Enhanced cyclic performance initiated via an in situ transformation of Cu/CuO nanodisk to Cu/CuO/Cu2O nanosponge

Environmental Science and Pollution Research - A simple oxidation method for preparing CuO nanodisks on a flexible Cu sheet is presented. The crystal structure of as-prepared CuO nanodisks was...     

Eutrophication induced changes in benthic community structure of a flow-restricted tropical estuary (Cochin backwaters), India

The influence of anthropogenic loading on the distribution of soft bottom benthic organisms of a tropical estuary (Cochin backwaters) was examined. The industrial activities were found to be high in the northern and central part of the estuary, where dissolved inorganic nitrogen (DIN > 210 ??M) and phosphorus (DIP > 6.5 ??M) have caused high abundance of chlorophyll a (up to 73 mg m^???3) and accumulation of organic carbon in sediments (up to 5%). Principal component analysis distinguished three zones in the estuary. The central zone (Z1) was characterized by organic enrichment, low species diversity, and increased number of pollution tolerant species. Long-term deterioration of the estuary is indicated by an increase in the nutrients and chlorophyll a levels by sixfold during the last few decades. Flow restrictions in the lower estuary have lead to a fourfold increase in sediment organic carbon over the period of three decades. The reduced benthic diversity followed by an invasion of opportunistic polychaetes (Capitella capitata), are indicative of a stress in the estuary.     

Possible cause of inhibition of seed germination in two rice cultivars by heavy metals Pb2+ and Hg2+

Seeds of two rice cultivars (Oryza sativa) cv. PR-116 and Pant Dhan-12 subjected to heavy metal lead (Pb²⁺) and mercury (Hg²⁺) exposure showed an inhibition in germination percentage, shoot and root length, and lower fresh and dry weight after 7 days. Both Pb²⁺ and Hg²⁺ inhibited the solubilization process of starch due to reduction in α-amylase activity, which is also evident from greater starch content and reduced soluble carbohydrate content of endosperms of treated seeds of the two cultivars. Mercury was more tolerated by Pant Dhan-12 when grown under in vitro culture medium containing 2% sucrose. The inhibitory effect of Pb²⁺ on embryo growth was not only abolished but also accelerated by 2% sucrose. The inhibitory effect, however, was not significantly blocked in Hg²⁺-treated embryos grown in vitro in sucrose containing medium. Embryos did not grow normally in a medium devoid of sucrose in either case. Data indicated that Pb²⁺ inhibited germination and seedling growth by impairing the solubilization of endosperm starch without markedly affecting the embryo, while Hg²⁺ inhibited germination and seedling growth by damaging the embryo itself.     

Mobile measurement of methane and hydrogen sulfide at natural gas production site fence lines in the Texas Barnett Shale

Production of natural gas from shale formations is bringing drilling and production operations to regions of the United States that have seen little or no similar activity in the past, which has generated considerable interest in potential environmental impacts. This study focused on the Barnett Shale Fort Worth Basin in Texas, which saw the number of gas-producing wells grow from 726 in 2001 to 15,870 in 2011. This study aimed to measure fence line concentrations of methane and hydrogen sulfide at natural gas production sites (wells, liquid storage tanks, and associated equipment) in the four core counties of the Barnett Shale (Denton, Johnson, Tarrant, and Wise). A mobile measurement survey was conducted in the vicinity of 4788 wells near 401 lease sites, representing 35% of gas production volume, 31% of wells, and 38% of condensate production volume in the four-county core area. Methane and hydrogen sulfide concentrations were measured using a Picarro G2204 cavity ring-down spectrometer (CRDS). Since the research team did not have access to lease site interiors, measurements were made by driving on roads on the exterior of the lease sites. Over 150 hr of data were collected from March to July 2012. During two sets of drive-by measurements, it was found that 66 sites (16.5%) had methane concentrations >3 parts per million (ppm) just beyond the fence line. Thirty-two lease sites (8.0%) had hydrogen sulfide concentrations >4.7 parts per billion (ppb) (odor recognition threshold) just beyond the fence line. Measured concentrations generally did not correlate well with site characteristics (natural gas production volume, number of wells, or condensate production). t tests showed that for two counties, methane concentrations for dry sites were higher than those for wet sites. Follow-up study is recommended to provide more information at sites identified with high levels of methane and hydrogen sulfide.

