A MANGANESE OXIDATION MODEL FOR RIVERS1

ABSTRACT: The presence of manganese in natural waters (>0.05 mg/L) degrades water-supply quality. A model was devised to predict the variation of manganese concentrations in river water released from an impoundment with the distance downstream. The model is one-dimensional and was calibrated using dissolved oxygen, biochemical oxygen demand, pH, manganese, and hydraulic data collected in the Duck River, Tennessee. The results indicated that the model can predict manganese levels under various conditions. The model was then applied to the Chattahoochee River, Georgia. Discrepancies between observed and predicted may be due to inadequate pH data, precipitation of sediment particles, unsteady flow conditions in the Chattahoochee River, inaccurate rate expressions for the low pH conditions, or their combinations.     

Balancing Emotion and Cognition: a Case for Decision Aiding in Conservation Efforts

Abstract: Despite advances in the quality of participatory decision making for conservation, many current efforts still suffer from an inability to bridge the gap between science and policy. Judgment and decision‐making research suggests this gap may result from a person's reliance on affect‐based shortcuts in complex decision contexts. I examined the results from 3 experiments that demonstrate how affect (i.e., the instantaneous reaction one has to a stimulus) influences individual judgments in these contexts and identified techniques from the decision‐aiding literature that help encourage a balance between affect‐based emotion and cognition in complex decision processes. In the first study, subjects displayed a lack of focus on their stated conservation objectives and made decisions that reflected their initial affective impressions. Value‐focused approaches may help individuals incorporate all the decision‐relevant objectives by making the technical and value‐based objectives more salient. In the second study, subjects displayed a lack of focus on statistical risk and again made affect‐based decisions. Trade‐off techniques may help individuals incorporate relevant technical data, even when it conflicts with their initial affective impressions or other value‐based objectives. In the third study, subjects displayed a lack of trust in decision‐making authorities when the decision involved a negatively affect‐rich outcome (i.e., a loss). Identifying shared salient values and increasing procedural fairness may help build social trust in both decision‐making authorities and the decision process.     

自动电位滴定法测定烟气氨法脱硫模拟浆液中氯离子的研究

氯离子含量是氨法脱硫工艺中的一个重要监控指标,用自动电位滴定法测定氨法脱硫浆液中的氯离子。结果表明,实验加入乙醇有利于增大电位突跃幅度;pH值为3~5时实验结果准确;加标回收率为90%~110%;与莫尔法相比,测定结果准确度、精密度更高,且不受灰分颜色干扰;与离子色谱法测定结果准确度、精密度相近,但测定高浓度氯离子电位滴定法更有优势。     

卷烟膨胀烟丝生产线冷端CO_2泵装置的优化改进

为解决干冰膨胀烟丝生产线冷端液体工艺泵因机械密封长期超压和气缚现象造成损坏发生CO2泄漏而导致紧急停机抢修的问题,对干冰膨胀线冷端工艺罐系统进行了优化改进。在工艺泵吸口前管路引一根气相平衡管至工艺罐顶部,当泵吸口前管路有CO2液体时,输送管路内气化的CO2气体通过气相平衡管线释放回工艺罐内,不会进入工艺泵体内。应用结果表明,工艺泵内的憋压和气缚现象消失了,机械密封受到保护。改造前机械密封平均一个季度更换一次,改造后机械密封使用5年未损毁,达到保护干冰膨胀线冷端工艺泵机械密封的目的。     

Kinetics characteristics of coal low-temperature oxidation in oxygen-depleted air

The longwall gob (mined-out) area is one of the main places that are prone to coal spontaneous combustion and most of the residual coal in it is in oxygen-depleted air as it is a semi-enclosed space. A DSC (Differential scanning calorimetry) test system was designed to accurately test the heat generation of coal oxidation in different oxygen concentration atmosphere, based on which the kinetics parameters (activation energy and pre-exponential factor) of coal low-temperature oxidation in oxygen-depleted air were solved out. The results show that the kinetics parameters present obvious stage features and the lower the oxygen concentration is, the smaller is the difference of the kinetics parameters that in different oxidation stages. When the oxygen concentration is lower than 5% and 3% for jet coal and meagre coal respectively, the kinetics parameters of slow oxidation start to be greater than that of rapid oxidation. Both in the slow oxidation and rapid oxidation stage, with the decrease of oxygen concentration, kinetics parameters present significant decline on the whole while in different oxygen concentration range, the decline rate is different. It's concluded that when assessing the residual coal's self-heating risk, we need to use the corresponding kinetics parameters of coal oxidation in the oxygen concentration of the location where the residual coal is and the safety factor will be greater to only use the kinetics parameters of coal oxidation in slow oxidation stage. This study is of great significance for the assessment and control of the self-heating risk of coal that in different oxygen concentration atmospheres of the longwall gob areas.     

