Changes of copper speciation in maize rhizosphere soil

Chemical forms of copper in the rhizosphere and bulk soil of maize were investigated using rhizobox cultivation and sequential extraction techniques. The copper accumulations were also determined. The results demonstrated that there were continuous changes in copper fractionation within the maize rhizosphere. Initially, the amount of exchangeable copper increased before dropping below the initial level after 40 days or so. Carbonate associated copper followed a similar trend of change, but with a slower pace than the exchangeable copper. The increase in carbonate associated copper only become evident after 30 days, with the net loss occurring after 60 days. There were also initial increases in oxide bound copper as well as decreases in the organic matter associated copper, both followed by a turnover after 40-50 days. The accumulation of copper in the maize plant was found to be biomass dependent. The amount of accumulated copper absorbed in the plant material exceeded the initial quantity of the exchangeable copper in the soil, revealing a transformation from less bioavailable to more bioavailable fractions. During cultivation, decreases in redox potential and increases in pH, dissolved organic carbon (DOC), and microbial activity in the maize rhizosphere were observed. The change in copper speciation may result from root-induced changes in DOC, redox potential, and microbial activity in the rhizosphere.     

Multivariate statistical study of heavy metal enrichment in sediments of the Pearl River Estuary

The concentrations and chemical partitioning of heavy metals in the sediment cores of the Pearl River Estuary were studied. Based on Pearson correlation coefficients and principal component analysis results, Al was selected as the concentration normalizer for Pb, while Fe was used as the normalizing element for Co, Cu, Ni and Zn. In each profile, sections with metal concentrations exceeding the upper 95% prediction interval of the linear regression model were regarded as metal enrichment layers. The heavy metal accumulation mainly occurred at sites in the western shallow water areas and east channel, which reflected the hydraulic conditions and influence from riparian anthropogenic activities. Heavy metals in the enrichment sections were evaluated by a sequential extraction method for possible chemical forms in sediments. Since the residual, Fe/Mn oxides and organic/sulfide fractions were dominant geochemical phases in the enriched sections, the bioavailability of heavy metals in sediments was generally low. The 206Pb/207Pb ratios in the metal-enriched sediment sections also revealed the influence of anthropogenic sources. The spatial distribution of cumulative heavy metals in the sediments suggested that the Zn and Cu mainly originated from point sources, while the Pb probably came from non-point sources in the estuary.     

3种不同基质潜流湿地对磷的去除效果

基质是潜流式人工湿地污水处理系统的重要组成部分，直接影响到系统的处理效果。本文研究了由沸石、页岩陶粒和碎石3种不同基质构建的潜流式人工湿地对磷的去除效果。结果表明，在设计水力停留时间3d，连续进出水情况下，碎石单元对磷的去除效果最好，页岩陶粒单元次之，沸石单元效果最差，平均去除率分别为95％、60％和35％。在潜流式人工湿地污水处理系统运行初期观察到磷释放现象，沸石单元最为明显。进水磷浓度较低时，磷的去除率随浓度升高而升高，当正磷、总磷浓度分别升高到2．4—2．5和3．1～3．3mg／L时，正磷、总磷的去除率开始迅速下降。     

高级氧化法脱除PVA浆料的清洁生产新工艺研究

为了研究高级氧化法脱除聚乙烯醇（PVA）浆料清洁生产新工艺的可行性，研究了3种高级氧化法UV／H2O2、UV／TiO2、Nation-Fe^2＋／H2O2对含PVA溶液的氧化降解，其降解效果依次为iUV／H2O2〉Nation-Fe^2＋／H2O2〉UV／TiO2。对于UV／H2O2法，PVA降解速率与H2O2的初始浓度成正相关，且H2O2浓度为2．95mmol／L时14min内就能使PVA的去除率达到98％；pH和温度对PVA的氧化降解效果影响不明显。在此基础上，对建立在高级氧化法基础上的退浆新工艺进行了探讨，结果表明，在65℃和75℃下，高级氧化法条件下的纯棉织物PVA退浆率分别达到70．16％和95．65％；该法不仅可以促进PVA从纯棉织物上的脱附，而且可以达到对PVA的较高降解效果，使得所排退浆废水的生化处理难度明显降低。     

人工湿地处理系统中多环芳烃的行为

采用Oasis HLB柱固相萃取的前处理技术,以气相色谱质谱联用仪（GC/MS）的分析方法,对我国北方永定河上游黑土洼人工湿地中多环芳烃污染的特征以及分布规律进行了研究.结果表明,该湿地系统以低环数多环芳烃污染为主,其中浓度最高的是菲和蒽,未检出高环数（5环、6环）多环芳烃.通过比较进水和出水的浓度,湿地系统总体上不能有效去除进水中的多环芳烃.但是比较不同工艺单元进出水浓度,复氧、植物根系及微生物等均影响到多环芳烃的去除效果,去除率在28%～65%之间.     

