Predicting methyl iodide emission, soil concentration, and pest control in a two-dimensional chamber system

Due to ever-increasing state and federal regulations, the future use of fumigants is predicted on reducing negative environmental impacts while offering sufficient pestcontrol efficacy. To foster the development of a best management practice, an integrated tool is needed to simultaneously predict fumigant movement and pest control without having to conduct elaborate and costly experiments. The objective of this study was (i) to present a two-dimensional (2-D) mathematical model to describe both fumigant movement and pestcontrol and (ii) to evaluate the model by comparing the simulated and observed results. Both analytical and numerical methods were used to predict methyl iodide (MeI) transport and fate. To predict pest control efficacy, the concentration-time index (CT) was defined and a two-parameter logistic survival model was used. Dose-response curves were experimentally determined for MeI against three types of pests (barnyardgrass [Echinochloa crus-galli] seed, citrus nematode [Tylenchulus semipenetrans], and fungi [Fusarium oxysporum]). Methyl iodide transport and pest control measurements collected from a 2-D experiimental system (60 by 60 cm) were used to test the model. Methyl iodide volatilization rates and soil gas-phase concentrations over time were accurately simulated by the model. The mass balance analysis indicates that the fraction of MeI degrading in the soil was underestimated when determined by the appearance of iodide concentration. The experimental results showed that after 24 h of MeI fumigation in the 2-D soil chamber, fungal population was not suppressed; > 90% of citrus nematodes were killed; and barnyardgrass seeds within 20-cm distance from the center were affected. These experimental results were consistent with the predicted results. The model accurately estimated the MeI movement and control of various pests and is a powerful tool to evaluate pesticides in terms of their negative environmental impacts and pest control under various environmental conditions and application methods.     

四川的能源问题与可持续发展

可持续发展战略的实施不能忽视能源问题。四川是一个能源生产与消费大省,能源问题对全省可持续发展有很大影响,改变能源消费结构、开发新能源和增强能源意识,对于四川走可持续发展的能源道路是十分重要的。     

改进的稳健统计技术在排水检测人员技能评价中的应用

目前排水检测行业中仍缺乏对技术人员进行技能评价的方法,或虽有评价方法,但方法存在不尽规范、合理等问题。稳健统计技术作为能力验证试验中广泛使用的结果评价方法,可消除异常数据的影响,使评价结果准确可靠。将稳健统计技术改进,作为技能评价要素中的一个分量,按照操作的准确性、规范性与熟练性三个方面评价排水检测人员检测数据结果,可以较科学、合理地反映检测人员的技能水平,为提高检测工作质量和实验室管理起到一定的借鉴作用。     

Volatile organic compounds in the unsaturated zone from radioactive wastes

Volatile organic compounds (VOCs) are often comingled with low-level radioactive wastes (LLRW), but little is known about subsurface VOC emanations from LLRW landfills. The current study systematically quantified VOCs associated with LLRW over an 11-yr period at the USGS Amargosa Desert Research Site (ADRS) in southwestern Nevada. Unsaturated-zone gas samples of VOCs were collected by adsorption on resin cartridges and analyzed by thermal desorption and GC/MS. Sixty of 87 VOC method analytes were detected in the 110-m-thick unsaturated zone surrounding a LLRW disposal facility. Chlorofluorocarbons (CFCs) were detected in 100% of samples collected. Chlorofluorocarbons are powerful greenhouse gases, deplete stratospheric ozone, and are likely released from LLRW facilities worldwide. Soil-gas samples collected from a depth of 24 m and a horizontal distance 100 m south of the nearest waste-disposal trench contained >60,000 ppbv total VOCs, including >37,000 ppbv CFCs. Extensive sampling in the shallow unsaturated zone (0-2 m deep) identified areas where total VOC concentrations exceeded 5000 ppbv at the 1.5-m depth. Volatile organic compound concentrations exceeded background levels up to 300 m from the facility. Maximum vertical diffusive fluxes of total VOCs were estimated to be 1 g m yr. Volatile organic compound distributions were similar but not identical to those previously determined for tritium and elemental mercury. To our knowledge, this study is the first to characterize the unsaturated zone distribution of VOCs emanating from a LLRW landfill. Our results may help explain anomalous transport of radionuclides at the ADRS and elsewhere.     

