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USGS2018

Hydrology-driven chemical loads transported by the Green River to the Lower Duwamish Waterway near Seattle, Washington, 2013–17

The sediments in the Lower Duwamish Waterway Superfund site in Seattle, Washington, are contaminated with chemicals including metals such as arsenic, polychlorinated biphenyls (PCBs), carcinogenic polycyclic aromatic hydrocarbons (cPAHs), and dioxins/furans from decades of intense anthropogenic activities. The U.S. Geological Survey, in cooperation with the Washington State Department of Ecology, collected new data from 2013 to 2017 to estimate sediment and chemical loads transported by the Green/Duwamish River to the Lower Duwamish Waterway Superfund site (the final 8-kilometer reach of the river) in support of sediment remediation within the site. Chemical loads were calculated as the product of river suspended-sediment loads and suspended sediment-bound chemical concentrations measured at river kilometer 16.7. Using four different approaches, annual suspended sediment-bound chemical load estimates transported by the river to the Lower Duwamish Waterway were in the range of 1,120–1,470 kilograms arsenic, 2,810–8,200 grams (g) toxic equivalent cPAHs, 205–407 milligrams toxic equivalent dioxins/furans, and 340–1,180 g PCBs. Storm events contributed a disproportionately large amount of the load of anthropogenic organic compounds such as cPAHs (54 percent), dioxins/furans (44 percent), and PCBs (52 percent) as compared to overall time (17 percent). Chemical concentrations and load estimates often were underestimated using results from unfiltered water analysis only, especially in samples with high suspended-sediment concentrations and for hydrophobic organic chemicals such as cPAHs that prefer to sorb to particulates and are at low concentrations near or below the analytical limits of water methods. For metals and PCBs, the dissolved concentration was relatively low and consistent between sampling events, whereas the suspended sediment-bound chemical concentrations contributed most of the chemical concentration in the water column during periods of high river suspended-sediment concentrations. However, the dissolved fraction, on average, contributed more than one-third of the estimated total chemical load in the river system for arsenic and PCBs, even given the hydrophobic nature of the chemicals. These results suggest that the sum of the chemical concentrations measured on two separate fractions—the particulate fraction and the dissolved fraction—more fully represents the total chemical concentration as compared to analysis of an unfiltered water sample, especially in samples with high suspended-sediment concentrations. Most of the suspended-sediment load (97 percent) and sediment-bound chemical load (92–94 percent) occurred during the wet winter half of the year from October 15 to April 14. However, the highest sediment-bound chemical concentrations often occurred during short intense storms or “first flush” autumn runoff events during the dry summer half of the year from April 15 to October 14. Because of the highly variable and dynamic river system characteristics (including precipitation, discharge, sediment concentration, and tidal fluctuations), it is critical to characterize the occurrence, frequency, concentrations, and loads during extreme conditions (for example, when the river is affected by storm-derived runoff) rather than time-averaged conditions. These short extreme events have a high potential for acute effects on ecological and human health, and may have a great influence on the effectiveness of the sediment remediation activities that are underway in the Lower Duwamish Waterway.

Washington↗

USGS2005

Environmental contaminants and biomarker responses in fish from the Rio Grande and its U.S. tributaries: Spatial and temporal trends

We collected, examined, and analyzed 368 fish of seven species from 10 sites on rivers of the Rio Grande Basin (RGB) during late 1997 and early 1998 to document temporal and geographic trends in the concentrations of accumulative contaminants and to assess contaminant effects on the fish. Sites were located on the mainstem of the Rio Grande and on the Arroyo Colorado and Pecos River in Texas (TX), New Mexico (NM), and Colorado. Common carp (Cyprinus carpio) and largemouth bass (Micropterus salmoides) were the targeted species. Fish were examined in the field for internal and external visible gross lesions, selected organs were weighed to compute ponderal and organosomatic indices, and samples of tissues and fluids were obtained and preserved for analysis of fish health and reproductive biomarkers. Whole fish from each station were composited by species and gender and analyzed for organochlorine chemical residues and elemental contaminants using instrumental methods, and for 2,3,7,8-tetrachloro dibenzo-p-dioxin-like activity (TCDD-EQ) using the H4IIE rat hepatoma cell bioassay. Overall, fish from lower RGB stations contained greater concentrations of organochlorine pesticide residues and appeared to be less healthy than those from sites in the central and upper parts of the basin, as indicated by a general gradient of residue concentrations and biomarker responses. A minimal number of altered biomarkers and few or no elevated contaminant concentrations were noted in fish from the upper RGB. The exception was elevated concentrations [up to 0.46 ??g/g wet-weight (ww)] of total mercury (Hg) in predatory species from the Rio Grande at Elephant Butte Reservoir, NM, a condition documented in previous studies. Arsenic (As) and selenium (Se) concentrations were greatest in fish from sites in the central RGB; Se concentrations in fish from the Pecos River at Red Bluff Lake, TX and from the Rio Grande at Langtry, TX and Amistad International Reservoir, TX exceeded published fish and wildlife toxicity thresholds. In the lower RGB, residues of p,p???-DDT metabolites (???1.69 ??g/g ww), chlordane-related compounds (???0.21 ??g/g ww), dieldrin (???0.0.05 ??g/g ww), and toxaphene (???2.4 ??g/g ww) were detected in fish from most sites; maximum concentrations were in channel catfish (Ictalurus punctatus) from the Arroyo Colorado at Harlingen, TX. Concentrations of one or more residues exceeded toxicity thresholds for fish and wildlife in fish from this site and from the Rio Grande at Mission, TX and Brownsville, TX; however, concentrations were lower than those reported by previous studies. In addition, the proportional concentrations of p,p???-DDT at all sites were low, indicating weathered DDT rather than the influx of new material. Concentrations of total PCBs (<0.05 ??g/g ww) and TCDD-EQ (???6 pg/g ww) were comparatively low in all samples. Hepatic ethoxyresorufin O-deethylase (EROD) activity in some fish was elevated relative to reference rates at most sites, but was generally lower than previously reported activity in fish from heavily contaminated locations. The comparatively low PCB and TCDD-EQ concentrations together with elevated EROD activity may reflect exposure to polycyclic aromatic hydrocarbons. Reproductive biomarkers were consistent with chronic contaminant exposure at lower RGB sites; comparatively large percentages of intersex male largemouth bass, relatively low gonadosomatic indices, and elevated plasma vitellogenin concentrations in male fish were noted at three of the four stations. Large percentages of atretic eggs were also observed in the ovaries of female common carp from the Rio Grande at Brownsville, TX. Although many of the conditions noted may have other causes in addition to contaminant exposure, the biomarker results for the lower RGB sites are consistent with subtle responses of fish to contaminants, an interpretation supported by the chemical data of this and other investigations.

