Risks from sediments contaminated with organochlorine pesticides in Hangzhou,China

In September 2009, we investigated the residues, enantiomer fractions (EFs) and biological risks of organochlorine pesticides (OCPs), including dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs), in three different depth ranges (0–5 cm, 5–10 cm and 10–15 cm) of sediments from 15 sites in Hangzhou, China. The concentration (ng g^?1 dry weight) ranges of HCHs and DDTs in surface sediments were 0.74–5.8 and 0.76–17, respectively. The vertical distribution of mean OCP concentrations was in the order of 10–15 cm > 5–10 cm > 0–5 cm and implied that the residues of HCHs and DDTs gradually decreased after they were banned. The residues of OCPs in the study area mainly originated from the historical OCP use. The isomer ratios of <alpha>-HCH (α-HCH)/<gamma>-HCH (γ-HCH) (0.10–7.6) implied that HCH residues were derived not only from historical technical HCH use but also from additional use of lindane in this area. The isomer ratios of o,p′-DDT/p,p′-DDT (51% of samples were in the range of 0.3–1.3) suggested that both dicofol-type DDT and technical DDT applications may be present in most study areas. The (+)-enantiomers of α-HCH and o,p′-DDT were more prevalent than (?)-enantiomer in most samples with the fractions contain different enantiomers greater than 0.5. DDTs, especially p,p′-DDE, are the main OCP species of more ecotoxicological concern in Hangzhou.     

Influence of toxicity and dissipation of racemic fenoxaprop and its R-enantiomer in Scenedesmus obliquus suspension by cyclodextrins

Cyclodextrins (CDs), a class of cyclic oligosaccharide molecules containing a variety of chiral centre, are capable of recognizing enantiomeric molecules through the formation of inclusion complexes. In this work, we selected three types of CDs, β-CD and its two derivatives, randomly methylated β-CD (RAMEB) and hydroxypropyl β-CD (HP-β-CD), to evaluate effects on toxicity of racemic fenoxaprop (rac-FA) and its R-enantiomer (R-FA) to freshwater alga Scenedesmus obliquus (S. obliquus) and their dissipation in S. obliquus suspension with and without CDs addition, respectively, in an attempt to get more detail about enantioselective behavior of fenoxaprop acid (FA) in the environment, using CDs as a remediation agent for FA and formulation additive for fenoxaprop-p-ethyl (FE). The significant difference between rac-FA and R-FA was not observed in their acute toxicity to S. obliquus and dissipation in S. obliquus suspension. RAMEB had no effect on either toxicity of FA to S. obliquus or dissipation of FA in S. obliquus suspension, and it also didn't change the extent of enantioselectivity in toxicity of FA to S. obliquus. But the addition of a certain amount of β -CD and HP-β -CD reduced the toxicity of FA to S. obliquus and increased dissipation of FA in S. obliquus suspension, as well as changed the enantioselectivity in toxicity of FA to S. obliquus. The results indicated β-CD and HP-β-CD could be used as a promising agent for remediation of aquatic contamination produced by FA, and RAMEB might be used as potential formulation additives for FE, the parent compound of FA, as RAMEB didn't decrease activity of R-FA and might be environmentally safer than the conventional additives.     

含氟水治理研究进展

综述了近年来国内外在吸附,化学沉淀和混凝沉降３种常用的除氟方法上的研究进展情况,并对除氟机理进行了探讨。     

Identifying sources and assessing potential risk of heavy metals in soils from direct exposure to children in a mine-impacted city, Changsha, China