我国公务员人力资源管理廉政考核体系研究

我国体制转轨时期,面对当前的腐败,究其原因除了腐败本身具有的顽固性尚未得到根本遇制外,缺少科学的廉政考核体系也是一个重要原因.本文从我国公务员康政概念开始,通过一系列指标体系的测量,充分利用现代科技不断进行制度和方法的创新,不断完善我国公务员康政考核的指标体系.     

印染废水静电场处理机理分析

本文提出一种利用静电场的印染废水处理方法，印染废水中的污染颗粒在电场的作用下，朝一定的方向迁移，从而发生“强制电中和”作用，这种电中和作用的场能消耗极小，而被中和的污染物颗粒由于凝聚作用，则会不断长大而易于通令过滤去除，这一处理工艺在经“自数”预处理之后，可继续使COD和色度的去除百分数分别达60％和63％以上。     

清洁发展机制在石油行业的潜力分析

系统分析了石油行业清洁发展机制项目的潜力,并提出了建议。在统计与石油行业相关的清洁发展机制方法学及其注册项目和温室气体减排量的基础上,给出了各方法学与石油行业的相关性。从勘探与生产、天然气与管道、炼油与化工三大领域,分析了石油行业潜在的清洁发展机制项目领域。最后,提出了对石油行业开展清洁发展机制相关工作的建议。     

Assessing Sediment Yield for Selected Watersheds in the Laurentian Great Lakes Basin Under Future Agricultural Scenarios

In the Laurentian Great Lakes Basin (GLB), corn acreage has been expanding since 2005 in response to high demand for corn as an ethanol feedstock. This study integrated remote sensing-derived products and the Soil and Water Assessment Tool (SWAT) within a geographic information system (GIS) modeling environment to assess the impacts of cropland change on sediment yield within four selected watersheds in the GLB. The SWAT models were calibrated during a 6 year period (2000–2005), and predicted stream flows were validated. The R ² values were 0.76, 0.80, 0.72, and 0.81 for the St. Joseph River, the St. Mary River, the Peshtigo River, and the Cattaraugus Creek watersheds, respectively. The corresponding E (Nash and Sutcliffe model efficiency coefficient) values ranged from 0.24 to 0.79. The average annual sediment yields (tons/ha/year) ranged from 0.12 to 4.44 for the baseline (2000 to 2008) condition. Sediment yields were predicted to increase for possible future cropland change scenarios. The first scenario was to convert all “other” agricultural row crop types (i.e., sorghum) to corn fields and switch the current/baseline crop rotation into continuous corn. The average annual sediment yields increased 7–42 % for different watersheds. The second scenario was to further expand the corn planting to hay/pasture fields. The average annual sediment yields increased 33–127 % compared with baseline conditions.     

Direct methanol fuel cell bubble removal mechanism using magnetic actuation

This article develops a direct methanol fuel cell (DMFC) with a magnet-actuated bubble removal mechanism. A micro-DC motor is used to control the bubble removal mechanism. The lower magnetic device is operated to extrude a Polydimethylsiloxane (PDMS) runner to compress the liquid fuel in the anode flow channel, forcing the CO₂ bubbles in the runner to flow toward the outlet end. The bubble retention in the anode flow channel is thereby improved, enhancing the cell performance. The proposed mechanism stability and performance and Polymethylmethacrylate (PMMA) runner are also discussed.     

紫露草微核技术对工业废水监测的应用

利用紫露草微核技术，以自来水为对照，不同浓度的氯化汞、三氧化二砷溶液及十几个工厂废水进行微核效应比较试验，筛选出破坏遗传物质的工业废水及其相应的污染水平。观察紫露草微核率变化及细胞的分裂情况，证明紫露草微核技术是监测工业废水的良好方法。