土壤-植物系统中的微界面过程及其生态环境效应

土壤 植物系统是地球生态系统中与人类生存与健康关系最为密切的亚系统 .该系统中的水分、养分 污染物的运移必须历经土壤固 液界面、根土界面 (根际微环境 )、细胞跨膜运输和植物体内不同组织和细胞内不同组分间的再分配等微界面过程 .这些微界面过程涉及到系统中许多生物、生物化学和物理化学反应机理 ,与植物对土壤中养分高效利用、污染物迁移转化及其归宿具有密切的关系 .理解这些微界面过程对提高农作物生长、改善土壤环境质量和提高农产品安全品质具有直接的理论和实践指导意义     

A2/O工艺污水处理厂运行参数优化的数值模拟

为了确定活性污泥系统A2/O工艺的最佳运行工况,将FCASM2-HYDRO模型应用于德清狮山污水处理厂A2/O工艺污水处理过程的数值模拟中.根据FCASM2-HYDRO模型分别建立了厌氧池、缺氧池、好氧池的数值模拟方程.采用有限元法求解,并使用MATLAB语言建立一套数值模拟程序.利用数值模拟程序分别模拟了工艺参数条件、流量、进水碳氮磷比对德清狮山污水处理厂污水处理效果的影响.由数值模拟结果得到了该厂目前最佳的运行工况:污泥回流比为50%,混合液回流比为100%,泥龄为15d,进水COD:NH4 -N:PO34-P比控制为100:8:1.     

α-Fe2O3砂芯微球制备及紫外辅助下活化PMS降解AO7

以FeCl₃为原料，尿素为沉淀剂，抗坏血酸为还原剂，聚乙烯吡咯烷酮为结构导向剂，纳米碳粉为模板，水热法制备了一种新型α-Fe₂O₃砂芯微球.通过透射电镜（TEM）、扫描电镜（SEM）、X射线衍射（XRD）和比表面积及孔径分析（BET/BJH）等手段对其结构和性能进行表征.结果表明新型α-Fe₂O₃砂芯微球尺寸均匀，直径为50μm左右，是由直径40nm"米粒状"纯相α-Fe₂O₃自聚而成，S_BET为25.45~32.46m²/g.在紫外（UV，高压汞灯）辐射下能够活化过硫酸盐（PMS）产生强氧化性的硫酸根自由基（SO₄^-·）.40min内AO7的降解率可达98.6%，采用电子自旋共振（ESR）技术鉴定了主要的活性氧自由基（ROS）为SO₄^-·.此外发现PMS作为一种电子捕获剂，能有效抑制光生电子（e_CB^-）和空穴（h_VB⁺）的复合，AO7能直接和h_VB⁺、SO₄^-·和羟基自由基（OH·）反应而迅速被氧化降解；α-Fe₂O₃回收重复使用10次，仍可以达到80%以上的去除率.通过考察α-Fe₂O₃投加量、PMS浓度、初始pH值、阴离子和初始AO7浓度等不同条件对AO7降解率的影响，发现在初始pH值为7.0，α-Fe₂O₃的投加量为1.0g/L，PMS浓度为0.3g/L时，40min内对AO7的降解率可以达到99%以上；阴离子CO₃^2-、NO₃^-以及Cl^-对该体系均有不同程度的促进作用.     

气液介质阻挡放电降膜反应器降解甲硝唑实验研究

针对抗生素药物甲硝唑难生物降解的难题,首次借助气液冷等离子体高级氧化的方法,采用连续气液介质阻挡放电降膜反应器对其进行降解实验研究.同时,定量测量和评价了反应器的·OH氧化能力,考察了不同初始浓度、不同放电气氛及加入叔丁醇对甲硝唑降解效果的影响,并重点探讨了·OH对甲硝唑降解的作用.结果表明,当甲硝唑在反应器内停留时间为3 s时,初始浓度为5、10和20 mg·L~(-1)的甲硝唑溶液的转化率分别为97.8%、85.4%和78.7%,说明气液介质阻挡放电降膜反应器对甲硝唑具有显著的氧化降解能力.同时实验进一步发现,氧化反应过程中·OH对甲硝唑的降解具有重要贡献.     