我国生物质气化发电行业综合风险评价

针对我国生物质气化发电行业的现状,总结诸多风险的影响因素,建立了我国生物质气化发电行业综合风险评价体系。该评价体系主要包括5个一级风险影响因素:市场风险、技术风险、安全风险、管理风险、环境风险,每个一级影响因素包括4个二级风险影响因素。由层次分析法获得各个一级影响因素和二级影响因素的权重值,根据所构建的评价集和评分标准,结合模糊综合评价法对我国生物质气化发电行业现状的综合风险等级做定量定性分析。综合风险评价研究结果表明,生物质气化发电行业处于"较高"的风险等级,与实际情况相符。综合风险评价体系的构建合理,所建立的评价方法以及相应对策分析可为决策者提供参考依据。     

Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake,Lake Taihu,China

The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT_1.92 > DGT_0.78 > DGT_0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.     

组合工艺在养猪废水处理中的工程应用研究

针对某猪场养殖废水排放所造成的严重污染问题,采用“固液分离+ UBF厌氧反应器+接触氧化+曝气生物滤池”的组合工艺,对废水中的COD、BOD、氨氮、SS去除效果明显,去除率分别为93.7％、94.4％、95％、77.1％,处理后的水质达到《国家畜禽养殖业污染物排放标准》.该工程运行费用仅为1.509元/m3,处理成本低.同时UBF池中产生的沼气可以收集并利用,猪粪和污泥可制作有机肥,实现了废物资源化利用.     

考虑齐口裂腹鱼产卵需求的山区河流生态基流过程确定

在原型观测的基础上,应用生态水力学法与生境模拟法,建立对考虑齐口裂腹鱼产卵需求的山区河流水电工程生态基流过程的确定方法,并以四川中型山区河流杂谷脑河薛城电站为背景,对所构建方法进行应用分析。通过原型观测,对生态水力学的齐口裂腹鱼生境水力参数标准在杂谷脑河应用的适宜性进行分析;应用生态水力学方法,对不同河道流量下薛城电站减水河段的齐口裂腹鱼生境水力参数进行数值模拟,根据模拟结果,结合齐口裂腹鱼生境水力参数标准,分析得到薛城电站满足其生存的最小下泄流量;应用生境模拟法,对齐口裂腹鱼产卵期不同河道流量下薛城电站减水河段集中产卵场的可利用生境面积进行计算,得到最大可利用生境面积对应的下泄流量。综合最小下泄流量值与最大可利用生境面积所对应的下泄流量值,考虑齐口裂腹鱼产卵对水文情势的要求,建立薛城电站考虑齐口裂腹鱼产卵需求的生态基流过程。采用所构建方法得到的考虑鱼类产卵需求的水电工程生态基流过程,由于考虑了鱼类生存对最低流量以及产卵对水文情势的要求,能更好地满足鱼类产卵需求,可作为电站运行调度的约束。     

基于CI指数的祁东县干旱特征分析

利用衡阳市祁东县气象站1960~2013年逐日平均气温、降水观测数据,计算综合气象干旱指数。以国家标准《气象干旱等级GB/T20481~2006》为依据划分不同干旱等级、计算干旱日数、干旱强度等,在此基础上统计干旱日的年、年代际统计并作了线性分析,并为应对干旱提出了自己的建议:祁东县干旱日每年均有出现,但不同强度干旱日发生频率不同,在全球变暖大背景下,干旱日等级越高,其增幅愈明显;祁东县的平均干旱过程数为2.5次/a,一年出现2次干旱过程几率最大,无旱过程的几率为9.3%;在统计年干旱强度时,选用持续时间最长的一次有较好代表性。近54a来,干旱强度年变化可分为三高两低,目前处于干旱强度较高期;祁东县大部分年份有季节性干旱,单季旱以秋旱为主,在双季干旱中,夏秋连旱居多,历史上夏秋冬连旱出现了三次;为了应对日趋严重的干旱,需增强人们的防旱抗灾意识、加大水利设置投入、推广节水农业和提高干旱监测预警能力。