Comparison of chemical contaminant measurements using CLAM, POCIS, and silicone band samplers in estuarine mesocosms.

Discrete water samples represent a snapshot of conditions at a particular moment in time and may not represent a true chemical exposure caused by changes in chemical input, tide, flow, and precipitation. Sampling technologies have been engineered to better estimate time-weighted concentrations. In this study, we consider the utility of three integrative sampling platforms: polar organic chemical integrative sampler (POCIS), silicone bands (SBs), and continuous, low-level aquatic monitoring (CLAM).

Assessment of the efficacy of six field cleaning protocols for hydrocarbon quantification.

The defensibility of field sampling data collected in support of natural resource damage assessments and other environmental investigations depends on rigorous quality assurance and control both in the field and laboratory. One important step in field procedures is the cleaning of sampling equipment between samples to minimize the carryover of contaminants. Large-scale sampling efforts during the Deepwater Horizon oil spill event have highlighted the importance of understanding how multiple equipment cleaning protocols affect interstation cross-contamination and the resulting chemical data quality.

What Goes Up Must Come Down: Integrating Air and Water Quality Monitoring for Nutrients.

Excess nitrogen and phosphorus ("nutrients") loadings continue to affect ecosystem function and human health across the U.S. Our ability to connect atmospheric inputs of nutrients to aquatic end points remains limited due to uncoupled air and water quality monitoring.

Chemical contaminants in surficial sediment in Coral and Fish Bays, St. John, U.S. Virgin Islands.

Land based sources of pollution have the potential to negatively impact coral reef ecosystems. Many coral systems, including environmentally sensitive marine protected areas, do not have assessments of their chemical contaminant status (magnitude and extent). Without a status assessment, it is impossible to measure change in a system.

Environmental PCBs in Guánica Bay, Puerto Rico: implications for community health.

Guánica Bay, located in southwestern Puerto Rico, has suffered oil spills and other pollution discharges since the 1960s. Previous research showed elevated concentrations of polychlorinated biphenyls (PCBs) in coral reef and sediment. This research examined PCB concentrations in sediment and fish.

Organic and metal contamination in marine surface sediments of Guánica Bay, Puerto Rico.

Land based sources of pollution have the potential to adversely impact valuable coral reef ecosystems. In Guánica Bay (Puerto Rico) sediment samples collected and analyzed in 2009 demonstrate unusually high concentrations of total chlordane, total PCBs, nickel and chromium. A variety of other contaminants (total DDT, total PAHs, As, Cu, Hg, and Zn) were also at levels which may indicate sediment toxicity.

Metolachlor metabolite (MESA) reveals agricultural nitrate-N fate and transport in Choptank River watershed.

Over 50% of streams in the Chesapeake Bay watershed have been rated as poor or very poor based on the index of biological integrity. The Choptank River estuary, a Bay tributary on the eastern shore, is one such waterway, where corn and soybean production in upland areas of the watershed contribute significant loads of nutrients and sediment to streams. We adopted a novel approach utilizing the relationship between the concentration of nitrate-N and the stable, water-soluble herbicide degradation product MESA {2-[2-ethyl-N-(1-methoxypropan-2-yl)-6-methylanilino]-2-oxoethanesulfonic acid} to distinguish between dilution and denitrification effects on the stream concentration of nitrate-N in agricultural subwatersheds.

Atrazine fate and transport within the coastal zone in southeastern Puerto Rico.

Agrichemical transport to coastal waters may have adverse ecological impact. This work examined atrazine fate and transport in a field adjacent to Puerto Rico's Jobos Bay National Estuarine Research Reserve. The herbicide's use was linked to residue detection in shallow groundwater and movement toward the estuary; however, data indicated that transport via this pathway was small.

Characterization of organic chemical contaminants in sediments from Jobos Bay, Puerto Rico.

