Stress-related ecophysiology of members of the genus Rhodanobacter isolated from a mixed waste contaminated subsurface

• Rhodanobacter spp. are dominant in acidic, high nitrate and metal contaminated sites. • Dominance of Rhodanobacter is likely due to tolerance to low pH and heavy metals. • High organic content increases stress tolerance capacity. • Longer incubation time is critical for accurate assessment of MIC (various stresses). This work examines the physiologic basis of stress tolerance in bacterial strains of the genus Rhodanobacter that dominate in the acidic and highly metal contaminated near-source subsurface zone of the Oak Ridge Integrated Field Research Challenge (ORIFRC) site. Tolerance of R. denitrificans to levels of different stresses were studied in synthetic groundwater medium and R2A broth. Two strains of R. denitrificans, strains 2APBS1^T and 116-2, tolerate low to circumneutral pH (4–8), high Uranium (1 mmol/L), elevated levels of nitrate (400 mmol/L) and high NaCl (2.5%). A combination of physiologic traits, such as growth at low pH, increased growth in the presence of high organics concentration, and tolerance of high concentrations of nitrate, NaCl and heavy metals is likely responsible for dominance of Rhodanobacter at the ORIFRC site. Furthermore, extended incubation times and use of low carbon media, better approximating site groundwater conditions, are critical for accurate determination of stress responses. This study expands knowledge of the ecophysiology of bacteria from the genus Rhodanobacter and identifies methodological approaches necessary for acquiring accurate tolerance data.     

Assessment of persistent organic pollutants in soil and sediments from an urbanized flood plain area

Polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and phenolic compounds (PCs) are persistent organic compounds. Contamination of these potentially toxic organic pollutants in soils and sediments is most studied environmental compartments. In recent past, studies were carried out on PAHs, OCPs and PCs in various soils and sediments in India. But, this is the first study on these pollutants in soils and sediments from an urbanized river flood plain area in Delhi, India. During 2018, a total of fifty-four samples including twenty-seven each of soil and sediment were collected and analyzed for thirteen priority PAHs, four OCPs and six PCs. The detected concentration of ∑PAHs, ∑OCPs and ∑PCs in soils ranged between 473 and 1132, 13 and 41, and 639 and 2112 µg/kg, respectively, while their concentrations in sediments ranged between 1685 and 4010, 4.2 and 47, and 553 and 20,983 µg/kg, respectively. PAHs with 4-aromatic rings were the dominant compounds, accounting for 51 and 76% of total PAHs in soils and sediments, respectively. The contribution of seven carcinogen PAHs (7CPAHs) in soils and sediments accounted for 43% and 61%, respectively, to ∑PAHs. Among OCPs, p, p’-DDT was the dominant compound in soils, while α-HCH was found to be dominated in sediments. The concentrations of ∑CPs (chlorophenols) were dominated over ∑NPs (nitrophenols) in both the matrices. Various diagnostic tools were applied for the identification of their possible sources in soil and sediments. The observed concentrations of PAHs, OCPs and PCs were more or less comparable with the recently reports from various locations around the world including India. Soil quality guidelines and consensus-based sediment quality guidelines were applied for the assessment of ecotoxicological health effect.

     

Relationships Between Landscape Characteristics and Nonpoint Source Pollution Inputs to Coastal Estuaries

The model can help in examining the relative sensitivity of water-quality variables to alterations in land use made at varying distances from the stream channel. The model also shows the importance of streamside management zones, which are key to maintenance of stream water quality. The linkage model can be considered a first step in the integration of GIS and ecological models. The model can then be used by local and regional land managers in the formulation of plans for watershed-level management.     

Acetamide hydrolyzing activity of Bacillus megaterium F-8 with bioremediation potential: Optimization of production and reaction conditions.

Bacillus megaterium F-8 exhibited an intracellular acetamide hydrolyzing activity (AHA) when cultivated in modified nutrient broth with 3 % tryptone, 1.5 % yeast extract, and 0.5 % sodium chloride, at pH 7.2, 45 °C for 24 h. Maximum AHA was recorded in the culture containing 0.1 M of sodium phosphate buffer, (pH 7.5) at 45 °C for 20 min with 0.2 % of acetonitrile and resting cells of B. megaterium F-8 equivalent to 0.2 ml culture broth. This activity was stable up to 55 °C and was completely inactivated at or above 60 °C. Maximum acyl transferase activity (ATA) was recorded in the reaction medium containing 0.1 M of potassium phosphate buffer, (pH 8.0) at 55 °C for 5 min with 0.85 mM of acetamide as acyl donor and hydroxylamine hydrochloride as acyl acceptor and resting cells of B. megaterium F-8 equivalent to 0.94 mg cells (dry weight basis). This activity was stable up to 60 °C and a rapid decline in enzyme activity was recorded above it. Under the optimized conditions, this organism hydrolyzed various nitriles and amides such as propionitrile, propionamide, caprolactam, acetamide, and acrylamide to corresponding acids. Acyl group transfer capability of this organism was used for the production of acetohydroxamic acid. ATA of B. megaterium F-8 showed broad substrate specificity such as for acetamide followed by propionamide, acrylamide, and lactamide. This amide hydrolyzing and amidotransferase activity of B. megaterium F-8 has potential applications in enzymatic synthesis of hydroxamic acids and bioremediation of nitriles and amides contaminated soil and water system.     