Science of the Total Environment↗

USGS2010

Polycyclic aromatic hydrocarbons in soil of the Canadian River floodplain in Oklahoma

The accumulation of polycyclic aromatic hydrocarbons (PAH) in soil, plants, and water may impart negative effects on ecosystem and human health. We quantified the concentration and distribution of 41 PAH (n = 32), organic C, total N, and S (n = 140) and investigated PAH sources using a chronosequence of floodplain soils under a natural vegetation succession. Soil samples were collected between 0- and 260-cm depth in bare land (the control), wetland, forest, and grassland areas near a closed municipal landfill and an active asphalt plant (the contaminant sources) in the north bank of the Canadian River near Norman, OK. Principal component, cluster, and correlation analyses were used to investigate the spatial distribution of PAH, in combination with diagnostic ratios to distinguish pyrogenic vs. petrogenic PAH suites. Total PAH concentration (SigmaPAH) had a mean of 1300 ng g(-1), minimum of 16 ng g(-1), and maximum of 12,000 ng g(-1). At 0- to 20-cm depth, SigmaPAH was 3500 +/- 1600 ng g(-1) (mean +/- 1 SE) near the contaminant sources. The most common compounds were nonalkylated, high molecular weight PAH of pyrogenic origin, i.e., fluoranthene (17%), pyrene (14%), phenanthrene (9%), benzo(b)fluoranthene (7%), chrysene (6%), and benzo(a)anthracene (5%). SigmaPAH in the control (130 +/- 23 ng g(-1)) was comparable to reported concentrations for the rural Great Plains. Perylene had a unique distribution pattern suggesting biological inputs. The main PAH contamination mechanisms were likely atmospheric deposition due to asphalt production at the 0- to 20-cm depth and past landfill operations at deeper depths.

Journal of Environmental Quality↗

USGS1995

Comparison of the in situ and desorption sediment-water partitioning of polycyclic aromatic hydrocarbons and polychlorinated biphenyls

In situ sediment−porewater partitioning of polycyclic aromatic hydrocarbons (PAHs) measured in three cores from Boston Harbor, MA, has led us to suggest that only a fraction of the total measured sediment PAH concentration is a vailable for e quilibrium p artitioning (AEP fraction). To test this, aqueous PAH concentrations were measured in laboratory desorption experiments using subsamples of the same Boston Harbor sediments. The observed concentrations were consistent with what we predicted from the field-derived AEP values: C aqueous = ( C sediment × AEP)/( f oc × K oc ) where f oc is the fraction organic carbon in the sediment and K oc is the organic carbon normalized sediment−water partition coefficient. Equilibrium partitioning models based on the total measured sediment PAH concentrations overestimated the measured aqueous PAH concentrations by as much as 100 times in some cases. Only a small fraction of the sediment phenanthrene and pyrene concentrations (1−40%) appeared to be available for equilibrium partitioning. Both in situ and laboratory desorption aqueous polychlorinated biphenyl (PCB) concentrations were consistent with equilibrium partitioning models and the assumption that 100% of these compounds was available for equilibrium partitioning. These results are particularly important to efforts to predict the environmental mobility and bioavailability of the PAHs.

Massachusetts↗

USGS2006

Effects of urbanization on stream ecosystems in the South Platte River basin, Colorado and Wyoming

This report describes the effects of urbanization on physical, chemical, and biological characteristics of stream ecosystems in 28 basins along an urban land-use gradient in the South Platte River Basin, Colorado and Wyoming, from 2002 through 2003. Study basins were chosen to minimize natural variability among basins due to factors such as geology, elevation, and climate and to maximize coverage of different stages of urban development among basins. Because land use or population density alone often are not a complete measure of urbanization, land use, land cover, infrastructure, and socioeconomic variables were integrated in a multimetric urban intensity index to represent the degree of urban development in each study basin. Physical characteristics studied included stream hydrology, stream temperature, and habitat; chemical characteristics studied included nutrients, pesticides, suspended sediment, sulfate, chloride, and fecal bacteria concentrations; and biological characteristics studied included algae, fish, and invertebrate communities. Semipermeable membrane devices (SPMDs), passive samplers that concentrate trace levels of hydrophobic organic contaminants like polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), also were used. The objectives of the study were to (1) examine physical, chemical, and biological responses along the gradient of urbanization; (2) determine the major physical, chemical, and landscape variables affecting the structure of aquatic communities; and (3) evaluate the relevance of the results to the management of water resources in the South Platte River Basin. Commonly observed effects of urbanization on instream physical, chemical, and biological characteristics, such as increased flashiness, higher magnitude and more frequent peak flows, increased concentrations of chemicals, and changes in aquatic community structure, generally were not observed in this study. None of the hydrologic, temperature, habitat, or chemical variables were correlated strongly (Spearman's rho greater than or equal to 0.7) with urban intensity, with the exception of some of the SPMD-based toxicity and chemical variables. SPMD-based measures of potential toxicity and PAH concentrations were positively correlated with urban intensity. The PAH concentrations also were positively correlated with measures of road density and negatively correlated with distance to the nearest road, indicating that automobile exhaust is a major source of these compounds in the study area. This source may be localized enough that the transport of PAHs would be minimally affected by water-management practices such as diversion or storage upstream. In contrast, the predominant sources of nutrients, bacteria, suspended sediment, sulfate, chloride, and pesticides may be more dispersed throughout the drainage area and, therefore, their transport to downstream sites may be subject to greater disruption by water regulation. Although no direct link was found between most water-chemistry characteristics and urbanization, invertebrate, algae, and fish-community characteristics were strongly associated with nutrients, pesticides, sulfate, chloride, and suspended sediment. None of the biological community variables were strongly correlated with the urban intensity index. Algal biomass predominantly was associated with total nitrogen concentrations, nitrite-plus-nitrate concentrations, and the duration of high flows. Fish communities predominantly were associated with housing age, the percentage of suspended sediment finer than 0.063 millimeters and chloride concentrations. Invertebrate communities predominantly were associated with the frequency of rising and falling flow events, the duration of high flows, total nitrogen concentrations, nitrite-plus-nitrate concentrations, and total herbicide concentrations. Historical records indicate that aquatic communities in the region may have been altered prior to any substantial urban development by early agricultural and water-management practices. Present-day aquatic communities are composed primarily of tolerant species even in areas of minimal urban development; when development does occur, the communities already may be resistant to disturbance. In addition to the effects of historical stressors on aquatic community structure, it is possible that current water-management practices in the study basins are having an effect. In the absence of natural, unaltered hydrologic conditions, more sensitive taxa may be unable to recolonize urban streams. The movement and storage of water also may lead to a disconnect between the land surface and streams, resulting in instream physical, chemical, and biological characteristics that, to some degree, are independent of land-cover characteristics.