Jobos Bay, located on the southeastern coast of Puerto Rico, contains a variety of habitats including mangroves, seagrass meadows, and coral reefs. The watershed surrounding the bay includes a number of towns, agricultural areas, and the Jobos Bay National Estuarine Research Reserve (NERR). Jobos Bay and the surrounding watershed are part of a Conservation Effects Assessment Project (CEAP), involving the Jobos Bay NERR, the US Department of Agriculture, and the National Oceanic and Atmospheric Administration (NOAA) to assess the benefits of agricultural best management practices (BMPs) on the terrestrial and marine environments.

Relating nutrient and herbicide fate with landscape features and characteristics of 15 subwatersheds in the Choptank River watershed.

Excess nutrients and agrochemicals from non-point sources contribute to water quality impairment in the Chesapeake Bay watershed and their loading rates are related to land use, agricultural practices, hydrology, and pollutant fate and transport processes. In this study, monthly baseflow stream samples from 15 agricultural subwatersheds of the Choptank River in Maryland USA (2005 to 2007) were characterized for nutrients, herbicides, and herbicide transformation products. High-resolution digital maps of land use and forested wetlands were derived from remote sensing imagery.

Characterization of land-based sources of pollution in Jobos Bay, Puerto Rico: status of heavy metal concentration in bed sediment.

As part of an assessment of land-based sources of pollution in Jobos Bay, Puerto Rico, sediment samples were collected at 43 sites to characterize concentrations of a suite of pollutants, including metals. Fifteen major and trace metals (Ag, Al, As, Cd, Cr, Cu, Fe, Hg, Mn Ni, Pb, Sb, Se, Sn, and Zn) were measured along with total organic carbon and grain size in surficial sediments. For most metals, maximum concentrations were seen in the eastern bay; however, values were still within concentration ranges found in other estuarine systems.

Pollutant fate and spatio-temporal variability in the choptank river estuary: factors influencing water quality.

Restoration of the Chesapeake Bay, the largest estuary in the United States, is a national priority. Documentation of progress of this restoration effort is needed. A study was conducted to examine water quality in the Choptank River estuary, a tributary of the Chesapeake Bay that since 1998 has been classified as impaired waters under the Federal Clean Water Act.

Assessment of eutrophication in estuaries: pressure-state-response and nitrogen source apportionment.

A eutrophication assessment method was developed as part of the National Estuarine Eutrophication Assessment (NEEA) Program. The program is designed to improve monitoring and assessment of eutrophication in the estuaries and coastal bays of the United States with the intent to guide management plans and develop analytical and research models and tools for managers. These tools will help guide and improve management success for estuaries and coastal resources.

Linking hypoxia to shrimp catch in the northern Gulf of Mexico.

Wide spread and reoccurring hypoxia has been observed in the northern Gulf of Mexico since routine monitoring began in the 1980s. Although the potential ecological effects of hypoxia (habitat loss, mortalities) are well known, there is relatively little information linking hypoxia in the northern Gulf of Mexico to fisheries decline. Previous analyses have shown a negative relationship between hypoxic area and brown shrimp (Farfantepenaeus aztecus) catch for the Texas and Louisiana coasts combined from 1985 to 1997.

Importance of atmospherically deposited nitrogen to the annual nitrogen budget of the Neuse River estuary, North Carolina.

Wet deposition of nitrogen, as NH(4)(+), NO(3)(-), and organic N, contributes up to 50% of the total externally supplied or 'new' N flux to the Neuse River Estuary (North Carolina). Excessive nitrogen (N) loading to N-sensitive waters such as the Neuse River Estuary has been linked to changes in microbial and algal community composition and function (harmful algal blooms), hypoxia/anoxia, and fish kills. In a 4-year study from July 1996 to July 2000, the weekly wet deposition of NH(4)(+), NO(3)(-), and dissolved organic N was calculated, based on concentration and precipitation measurements, at 11 sites on a northwest-southeast transect in the watershed.