The EU effect: does trade with the EU reduce CO2 emissions in the developing world?

The European Union (EU) is an important destination for developing country exports. Has the EU’s commitment to the Kyoto Protocol induced developing countries to reduce their carbon dioxide (CO₂) emissions? Our analyses of 136 developing countries from 1981 through 2007 suggests that: developing countries’ export dependence on the EU is associated with CO₂ emission reductions post-Kyoto in relation to the pre-Kyoto time period; this also holds for SO_2, which, while not covered under Kyoto, is linked with CO₂ emission levels; this does not hold for PM₁₀, a pollutant which is not covered under Kyoto and is not directly associated with CO₂ emissions related to industrial activities; developing countries’ export dependence on non-EU developed countries and on the rest of the world is not associated with significant reductions in emissions between pre- and post-Kyoto for these pollutants . In sum, even in the absence of binding regulatory mandates, the EU appears to exert market leverage to project its regulatory preferences abroad.     

Consultant Guide/1989

The European Economic Community (EEC) has proposed strict limits on emissions of dioxins and furans from hazardous waste incinerators. The proposed limit is 0.1 ng/Nm³, expressed as the 2,3,7,8 TCDD toxic equivalent of 17 specific dioxin and furan congeners. These limits will potentially redefine technology selection and design for combustion, energy recovery, and air pollution control. The EPA has a different approach for controlling emissions of products of incomplete combustion (PICs) and reformation products such as dioxins and furans. Rather than limiting these contaminants individually and quantitatively, EPA proposes controlling them by assuring good combustion as measured by stack emissions of carbon monoxide (CO) and total hydrocarbons (THC).

Dioxins and furans are combustion by-products and emission control relies mainly on control of the combustion process. These compounds can also be reformed from certain precursor compounds and elements in lower temperature regions of the system downstream of the combustion process. Air pollution control technologies have demonstrated the ability to remove dioxins and furans as contaminants on fine particulate.

This paper will discuss the two regulatory approaches, the mechanisms for the formation and reformation of dioxins and furans, and the technologies available to control emissions.     

Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management1

Damodaram, Chandana, Marcio H. Giacomoni, C. Prakash Khedun, Hillary Holmes, Andrea Ryan, William Saour, and Emily M. Zechman, 2010. Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management. Journal of the American Water Resources Association (JAWRA) 1-12. DOI: 10.1111/j.1752-1688.2010.00462.x Abstract: Urbanization causes increased stormwater runoff volumes, leading to erosion, flooding, and the degradation of instream ecosystem health. Although Best Management Practices (BMPs) are used widely as a means for controlling flood runoff events, Low Impact Development (LID) options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID practices such as rainwater harvesting, green roofs, and permeable pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices in an existing hydrologic model to estimate the effects of LID choices on streamflow. The modeling approach has been applied to a watershed located on the campus of Texas A&M University in College Station, Texas, to predict the stormwater reductions resulting from retrofitting existing infrastructure with LID technologies. Results demonstrate that use of these LID practices yield significant stormwater control for small events and less control for flood events. A combined BMP-LID approach is tested for runoff control for both flood and frequent rainfall events.     

Feasibility of PV–biodiesel hybrid energy system for a cement technology institute in India

This paper compares an existing unreliable grid supply with a proposed PV–biodiesel hybrid energy system in order to find the feasibility of the latter for improvement in reliability of power supply, lower pollutant emissions and saving of coal reserves. In the present study, the electrical load of a cement technology institute located in Bhilai, India, has been selected for the purpose of analysis. The results show that hybrid PV–biodiesel system comprising 25 kW PV array, 8 kW biodiesel generator-1, 20 kW biodiesel generator-2, 10 kW inverter and 10 kW rectifier will supply power to the institute avoiding addition of 27.744 tons of CO₂ in atmosphere and save 55,080 kg of coal per year with improvement in reliability from 93.15 to 100%.     

Exploring the Adaptation-mitigation Relationship: Does Information on the Costs of Adapting to Climate Change Influence Support for Mitigation?

Can information about adaptation costs influence citizens’ willingness to support climate change mitigation? Some scholars are concerned that policy discussions on adaptation might present climate change as a more manageable problem, and therefore crowd out mitigation efforts. On the other hand, providing information on adaptation costs may sensitize citizens to these costs, thereby increasing their willingness to support mitigation. To assess these conflicting predictions, we fielded a web-based survey experiment using a sample of 2,000 US-based respondents. We presented the respondents with a hypothetical newspaper article regarding a proposed gasoline tax (a mitigation strategy) and measured the support for this proposal across different treatment groups. In the control group, the respondents were told that failure to mitigate climate change could result in a potentially catastrophic outcome, whereas in each of the treatment groups the respondents were provided with information concerning possible adaptation costs. The respondents were then asked about their willingness to support a gasoline tax. Our key finding is that the provision of information about adaptation costs leads to a small increase in the respondents’ willingness to support mitigation efforts. Furthermore, we find that this effect becomes larger when the information regarding adaptation costs is made more specific.