorophyll_a (Chl_a); specific conductance (SpC); dissolved oxygen (DO); pH; oxidation reduction potential (Eh); and temperature. The list of bed sediment constituents include: THg, MeHg, RHg, iron speciation [ferrous iron (Fe(ll)), crystalline and amorphous ferric iron (Fe(lll))]; total reduced sulfur (TRS); Eh; organic content as percent loss on ignition (%LOI); grain size; porosity; bulk density; and temperature. This data release includes five data tables given both as

The Hamilton Wetland Restoration Project (HWRP) is a joint venture between the US Army Corps of Engineers (USACE; San Francisco District) and the California State Coastal Conservancy. The site is located on the property of the former Hamilton Army Airfield in Novato, California, along the western edge of San Pablo Bay, which is part of northern San Francisco Bay. The initial stages of wetland restoration, which included dredged sediment reuse, took place during 2009–2011. From 2011 until April 2014, the site was maintained as partially flooded through a temporary one-way culvert that allowed bay water onto the site. On April 25th, 2014, the outboard levee towards the north-eastern corner of the site was breached to restore tidal connectivity from the bay to the restoration area. The anticipated period for complete site restoration and marsh evolution is 10–15 years. During this period an active wetland vegetation replanting program was established by the USACE to augment the natural seeding by native plants. The various habitats on the restoration site include open-water sub-tidal, mudflats, emergent marsh, grassland, and upland transition zone. San Francisco Bay is contaminated with legacy mercury (Hg) from historic use in mining areas throughout the watershed, as well as from contemporary atmospheric and point-source inputs. Since wetlands are known to be particularly effective zones for the production of toxic methylmercury (MeHg) from inorganic Hg(II), the National Environmental Policy Act (NEPA) and California Environmental Quality Act (CEQA) documentation associated with the HWRP restoration identified MeHg production as a potentially significant impact of restoring the site to wetland habitat. As part of the USACE Monitoring and Adaptive Management plan (MAMP) for the restoration, the USACE was directed by the Regional Water Quality Control Board (RWQCB) and the San Francisco Bay Conservation and Development Commission (BCDC) to assess MeHg concentrations at the HWRP site. To fulfill this requirement, the USACE entered into an agreement with the U.S. Geological Survey (USGS) to conduct a multi-year and multi-phase investigation of mercury in biota (fish), water, and sediment at the HWRP site. The Sample and Analysis Plan (SAP) covers a period of 13 years and is divided into three phases. Phase 1 included the monitoring of sediment and water pre-breach [2013] and post-breach [2014], and the monitoring of fish pre-breach [2013 only]. Phase 2 covers the three-year period 2014-2016 (near-term post-breach). Phase 3 covers the nine-year period from 2017-2025 (long-term post-breach). Field sampling occurred once per year during a two-week window from mid to late June. A reference site, (Sonoma Baylands) managed by the U.S. Fish and Wildlife Service, was similarly sampled coincident with the HWRP site throughout the study. During the first year of study (2013, pre-breach), an additional reference site was sampled (China Camp) but was subsequently dropped. This data release summarizes the result to date for surface water and bed sediment. Fish data are not included. The list of surface water constituents include: filter-passing total mercury (THg) and methylmercury (MeHg); particulate THg, MeHg and divalent reactive mercury (RHg, operationally defined); particulate organic carbon (POC) along with the carbon-13 isotopic composition (δ 13C-POC); particulate nitrogen (PN) along with the nitrogen-15 isotopic composition (δ 15N-PN); total suspended solids (TSS); chlorophyll_a (Chl_a); specific conductance (SpC); dissolved oxygen (DO); pH; oxidation reduction potential (Eh); and temperature. The list of bed sediment constituents include: THg, MeHg, RHg, iron speciation [ferrous iron (Fe(ll)), crystalline and amorphous ferric iron (Fe(lll))]; total reduced sulfur (TRS); Eh; organic content as percent loss on ignition (%LOI); grain size; porosity; bulk density; and temperature. This data release includes five data tables given both as