噬菌体MS2作为水中肠道病毒指示生物的特征及其影响因素

噬菌体MS2作为潜在的水中肠道病毒指示生物,已逐渐成为回用水微生物学安全评价指标的主要研究方向之一。在此,阐述噬菌体MS2作为水中肠道病毒指示生物的主要特征,并介绍噬菌体MS2作为水中肠道病毒指示生物应用的影响因素。     

P-25纳米TiO2在含酚废水处理方面的应用

采用室内模拟研究,以P-25纳米TiO2作为光催化剂进行了苯酚水溶液的光催化降解性能探讨,初步考察了溶液的pH、P-25纳米TiO2用量对光催化降解苯酚过程的影响,以获得P-25纳米TiO2光降解含酚废水的较好反应条件.实验结果表明,当溶液pH=8时,降解水体中苯酚效果最佳,强酸和强碱条件均不利于苯酚的降解;在pH 8的反应体系中,当光催化剂用量为0.4g/L时,催化水体中苯酚降解的效果最好.     

Clean Water State Revolving Fund Loans and Landowner Investments in Agricultural Best Management Practices in Iowa1

Arbuckle, Jr., J. Gordon, 2012. Clean Water State Revolving Fund Loans and Landowner Investments in Agricultural Best Management Practices in Iowa. Journal of the American Water Resources Association (JAWRA) 1‐9. DOI: 10.1111/j.1752‐1688.2012.00688.x Abstract: Clean Water State Revolving Fund (CWSRF) loan programs for water quality have traditionally funded infrastructure projects at the community, municipality, or state level. They are increasingly being used to support individual landowner adoption of agricultural best management practices (BMPs) for nonpoint source pollution abatement. In 2005, the Iowa CWSRF initiated the Local Water Protection Program (LWPP) to increase the scope, scale, and rate of agricultural BMP establishment. This research examines the effectiveness of that program through a comparison of survey data from LWPP participants and state cost‐share recipients who were eligible for loans, but did not take them. Loan recipients’ assessments of the program were overwhelmingly positive, with near‐universal satisfaction with both the loan product and process. Results of statistical analyses indicate that loan recipients invested substantially more in conservation than nonrecipients. Evidence suggests that by helping program participants to overcome financial constraints, loans are facilitating larger and accelerated investments in conservation. Although findings indicate that conservation loans can play an important role in funding conservation, loan recipients also still depend on cost‐share. Loans are not necessarily a substitute for traditional forms of conservation funding, but rather another tool that landowners and conservation professionals can employ to facilitate investments in BMPs.     

Characterization of Storm Flow Dynamics of Headwater Streams in the South Carolina Lower Coastal Plain1

Epps, Thomas H., Daniel R. Hitchcock, Anand D. Jayakaran, Drake R. Loflin, Thomas M. Williams, and Devendra M. Amatya, 2012. Characterization of Storm Flow Dynamics of Headwater Streams in the South Carolina Lower Coastal Plain. Journal of the American Water Resources Association (JAWRA) 1‐14. DOI: 10.1111/jawr.12000 Abstract: Hydrologic monitoring was conducted in two first‐order lower coastal plain watersheds in South Carolina, United States, a region with increasing growth and land use change. Storm events over a three‐year period were analyzed for direct runoff coefficients (ROC) and the total storm response (TSR) as percent rainfall. ROC calculations utilized an empirical hydrograph separation method that partitioned total streamflow into sustained base flow and direct runoff components. ROC ratios ranged from 0 to 0.32 on the Upper Debidue Creek (UDC) watershed and 0 to 0.57 on Watershed 80 (WS80); TSR results ranged from 0 to 0.93 at UDC and 0.01 to 0.74 at WS80. Variability in event runoff generation was attributed to seasonal trends in water table elevation fluctuation as regulated by evapotranspiration. Groundwater elevation breakpoints for each watershed were identified based on antecedent water table elevation, streamflow, ROCs, and TSRs. These thresholds represent the groundwater elevation above which event runoff generation increased sharply in response to rainfall. For effective coastal land use decision making, baseline watershed hydrology must be understood to serve as a benchmark for management goals, based on both seasonal and event‐based surface and groundwater interactions.     

Treatment of Dichloromethane Using Gliding Arc Plasma

Decomposition of dichloromethane (CH₂Cl₂) using a gliding plasma was examined and reported in this paper. The effects of initial concentrations of CH₂Cl₂, total gas flow rates, and input frequency have been studied to evaluate the performance of gliding arc on CH₂Cl₂ decomposition. Using atmospheric pressure air as the carrier gas, experimental results indicate that the maximum conversion of CH₂Cl₂ was 95.1% at a total gas flow rate of 180 L/hr containing 1% by volume of CH₂Cl₂. The reaction occurred at an exothermic condition and gaseous products are dominated by CO, CHCl₃, and Cl₂. CO₂ and CCl₄ are also detected in the product stream in small amounts. The conversion of CH₂Cl₂ increases with the increasing applied voltage and decreasing total gas flow rate.     

