Efficiency and degradation products elucidation of the photodegradation of mefenpyrdiethyl in water interface using TiO2 P-25 and Hombikat UV100

The photodegradation of mefenpyrdiethyl (MFD), an herbicide safener, was investigated in aqueous suspensions by using Degussa P-25 and Hombikat UV100 titanium oxide under simulated sunlight irradiation. The effects of initial concentration of the herbicide, pH, catalysts and hydrogen peroxide doses as well as their combinations were studied and optimized. Accordingly, the kinetic parameters were determined and the effectiveness of the processes was assessed by calculating the rate constants. A pseudo first-order kinetics was observed. Under experimental conditions, the degradation rate constants were strongly influenced using P-25 and no noticeable effect was observed for Hombikat UV100. DFT calculations with B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d,p) level of theory were performed to check whether significant conformational changes occur when the charge state of the MFD substrate changes and whether these changes could play a role in the dependency of photodegradation rate constant on the studied pH. High resolution mass spectrometry (FT-ICR/MS) was implemented to identify the main degradation products.     

生命周期评价与社会影响

生命周期评价(LCA)在提供数据、管理工具、软件和方法论中再加之更精确的测定方面已经取得了巨大的进步,然而与此同时仍然还有许多问题要解决.许多这些问题涉及到LCA方法在世界范围内的推广,以及这些方法如何通过建立数据库和按当地需要定制管理工具而适应发展中国家.……     

Investigation of different treatment techniques for PCDD/PCDF in fly ash

A number of different pretreatment and extraction procedures were compared with regard to recovery of PCDD/PCDF from fly ash. Highest results were obtained using an acid digestion with excess dilute HCl, followed by freeze drying of the residue and hot extraction by toluene.     

Stockholm Recommendation 96: Viable in the Dominican Republic

Summary The Dominican Republic and other Caribbean countries face serious challenges to their natural resource base. In recent years the government of the Dominican Republic has taken major steps toward the development and implementation of a comprehensive plan for national natural resources management. This plan is called Plan Sierra. An important component of this plan is the outline of actions for carrying out an environmental education programme within the country. This demonstrates a commitment to fulfill Recommendation No. 96 of the Stockholm Conference in a way that could become a model for other Latin American nations. Clinton L. Shepard is Assistant Professor in the Division of Environmental Education, School of Natural Resources, The Ohio State University. Dr Shepard holds a Bachelor of Science degree in Zoology from the University of Kentucky and graduate degrees from The Ohio State University in Natural Resources/Environmental Education and Education-Foundations and Research. He has worked as an interpreter and Environmental Education Coordinator for the State of Ohio Department of Natural Resources, a research associate for ERIC—Science, Math, and Environmental Education Clearinghouse, and College instructor in interpretive methods, environmental education methodology, resident outdoor programming, and natural resources development. He is also involved in international research and development, especially in the Caribbean Basin. Robert E. Roth is Chairman/Professor in the Division of Environmental Education, School of Natural Resources, The Ohio State University. Dr Roth received a Bachelor's degree in Wildlife Management, a Bachelor's degree in Secondary Science Education, a Master's degree in Conservation Education from The Ohio State University, and his Ph.D. in Environmental Education from The University of Wisconsin. he came to OSU in 1969 and since that time has designed and institutionalized the only academic unit in the US that offers both well developed undergraduate and graduate programmes in Environmental Communications, Education and Interpretation and has published over 40 works in the field. He has been instrumental in implementing a growing international environmental education research and development emphasis in the wider Caribbean, he continues as an Executive Editor of theJournal of Environmental Education.     

An appraisal of emissions control requirements in the California South Coast Air Basin

The purpose of this study is to evaluate the effect of reductions of reactive organic gases (ROG) and NO_x emissions on short-term O₃ and NO₂ concentrations and annual average NO₂ concentrations in the California South Coast Air Basin. Short-term air quality predictions were obtained by applying the Systems Applications Airshed Model to summer O₃ and autumn NO₂ episodes. Effects of emission controls on annual NO₂ concentrations were estimated using CDM and a new parcel tracking model NOXTRAK. Results for the summer O₃ episode indicate that ROG emission reduction in an effective means for reducing peak O₃ concentrations. NO_x emission reduction imposed in addition to ROG emission reductions are counterproductive in reducing peak O₃ concentrations. The modeling results also suggest that attainment of the 1-h federal O₃ standard requires ROG emission reductions on the order of 80% from 1987 levels. Results for the autumn NO₂ episode indicate that NO_x emission reductions approximating those recommended in a proposed Air Quality Management Plan (about 22%) will result in only small (about 5%) reductions in the peak NO₂ concentrations. ROG emission reduction may be more effective than NO_x emission reduction in reducing the peak NO₂ concentration. For the episode studied, a reduction of 36% in ROG emissions is estimated to result in a reduction in peak NO₂ concentrations commensurate with that required to attain the 1-h state NO₂ standard. Model calculations also indicate that the federal NO₂ standard may not be meet by 1987 at one or two stations, but may blosely approached.