Geochemical analysis of sediment core pore fluids collected from seep fields on the FK190612 research expedition in the north Pacific Ocean along the Cascadia margin in June 2019. Samples were collected to deconvolve the different processes impacting the fluid chemistry, including hydrate dissociation and clay mineral dehydration during the smectite-illite transformation that releases inter-layer water.

The accretion history of fringing salt marshes in Narragansett Bay, Rhode Island, was reconstructed from sediment cores. Age models, based on excess lead-210 and cesium-137 radionuclide analysis, were constructed to evaluate how vertical accretion and carbon burial rates have changed during the past century. The Constant Rate of Supply (CRS) age model was used to date six cores collected from three salt marshes. Both vertical accretion rates and carbon burial increased from 1900 to 2016, the year the data were collected. Cores were up to 90 cm in length with dry bulk density ranging from 0.07 to 3.08 grams per cubic centimeter and carbon content 0.71 % to 33.58 %.

In order to test hypotheses about groundwater flow under and into estuaries and the Atlantic Ocean, geophysical surveys, geophysical probing, submarine groundwater sampling, and sediment coring were conducted by U.S. Geological Survey (USGS) scientists at Cape Cod National Seashore (CCNS) from 2004 through 2006. Coastal resource managers at CCNS and elsewhere are concerned about nutrients that are entering coastal waters via submarine groundwater discharge, which are contributing to eutrophication and harmful algal blooms. The research carried out as part of the study described here was designed, in part, to help refine assumptions required by earlier versions of models about the nature of submarine groundwater flow and discharge at CCNS. This study was conducted in four phases, with a variety of field techniques and equipment employed in each phase. Phase 1 consisted of continuous resistivity profiling (CRP) surveys of the entire study area conducted in 2004. Phase 2 consisted of CRP ground-truthing via resistivity probe measurements and submarine groundwater sampling from hydraulically-drive piezometers using a barge in the Salt Pond/Nauset Marsh area in 2005. Phase 3 consisted of supplemental detailed CRP surveys in the Salt Pond/Nauset Marsh area in 2006. Finally, Phase 4 consisted of sediment coring and porewater extraction in the Salt Pond/Nauset Marsh area later in 2006 to supplement the 2005 sampling.

Continuous water quality sensor data were collected at USGS 292939089544400 Wilkinson Bayou cutoff north of Wilkinson Bay, LA gage. Field water-quality measurements were collected using a YSI EXO2 water-quality sonde equipped with a data logger to capture hourly data using sensors for measuring water temperature, specific conductance, salinity, pH, oxidation and reduction potential (ORP), fluorescent dissolved organic matter (fDOM), and turbidity. The monitor was housed in an 8-inch diameter polyvinyl chloride (PVC) pipe attached to a temporary wooden structure near the gage. Measurements were collected from a fixed mid-depth point in the water column. All data were collected using U.S. Geological Survey (USGS) protocols and data are stored in the National Water Information System (NWIS) database. Records processing of measurement results for fouling and drift corrections of the data followed the USGS Techniques and Methods for continuous water-quality monitors (Wagner, et al., 2006), except for ORP and drift corrections for fDOM. ORP were uncorrected and were reported from the sonde directly. fDOM was evaluated for drift using periodic side by side comparisons with a new factory calibrated sensor to check for lamp degradation in the sensor and calibration checks were performed using onsite prepared fDOM standard. fDOM data have not been corrected for temperature, turbidity, or inner-filter effects (Booth et al., 2023). Turbidity drift corrections were applied using Wagner et al. (2006) except in some cases where it was determined not helpful to apply the correction based on unstable site conditions during the site visit. Sample results from July of 2019 to May 2022 are reported in this data release. Booth, A., Fleck, J., Pellerin, B.A., Hansen, A., Etheridge, A., Foster, G.M., Graham, J.L., Bergamaschi, B.A., Carpenter, K.D., Downing, B.D., Rounds, S.A., and Saraceno, J., 2023, Field techniques for fluorescence measurements targeting dissolved organic matter, hydrocarbons, and wastewater in environmental waters: Principles and guidelines for instrument selection, operation and maintenance, quality assurance, and data reporting: U.S. Geological Survey Techniques and Methods, book 1, chap. D11, 41 p., https://doi.org/10.3133/tm1D11. Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006, Guidelines and standard procedures for continuous water-quality monitors—Station operation, record computation, and data reporting: U.S. Geological Survey Techniques and Methods 1–D3, 51 p. + 8 attachments; accessed August 3, 2022, at https://pubs.usgs.gov/tm/2006/tm1D3/pdf/TM1D3.pdf.