Colorado, Wyoming↗

USGS2013

Comparison of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenylethers, and organochlorine pesticides in Pacific sanddab (Citharichthys sordidus) from offshore oil platforms and natural reefs along the California coast

Recently, the relative exposure of Pacific sanddab ( Citharichthys sordidus ) to polycyclic aromatic hydrocarbons (PAHs) at oil-production platforms was reported, indicating negligible exposure to PAHs and no discernible differences between exposures at platforms and nearby natural areas sites. In this report, the potential for chronic PAH exposure in fish is reported, by measurement of recalcitrant, higher molecular weight PAHs in tissues of fish previously investigated for PAH metabolites in bile. A total of 34 PAHs (20 PAHs, 11 alkylated PAHs, and 3 polycyclic aromatic thiophenes) were targeted. In addition, legacy contaminants—polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs),—and current contaminants, polybrominated diphenylethers (PBDEs) linked to endocrine disruption, were measured by gas chromatography with electron-capture or mass spectrometric detection, to form a more complete picture of the contaminant-related status of fishes at oil production platforms in the Southern California Bight. No hydrocarbon profiles or unresolved complex hydrocarbon background were found in fish from platforms and from natural areas, and concentrations of aliphatics were low less than 100 nanograms per gram (ng/g) per component]. Total-PAH concentrations in fish ranged from 15 to 37 ng/g at natural areas and from 8.7 to 22 ng/g at platforms. Profiles of PAHs were similar at all natural and platform sites, consisting mainly of naphthalene and methylnaphthalenes, phenanthrene, fluoranthene, and pyrene. Total-PCB concentrations (excluding non-ortho-chloro-substituted congeners) in fish were low, ranging from 7 to 22 ng/g at natural areas and from 10 to 35 ng/g at platforms. About 50 percent of the total-PCBs at all sites consisted of 11 congeners: 153 > 138/163/164 > 110 > 118 > 15 > 99 > 187 > 149 > 180. Most OCPs, except dichlorodiphenyltrichloroethane (DDT)-related compounds, were not detectable or were at concentrations of less than 1 ng/g in fish. p,p′ -dichlorodiphenyltrichloroethane ( p,p′ -DDE) ranged from 5.6 to 33 ng/g at natural areas and from 17 to 76 ng/g at platforms, and comprised greater than 90 percent of the total-DDT concentrations at all sites. The only detectable PBDE congeners were PBDE-47 and PBDE-100, the total concentrations of which ranged from 0.4 to 1.8 ng/g at natural areas and from 0.5 to 3.0 ng/g at platforms. Total-PAH, -PCB, and -DDT concentrations were compared with other Southern California Bight studies involving shoreline mussel, ( Mytilus Species, Kimbrough and others, 2008) and near shore sampling (Pacific sanddab, Schiff and Allen, 2000). At corresponding sites, only total-PCB concentrations agreed well with results from this study; total-DDT concentrations were generally much lower than concentrations documented in previous studies for samples collected nearer to shore by sewage treatment outfalls or 14 years earlier or closer in time to when DDT production was halted (1970). Natural areas and platforms in the Bight do not appear to be affected by harbor or urban pollution. Platforms were no more polluted than the nearby natural areas, with these locations exhibiting only low concentrations of PAHs, PCBs, DDTs, and other contaminants.

California↗

USGS2018

Land-cover changes associated with oil and natural-gas production and concentrations of selected constituents in surface-water and streambed-sediment samples collected upstream from and within an area of oil and natural-gas production, south Texas, 2008–17

The extensive development of oil and natural-gas resources in south Texas during the past 10 years has led to questions regarding possible environmental effects of processes associated with oil and natural-gas production, in particular the process of hydraulic fracturing, on water and other natural resources. Part of the lower San Antonio River watershed intersects an area of oil and natural-gas production from the sedimentary rocks that compose the Eagle Ford Group. The rapid expansion of infrastructure associated with oil and natural-gas production increases potential pathways for inorganic and organic contaminants to enter surface-water systems. The U.S. Geological Survey, in cooperation with the San Antonio River Authority, analyzed geospatial data from different years (2008 and 2015) to evaluate changes in land cover associated with oil and natural-gas production activities in the lower San Antonio River watershed. Impervious surface in this study is defined as land cover consisting of well pads, oil- and gas-related features, or roads. The areal coverage associated with impervious surface increased from 201 acres to 5,390 acres (net increase of 5,189 acres) between 2008 and 2015. The total percentage of the study area accounted for by impervious surface resulting from oil and natural-gas production activities increased from 0.034 percent to 0.912 percent, which is an increase of approximately 27-fold. Collectively, 0.878 percent of the study area was converted to new impervious surface between 2008 and 2015. If the area associated with new storage ponds (0.066 percent) is added to the estimate of total land-cover changes as a result of oil and natural-gas production, then 0.944 percent of the study area was altered. During 2015–17, surface-water samples collected from 5 sites and streambed-sediment samples collected from 17 sites in the lower San Antonio River watershed were analyzed for a broad range of constituents that might be associated with oil and natural-gas production. All major elements, trace elements, semivolatile organic compounds (SVOCs), and volatile organic compounds (VOCs) measured in surface-water samples were detected at concentrations less than any of the U.S. Environmental Protection Agency’s water-quality standards. In general, the greatest SVOC and VOC concentrations were observed in samples collected from sites upstream from the area of active oil and natural-gas production and just downstream from urban areas. The lack of benzene, toluene, ethylbenzene, and all isomers of xylene (hereinafter referred to as BTEX) for most sites within the area of active oil and natural-gas production indicates that little, if any, local runoff associated with the area of active oil and natural-gas production has contaminated the surface water with BTEX compounds. Glycols, which are commonly used in hydraulic fracturing fluids as scale inhibitors, were detected in one surface-water sample from Ecleto Creek within the area of oil and natural-gas production; however, the presence of glycols does not necessarily indicate contamination from hydraulic fracturing fluid. The glycols detected also have other potential sources including the use of diethylene and ethylene glycols in antifreeze used in vehicles and the use of triethylene glycol in antibacterial air sanitizers. The concentrations of select constituents in the streambed-sediment samples were compared to sediment quality guidelines (SQGs). The SQGs evaluate the potential toxicity of bed sediments to sediment-dwelling organisms. Two SQG concentration levels are used: (1) a lower level, called the threshold effect concentration (TEC), below which harmful effects to benthic biota are not expected, and (2) a higher level, the probable effect concentration (PEC), above which harmful effects are expected to occur frequently. The PEC for arsenic was exceeded in a sample collected from one site on Ecleto Creek. The origin of the elevated arsenic concentration is unknown; the contamination likely is not related to oil and natural-gas production because the site of the sample collection is located upstream from the area of active oil and natural-gas production. Streambed-sediment samples were analyzed for selected polycyclic aromatic hydrocarbons (PAHs) because PAHs can be used as indicators of petroleum hydrocarbons associated with produced waters. Each streambed-sediment sample was analyzed for two size fractions of PAHs: less than (<) 63 micrometers (μm) and < 2 millimeters (mm). Total PAH concentrations in all samples, regardless of size fraction, were less than the TEC for total PAHs of 1,610 micrograms per kilogram. Total PAH concentrations generally were greater in the <63-μm size-fraction samples than in the <2-mm size-fraction samples, indicating that PAHs could potentially sorb more readily to the exclusively silt- and clay-sized particles that compose <63-μm size-fraction samples than to the mixture of silt and clay and larger sized particles that compose the <2-mm size-fraction samples. Total PAH concentrations typically were greater in the samples collected from the sites upstream from the area of active oil and natural-gas production compared to those collected from sites within the area in both the <2-mm and <63-μm size-fraction samples. The smaller PAH concentrations measured in samples collected from within the area of active oil and natural-gas production in comparison to the upstream urbanized areas indicate relatively minor additional local contributions of PAHs of uncertain origin to the watershed.

