Reductive dechlorination of a chlorinated solvent plume in Houston,Texas

Chlorinated solvents such as tetrachloroethene (perchloroethene, PCE) and trichloroethene (TCE) have been extensively used in various industrial applications for many years. Because neither are typically consumed through their various uses, they are often released to the environment through industrial application or disposal. Once released, PCE and TCE tend to migrate downward into groundwater, where they persist. In the current case study, cheese whey was used as a groundwater amendment to facilitate the reductive dechlorination of a chlorinated solvent plume underlying an auto dealer/repair shop in Harris County, Texas. From September 2010 to January 2014, over 32,000 gallons of cheese whey were injected into the subsurface resulting in a marked reduction in oxidation–reduction potential (ORP) and nitrate concentrations, coupled with an increase in ferrous iron concentrations. Statistical trend analyses indicate the primary contaminants, PCE and TCE, as well as the daughter product cis‐1,2‐dichloroethene (cDCE), all exhibited a positive response, as evidenced by statistically decreasing trends, and/or reversal in concentration trends, subsequent to cheese whey injections. Maximum concentrations of PCE and TCE in key test wells decreased by as much as 98.97 percent and 99.17 percent, respectively. In addition, the bacterial genus Dehalococcoides, capable of complete reduction of PCE to non‐toxic ethene, was found to be more abundant in the treatment area, as compared to background concentrations. Because cheese whey is a by‐product of the cheese making process, the cost of the product is essentially limited to transport. This study demonstrates cheese whey to be an effective groundwater amendment at a cost which is orders of magnitude lower than popular industry alternatives.     

Air pollutant emissions from the development,production, and processing of Marcellus Shale natural gas

The Marcellus Shale is one of the largest natural gas reserves in the United States; it has recently been the focus of intense drilling and leasing activity. This paper describes an air emissions inventory for the development, production, and processing of natural gas in the Marcellus Shale region for 2009 and 2020. It includes estimates of the emissions of oxides of nitrogen (NO_x), volatile organic compounds (VOCs), and primary fine particulate matter (≤2.5 µm aerodynamic diameter; PM_2.5) from major activities such as drilling, hydraulic fracturing, compressor stations, and completion venting. The inventory is constructed using a process-level approach; a Monte Carlo analysis is used to explicitly account for the uncertainty. Emissions were estimated for 2009 and projected to 2020, accounting for the effects of existing and potential additional regulations. In 2020, Marcellus activities are predicted to contribute 6–18% (95% confidence interval) of the NO_x emissions in the Marcellus region, with an average contribution of 12% (129 tons/day). In 2020, the predicted contribution of Marcellus activities to the regional anthropogenic VOC emissions ranged between 7% and 28% (95% confidence interval), with an average contribution of 12% (100 tons/day). These estimates account for the implementation of recently promulgated regulations such as the Tier 4 off-road diesel engine regulation and the U.S. Environmental Protection Agency's (EPA) Oil and Gas Rule. These regulations significantly reduce the Marcellus VOC and NO_x emissions, but there are significant opportunities for further reduction in these emissions using existing technologies.

Implications: The Marcellus Shale is one of the largest natural gas reserves in United States. The development and production of this gas may emit substantial amounts of oxides of nitrogen and volatile organic compounds. These emissions may have special significance because Marcellus development is occurring close to areas that have been designated nonattainment for the ozone standard. Control technologies exist to substantially reduce these impacts. PM_2.5 emissions are predicted to be negligible in a regional context, but elemental carbon emissions from diesel powered equipment may be important.     

Oxidation of natural and synthetic hormones by the horseradish peroxidase enzyme in wastewater

Steroid estrogens, including both natural estrogens (e.g., estrone - E1; 17beta-estradiol - E2; and estriol - E3) and synthetic estrogens (e.g., 17alpha-ethinylestradiol - EE2), are known as endocrine-disrupting compounds. The objective of this research was to evaluate the feasibility of the enzymatic oxidation of estrogens and to optimize this process in municipal wastewater contaminated with steroid estrogens using horseradish peroxidase (HRP) and hydrogen peroxide. An initial HRP activity of 0.02 U ml(-1) was sufficient to completely remove EE2 from the synthetic solution, although greater HRP doses (up to 0.06 U ml(-1)) were required to remove E1, E2 and E3. The optimal molar peroxide-to-substrate ratio was determined to be approximately 0.45. Based on the Michaelis-Menten kinetics, the HRP had an increasing reactivity with E1, E3, E2, and EE2, in increasing order. In real activated sludge process effluent, an HRP dose of 8-10 U ml(-1) was required to completely remove all of the studied estrogens, while only 0.032 U ml(-1) of HRP was necessary to treat synthetic water containing the same estrogen concentrations.     

