A PAH fate model for San Francisco Bay

A mass balance model was applied to simulate the long-term fate of PAHs in San Francisco Bay. The model treats the Bay as a single box with interacting water and sediment compartments, and includes loading, volatilization, outflow to the ocean, degradation, and burial in deep sediment. The estimated time required for loss of one-half of the mass in the Bay in the absence of loading ranged from 20 d for naphthalene to 5 yr for benzo(b)fluoranthene. Uncertainty analysis using Monte Carlo simulation indicated a high degree of influence and uncertainty for degradation rates, suggesting that improved estimates of degradation would significantly improve the predictive ability of the model. A comparison of model calculations to literature values suggested that external PAH loading to San Francisco Bay was at or above previous estimates of 3600 kgyr(-1), and that degradation in the Bay was within the range of commonly published estimates for high molecular weight PAHs (4.0 x 10(-5) to 4.0 x 10(-4)d(-1)).     

A case study of contaminants on military ranges: Camp Edwards, Massachusetts, USA

An extensive investigation at the Camp Edwards, Massachusetts Military Reservation (MMR) demonstrates that assessment of groundwater and soil contamination at military ranges can be limited primarily to explosive-related compounds such as RDX, HMX, perchlorate, TNT and their transformation products. A modified analytical method is recommended to expand the list of explosives and to improve the detection limits. Analyses of metals, VOCs, SVOCs, and TICs are unnecessary. Soil samples may require the analyses of PAHs and PCNs for burn areas. Camp Edwards, as one of the few military ranges that have been exhaustively investigated for contaminants, is an ideal point of departure for evaluating other ranges. The permeable site soils promote leaching of contaminants and inhibit biotic and abiotic transformations. Moreover, the site has experienced an unusual extent of activities in its more than ninety years of active use. The recommendations in this report are based on data obtained for more than 200 analytes from more than 15,000 environmental samples.     

A diagnostic test for autocorrelation in increment-averaged data with application to soil sampling

Motivated by the problem of detecting spatial autocorrelation in increment- averaged data from soil core samples, we use the Cholesky decomposition of the inverse of an autocovariance matrix to derive a parametric linear regression model for autocovariances. In the absence of autocorrelation, the off-diagonal terms in the lower triangular matrix from the Cholesky decomposition should be identically zero, and so the regression coefficients should be identically zero. The standard F-test of this hypothesis and two bootstrapped versions of the test are evaluated as autocorrelation diagnostics via simulation. Size is assessed for a variety of heteroskedastic null hypotheses. Power is evaluated against autocorrelated alternatives, including increment-averaged Ornstein-Uhlenbeck and Matérn processes. The bootstrapped tests maintain approximately the correct size and have good power against moderately autocorrelated alternatives. The methods are applied to data from a study of carbon sequestration in agricultural soils.     

Restoration of a Canadian Prairie Wetland with Agricultural and Municipal Wastewater

3 /day (800,000 US gallons) of municipal wastewater and beef processing wastewater. A large nongovernmental organization hastened restoration with a development process that outlined restoration goals and management objectives to satisfy a dual mandate of wastewater treatment and wildlife habitat creation. In 1995, after five years of wastewater additions, the basins had been refilled and the surrounding uplands had been acquired and restored. The Frank Lake Conservation Area currently provides high-quality habitat for a variety of wildlife in a region where many of the native plants and animals species have been lost due to habitat loss and fragmentation. The success of upland and water management strategies is reflected in the increase of target species' abundance and richness: 50 shorebird species, 44 waterfowl species, 15 raptor species, and 28 other new bird species have returned to the marsh since restoration. As well, significant N and P reduction occurs as waters flow through the first basin of the marsh. The management strategies of this project that satisfied a dual mandate serve as a model to guide managers of other large-scale wetland restoration projects.     

Species-specific variation in cuttlebone δ13C and δ18O for three species of Mediterranean cuttlefish

Stable carbon (δ¹³C) and oxygen (δ¹⁸O) isotopes in cuttlebones of three species of Mediterranean cuttlefish (Sepia elegans, S. officinalis, and S. orbignyana) with different life histories were contrasted. Cuttlebone δ¹³C and δ¹⁸O were quantified at both the core and edge (representing early life and recent deposition, respectively) for all three species sampled from the southern Adriatic Sea in 2010 (n = 28). For S. officinalis, cuttlebone δ¹³C and δ¹⁸O values were both lower relative to S. elegans and S. orbignyana at the core by approximately 1.0–2.0 and 3.0 ‰, respectively. Differences between core and edge in cuttlebone δ¹³C and δ¹⁸O were also observed for S. officinalis with observed values at the cuttlebone edge (recent) exceeding core (early life) values by 2.5 ‰ for δ¹³C and 1.4 ‰ for δ¹⁸O. Differences in isotopic composition across S. officinalis cuttlebones are possibly reflective of ontogenetic migrations from nearshore nurseries (lower seawater δ¹³C and δ¹⁸O values) to offshore overwintering habitats (higher seawater δ¹³C and δ¹⁸O values). Overall, results from this study suggest that cuttlebone δ¹³C and δ¹⁸O hold promise as natural tags for determining the degree of spatial connectivity between nearshore and offshore environments used by cuttlefish.     

