Spatial distribution of soil heavy metal pollution estimated by different interpolation methods: accuracy and uncertainty analysis

Mapping the spatial distribution of contaminants in soils is the basis of pollution evaluation and risk control. Interpolation methods are extensively applied in the mapping processes to estimate the heavy metal concentrations at unsampled sites. The performances of interpolation methods (inverse distance weighting, local polynomial, ordinary kriging and radial basis functions) were assessed and compared using the root mean square error for cross validation. The results indicated that all interpolation methods provided a high prediction accuracy of the mean concentration of soil heavy metals. However, the classic method based on percentages of polluted samples, gave a pollution area 23.54-41.92% larger than that estimated by interpolation methods. The difference in contaminated area estimation among the four methods reached 6.14%. According to the interpolation results, the spatial uncertainty of polluted areas was mainly located in three types of region: (a) the local maxima concentration region surrounded by low concentration (clean) sites, (b) the local minima concentration region surrounded with highly polluted samples; and (c) the boundaries of the contaminated areas.     

以剩余污泥水解酸化液为外加碳源的污水生物脱氮

为解决低碳氮比污水生物脱氮过程反硝化碳源不足的问题,利用剩余污泥水解酸化液为外加碳源,通过具有曝气段与非曝气段的一体化曝气生物滤池（BAF）,研究低碳氮比污水生物脱氮的性能与工艺条件。实验结果表明,预处理后的水解酸化液VFAs为3134．9～5251．4mg／L、ThODVFAs／COD为59．87％～91．85％,适合作为生物脱氮的外加碳源;水解酸化液的投配量、进水TN浓度对系统生物脱氮效果的影响较大,气水比、曝气段与非曝气段比例对系统的硝化和反硝化性能有重要的影响;在温度为25±1℃,水解酸化液COD平均为7555．1mg／L,进水TN、NH4-N和COD分别平均为43．88mg／L、39．04mg／L和56．8mg／L,碳源与污水投配的流量比为1：75的条件下,当BAF水力停留时间（HRT）为8h、曝气段与非曝气段比例为3：3、气水比为10：1、回流比为2：1时,NH4-N和TN的去除率分别超过98％和75％,出水COD平均为28．6mg／L。研究指出,剩余污泥水解酸化液经过预处理后可用作低碳氮比污水生物脱氮的外加碳源,有效地提高了反硝化效果,并不会造成二次污染,同时又可以实现剩余污泥的减量化和资源化。     

Reducing H2S production by O2 feedback control during large-scale sewage sludge composting

Hydrogen sulfide (H₂S) production patterns and the influence of oxygen (O₂) concentration were studied based on a well operated composting plant. A real-time, online multi-gas detection system was applied to monitor the concentrations of H₂S and O₂ in the pile during composting. The results indicate that H₂S was mainly produced during the early stage of composting, especially during the first 40 h. Lack of available O₂ was the main reason for H₂S production. Maintaining the O₂ concentration higher than 14% in the pile could reduce H₂S production. This study suggests that shortening the interval between aeration or aerating continuously to maintain a high O₂ concentration in the pile was an effective strategy for restraining H₂S production in sewage sludge composting.     

新型混凝剂聚磷氯化铝铁的表征及应用

以FeCl3·6H2O、AlCl3·6H2O和Na2HPO4·12H2O为主要原料,采用共聚工艺,制备了聚磷氯化铝铁(PPAFC)混凝剂.采用FTIR及SEM进行结构表征,推断磷酸根为与聚合氯化铝铁(PAFC)接聚,而不是磷酸盐与PAFC之间简单的物理混合.实验结果表明,以PPAFC处理含油乳化液废水、造纸废水及受污染...     

UV/H2O2联合氧化法去除畜禽养殖废水中抗生素

随着畜禽养殖业的迅猛发展,畜禽养殖废水污染问题日益突出,尤其是养殖过程中大量使用抗生素,致使畜禽养殖废水含有抗生素,成为一类新型环境危害污染物.如何有效去除畜禽养殖废水中的抗生素,成为国内外研究热点.采用UV/H2O2联合氧化法去除畜禽养殖废水中抗生素(磺胺甲恶唑、磺胺噻唑、磺胺甲噻二唑、磺胺二甲氧嘧啶、磺胺二甲嘧啶)...     