Zinc, copper and nickel concentrations in soil extracts and crops grown on four soils treated with metalloaded sewage sludges

Sludges containing high concentrations of zinc, copper or nickel and an uncontaminated sludge were added to two sandy loams (pH 6.5 and 7.1), a heavy clay (pH 6.3) and a calcareous clay (pH 7.8) to give ten sludge treatments for each soil. The mixtures were incubated fallow, cropped continuously with clover, or cropped with barley and red beet in rotation for 21 months. The quantity of added metal either in the soil solution or extracted by 0.1m CaCl(2) depended on the metal loading, pH and soil cation exchange capacity, and changed with time after mixing soils and sludges. Crop metal concentrations, and the occurrence of metal-induced yield reductions, also depended on soil properties as well as metal loading. The best chemical extractant for predicting plant metal concentrations was 0.1m CaCl(2).     

The effects of pH and soil type on concentrations of zinc, copper and nickel extracted by calcium chloride from sewage sludge-treated soils

The effects of pH on concentrations of zinc, copper and nickel extracted by calcium chloride from a clay loam and two sandy loam soils that had been treated with sewage sludge were studied. Concentrations of all the metals increased rapidly as pH decreased below a threshold value ranging from 6.2 to 7.0 for Zn, 6.2 to 7.2 for Ni and 4.7 to 5.7 for Cu. Both the total concentrations and the threshold pH values were influenced by differences in soil texture and (between the two light-textured soils) by differences in soil cation exchange capacity. The amount of zinc and copper extracted from the mixtures was considerably less than that extracted from the same quantity of sludge alone.     

A habitat‐based approach to predict impacts of marine protected areas on fishers

Although marine protected areas can simultaneously contribute to biodiversity conservation and fisheries management, the global network is biased toward particular ecosystem types because they have been established primarily in an ad hoc fashion. The optimization of trade‐offs between biodiversity benefits and socioeconomic values increases success of protected areas and minimizes enforcement costs in the long run, but it is often neglected in marine spatial planning (MSP). Although the acquisition of spatially explicit socioeconomic data is perceived as a costly or secondary step in MSP, it is critical to account for lost opportunities by people whose activities will be restricted, especially fishers. We developed an easily reproduced habitat‐based approach to estimate the spatial distribution of opportunity cost to fishers in data‐poor regions. We assumed the most accessible areas have higher economic and conservation values than less accessible areas and their designation as no‐take zones represents a loss of fishing opportunities. We estimated potential distribution of fishing resources from bathymetric ranges and benthic habitat distribution and the relative importance of the different resources for each port of total catches, revenues, and stakeholder perception. In our model, we combined different cost layers to produce a comprehensive cost layer so that we could evaluate of trade‐offs. Our approach directly supports conservation planning, can be applied generally, and is expected to facilitate stakeholder input and community acceptance of conservation.     

Climatic risks and impacts in South Asia: extremes of water scarcity and excess

Regional Environmental Change - This paper reviews the current knowledge of climatic risks and impacts in South Asia associated with anthropogenic warming levels of 1.5–4 °C...     

Molecular and morphological analyses of the cuttlefish<Emphasis Type="Italic"> Sepia apama</Emphasis> indicate a complex population structure

The giant Australian cuttlefish Sepia apama Gray, 1849 annually forms a massive and unique spawning aggregation in northern Spencer Gulf, South Australia, which has attracted commercial fishing interests in recent years. However, many basic life-history characteristics of S. apama are unknown, and anecdotal evidence suggests that there is more than one species. The present study assessed the population structure and species status of S. apama using data from allozyme electrophoresis, microsatellite loci, nucleotide sequences of the mitochondrial COXIII gene, multivariate morphometrics and colour patterns. Analyses of allozyme and microsatellite allele frequencies revealed two very divergent but geographically separated populations consisting of specimens from the east coast and southern Australia. However, the presence of a heterozygote in a putative contact zone between the east coast and southern Australia suggested that these populations were not reproductively isolated. Mitochondrial haplotypes seem to have introgressed further north into the contact zone than have nuclear alleles. Differences in colour patterns that previously had been attributed anecdotally to different geographic populations were, in fact, correlated with sexual dimorphism. These data are most consistent with S. apama being one species the populations of which were geographically isolated in the past (historical vicariance) and have come into secondary contact. Comparison of microsatellite allele frequencies among four South Australian samples indicated significant deviations from panmixia. South Australian samples were also reliably diagnosed by means of multivariate morphometrics. Significant differences in mantle length were observed among populations.Communicated by M.S. Johnson, Crawley