An EPA program for monitoring ecological status and trends

Despite hundreds of millions of dollars spent annually in the United States on environmental monitoring, policy and decision makers seldom have ready access to monitoring data to aid in prioritizing reasearch and assessment efforts or to assess the extent to which current policies are meeting the desired objectives. EPA is currently conducting research to evaluate options for establishing an integrated, cooperative monitoring program, with participation by federal, state, and private entities, that could result in annual statistical reports and interpretive summaries on the status and trends in indicators of adverse disturbance and corresponding health of the nation's ecosystem on the regional and national scale.The research described in this article has not been subjected to U.S. Environmental Protection Agency review and therefore does not necessarily reflect the views of the Agency, and no official endorsement should be inferred.     

Efficient degradation of tetracycline by singlet oxygen-dominated peroxymonosulfate activation with magnetic nitrogen-doped porous carbon

Nonradical reaction driven by peroxymonosulfate (PMS) based advanced oxidation processes has drawn widespread attention in water treatment due to their inherent advantages, but the degradation behavior and mechanism of organic pollutants are still unclear. In this study, the performance, intermediates, mechanism and toxicity of tetracycline (TC) degradation were thoroughly examined in the constructed magnetic nitrogen-doped porous carbon/peroxymonosulfate (Co-N/C-PMS) system. The results showed that 85.4% of TC could be removed within 15 min when Co-N/C and PMS was simultaneously added and the degradation rate was enhanced by 3.4 and 14.7 folds compared with Co-N/C or PMS alone, respectively. Moreover, the performance of Co-N/C was superior to that of most previously reported catalysts. Many lines of evidence indicated that Co-N/C-PMS system was a singlet oxygen-dominated nonradical reaction, which was less interfered by pH and water components, and displayed high adaptability to actual water bodies. Subsequently, the degradation process was elaborated on the basis of three-dimensional excitation-emission matrix spectra and liquid chromatography-mass spectrometry. At last, the toxicity of treated TC was greatly reduced by using microalgae Coelastrella sp. as ecological indicator. This study provides a promising approach based on singlet oxygen-dominated nonradical reaction for eliminating TC in water treatment.     

Small farm ponds: overlooked features with important impacts on watershed sediment transport

Despite their size, small farm ponds are important features in many landscapes. Yet hydrographical databases often fail to capture these ponds, and their impacts on watershed processes remain unclear. For a 230‐km² portion of central Texas, United States (U.S.), we created a historical inventory of ponds and quantified the accuracy of automated detection methods under varying drought conditions. In addition, we documented pond dredging/enlargement events and identified sites that had been abandoned. We also analyzed sediment cores from downstream reservoirs to track changes in watershed sediment transport. Over 75 years, pond densities increased more than 350% — to among the highest documented in the U.S. — and the ability of automated methods to detect these ponds was highly dependent on drought severity (R² = 0.96). Approximately 5% of ponds present in the 1950s were no longer present in 2012, while 33% were dredged between 1937 and 2012. Downstream reservoir sedimentation has decreased by an average of 55% as ponds have increased in number. These findings suggest that small ponds and the maintenance of trapping efficiency have large‐scale impacts on sediment dynamics. Accurately accounting for these storage effects is vital to water resource planning efforts.     

Reduction of pathogen indicator organisms in dairy wastewater using an ecological treatment system

Ecological treatment systems can provide a sustainable, plant-based alternative to traditional wastewater treatment. One factor essential to the success of these systems is ensuring their ability to reduce coliform concentrations in wastewater. Wastewater is the primary source of fecal contamination in aquatic ecosystems, containing total and fecal coliforms on the order of 10(8)-10(10) and 10(7)-10(9) CFU L(-1), respectively. This study assessed the ability of an ecological treatment system to reduce concentrations of total coliforms and Escherichia coli from dairy wastewater. Low strength wastewater was pumped into the system during July of 2005 and high strength in September 2005. Wastewater passes through a series of anaerobic, aerobic, and clarifier reactors and wetland cells before exiting the system. Regardless of wastewater strength, average total coliform and E. coli concentrations were consistently reduced by at least 99% from influent to effluent, with the majority of the reduction (76%) occurring in the first two reactors. Relationships between internal concentrations of solids and coliforms indicated that increased reduction of solids may further reduce coliform concentrations. Although U.S. Environmental Protection Agency discharge requirements for E. coli were not always met, the substantial reductions achieved indicate that ecological treatment systems have the potential to successfully reduce coliforms in wastewater to meet discharge limits. The results from this study will be used to guide design and management of future ecological treatment systems, so that larger and more consistent coliform reductions can be achieved.