Texas↗

USGS2014

Concentrations of selected constituents in surface-water and streambed-sediment samples collected from streams in and near an area of oil and natural-gas development, south-central Texas, 2011-13

During 2011–13, the U.S. Geological Survey, in cooperation with the San Antonio River Authority and the Guadalupe-Blanco River Authority, analyzed surface-water and streambed-sediment samples collected from 10 sites in the San Antonio River Basin to provide data for a broad range of constituents that might be associated with hydraulic fracturing and the produced waters that are a consequence of hydraulic fracturing. Among surface-water samples, all sulfide concentrations were less than the method detection limit of 0.79 milligrams per liter. Four glycols—diethylene glycol, ethylene glycol, propylene glycol, and triethylene glycol—were analyzed for in surface-water samples collected for this study, and none were detected. Of the 91 semivolatile organic compounds analyzed for this study, there were six detections, all but one of which were in storm-runoff samples. The base-flow sample collected at the San Antonio River at Goliad, Tex. (SAR Goliad), site contained bis(2-ethylhexyl) phthalate, a plasticizer in polyvinyl chloride and a constituent in hydraulic fracturing fluids. The storm-runoff samples collected at the San Antonio River near Elmendorf, Tex. (SAR Elmendorf), and Ecleto Creek at County Road 326 near Runge, Tex. (Ecleto 2), sites also contained bis(2-ethylhexyl) phthalate. The storm-runoff sample collected at the SAR Elmendorf site contained the plasticizer diethyl phthalate. Both storm-runoff samples collected at the Ecleto Creek near Runge, Tex. (Ecleto 1), and Ecleto 2 sites contained benzyl alcohol, a solvent commonly used in paints. Of the 67 volatile organic compounds analyzed in this study, there were a total of six detections, all of which were in base-flow samples. The surface-water sample collected at the SAR Elmendorf site contained bromodichloromethane, dibromochloromethane, and trichloromethane, all of which are disinfection byproducts associated with the chlorination of municipal water supplies and of treated municipal wastewater. The sample collected at the Cibolo Creek near Saint Hedwig, Tex. (Cibolo St. Hedwig), site contained toluene, a fuel additive, solvent, and industrial feedstock used to produce benzene and a constituent associated with produced waters. The Cibolo St. Hedwig site is upstream from current (2014) oil and natural-gas production areas. Dichloromethane, an industrial solvent with multiple uses, was detected in surface-water samples at both the San Antonio River at State Highway 72 near Runge, Tex. (SAR 72), and SAR Goliad sites. In streambed-sediment samples, concentrations of total saturated hydrocarbons (TSH) ranged from an estimated 260 micrograms per kilogram (μg/kg) in the less than (<) 2-millimeter (mm) size-fraction sample collected at the SAR Goliad site to 11,000 μg/kg in the <2-mm size-fraction sample collected at the Ecleto 1 site. TSH concentrations were greater in the <63-micrometer (μm) size-fraction samples than in the <2-mm size-fraction samples in streambed-sediment samples collected from 5 of the 9 sites. Total polycyclic aromatic hydrocarbons (PAHs) were calculated as the sum of the individual PAHs and alkylated PAHs. Total PAH concentrations ranged from less than the method detection limit in the <2-mm size-fraction samples collected from multiple sites to 1,600 μg/kg in the <2-mm size-fraction sample collected from the San Antonio River near McFaddin, Tex. (SAR McFaddin), site. Total PAH concentrations were greater in the <63-μm size-fraction samples than in the <2-mm size-fraction samples at 7 of the 9 sites. During collection of streambed-sediment samples, additional samples from a subset of three sites (the SAR Elmendorf, SAR 72, and SAR McFaddin sites) were processed by using a 63-µm sieve on one aliquot and a 2-mm sieve on a second aliquot for PAH and n -alkane analyses. The purpose of analyzing PAHs and n -alkanes on a sample containing sand, silt, and clay versus a sample containing only silt and clay was to provide data that could be used to determine if these organic constituents had a greater affinity for silt- and clay-sized particles relative to sand-sized particles. The greater concentrations of PAHs in the <63-μm size-fraction samples at all three of these sites are consistent with a greater percentage of binding sites associated with fine-grained (<63 μm) sediment versus coarse-grained (<2 mm) sediment. The larger difference in total PAHs between the <2-mm and <63-μm size-fraction samples at the SAR Elmendorf site might be related to the large percentage of sand in the <2-mm size-fraction sample which was absent in the <63-μm size-fraction sample. In contrast, the <2-mm size-fraction sample collected from the SAR McFaddin site contained very little sand and was similar in particle-size composition to the <63-μm size-fraction sample.

