蜂蜜中氯霉素残留的检测及净化方法研究

建立了反相高效液相色谱-离子阱质谱法检测蜂蜜中氯霉素残留的方法.前处理采用改良的QuEChERS方法进行快速提取和净化.采用初级次级胺进行固相分散净化,可有效吸附蜂蜜中的糖类及有机色素等杂质.提取物在流动相甲醇:水(0.2%乙酸胺)=45:55(体积比)中,用整体色谱柱进行快速分离和质谱检测.并对MS检测中2种离子化方式(电喷雾ESI及大气压化学APCI)、各种离子化方式下正负离子模式及离子检测方法(总离子检测TIC和选择性离子监测MRM)进行了综合比较,最终确定采用电喷雾电离法(ESI)负离子模式、多反应离子监测(MRM)对氯霉素进行定性定量分析.在0.2～200μg/kgg添加浓度下,添加回收率水平在78%～93%间,变异系数在3.9%以下.该方法的检出限为0.1μg/kg,在0.1～100 μg/L浓度范围内,线性方程为y=58.753x 34867,相关系数R2=0.999 5.     

The effect of a biofilm on solute diffusion in fractured porous media

At sites in fractured rock where contamination has been exposed to the rock matrix for extended periods of time, the amount of contaminant mass residing in the matrix can be considerable. Even though it may be possible to diminish concentrations by the advection of clean water through the fracture features, back diffusion from mass held in the matrix will lead to a continuing source of contamination. In such an event, the development of a biofilm (a thin film of microbial mass) on the wall of the fractures may act to limit or prevent the back diffusion process. The objective of this preliminary study is to explore the influence imparted by the presence of a biofilm on the process of matrix diffusion. The investigation was conducted using radial diffusion cells constructed from rock core in which biofilm growth was stimulated in a central reservoir. Once biofilms were developed, forward diffusion experiments were conducted in which a conservative solute migrated from the central reservoir into the intact rock sample. Diffusion experiments were performed in a total of 11 diffusion cell pairs where biofilm growth was stimulated in one member of the pair and inhibited in the other. The effect of the presence of a biofilm on tracer diffusion was determined by comparison of the diffusion curves produced by each cell pair. A semi-analytical model that accounts for the presence of a biofilm was used to investigate the effect of the biofilm on mass transfer due to changes in the effective porosity, effective diffusion coefficient, and the depth of penetration of the biofilm into the intact rock. The results show that the biofilm acted to plug the rock matrix, rather than forming a discrete layer on the reservoir surface. The reduction in effective porosity due to the biofilm ranged from 6% to 52% with the majority of the samples in the 30% to 50% range. Based on the present results, with more efficient biofilm stimulation, it is reasonable to assume that a more complete plugging of the microcrack porosity might be possible, leaving a much thicker and efficient barrier than could be achieved via a surface biofilm.     

人口、资源与环境经济学教材比较研究

人口、资源与环境经济学是理论经济学下设立的一个二级学科。自1997年设立以来，很多学者对其学科体系进行了探索。出版了一些著作和教材。本文以现代课程与教学论的观点为指导．采用文献研究、比较分析、统计分析的方法．从教材现状、体系结构、内容、表现形式和手段等方面对国内外人口、资源与环境经济学教材进行了详细的比较研究，并在此基础上为新教材建设提出了建议。以期为国内相关教材的改进和完善提供参考依据。这些建议是：统一并完善教材体系；理论要联系实际．培养学生学习兴趣和解决实际问题能力；注重学科领域最新成果的运用。增强教材的时代性和科学性；注重表现形式和手段多样性，帮助读者理解抽象的经济理论。     

Rhetoric and Reality of Water Quality Trading and the Potential for Market‐like Reform1

Stephenson, Kurt and Leonard Shabman, 2011. Rhetoric and Reality of Water Quality Trading and the Potential for Market‐Like Reform. Journal of the American Water Resources Association (JAWRA) 47(1):15‐28. DOI: 10.1111/j.1752‐1688.2010.00492.x Abstract: Many public interest groups, government agencies, and professional economists argue that current approaches to water quality trading are a cost‐effective, politically practical innovation for achieving water quality standards, in part by addressing one of the most difficult water quality improvement challenges – limiting the discharge from nonpoint sources. A critical analysis shows that these claims for current water quality trading programs are often unrealized. This rhetoric, without adherence to principles of market‐like reform, can undermine the support of regulated parties for meaningful water quality policy reform, contribute to missed opportunities to implement cost‐effective programs, and postpone successfully meeting the challenge of limiting nonpoint source discharges. A better understanding and application of market‐like principles can result in an improved design of trading as well as general water quality management programs.     

A combined ecosystem and value chain modeling approach for evaluating societal cost and benefit of fishing

We describe a combined ecological and economic approach aimed at giving more equal emphasis to both disciplines, while being integrated so that design, analysis, data entry and storage, and result capabilities are developed with emphasis on deriving a user-friendly, easily accessible tool. We have thus developed the approach as an integrated module of the freely available Ecopath with Ecosim scientific software; the world's most widely applied ecological modeling tool. We link the trophic ecosystem model to a value-chain approach where we explicitly and in considerable detail keep track of the flow (amounts, revenue, and costs) of fish products from sea through to the end consumer. We also describe the social aspects of the fish production and trade, by evaluating employment and income diagnostics. This is done with emphasis on distribution income while accounting for social aspects of the fishing sector. From a management perspective, one of the interesting aspects of the approach we introduce here, is that it opens for direct evaluation of what impact management interventions, e.g., quota settings, effort regulation, or area closures, may have on the ecosystem, the economy and the social setting, as well as on food availability for the consumer.     