Techno-Economic Study of CO2 Capture from an Existing Cement Plant Using MEA Scrubbing

Carbon dioxide is the major greenhouse gas responsible for global warming. Man-made CO₂ emissions contribute approximately 63% of greenhouse gases and the cement industry is responsible for approximately 5% of CO₂ emissions emitting nearly 900 kg of CO₂ per 1000 kg of cement. CO₂ from a cement plant was captured and purified to 98% using the monoethanolamine (MEA) based absorption process. The capture cost was $51 per tonne of CO₂ captured, representing approximately 90% of total cost. Steam was the main operating cost representing 39% of the total capture cost. Switching from coal to natural gas reduces CO₂ emissions by about 18%. At normal load, about 36 MW of waste heat is available for recovery to satisfy the parasitic heat requirements of MEA process; however, it is very difficult to recover.     

Control Issues in the Design of a Gas Turbine Cycle for CO2 Capture

This article is concerned with control issues related to the design of a semi-closed O ₂/CO ₂ gas turbine cycle for CO ₂ capture. Some control strategies and their interaction with the process design are discussed. One control structure is implemented on a dynamic simulation model using a predictive controller, and simulations assess the performance and compare its merits with a conventional PI structure. The results indicate that it can be advantageous for operability to allow a varying (as opposed to fixed) compressor inlet pressure, at the cost of a more expensive design. Furthermore, the results show that a predictive controller has some advantages with respect to the simpler conventional PI control structure, in particular in terms of constraint handling.     

Impact of Human Activities on Carbon Dioxide (CO<Subscript>2</Subscript>) Emissions: A Statistical Analysis

Summary The balance of evidence suggests a perceptible human influence on global ecosystems. Human activities are affecting the global ecosystem, some directly and some indirectly. If researchers could clarify the extent to which specific human activities affect global ecosystems, they would be in a much better position to suggest strategies for mitigating against the worst disturbances. Sophisticated statistical analysis can help in interpreting the influence of specific human activities on global ecosystems more carefully. This study aims at identifying significant or influential human activities (i.e. factors) on CO₂ emissions using statistical analyses. The study was conducted for two cases: (i) developed countries and (ii) developing countries. In developed countries, this study identified three influential human activities for CO₂ emissions: (i) combustion of fossil fuels, (ii) population pressure on natural and terrestrial ecosystems, and (iii) land use change. In developing countries, the significant human activities causing an upsurge of CO₂ emissions are: (i) combustion of fossil fuels, (ii) terrestrial ecosystem strength and (iii) land use change. Among these factors, combustion of fossil fuels is the most influential human activity for CO₂ emissions both in developed and developing countries. Regression analysis based on the factor scores indicated that combustion of fossil fuels has significant positive influence on CO₂ emissions in both developed and developing countries. Terrestrial ecosystem strength has a significant negative influence on CO₂ emissions. Land use change and CO₂ emissions are positively related, although regression analysis showed that the influence of land use change on CO₂ emissions was still insignificant. It is anticipated, from the findings of this study, that CO₂ emissions can be reduced by reducing fossil-fuel consumption and switching to alternative energy sources, preserving exiting forests, planting trees on abandoned and degraded forest lands, or by planting trees by social/agroforestry on agricultural lands.     

WATER QUALITY IMPROVEMENT PROGRAM EFFECTIVENESS FOR CARBONATE AQUIFERS IN GRAZED LAND WATERSHEDS1

ABSTRACT: Water quality indicators of two agriculturally impacted karst areas in southeastern West Virginia were studied to determine the water quality effects of grazing agriculture and water quality trends following initiation of water quality improvement programs. Both areas are tributaries of the Greenbrier River and received funding for best management practices under the President's Initiative for Water Quality and then under the Environmental Quality Incentives Program (EQIP). After 11 years of study there was little evidence to suggest that water quality improved in one area. Three and a half years of study in the other area showed little evidence of consistent water quality improvement under EQIP. Lack of consistent water quality improvement at the catchment scale does not imply that the voluntary programs were failures. Increased livestock numbers as a result of successful changes in forage management practices may have overridden water quality improvements achieved through best management practices. Practices that target well defined contributing areas significantly impacting aquifer water quality might be one way to improve water quality at catchment scales in karst basins. For example, a significant decrease in fecal coliform concentrations was observed in subterranean drainage from one targeted sinkhole after dairy cattle were permanently excluded from the sinkhole.     

GEOMORPHOLOGY OF STEEPLAND HEADWATERS: THE TRANSITION FROM HILLSLOPES TO CHANNELS1

Headwater streams comprise 60 to 80 percent of the cumulative length of river networks. In hilly to mountainous terrain, they reflect a mix of hillslope and channel processes because of their close proximity to sediment source areas. Their morphology is an assemblage of residual soils, landslide deposits, wood, boulders, thin patches of poorly sorted alluvium, and stretches of bedrock. Longitudinal profiles of these channels are strongly influenced by steps created by sediment deposits, large wood, and boulders. Due to the combination of small drainage area, stepped shallow gradient, large roughness elements, and cohesive sediments, headwater streams typically transport little sediment or coarse wood debris by fluvial processes. Consequently, headwaters act as sediment reservoirs for periods spanning decades to centuries. The accumulated sediment and wood may be episodically evacuated by debris flows, debris floods, or gully erosion and transported to larger channels. In mountain environments, these processes deliver significant amounts of materials that form riverine habitats in larger channels. In managed steepland forests, accelerated rates of landslides and debris flows resulting from the harvest of headwater forests have the potential to seriously impact the morphology of headwater streams and downstream resources.