Texas↗

USGS2003

Trace elements and synthetic organic compounds in streambed sediment and fish tissue in the Great and Little Miami River basins, Ohio and Indiana, 1990-98

Streambed-sediment and fish-tissue samples were collected at eight sites in the Great and Little Miami Basins as part of the U.S. Geological Survey's National Water Quality Assessment Program. The samples were analyzed for trace elements and synthetic organic compounds, including organochlorine insecticides, polychlorinated biphenyls (PCBs), and semivolatile compounds (SVOCs). Data from state-agency investigations within the study unit (more than 200 sites) were incorporated to gain a broader perspective of the occurrence and distribution of contaminants in the study unit. All data were compared to streambed-sediment-quality guidelines and fish-tissue guidelines to identify elevated contaminant concentrations. Guideline exceedances were plotted on distribution maps to identify areas in the study unit that may be of potential concern for wildlife health. Several trace elements were detected in both sediment and fish-tissue samples. In sediment, lead and zinc were most frequently detected at levels that may have adverse effects on aquatic organisms. Generally, only one of the trace elements analyzed for per site exceeded concentrations above which adverse biological effects are frequently anticipated. Organochlorine insecticides were infrequently detected in sediment or fish tissue throughout the study unit. More organochlorine insecticides were detected in fish tissues than in sediment; however, more guidelines were exceeded in sediment. No distinct geographic overlap between sediment and fish-tissue sites was evident with respect to elevated organochlorine insecticide concentrations. Sediment-quality guideline exceedances were generally widespread throughout the study unit, whereas fish-tissue guidelines were exceeded only on the Mad River. PCBs were detected more often in fish tissue than in sediment throughout the study unit. Elevated PCB concentrations in fish tissue were common and widespread. No distinct geographic overlap of PCB exceedances was evident between sediment and fish-tissue sites. In sediments, elevated concentrations were detected most often for SVOCs, particularly for polycyclic aromatic hydrocarbons (PAHs). Areas where SVOC guidelines were frequently exceeded include the Great Miami River main stem from Dayton to south of Hamilton, and the Upper Little Miami River Basin in Greene County. Overall, a higher frequency of trace-element detections in fish tissue and sediment trace-element guideline exceedances was found in the Great Miami River Basin than in the Little Miami River Basin. Organochlorine insecticide guidelines for fish tissue and sediment, as well as PCB and SVOC guidelines for sediment also were exceeded more frequently in the Great Miami River Basin. PCB guideline exceedances for fish tissue were found more often in the Little Miami River Basin.

Water-Resources Investigations Report↗

USGS2008

Davis Pond freshwater prediversion biomonitoring study: freshwater fisheries and eagles

