我国不同区域水源水拉森指数比较分析

目前远距离调水已经成为解决区域水资源不足的一项重要措施。但在水源切换时,切换前后水源水的腐蚀性如果存在显著差异,可能会因腐蚀加剧而出现"黄水"或"红水"现象。因此,了解不同区域、不同类型水源的腐蚀性差异,对于科学合理地进行水资源调配具有重要意义。拉森指数(LR)是目前评价水质对铁质管网腐蚀程度的常用方法。本研究以14个城市的26个水源水为研究对象,对模拟常规工艺处理后的滤后水进行了水质分析,并计算出其拉森指数。结果表明,相对于湖库水和地下水,河流水的拉森指数偏高,有44%的河流水拉森指数大于1,具有较强的腐蚀倾向。按区域分华东和中南地区、按流域分黄河和珠江流域的水源水拉森指数平均值大于1,水源切换条件下应关注其腐蚀性情况。     

Water Transport in Polylactide and Polylactide/Montmorillonite Composites

Polylactide–montmorillonite composites were fabricated by melt-blending followed by compression molding, and water permeability of the composites was studied by both experiments and theoretical models. The water permeation in composites decreases with increasing concentration of montmorillonite. Specifically, at a concentration of 10 wt% of montmorillonite, the water permeation is 34 % less than in the neat polymer. Transmission electron microscopy (TEM) and wide-angle X-ray scattering (WAXS) results show that most of the montmorillonite particles are well-dispersed and randomly exfoliated in the polymer matrix. A fit of theoretical models to the permeation data estimates that montmorillonite platelets are mostly exfoliated in the polymer matrix and oriented randomly, which matches with results from WAXS and TEM.     

Remote sensing of aquatic vegetation distribution in Taihu Lake using an improved classification tree with modified thresholds

Classification trees (CT) have been used successfully in the past to classify aquatic vegetation from spectral indices (SI) obtained from remotely-sensed images. However, applying CT models developed for certain image dates to other time periods within the same year or among different years can reduce the classification accuracy. In this study, we developed CT models with modified thresholds using extreme SI values (CT(m)) to improve the stability of the models when applying them to different time periods. A total of 903 ground-truth samples were obtained in September of 2009 and 2010 and classified as emergent, floating-leaf, or submerged vegetation or other cover types. Classification trees were developed for 2009 (Model-09) and 2010 (Model-10) using field samples and a combination of two images from winter and summer. Overall accuracies of these models were 92.8% and 94.9%, respectively, which confirmed the ability of CT analysis to map aquatic vegetation in Taihu Lake. However, Model-10 had only 58.9-71.6% classification accuracy and 31.1-58.3% agreement (i.e., pixels classified the same in the two maps) for aquatic vegetation when it was applied to image pairs from both a different time period in 2010 and a similar time period in 2009. We developed a method to estimate the effects of extrinsic (EF) and intrinsic (IF) factors on model uncertainty using Modis images. Results indicated that 71.1% of the instability in classification between time periods was due to EF, which might include changes in atmospheric conditions, sun-view angle and water quality. The remainder was due to IF, such as phenological and growth status differences between time periods. The modified version of Model-10 (i.e. CT(m)) performed better than traditional CT with different image dates. When applied to 2009 images, the CT(m) version of Model-10 had very similar thresholds and performance as Model-09, with overall accuracies of 92.8% and 90.5% for Model-09 and the CT(m) version of Model-10, respectively. CT(m) decreased the variability related to EF and IF and thereby improved the applicability of the models to different time periods. In both practice and theory, our results suggested that CT(m) was more stable than traditional CT models and could be used to map aquatic vegetation in time periods other than the one for which the model was developed.     

生态—水力学法在山区小型引水电站最小下泄流量计算中的应用

以川西某山区小型引水式电站为例,选择水深和流速为生境参数,以华鲮为生态保护目标,计算河道的最小生态需水量和对应的电站最小下泄流量,并与Tennant法、代表年法的计算结果对比。结果表明,生态水深0.12m对应的最小生态流量和Ten nant法的结果差异度为8.63%,较合理;生境参数标准值对计算结果影响显著;在选择合适的参数和参数标准值的前提下,生态—水力学法适用于山区小型河流。     

环保修井作业配套技术研究

以吉林油田为例,对油水井修井过程中产生的污染源进行查找分析。针对井下作业工序多,工况复杂的特点,分析了修井作业施工过程的污染源,对污染源采取有效的清洁生产新工艺、新设备,在地面污染防治方面取得了较好的效果。该项技术在减少原油落地损失、降低劳动强度、改善工作环境以及节能等方面取得了较好的经济和社会效益。     

Effect of short-chain organic acids and pH on the behaviors of pyrene in soil-water system