Continuous water quality sensor data were collected at USGS 292939089544400 Wilkinson Bayou cutoff north of Wilkinson Bay, LA gage. Field water quality measurements were collected using a YSI EXO2 water quality sonde equipped with a data logger to capture hourly data using sensors for measuring water temperature, specific conductance, salinity, pH, oxidation and reduction potential (ORP), fluorescent dissolved organic matter (fDOM), turbidity, and dissolved oxygen (DO). The monitor was housed in an 8-inch diameter polyvinyl chloride (PVC) pipe attached to a temporary wooden structure near the gage. Measurements were collected from a fixed mid-depth point in the water column. All data were collected using U.S. Geological Survey (USGS) protocols and data are stored in the National Water Information System (NWIS) database. Records processing of measurement results for fouling and drift corrections of the data followed the USGS Techniques and Methods for continuous water-quality monitors (Wagner et al., 2006), except for ORP and drift corrections for fDOM. ORP were uncorrected and were reported from the sonde directly. fDOM was evaluated for drift using periodic side-by-side comparisons with a new factory-calibrated sensor to check for lamp degradation in the sensor, and calibration checks were performed using on-site prepared fDOM standard. fDOM data have not been corrected for temperature, turbidity, or inner-filter effects (Booth et al., 2023). Turbidity drift corrections were applied using Wagner et al. (2006) except in some cases where it was determined not helpful to apply the correction based on unstable site conditions during the site visit. Sample results from June of 2022 to October 2023 are reported in this data release. References: Booth, A., Fleck, J., Pellerin, B.A., Hansen, A., Etheridge, A., Foster, G.M., Graham, J.L., Bergamaschi, B.A., Carpenter, K.D., Downing, B.D., Rounds, S.A., and Saraceno, J., 2023, Field techniques for fluorescence measurements targeting dissolved organic matter, hydrocarbons, and wastewater in environmental waters: Principles and guidelines for instrument selection, operation and maintenance, quality assurance, and data reporting: U.S. Geological Survey Techniques and Methods, book 1, chap. D11, 41 p., https://doi.org/10.3133/tm1D11. Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006, Guidelines and standard procedures for continuous water-quality monitors—Station operation, record computation, and data reporting: U.S. Geological Survey Techniques and Methods 1–D3, 51 p. + 8 attachments; accessed August 3, 2022, at https://pubs.usgs.gov/tm/2006/tm1D3/pdf/TM1D3.pdf.

This data release includes monitoring data collected by the U.S. Geological Survey (USGS) Humboldt Bay Water Quality and Salt Marsh Monitoring Project. The datasets include continuous water levels collected at a 6-minute time step collected in two study marshes (Mad River and Hookton). Surface deposition, elevation changes and carbon storage (in marsh edge environments) measured in five USGS study marshes (Mad River, Manila, Jacoby, White and Hookton). The monitoring data presented in this data release represent fundamental datasets needed to manage blue carbon stocks, assess marsh vulnerability, inform sea-level rise (SLR) adaptation planning, and build coastal resiliency to climate change in Humboldt Bay, CA Additional documentation is provided in a companion report. Curtis et al, 2022 A Summary of Water-Quality and Salt Marsh Monitoring during Water Years 2013 to 2019, Humboldt Bay, CA.

This data release contains coastal wetland synthesis products for the state of Connecticut. Metrics for resiliency, including the unvegetated to vegetated ratio (UVVR), marsh elevation, tidal range, wave power, and exposure potential to environmental health stressors are calculated for smaller units delineated from a digital elevation model, providing the spatial variability of physical factors that influence wetland health. The U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands with the intent of providing federal, state, and local managers with tools to estimate the vulnerability and ecosystem service potential of these wetlands. For this purpose, the response and resilience of coastal wetlands to physical factors need to be assessed in terms of the ensuing change to their vulnerability and ecosystem services. This project has been funded in part by the United States Environmental Protection Agency under assistance agreement DW-014-92531201-1 to N. Ganju.