In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle ( Haliaeetus leucocephalus ) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet ( Mugil cephalus ), omnivorous blue catfish ( Ictalurus furcatus ), and carnivorous largemouth bass ( Micropterus salmoides ). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams ( Rangia cuneata ) were collected at the downstream marsh sites, and zebra mussels ( Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate pesticides and other contaminants. Biomarker data on individual fish, generated at the USGS National Wetlands Research Center (Lafayette, La.), included percent white blood cells in whole blood, spleen weight to body weight ratio, liver weight to body weight ratio, condition factor, splenic macrophage aggregates, and liver microsomal 7-ethoxyresorufin-o-deethylase (EROD) activity. Fish age was estimated by comparing total lengths with values from the same species in the Southeast United States as determined from the literature. Contaminant analyses were coordinated by the U.S. Fish and Wildlife Service (USFWS) Analytical Control Facility (Laurel, Md.), where residues of organochlorine (OC) pesticides, total polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs), and trace elements were determined. The organic contaminant data were generated at the Mississippi State University Chemical Lab (Mississippi State, Miss.), and the inorganic contaminant data were generated by the Texas A&M University Geochemical and Environmental Research Group (College Station, Tex.). Statistical tests were performed to assess relationships among contaminants, fish age, fish species, and collection sites. Trends in interspecific differences among fish in concentrations of contaminants were noted. Striped mullet (hereafter mullet) frequently displayed the highest chemical concentrations. Levels of contaminants were generally higher in samples obtained from the Mississippi River than in those collected from the diversion area and were higher in mussels and clams (hereafter bivalves) than in fish. Because the Mississippi River sampling site for mullet and largemouth bass was downriver of the structure and south of New Orleans and the catfish site was upriver, the downriver data may not be directly reflective of the results from the receiving waters at the Davis Pond structure. Compared to the Caernarvon freshwater prediversion study in 1990 that assessed possible influx of contaminants with the freshwater diversion, contaminant levels in fishes and bivalves in this study were generally lower, yet three nontoxic inorganic elements in Davis Pond fish samples exhibited ranges of concentrations that were more than two times higher than did those from Caernarvon. Levels in bivalves were different between diversions but about equal in the numbers of trace elements showing high levels per location. Contaminant values were compared to those listed in various literature and agency sources, both regional and national, including the National Contaminant Biomonitoring Program (NCBP), in which the 85th percentile and above represents what is considered to be an elevated contaminant concentration and cause for concern. Generally, bivalves were at the high end of their ranges for both organic and inorganic contaminants. In this study, OCs were detectable in 67 percent of fish from the Mississippi River site, ranging from 0.15 to 1.09 μg/g wet weight (ww) or fresh weight (fw), and in 11 percent of the fish from the marsh sites, ranging from 0.06 to 0.612 μg/g ww. Bivalves from the Mississippi River had OC levels of 0.096 μg/g ww, whereas none were detectable in bivalves at the marsh sites. In this study, p,p ’-dichlorodiphenyldichloroethylene ( p,p’ -DDE) (a biodegradation product of DDT [dichlorodiphenyl trichloroethane]) and total PCBs were the most frequently detected OCs and were primarily from the Mississippi River. For total OC content, using adjusted least squares means, some significant interactions were noted between fish species and sites. PAHs were detected in aquatic animals at all sites (range of 0.017–17.534 μg/g ww), as were AHs (range of 0.423–4.549 μg/g ww); the highest levels of PAHs and AHs were found in bivalves from the Mississippi River. When analysis of variance (α = 0.05) was performed with data from aquatic animals, there were only two significant relationships between PAHs, AHs, and OCs between species, site, and age or the interaction among these variables. There was an interaction between fish species and n-decane (an AH) in that mullet and largemouth bass had significantly higher levels than did catfish ( P = 0.0175). When general linear means were used to investigate associations of inorganic contaminants among fish species, site, and age or any interactions among these variables, no significant results were noted for arsenic, cadmium, lead, beryllium, boron, molybdenum, or nickel. The range of mercury in fish in this study was 0.04–0.14 μg/g ww (0.14– 0.48 μg/g dry weight [dw]), with the most elevated levels detected in predatory largemouth bass at the sampling point farthest downstream from the structure and within the marsh area. Mercury was positively correlated with fish age ( P = 0.0152), where levels were estimated to increase 0.0253 parts per million (ppm) dw per year. In the Mississippi River, catfish showed significantly higher levels of mercury than did mullet or largemouth bass ( P = 0.00167). Among fish species, mullet displayed the highest levels in fish of aluminum, barium, manganese, and iron, all considered to have low toxicity in hydrologic systems. An interaction between fish and site was seen with aluminum ( P = 0.0031), where concentrations in mullet were significantly higher in the Mississippi River than at the other sites, as was also seen with barium ( P = 0.0009), chromium ( P = <0.0001), manganese ( P = 0.0004), strontium ( P = 0.0074), vanadium ( P = 0.0156), and zinc ( P = 0.0059). For iron ( P = 0.0.0001), mullet and largemouth bass at both the Mississippi River and Lake Salvador showed higher levels than did catfish, and these two species showed higher levels at two of the four sites. An interaction between fish and site was also seen with chromium ( P = <0.0001) in that concentrations in mullet were significantly higher in the Mississippi River than at the other sites, as was also seen with strontium ( P = 0.0074), vanadium ( P = 0.0156), and zinc ( P = 0.0059), metals for which deleterious effects have been demonstrated in other ecosystems. The NCBP program lists the 85th percentile for zinc at 34.2 μg/g fw (117.9 μg/g dw). In the Davis Pond prediversion biomonitoring study (hereafter the current study), one fish (MUL31RIVER, fish ID 8) showed values higher than that (125.4 μg/g dw or 37.54 μg/g ww), and the Mississippi River bivalve sample (MUSSRIVER) had a value of 140 μg/g dw (41.2 μg/g ww). In the current study, approximately 86 percent of the fish had measurable selenium levels, yet none reached the 85th percentile. The 85th percentile for selenium from the NCBP was 0.73 μg/g ww. Significantly higher levels of selenium were seen in mullet than in largemouth bass and catfish ( P = 0.0023). The NCBP 85th percentile for lead is 0.22 μg/g ww (0.76 μg/g dw). In the current study, the range of concentrations of lead was as much as 18.3 ppm dw (MUL31RIVER, fish ID 8), with the three most elevated values (range of 3.46–5.31 μg/g ww) coming from mullet from the Mississippi River. Biomarker data are measurable and directly reflect the condition of the animal, and measuring more than one biomarker in an individual increases confidence in health assessments. In the current study, biomarkers included macrophage aggregates (MAs), liver (hepatosomatic index [HSI]) and spleen (splenosomatic index [SSI]) weight to body weight ratios, percent white blood cells (WBCs) in whole blood, and condition factor. Few significant differences were noted with any of the biomarkers between sites, and there were no relationships between species and sites. For improved use of biomarker assessments, an increase in fish sample size would be useful for postdiversion sampling, as would comparisons of fish of the same sex and reproductive condition. During the current study, success for eagle nests in the diversion area and reference sites was similar as determined by numbers of nestlings fledged. When temperatures were below average during winter 2000, nests in both regions similarly failed. At each nest, the primary evidence of food items was small mammals. Eaglets (n = 6) generally appeared healthy, and whole blood concentrations of organic contaminants exceeded detection limits with three incidences of p,p’ -DDE (0.002–0.006 μg/L ww) and one incidence of oxychlordane (0.002 μg/L ww). The levels of p,p’ -DDE were well below those that have been inversely correlated with productivity and success rates of nesting bald eagles on a regional scale. The low values found in the whole blood samples for OC pesticides and PCBs were even lower when corrected for plasma volume. Aluminum values were 3.66 and 5.75 μg/L in two samples, zinc ranged from 5.21 to 6.77 μg/L ww in six samples, and silicon ranged from 1.7 to 4.6 μg/L in four samples. Selenium was detectable in each bird with the range at 0.332–0.566 μg/L ww, and strontium ranged from 0.0581 to 0.0975 μg/L ww. Mercury was detectable in blood samples from each bird and ranged from 0.0254 to 0.0845 μg/L ww, whereas lead was detectable in four samples and ranged from 0.0042 to 0.0136 μg/L ww. Although no detectable levels of total PCBs were found (also correlated with decreased reproductive productivity), 70 percent of the aquatic animals from the Mississippi River contained total PCBs (range 0.13–0.79 μg/L), whereas only about 7 percent of the aquatic animals sampled from the marsh area contained PCBs. Suggestions for postdiversion sampling include lowering the analytical detection limit for some metals, sampling aquatic animals over the course of a single season, obtaining a higher sample number of mature fish of one species (for example, blue catfish) within a range of total lengths for biomarker analyses, obtaining otoliths for estimating fish ages, assessing dioxins in eaglet blood, examining triazines in water, and obtaining all Mississippi River fish samples as close to the Davis Pond structure intake as possible. Because contaminants found in blood of eaglets reflect their prey species and because of the contaminant levels found in fish in the current study, eaglets may not be consuming primarily these species; therefore, obtaining juvenile nutria ( Myocastor coypus ) or turtle species for contaminant analyses might be considered, as well as collecting greater blood volume and using plasma to measure OCs and PCBs. Data obtained postdiversion will be compared with prediversion data to monitor changes.

Louisiana↗

USGS2009

Quality of Streams in Johnson County, Kansas, and Relations to Environmental Variables, 2003-07