硫酸盐还原条件下三氯乙烯的降解研究

三氯乙烯(TCE)是地下水和土壤中主要的有机污染物之一.以受TCE等氯代烃严重污染的地下泥样为材料,采用室内模拟的方法.研究硫酸盐初始质量浓度为100、500、2 500 mg/L时.硫酸盐对TCE降解的影响.结果表明.高浓度硫酸盐更有利于TCE的降解;在硫酸盐还原条件下,通过添加2-溴乙基磺酸钠抑制产甲烷菌.发现产甲烷菌在TCE的降解过程中起到很重要的作用;硫酸盐浓度变化与TCE降解趋势一致.     

光源和溶剂对十溴联苯醚光降解的影响

研究了不同光源和溶剂对十溴联苯醚(DecaBDE)光降解特性的影响,并对其降解产物进行了探讨.结果表明,在所试光源和溶剂条件下,DecaBDE均有一定程度的光降解,且都近似符合一级降解动力学.同一光源下,不同溶剂对DecaBDE降解表现出不同的影响.在太阳光照射下,DecaBDE降解速率为甲苯>甲醇>正己烷>正己烷/丙酮>甲醇/水>乙醇/水;在模拟光源照射下,DecaBDE降解速率为甲苯>甲醇>甲醇/水>乙醇/水>正己烷>正己烷/丙酮;在紫外光照射下,DecaBDE降解速率为甲苯>甲醇>正己烷/丙酮>正己烷>甲醇/水>乙醇/水.同一溶剂中,DecaBDE降解速率均为紫外光>太阳光>模拟光源.尽管光源和溶剂对DecaBDE降解速率产生了一定影响,但降解途径基本一致,均为DecaBDE经光解脱溴产生低溴联苯醚.     

Measuring atmospheric composition change

Scientific findings from the last decades have clearly highlighted the need for a more comprehensive approach to atmospheric change processes. In fact, observation of atmospheric composition variables has been an important activity of atmospheric research that has developed instrumental tools (advanced analytical techniques) and platforms (instrumented passenger aircrafts, ground-based in situ and remote sensing stations, earth observation satellite instruments) providing essential information on the composition of the atmosphere. The variability of the atmospheric system and the extreme complexity of the atmospheric cycles for short-lived gaseous and aerosol species have led to the development of complex models to interpret observations, test our theoretical understanding of atmospheric chemistry and predict future atmospheric composition. The validation of numerical models requires accurate information concerning the variability of atmospheric composition for targeted species via comparison with observations and measurements.In this paper, we provide an overview of recent advances in instrumentation and methodologies for measuring atmospheric composition changes from space, aircraft and the surface as well as recent improvements in laboratory techniques that permitted scientific advance in the field of atmospheric chemistry. Emphasis is given to the most promising and innovative technologies that will become operational in the near future to improve knowledge of atmospheric composition. Our current observation capacity, however, is not satisfactory to understand and predict future atmospheric composition changes, in relation to predicted climate warming. Based on the limitation of the current European observing system, we address the major gaps in a second part of the paper to explain why further developments in current observation strategies are still needed to strengthen and optimise an observing system not only capable of responding to the requirements of atmospheric services but also to newly open scientific questions.     

酸渣制备无水硫酸钠

采用炼油厂酸渣经水稀释后,添加含钠化合物进行中和反应,制备无水Na_2SO_4.最佳工艺条件为:将酸渣用水稀释20倍,按n(Na_2CO_3):n(SO_4~(2-))=1.10或n(NaOH):n(SO_4~(2-))=1.20的比例加入Na_2CO_3,溶液或NaOH溶液,油水分离去除油相后蒸发、干燥,在650℃下灼烧后溶解、过滤、蒸发、结晶,得到Na_2SO_4产品.NaCO_3法可将酸渣中约78%的SO_4~(2-)转化到产品Na_2SO_4中;NaOH法可将酸渣中约66%的SO_4~(2-)转化到产品Na_2SO_4中.制备的无水Na_2SO_4产品均达到GB/T6009-2003<工业无水硫酸钠>二类标准.