高效喷淋泡沫脱硫技术及装置的应用

SO2是产生酸雨的主要气体，其主要来源于工业燃煤锅炉。以沈阳一家电厂为例，该厂选用新型高效的喷淋泡沫脱硫除尘器对锅炉排放的SO2进行治理。进入喷淋泡沫塔前的SO2平均浓度为2780mg／m^3，经脱硫后出塔平均浓度为289．3mg／m^3，去除率为89．6％。结果表明，这种有别于传统湿法的新型高效的喷淋泡沫脱硫技术及装置具有脱硫效率高、装置占地少、运行稳定、沉淀物易于回收利用等特点，对锅炉排放的SO2进行治理是非常有效的。     

Ce掺杂纳米TiO2光催化剂的制备及降解甲醛的研究

介绍了溶胶-凝胶法制备Ce离子掺杂纳米TiO2的工艺流程.采用X射线衍射(XRD)、紫外可见分光光度法(UV-Vis)等方法表征了Ce掺杂TiO2的相组成、紫外可见漫反射率与掺杂量的关系.结果表明,掺杂的TiO2在520℃、650℃焙烧2 h呈锐钛矿结构,在520℃焙烧2 h的TiO2的晶粒尺寸大约为20 nm,而掺杂Ce后其晶粒尺寸均减小,大约为12nm.UV-Vis吸光度分析表明,掺Ce后吸收带边明显发生红移,但随着Ce掺杂浓度的增大,其对可见光的吸收影响不大.光催化降解反应表明,未掺杂Ce的TiO2反应2 h后对甲醛的没有降解作用,而Ce掺杂TiO2反应2 h后甲醛降解率达15%.     

用于干式脱污的CaO蒸汽活化实验研究

利用小型活化转炉实验台对以CaO为主要成分的钙基脱污剂在300～650℃的温度范围内进行蒸汽活化处理,结合X射线衍射和压汞仪的分析结果,初步探讨了蒸汽活化的机理.研究表明,蒸汽活化温度在600℃以上时,脱污剂孔隙结构有显著的改善,比孔容积和比表面积有着显著的增加,微孔(＜100nm)的数量大量增加,而低温下蒸汽活化的效果不是十分明显;研究还发现高温下延长活化时间有利于改善脱污剂的孔隙结构.     

错流式动态膜-生物反应器中污泥活性的研究

应用错流式动态膜-生物反应器(CDMBR)对己内酰胺废水进行了180 d的实验,实验过程中测定反应器的膜出水和上清液的水质,并对污泥进行了耗氧呼吸速率测定.结果表明,上清液COD一直保持在100mg/L以下,而膜出水的则保持在50 mg/L以下,膜对上清液的COD去除率达50%,而对氮的去除没有贡献.可溶性细胞产物(SMP)在反应器内容易积累,停留足够的时间后能被生物降解.通过投加抑制剂测定耗氧呼吸速率,发现异养菌、硝化细菌和亚硝化细菌的活性由于F/M的降低和SMP积累受到一定的抑制,但不影响系统的处理效率.跨膜压力、膜面流速越大,通量衰减得也就越快.     

纳米级铁粉脱氯降解四氯化碳

四氯化碳的生产和使用,给人类带来了较大危害.为此,采用纳米铁粉这一新方法对其进行脱氯处理.试验以纳米级铁粉对四氯化碳的脱氯率为考察指标,选用L25(56)正交试验方案,考察了降解介质的初始pH值、纳米铁粉的质量、降解温度、摇床转速和脱氯时间5个影响因素.结果表明,pH值这一因素有极显著影响;在得出的纳米铁粉对四氯化碳脱氯的最佳工艺条件下,获得了99.5%的脱氯率,为有机氯化物脱氯开辟了一条新途径.