The quality of streams and relations to environmental variables in Johnson County, northeastern Kansas, were evaluated using water, streambed sediment, land use, streamflow, habitat, algal periphyton (benthic algae), and benthic macroinvertebrate data. Water, streambed sediment, and macroinvertebrate samples were collected in March 2007 during base flow at 20 stream sites that represent 11 different watersheds in the county. In addition, algal periphyton samples were collected twice (spring and summer 2007) at one-half of the sites. Environmental data including water and streambed-sediment chemistry data (primarily nutrients, fecal-indicator bacteria, and organic wastewater compounds), land use, streamflow, and habitat data were used in statistical analyses to evaluate relations between biological conditions and variables that may affect them. This report includes an evaluation of water and streambed-sediment chemistry, assessment of habitat conditions, comparison of biological community attributes (such as composition, diversity, and abundance) among sampling sites, placement of sampling sites into impairment categories, evaluation of biological data relative to environmental variables, and evaluation of changes in biological communities and effects of urbanization. This evaluation is useful for understanding factors that affect stream quality, for improving water-quality management programs, and for documenting changing conditions over time. The information will become increasingly important for protecting streams in the future as urbanization continues. Results of this study indicate that the biological quality at nearly all biological sampling sites in Johnson County has some level of impairment. Periphyton taxa generally were indicative of somewhat degraded conditions with small to moderate amounts of organic enrichment. Camp Branch in the Blue River watershed was the only site that met State criteria for full support of aquatic life in 2007. Since 2003, biological quality improved at one rural sampling site, possibly because of changes in wastewater affecting the site, and declined at three urban sites possibly because of the combined effects of ongoing development. Rural streams in the western and southern parts of the county, with land-use conditions similar to those found at the State reference site (Captain Creek), continue to support some organisms normally associated with healthy streams. Several environmental factors contribute to biological indicators of stream quality. The primary factor explaining biological quality at sites in Johnson County was the amount of urbanization upstream in the watershed. Specific conductance of stream water, which is a measure of dissolved solids in water and is determined primarily by the amount of groundwater contributing to streamflow, the amount of urbanization, and discharges from wastewater and industrial sites, was strongly negatively correlated with biological stream quality as indicated by macroinvertebrate metrics. Concentration of polycyclic aromatic hydrocarbons (PAHs) in streambed sediment also was negatively correlated with biological stream quality. Individual habitat variables that most commonly were positively correlated with biological indicators included stream sinuosity, buffer length, and substrate cover diversity. Riffle substrate embeddedness and sediment deposition commonly were negatively correlated with favorable metric scores. Statistical analysis indicated that specific conductance, impervious surface area (a measure of urbanization), and stream sinuosity explained 85 percent of the variance in macroinvertebrate communities. Management practices affecting environmental variables that appear to be most important for Johnson County streams include protection of stream corridors, measures that reduce the effects of impervious surfaces associated with urbanization, reduction of dissolved solids in stream water, reduction of PAHs entering streams and

Scientific Investigations Report↗

USGS2018

Nearshore sediment monitoring for the Stormwater Action Monitoring (SAM) Program, Puget Sound, western Washington

Chemicals such as metals and organics (polychlorinated biphenyl [PCBs], polybrominated diphenyl ethers [PBDEs], polycyclic aromatic hydrocarbons [PAHs], and phthalates) continue to enter Puget Sound, western Washington, from point sources (such as industrial and municipal outfalls) and combined sewer outfalls and non-point sources (such as stormwater runoff). Runoff during storm events has been identified as a major source of contamination entering Puget Sound and has been implicated in the degradation of nearshore habitats and biota. Metals, organic chemicals, and other pollutants are known to accumulate in sediments such as those present along the shoreline of Puget Sound. In addition to chemical contaminants, small plastic particles (known as microplastics), found in marine waters of Puget Sound and suspected of being in aquatic sediments, are a potential concern because they can be ingested by animals and are suspected of transporting sorbed chemicals such as PCBs and metals. The Stormwater Work Group of Puget Sound (SWG) (composed of State and municipal stormwater permittees, and other stakeholders) developed a strategy to address sediment conditions in the nearshore environment of Puget Sound. As part of this strategy, the SWG developed a regional stormwater monitoring strategy designed to inform monitoring requirements in National Pollutant Discharge Elimination System (NPDES) stormwater permits issued by the Washington State Department of Ecology (Ecology). The monitoring program is referred to as the Stormwater Action Monitoring (SAM). The overall focus of the work described in this report is to address one of the goals of SAM, which is to characterize the status, spatial extent, and quality of Puget Sound sediment chemicals in the nearshore urban areas. The nearshore urban areas are defined as areas parallel to established Urban Growth Areas (UGAs) using a spatially balanced probabilistic Generalized Random Tessellation Stratified (GRTS) sampling design. One of the benefits of the GRTS sampling design used for this study is that it allows one to efficiently extrapolate from a relatively small number of sampled nearshore sites to the entire nearshore shoreline within the 2011 defined UGA boundaries of Puget Sound. In addition to characterizing nearshore sediment chemical concentrations, this study also characterized the abundance of microplastics in the nearshore sediment. A total of 41 randomly selected sites were sampled throughout Puget Sound in summer and early autumn of 2016. All sampling sites were located at 6 feet below the Mean Lower Low Water line. The top 2–3 centimeters of sediment were collected using a boat-mounted, pre-cleaned stainless-steel box corer. All chemical samples were sieved to 2 millimeters and placed in appropriate containers for chemical analysis for PCBs, PBDEs, PAHs, phthalates, metals, total organic carbon, and grain size. Pre-sieved sediment samples were stored in glass containers for microplastic analysis. Nearshore sediment chemical concentrations were summarized using numerous statistical approaches to examine the minimum, mean, and maximum concentrations for each of the compounds analyzed and to compare the results to criteria and other nearshore and marine sediment studies. The GRTS sampling design also allowed the authors to assess the percentage of the UGA nearshore environment that did not meet established standards or criteria for each chemical analyzed. Additionally, regression and machine learning statistical analyses were used to examine relations between measured chemical concentrations, and land cover and geologic features at multiple scales within the watersheds adjacent to sampling sites. The influence of marine hydrodynamic factors on nearshore sediment chemical concentrations was statistically evaluated with nonparametric methods by assigning each sampling site to one of five nearshore drift cell types based on its location. The Puget Sound shoreline can be divided into segments, referred to as drift cells, based on the movement of sediment along the shore by waves. Each drift cell type has a unique influence on nearshore sediment transport. The nearshore sediment chemical concentrations for organics and metals generally were low, and in most cases less than Washington State criteria. The concentrations of some PAHs were greater than the criteria, but these exceedances were limited to one or two sites. The results of the probabilistic study design determined that, for the PAHs examined, 96 percent or more of the 1,344 km of shoreline represented by this study had concentrations less than any established criteria. For the remaining organics (PCBs and PBDEs), the probabilistic study design indicates that more than 98 percent of shoreline examined had concentrations less than criteria or proposed standards. For the metals, the results of the study indicate that 100 percent of the nearshore sediment had concentrations less than the criteria. The relations between sediment organic and metal concentrations, and adjacent watershed land cover and the particle size of the samples, were determined to be weakly related. Although weakly related, the particle size of the sediment in a sample typically explained more of the variation in metal concentrations than organics. While the measured watershed attributes adjacent to the sampling sites and sediment size of the samples were weakly related to chemical concentrations, they were significantly related to unique drift cells along the shoreline of Puget Sound known as drift cells. Each drift cell represents a long-term directional transport of sediment from its source to its depositional zone. Sediment chemical concentrations were significantly higher in drift cells with limited sediment movement compared to those with higher sediment transport energy. Microplastics in the nearshore sediment ranged from 0.02 to 0.65 pieces per gram of sediment, with a mean of 0.19 pieces per gram of sediment, and were dominated by small fibers (355–1,000 micrometers). Like chemical concentrations, microplastics concentrations in the nearshore sediment were poorly related to watershed land cover. Although not significantly different, microplastics concentrations generally were higher in the low energy drift cells compared to the high energy drift cells. The results of this study provide a statistically valid status assessment of current nearshore sediment chemical conditions throughout Puget Sound in those areas adjacent to defined UGAs. In addition to the study findings of relatively low concentrations of PCBs, PBDEs, PAHs, phthalates, and metals, the study design provides a statistically valid tool for evaluating changes in these compounds over time if future nearshore sediment assessments are done. Furthermore, the assessment of microplastic abundance represents the first study of its kind that can be used as a benchmark for future evaluations. The results of this study will help inform Ecology in the implementation of monitoring requirements as part of its NPDES stormwater permitting process.

