Metal contaminated sediments can be toxic to aquatic organisms and are common in human-dominated ecosystems, which results in metals being a leading cause of ecosystem impairment. Bioavailability of metals is influenced by their affinity for dissolved and solid-phase ligands, including iron (Fe) oxyhydroxides, which have been hypothesized to reduce metal toxicity in sediments. The authors examined the adsorption kinetics of copper (Cu) and nickel (Ni) with goethite (α-FeOOH) and characterized the influences of solute metal concentration, pH, ionic strength, and humate concentration on steady-state partitioning of the metals with goethite under conditions representative of natural aquatic environments. Copper and Ni readily adsorbed to goethite, and steady-state partitioning was achieved within 2 h. Although ionic strength had no effect on metal partitioning, adsorption of Cu and Ni to goethite was enhanced by alkaline pH and reduced by competition with humate. Because distribution coefficient (KD ) values for Cu and Ni from the present study are comparable to values measured in natural systems, the authors hypothesize that goethite may contribute significantly to the adsorption of both Ni and Cu to particles in the environment. The authors suggest that incorporating binding by Fe oxides in metal bioavailability models should be a priority for improving risk assessment of metal-contaminated oxic sediments.
This dataset corresponds to the output files that were produced for the study reported in: Knights, Deon, Kevin C. Parks, Audrey H. Sawyer, Cédric H. David, Trevor N. Browning, Kelsey M. Danner, and Corey D. Wallace, (2017), Direct groundwater discharge and vulnerability to hidden nutrient loads along the Great Lakes coast of the United States, Journal of Hydrology, 554, 331-341 Data sources The following sources were used to produce files in this dataset: The National Hydrography Dataset Plus (NHDPlus) Version 2, obtained from http://www.horizon-systems.com/nhdplus/NHDplusV2_data.php. Region used is: Great Lakes (04) The second phase of the North American Land Data Assimilation System (NLDAS2), obtained from ftp://hydro1.sci.gsfc.nasa.gov/data/s4pa/NLDAS. Model outputs used are: NLDAS_MOS0125_MC.002, NLDAS_NOAH0125_MC.002, and NLDAS_VIC0125_MC.002. The United States 2011 National Land Cover Database (NLCD 2011), obtained from: http://www.mrlc.gov/nlcd2011.php. Description of files The files in this dataset contain are described below: Flowlines: This folder contains a shapefile (GL_coastcatchment_NHDflowline) with the coastline of the Contiguous United States as described by NHDPlus V2, and was merged from a subsample of all river reaches available in the region used. Catchment: This folder contains a shapefile (GL_coastcatchment_polygon) with the contributing catchments of NHDPlus V2 corresponding to the above coastline, and was merged from a subsample of all catchments available in the region used. Centroid: This folder contains a shapefile (GL_coastcatchment_centroid) with the centroids of the above catchments. DischargeVulnerabilities.csv. This .csv file contains the following data (units are in parentheses): COMID: Unique feature identifier in NHDPlusV2 (). Length_km: Length of coastline feature (km). Area_sqkm: Area of coastal catchment feature (km2). Infiltration_kgsqm: Average annual infiltrating runoff for REACHCODE (kg/m2) REACHCODE: Reach identifier in NHDPlusV2; reaches can include multiple features; Submarine Groundwater Discharge (SGD) is computed by reach, not feature (). RLength_km: Total length of coastline accumulated by REACHCODE (km). RArea_sqkm: Total area of coastal catchment accumulated by REACHCODE (km2). RInfiltration_kgsqm: Average annual infiltrating runoff for REACHCODE (kg/m2) DGWD: Average annual direct groundwater discharge for REACHCODE (m2/y). Vulnerable_percent: Percentage of reach area with developed or agricultural land use in 2011 (%). Vulnerable: Vulnerability to coastal contamination (0- not vulnerable; 1-vulnerable)