大型钢铁企业典型工序碳排放系数的确定方法探讨

为准确合理地确定适合于钢铁行业实际的碳排放系数,通过碳平衡算法求出了各工序的碳排放量,然后按碳排放系数的定义反算出了各工序的碳排放系数.同时,通过对某大型钢铁企业焦化、烧结、炼铁3个典型工序的原料产能的实测数据调查,首先基于碳平衡方程计算出典型工序的碳排放量,然后由碳排放量计算其碳排放系数.最后以该大型钢铁企业2009年的调查数据为例,按本方法计算出的焦化、烧结、炼铁工序的碳排放系数分别为0.518、0.210、1.375,与IPCC提供的默认值(0.56、0.20、1.35)极为吻合.这一结果表明,该方法用于我国钢铁行业碳排放系数体系的建立是可行的.     

Hydrodynamic characteristics of a four-compartment periodic anaerobic ba ed reactor

Periodic anaerobic baffled reactor (PABR) is a novel reactor based on the design concept of anaerobic baffled reactor (ABR). Residence time distribution (RTD) studies on both clean and working reactors at the same hydraulic residence time (HRT) of 2 d were carried out to investigate the dead spaces and mixing patterns in PABRs at different organic loading rates (OLRs) in various switching manners and frequencies.The results showed that the fraction of dead space in PABR was similar to that in ABR,which was low in comparison with other reactor designs.Dead space may be divided into two categories,hydraulic and biological.In RTD studies without biomass,the hydraulic dead space in the PABR run in an"every second"switching manner with T=2 d was the lowest whereas that in the PABR run in a T=∞(ABR) switching manner was the highest.The same trend was obtained with the total dead space in RTD studies with biomass no matter what the OLR was.Biological dead space was the major contributor to dead space but affected decreasingly at higher OLR whichever switching manner the PABR run in.The flow patterns within the PABRs were intermediate between plug-flow and perfectly mixed under all the conditions tested.     

泸沽湖沉积物－水界面扩散作用对上覆水体基本化学组成的影响

通过云南泸沽湖──半封闭深水湖泊湖水和沉积物孔隙水中Ｃａ２＋、Ｋ＋、Ｎａ＋、ＨＣＯ等基本组分及ｐＨ等剖面分布的研究,结果表明,这些基本组分可以自底部沉积物向上覆水体扩散迁移。定量地估算了扩散通量及其对上覆水体的影响程度,说明湖泊沉积物－水界面作用在控制整个水体水化学基本组成中起着重要的作用。     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Gaseous elemental mercury concentration in atmosphere at urban and remote sites in China

An investigation of gaseous elemental mercury concentration in atmosphere was conducted at Beijing and Guangzhou urban, Yangtze Delta regional sites and China Global Atmosphere Watch Baseline Observatory (CGAWBO) in Mt. Waliguan of remote continental area of China. High temporal resolved data were obtained using automated mercury analyzer RA-915 . Results showed that the overall hourly mean Hg0 concentrations in Mt. Waliguan were 1.7± 1.1 ng/m3 in summer and 0.6±0.08 ng/m3 in winter. The concentration in Yangtze Delta regional site was 5.4±4.1 ng/m3, which was much higher than those in Waliguan continental background area and also higher than that found in North America and Europe rural areas. In Beijing urban area the overall hourly mean Hg0 concentrations were 8.3±3.6 ng/m3 in winter, 6.5±5.2 ng/m3 in spring, 4.9±3.3 ng/m3 in summer, and 6.7±3.5 ng/m3 in autumn, respectively, and the concentration was 13.5±7.1 ng/m3 in Guangzhou site. The mean concentration reached the lowest value at 14:00 and the highest at 02:00 or 20:00 in all monitoring campaigns in Beijing and Guangzhou urban areas, which contrasted with the results measured in Yangtze Delta regional site and Mt. Waliguan. The features of concentration and diurnal variation of Hg0 in Beijing and Guangzhou implied the importance of local anthropogenic sources in contributing to the high Hg0 concentration in urban areas of China. Contrary seasonal variation patterns of Hg0 concentration were found between urban and remote sites. In Beijing the highest Hg0concentration was in winter and the lowest in summer, while in Mt. Waliguan the Hg0 concentration in summer was higher than that in winter. These indicated that different processes and factors controlled Hg0 concentration in urban, regional and remote areas.