The effects of five short-chain organic acids (SCOAs) on the behaviors of pyrene in soil-water system were investigated. The influences of the quantity and species of organic acids, pH, and soil dissolved organic matter were considered. The results showed the presence of SCOAs inhibited the adsorption and promoted the desorption of pyrene in the following order: citric acid>oxalic acid>tartaric acid>lactic acid>acetic acid. The decreased extents of pyrene adsorption performance enhanced with increasing SCOA concentrations, while the decreasing rate became less pronounced at high SCOA concentrations. In the presence of organic acids, the adsorption ability of pyrene decreased with increasing pH. However, there was a slight increase of pyrene adsorption with the addition of oxalic acid, tartaric acid and citric acid above pH 8. The capacity for pyrene retention differentiated significantly between the soils with and without dissolved organic matter. The presence of SCOAs was also favorable for the decrease of pyrene adsorption on soil without dissolved organic matter. The results of this study have important implications for the remediation of persistent organic pollutants in soil and groundwater.     

Characteristics and source apportionment of VOCs measured in Shanghai,China

Volatile organic compounds (VOCs) were measured from 2007 to 2010 at the center of Shanghai, China. Because VOCs are important precursors for ozone photochemical formation, detailed information of VOC sources needs to be investigated. The results show that the measured VOC concentrations in Shanghai are dominated by alkanes (43%) and aromatics (30%), following by halo-hydrocarbons (14%) and alkenes (6%). Based on the measured VOC concentrations, a receptor model (PMF; positive matrix factorization) coupled with the information related to VOC sources (the distribution of major industrial complex, meteorological conditions, etc.) is applied to identify the major VOC sources in Shanghai. The result shows that seven major VOC sources are identified by the PMF method, including (1) vehicle related source which contributes to 25% of the measured VOC concentrations, (2) solvent based industrial source to 17%, (3) fuel evaporation to 15%, (4) paint solvent usage to 15%, (5) steel related industrial production to 12%, (6) biomass/biofuel burning to 9%, and (7) coal burning to 7%. Furthermore, ozone formation potential related to VOC sources is calculated by the MIR (maximum incremental reactivity) technique. The most significant VOC source for ozone formation potential is solvent based industrial sources (27%), paint solvent usage (24%), vehicle related emissions (17%), steel related industrial productions (14%), fuel evaporations (9%), coal burning (6%), and biomass/biofuel burning (3%). The weekend effect on the VOC concentrations shows that VOC concentrations are generally higher in the weekdays than in the weekends at the sampling site, suggesting that traffic conditions and human activities have important impacts on the VOC emissions in Shanghai.     

一次光化学污染过程中O_3和NOx的垂直梯度观测研究

为了研究2008年北京奥运会前期污染物浓度变化特征,对北京气象塔3层高度上的大气污染物(NO2和O3)进行加强观测,分析其变化特征。观测结果表明,由于北京奥运会前期采取了严格的空气质量控制措施,NO2浓度相对车辆限行前下降了45.3%,且随着高度递增逐渐降低;O3浓度最大值和日均值有所降低,其最大值出现时间较10年前提前了1~2 h,且有4 h左右处于相对平稳状态。O3浓度峰值主要是受NO2的控制,O3浓度峰值出现时间提前反映出北京大气氧化效率不断提高。对于观测期间出现光化学污染事件,利用同期气象资料和大气污染监测数据分析,发现造成这次大气污染的主要原因是气象因子:地面多处于弱高压场控制中,大气层结稳定,风力较弱(小于2 m/s),并伴随着连续高温、强辐射和低湿。     

光催化与生物技术联用工艺处理油漆废气中试研究

光催化与生物技术联用工艺用于油漆生产、加工过程有机废气的现场处理,中试实验结果表明:油漆生产、加工过程现场的主要污染物是甲苯、乙苯、间/对二甲苯和邻二甲苯等苯系物,浓度在27～55 mg/m3之间。单独使用光催化和微生物技术现场处理这些苯系物,其去除效率都不很高。虽然在中试开始阶段光催化对苯系物的平均去除效率达到了86.2%,在中试稳定期,光催化技术对苯系物的平均去除效率却只有67.6%,而生物滴滤床在成功挂膜之后对现场有机废气的平均去除效率也仅为67.5%。但是将这两种工艺联合使用之后,在中试稳定期该组合工艺对苯系物的平均去除效率可以达到99.2%。     

斜发沸石对城市污水处理厂二级出水中氨氮的处理效果研究

通过静态实验,研究天然斜发沸石去除城市污水处理二级出水中氨氮的性能。研究结果表明,投加量越大,沸石对废水中氨氮的去除率越高,但是吸附容量越低;沸石对氨氮的去除具有短时间内快速吸附,然后缓慢平衡的特点;粉末状沸石对氨氮的去除效果明显好于颗粒状沸石;pH对氨氮去除率有显著影响,pH值为6时,沸石对氨氮的去除率最高。NaCl和NaOH溶液对沸石的改性具有明显的效果,HCl溶液对沸石的改性作用不明显。