To better understand sediment deposition in marsh environments, scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center (USGS-SPCMSC) selected four study sites (Sites 5, 6, 7, and 8) along the Point Aux Chenes Bay shoreline of the Grand Bay National Estuarine Research Reserve (GNDNERR), Mississippi. These datasets were collected to serve as baseline data prior to the installation of a living shoreline (a subtidal sill). Each site consisted of five plots located along a transect perpendicular to the marsh-estuary shoreline at 5-meter (m) increments (5, 10, 15, 20, and 25 m from the shoreline). Each plot contained six net sedimentation tiles (NST) that were secured flush to the marsh surface using polyvinyl chloride (PVC) pipe. NST are an inexpensive and simple tool to assess short- and long-term deposition that can be deployed in highly dynamic environments without the compaction associated with traditional coring methods. The NST were deployed for three month sampling periods, measuring sediment deposition from July 2018 to January 2020, with one set of NST being deployed for six months. Sediment deposited on the NST were processed to determine physical characteristics, such as deposition thickness, volume, wet weight/dry weight, grain size, and organic content (loss-on-ignition [LOI]). For select sampling periods, ancillary data (water level, elevation, and wave data) are also provided in this data release. Data were collected during USGS Field Activities Numbers (FAN) 2018-332-FA (18CCT01), 2018-358-FA (18CCT10), 2019-303-FA (19CCT01, 19CCT02, 19CCT03, and 19CCT04, respectively), and 2020-301-FA (20CCT01). Additional survey and data details are available from the U.S. Geological Survey Coastal and Marine Geoscience Data System (CMGDS) at, https://cmgds.marine.usgs.gov/. Data collected between 2016 and 2017 from a related NST study in the GNDNERR (Middle Bay and North Rigolets) can be found at https://doi.org/10.5066/P9BFR2US. Please read the full metadata for details on data collection, dataset variables, and data quality.

Biomass production is positively correlated with mean tidal range in salt marshes along the Atlantic coast of the United States of America. Recent studies support the idea that enhanced stability of the marshes can be attributed to increased vegetative growth due to increased tidal range. This dataset displays the spatial variation of mean tidal range (i.e. Mean Range of Tides, MN) in the Fire Island National Seashore and central Great South Bay salt marsh complex, based on conceptual marsh units defined by Defne and Ganju (2018). MN was based on the calculated difference in height between mean high water (MHW) and mean low water (MLW) using the VDatum (v3.5) database ( http://vdatum.noaa.gov/ ). Through scientific efforts initiated with the Hurricane Sandy Science Plan, the U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands, including the Fire Island National Seashore and central Great South Bay salt marshes, with the intent of providing Federal, State, and local managers with tools to estimate the vulnerability and ecosystem service potential of these wetlands. For this purpose, the response and resilience of coastal wetlands to physical factors need to be assessed in terms of the ensuing change to their vulnerability and ecosystem services. References: Defne, Z., and Ganju, N.K., 2018, Conceptual marsh units for Fire Island National Seashore and central Great South Bay salt marsh complex, New York: U.S. Geological Survey data release, https://doi.org/10.5066/P95U2MQ7.

To parameterize accretion for SLR models, we measured historic rates of mineral and organic matter accumulation at each site by collecting deep soil cores with a Russian peat borer. At each site, we obtained cores in each of three vegetation zones: low, medium, and high marsh. Two replicate cores were sampled from each station for a total of 6 cores per site (except Coos Bay where 7 cores were taken). Coring locations were determined by RTK GPS elevation and tidal inundation data. Transects for core sampling were determined in ArcGIS, using a digitial elevation model and site-specific tidal datums to choose station locations below MHW (low), between MHW and MHHW (mid), and above MHHW (high). Sediment cores were 50 cm deep and 5 cm in diameter. In the lab, we cut cores into 1 cm sections to process for bulk density, porosity, and organic matter composition using loss on ignition in a muffle furnace at 550ºC for 8 hr. Only half of the cores collected were processed for bulk density, organic matter and Cesuim dating (one replicate). We used Cesium-137 (137Cs) isotope dating techniques to determine accumulation rates in deep soil cores. Atmospheric nuclear testing prior to 1964 resulted in the spread of 137Cs across the globe creating a reliable marker horizon in soils. We used a gamma spectrometer at the Oregon State University Radiation Center to detect 137Cs activity, measured in picocuries (pCi), in 1 cm core samples for 24 hr. We standardized the 137Cs activity of each sample to its mass. The depth of the 137Cs peak activity indicated the 1964 marker horizon, which we used to determine average soil accretion rates over the last half century. Not every processed core had a distinct peak of Cesium 137.