Washington↗

USGS2011

Organic contaminants, trace and major elements, and nutrients in water and sediment sampled in response to the Deepwater Horizon oil spill

Beach water and sediment samples were collected along the Gulf of Mexico coast to assess differences in contaminant concentrations before and after landfall of Macondo-1 well oil released into the Gulf of Mexico from the sinking of the British Petroleum Corporation's Deepwater Horizon drilling platform. Samples were collected at 70 coastal sites on the Gulf of Mexico between May 7 and July 7, 2010, to document baseline, "pre-landfall" conditions. A subset of these sites was resampled during October 4 to 14, 2010, after oil had made landfall on the Gulf of Mexico coast ("post-landfall") to determine if actionable concentrations of oil were present along shorelines. Few organic contaminants were detected in water; their detection frequencies were generally low and similar in pre-landfall and post-landfall samples. Only one organic contaminant, toluene, had significantly higher concentrations in post-landfall than pre-landfall water samples. No samples exceeded any human-health benchmarks, and only one sample exceeded an aquatic-life benchmark-the toxic-unit benchmark for polycyclic aromatic hydrocarbons (PAH) mixtures was exceeded in one post-landfall water sample from Louisiana. No exceedance was observed in the corresponding pre-landfall water sample at this site. In sediment, several PAHs were detected at over 20 percent of sites. Concentrations of 3 parent PAHs and 17 alkylated PAH groups were significantly higher in post-landfall samples than pre-landfall samples. One pre-landfall sample from Texas exceeded the sediment toxic-unit benchmark for PAH mixtures; this site was not sampled during the post-landfall period, so no comparison between sampling periods could be made. Twenty-seven percent of sediment samples exceeded empirical sediment-quality benchmarks (upper screening values) for PAHs, indicating these samples are in the probable-effect range. A higher percentage of post-landfall samples exceeded upper screening-value benchmarks (37 percent) than did pre-landfall samples (22 percent), but there was no significant difference in the proportion of samples exceeding one or more benchmarks between paired pre-landfall and post-landfall samples. Seven sites had the largest concentration differences between post-landfall and pre-landfall samples for fifteen alkylated PAHs. Five of these seven sites (1 site in Louisiana, 1 in Mississippi, and 3 in Alabama) were identified on the basis of diagnostic geochemical biomarkers as containing Macondo-1 oil in post-landfall sediments and tarballs, as described in a companion report by Rosenbauer and others (2010). For trace and major elements in water, analytical reporting levels for several elements were highly variable; after censoring to a common reporting threshold, concentrations were significantly different between pre-landfall and post-landfall samples for a few elements, all of which are elements in seawater. No human-health benchmarks were exceeded, although these were available for only two elements. Aquatic-life benchmarks for trace elements were exceeded in almost 50 percent of water samples. Post-landfall samples exceeded one or more acute benchmarks in 21 percent, and chronic benchmarks in 93 percent of samples, compared to 1 percent (acute) and 39 percent (chronic) for pre-landfall samples. The elements responsible for the most exceedances in post-landfall samples were boron (48 samples), copper (22), and manganese (12). Nickel and vanadium, which U.S. Environmental Protection Agency specifically identified as relevant to the oil spill, were responsible for exceedances in only one of the fifty-two post-landfall samples with exceedances. These results represent the minimum number of exceedances for several trace elements because a substantial number of samples could not be compared with benchmarks because the element was determined during only one sampling period (boron and vanadium) or the reporting level for the sample was higher than the applicable benchmark value (for example, cobalt, copper, lead, and nickel). The high and variable reporting levels for trace elements in water also precluded the statistical comparison between sampling periods of the proportion of samples exceeding benchmarks. For trace elements in whole (unsieved) sediment, 47 percent of samples exceeded empirical upper screening-value benchmarks, indicating these samples are in the probable-effect range. However, there was no significant difference in the proportion of samples exceeding one or more benchmarks between paired pre-landfall post-landfall samples. Benchmark exceedance frequencies could be conservatively high, because they are based on measurements of total trace-element concentrations, including the sediment matrix. In fine sediment (the less than 63-micrometer sediment fraction), one or more trace or major elements were anthropogenically enriched relative to national baseline values for U.S. streams for almost all sediment samples (123 of 124). Sixteen percent of sediment samples exceeded upper screening-value benchmarks for, and were enriched in, one or more of the element(s) barium (in 14 samples), vanadium (5), aluminum (3), manganese (3), arsenic (2), chromium (2), and cobalt (1). These samples, collected from Louisiana and Texas, were evenly divided between the pre-landfall (9 samples) and post-landfall (10 samples) periods. Considering all the information evaluated in this report, there were significant differences between pre-landfall and post-landfall samples for PAH concentrations in sediment. Pre-landfall and post-landfall samples did not differ significantly in concentrations or benchmark exceedances for most organics in water or trace elements in sediment. For trace elements in water, aquatic-life benchmarks were exceeded in almost 50 percent of samples, but the high and variable analytical reporting levels precluded statistical comparison of benchmark exceedances between sampling periods. Concentrations of several PAH compounds in sediment were significantly higher in post-landfall samples than pre-landfall samples, and five of seven sites with the largest differences in PAH concentrations also had diagnostic geochemical evidence of Deepwater Horizon Macondo-1 oil from Rosenbauer and others (2010).

Open-File Report↗