Abstract Microcystin is one of the most common toxins associated with freshwater harmful algal blooms, but little is known about microcystin fate in the aquatic environment. Laboratory wave tank experiments were performed to determine whether exchange of surface water and pore water (benthic exchange) removes and dilutes microcystin‐LR (MC‐LR) at environmentally relevant concentrations in coastal waters overlying permeable sediments. Over the 100 h experiment, 60% of MC‐LR mass was removed due to interaction with sediment (via adsorption and/or biodegradation), while only 20% was removed in an experiment without sediment. The observed fate and transport of MC‐LR in sediments was adequately described with a one‐dimensional reactive transport model that uses an enhanced diffusion coefficient to represent benthic exchange of solutes. Numerical sensitivity studies showed that MC‐LR removal increases with hydraulic conductivity of sediment and wave height and decreases with water depth. For MC‐LR concentration at the WHO recreational guideline (20 ppb), sandy sediments can remove the equivalent MC‐LR mass in 1 m of surface water under typical nearshore wave conditions within tens of hours. In open water at large depths above a silty bed, removal times are much longer (on the order of weeks). Wave‐driven benthic exchange is therefore an important control on MC‐LR fate in energetic coastal areas but not in deep or calm settings where sediment–water interactions are greatly reduced. The nearshore fate of algal toxins is important to human health and socioeconomic vitality, since recreational activities and direct human exposures are concentrated along coasts.
This dataset corresponds to the output files that were produced for the study reported in: Knights, Deon, Kevin C. Parks, Audrey H. Sawyer, Cédric H. David, Trevor N. Browning, Kelsey M. Danner, and Corey D. Wallace, (2017), Direct groundwater discharge and vulnerability to hidden nutrient loads along the Great Lakes coast of the United States, Journal of Hydrology, 554, 331-341 Data sources The following sources were used to produce files in this dataset: The National Hydrography Dataset Plus (NHDPlus) Version 2, obtained from http://www.horizon-systems.com/nhdplus/NHDplusV2_data.php. Region used is: Great Lakes (04) The second phase of the North American Land Data Assimilation System (NLDAS2), obtained from ftp://hydro1.sci.gsfc.nasa.gov/data/s4pa/NLDAS. Model outputs used are: NLDAS_MOS0125_MC.002, NLDAS_NOAH0125_MC.002, and NLDAS_VIC0125_MC.002. The United States 2011 National Land Cover Database (NLCD 2011), obtained from: http://www.mrlc.gov/nlcd2011.php. Description of files The files in this dataset contain are described below: Flowlines: This folder contains a shapefile (GL_coastcatchment_NHDflowline) with the coastline of the Contiguous United States as described by NHDPlus V2, and was merged from a subsample of all river reaches available in the region used. Catchment: This folder contains a shapefile (GL_coastcatchment_polygon) with the contributing catchments of NHDPlus V2 corresponding to the above coastline, and was merged from a subsample of all catchments available in the region used. Centroid: This folder contains a shapefile (GL_coastcatchment_centroid) with the centroids of the above catchments. DischargeVulnerabilities.csv. This .csv file contains the following data (units are in parentheses): COMID: Unique feature identifier in NHDPlusV2 (). Length_km: Length of coastline feature (km). Area_sqkm: Area of coastal catchment feature (km2). Infiltration_kgsqm: Average annual infiltrating runoff for REACHCODE (kg/m2) REACHCODE: Reach identifier in NHDPlusV2; reaches can include multiple features; Submarine Groundwater Discharge (SGD) is computed by reach, not feature (). RLength_km: Total length of coastline accumulated by REACHCODE (km). RArea_sqkm: Total area of coastal catchment accumulated by REACHCODE (km2). RInfiltration_kgsqm: Average annual infiltrating runoff for REACHCODE (kg/m2) DGWD: Average annual direct groundwater discharge for REACHCODE (m2/y). Vulnerable_percent: Percentage of reach area with developed or agricultural land use in 2011 (%). Vulnerable: Vulnerability to coastal contamination (0- not vulnerable; 1-vulnerable)