COST EFFECTIVENESS OF VEGETATIVE FILTER STRIPS AND INSTREAM HALF‐LOGS FOR ECOLOGICAL RESTORATION1

ABSTRACT: This paper presents the results of cost effectiveness (CE) analysis of vegetative filter strips (VFS) and instream half‐logs as tools for recovering scores on a fish Index of Biotic Integrity (IBI) in the upper Wabash River watershed (UW) in Indiana. Three assumptions were made about recovery time for IBI scores (5,15, and 30 years) and social discount rates (1, 3, and 5 percent), which were tested for sensitivity of the estimated CE ratios. Effectiveness of VFS was estimated using fish IBIs and riparian forest cover from 49 first‐order to fifth‐order stream reaches. Half‐log structures had been installed for approximately two years in the UW prior to the study and provided a basis for estimates of cost and maintenance. Cost effectiveness ratios for VFS decreased from $387 to $277 per 100 m for a 1 percent increase in IBI scores from first‐to fifth‐order streams with 3 percent discount and 30‐year recovery. This cost weighted by proportion of stream orders was $360. The ratio decreased with decreasing time of recovery and discount rate. Based on installation costs and an assumption of equal recovery rates, half‐logs were two‐thirds to one‐half as cost‐effective as VFS. Half‐logs would be a cost‐effective supplement to VFS in low order streams if they can be proven to recover IBI scores faster than VFS do. This study provides baseline data and a framework for planning and determining the cost of stream restoration.     

经济学帝国主义与人口资源环境经济学学科发展

与主流经济学与时俱进是人口、资源环境经济学生存和发展的根基。通过人口、资源与环境经济学兴起和发展的简单回顾和相关研究成功案例的介绍，分析了经济学帝国主义对人口、资源与环境经济学学科发展的启示。提出高举经济学大旗，建立与主流经济学与时俱进的人口、资源与环境经济学。     

FARM-LEVEL MANAGEMENT OF DEEP PERCOLATION EMISSIONS IN IRRIGATED AGRICULTURE1

ABSTRACT: Source control costs for deep percolation emissions from irrigated agriculture are analyzed using a farm-level model. Crop area, irrigation system and applied water are chosen to maximize the net benefits of agricultural production while accounting for the environmental damages and disposal costs of those emissions. Deep percolation is progressively reduced as environmental and disposal costs are increased. This occurs primarily through the adoption of more efficient irrigation technology and reductions in applied water for a given technology Higher surface water prices, such as through irrigation reform and constrained surface supplies, are additionally considered in light of the drainage problem, as are the effects, both short- and long-term, on ground water use.     

APPLICATION OF CROP YIELD FUNCTIONS IN RESERVOIR OPERATION1

ABSTRACT: A model is developed for real-time operation of an irrigation reservoir with the objective of maximizing the value of multiple crop yields during a growing season. The model employs monthly additive and product forms of crop yield functions for dry matter and grain crops, respectively. The resulting nonlinear optimization model uses a log transform to reduce nonlinearities in the model. An application of the proposed model is compared to a common operating rule used in simulation models. The proposed model results were better in terms of net benefits from crop yields. The model uses GAMS (General Algebraic Modeling System) language. It requires an IBM-compatible microcomputer and is suitable for use by a reservoir manager.     

四溴乙基环己烷(TBECH)立体异构体的分析方法与环境行为及毒性效应研究进展

1,2-二溴-4-（1,2-二溴乙基）-环己烷,又名TBECH（tetrabromoethylcyclohexane,四溴乙基环己烷）,是一种添加型的新型溴代阻燃剂.TBECH的立体结构复杂,具有4个异构体,每个异构体又均含有一对对映体.随着传统溴代阻燃剂的禁止生产或限制使用,TBECH作为替代品之一被广泛用于建筑业、纺织业和电子等各行业.TBECH具有长距离迁移性、生物累积性和潜在毒性,被认为是一种可能的持久性有机污染物.通过对TBECH立体异构体的分析方法、环境行为和毒性效应研究的最新进展进行综述发现,TBECH的检测通常采用气相色谱质谱联用法,但仅集中于对环境样品中TBECH非对映异构体的分离分析,对映体水平的检测将成为未来TBECH立体异构体分析的发展方向.TBECH已在大气、水体、沉积物、土壤等环境介质和生物体中被陆续检出,并对生物体产生内分泌干扰、生殖发育等毒性效应,其各立体异构体具有特异的环境行为,表现出选择性的生物累积、转化和毒性效应.鉴于目前TBECH环境行为的研究主要关注水生生态系统,而从立体异构体水平出发的研究还很欠缺,建议今后加强对陆生生态系统中TBECH污染状况、分布特征以及环境行为的研究,进一步从异构体和对映体水平深入探讨TBECH的环境过程和生物效应,全面认识环境中TBECH的迁移转化规律及最终归趋.