Implications:Information regarding air emissions from shale gas production is important given the recent increase in number of wells in various regions in the United States. Methane, the primary natural gas constituent, is a greenhouse gas; hydrogen sulfide, which can be present in gas condensate, is an odor-causing compound. This study surveyed wells representing one-third of the natural gas production volume in the Texas Barnett Shale and identified the percent of sites that warrant further study due to their fence line methane and hydrogen sulfide concentrations.     

Biodegradation of Polyaromatics Synthesized by Peroxidase-Catalyzed Free-Radical Polymerization

Polymers formed from peroxidase-based free-radical polymerization reactions were characterized for rates of mineralization against lignin and humic acid controls. Degradation studies were carried out in soil systems over 202 days and cumulative net CO₂ was determined. Whereas mineralization of the humic acid and alkali lignin controls totaled ca. 20% at the end of the test exposure, there was essentially no net mineralization of the hydrolytic lignin control. Mineralization of the test samples totaled 5% for poly(p-ethylphenol) and 11% for poly(m-cresol). At the same time, mineralization of the poly(p-phenyl phenol) totaled 64%. Conversely, the readily biodegradable polymers cellulose and PHB reached values of 91 to 97% in less than 60 days. Our data suggest that the mineralization kinetics of the enzymatically derived polyaromatics mimic those of the naturally occurring heteropolymers.     

Preface: Climate Change and Environmental Policy

Mitigation and Adaptation Strategies for Global Change -     

Biodegradation of Pro-oxidant Filled Polypropylene Films and Evaluation of the Ecotoxicological Impact

The biodegradability of calcium stearate (CaSt) and cobalt stearate (CoSt) filled polypropylene (PP) films were investigated in this work. The PP films were prepared using melt blending technique followed by hot press moulding. On the basis of their tensile properties, the optimum amount of pro-oxidants was taken as 0.2 phr. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used for the characterization of optimized films. Presence of pro-oxidant in the PP was confirmed by the FTIR studies. Addition of pro-oxidants in the films decreased the thermal stability as revealed by TGA analysis. Crystallinity of the pro-oxidant filled PP decreased with addition of pro-oxidants as showen by DSC. The maximum biodegradation of CaSt and CoSt containing PP films was showen 7.65 and 8.34%, respectively with 0.2 phr. Both the microbial test and plant growth test (on corn and tomato) indicated that biodegradation intermediates were non toxic.     

Alternative transportation fuel standards: Welfare effects and climate benefits

This paper develops an integrated model of the fuel and agricultural sectors to analyze the welfare and greenhouse gas emission (GHG) effects of the existing Renewable Fuel Standard (RFS), a Low Carbon Fuel Standard (LCFS) and a carbon price policy. The conceptual framework shows that these policies differ in the incentives they create for the consumption and mix of different types of biofuels and in their effects on food and fuel prices and GHG emissions. We also simulate the welfare and GHG effects of these three policies which are normalized to achieve the same level of US GHG emissions. By promoting greater production of food-crop based biofuels, the RFS is found to lead to a larger reduction in fossil fuel use but also a larger increase in food prices and a smaller reduction in global GHG emissions compared to the LCFS and carbon tax. All three policies increase US social welfare compared to a no-biofuel baseline scenario due to improved terms-of-trade, even when environmental benefits are excluded; global social welfare increases with a carbon tax but decreases with the RFS and LCFS due to the efficiency costs imposed by these policies, even after including the benefits of mitigating GHG emissions.     

Identification of polycyclic aromatic hydrocarbons in unleaded petrol and diesel exhaust emission

Inhalation of emissions from petrol and diesel exhaust particulates is associated with potentially severe biological effects. In the present study, polycyclic aromatic hydrocarbons (PAHs) were identified from smokes released by the automobile exhaust from petrol and diesel. Intensive sampling of unleaded petrol and diesel exhaust were done by using 800-cm³ motor car and 3,455-cm³ vehicle, respectively. The particulate phase of exhaust was collected on Whatman filter paper. Particulate matters were extracted from filter paper by using Soxhlet. PAHs were identified from particulate matter by reverse phase high performance liquid chromatography using C₁₈ column. A total of 14 PAHs were identified in petrol and 13 in case of diesel sample after comparing to standard samples for PAH estimation. These inhalable PAHs released from diesel and petrol exhaust are known to possess mutagenic and carcinogenic activity, which may present a potential risk for the health of inhabitants.