Heavy metal pollutants in soils can usually enter the human body and pose heath risks through a soil-crop-human body pathway (indirect exposure) or soil-human body pathway (direct exposure). Previous studies often neglected the direct exposure in human health risk assessment, especially for children. We collected surface soil samples from urban and suburb areas in Changsha City, China, to analyze the content ofAs, Cd, Hg, Ni, Pb, and Zn. A combination of principal component analysis, geostatistics, and triangulated irregular network (TIN) model was successfully used to discriminate the sources of heavy metals. The direct exposure method, sequential indicator simulation, and geographical information system (GIS) technologies were used to perform a health risk assessment of heavy metal exposure to children living in the study area. Results show that heavy metal contamination in Changsha may originate from coal usage and industrial activities. One thousand equiprobable realizations suggest that not all sites within the study area may be suitable for housing or allotments without remediation. Most high hazard indexes are located in the suburb and mining areas. Moreover, arsenic presents a high health risk in comparison with other elements. Compared with inhalation and dermal contact in direct soil exposure, soil ingestion is the largest contribution to potential health risks for children. This study indicates that we should attach great importance to the direct soil exposure for children's health.     

基于荧光素酶发光检测体系的几种工业污染物综合毒性评价

利用化工污染物能抑制荧光素酶催化发光反应这一特性,对水质中6种化工化合物分别进行毒性测试,建立一种快速检测水质中化工污染物毒性的生物学方法。实验结果表明,对苯二酚、4-氨基酚、苯胺、氯仿、盐酸邻联甲苯胺和硫柳汞的EC50值分别为:5.563、10.225、20.236、38.432、8.827和0.6 mg/L,6种污染物毒性大小依次为:硫柳汞>对苯二酚>盐酸邻联甲苯胺>4-氨基酚>苯胺>氯仿,相关系数>0.95。该方法为进一步研究基于荧光素酶反应体系检测水质中化工污染物综合毒性的生物传感器方法奠定基础。     

生物膜与A/O工艺耦合快速降解氨氮

应用由城市污水处理厂序批式间歇反应器(SBR)中筛选得到的4株特殊氨氧化菌,分别在SBR和有回流的生物膜与A/O工艺耦合体系培养中,考察其降解低碳高氨氮废水的功能.结果表明,自养硝化与异养氨氧化菌的混合菌群较单一自养硝化菌株降解氨氮速率快;在生物膜与A/O工艺耦合系统中,自养硝化与异养氨氧化菌协同代谢加速氨氮氧化脱除,氨氮脱除速率远比SBR系统快.对生物膜与A/O工艺耦合系统中氨氮脱除动力学进行了研究,模拟了NH4 、NO2-质量浓度与氨氮脱除比速率之间的关系,模型得到了较好的验证.     

矿化垃圾生物反应床处理含酚废水工艺研究

研究了矿化垃圾生物反应床处理含酚废水的工艺参数.矿化垃圾生物反应床在经过驯化后,形成了稳定的微生物系统,反应床对有机酚具有较高的去除率.有机酚的去除率受湿干比影响较大,随着配水速率的提高,反应床对有机酚的去除率逐渐下降,配水速率大于0.342 cm/min时,去除率急速下降.在进水有机酚质量浓度为20 mg/L,连续配水时间6 h,湿干比为1∶8,配水速率为0.254 cm/min的条件下,反应床出水可达到或接近国家三级排放标准.     

Environmental sustainability analysis of dairy bedding regeneration system based on emergy evaluation and life cycle assessment methods

Environmental Science and Pollution Research - Dairy farm bedding can be produced by composting technology using dairy manure, which offers advantages in terms of cost, availability, and economic...     

基于细观结构的压实黄土抗剪特性试验研究∗

压实度是填方工程质量验收的主要控制项目之一,较高压实度对改善黄土力学性能效果显著。为全面系统分析压实对黄土抗剪特性的影响规律,更好地揭示较高压实度提高黄土抗剪能力的内在原因,利用室内三轴剪切试验和电镜扫描试验,基于 4 种不同压实度,对甘肃省临夏市北塬地区压实黄土的抗剪特性和细观结构进行了研究。研究表明：压实黄土应力—应变满足双曲线形式,较高压实度对提高黄土体抗剪强度和剪切模量作用显著;较高压实度通过改变土体颗粒之间的接触形式以改善黄土体抗剪特性,主要表现为压实黄土颗粒之间的接触形式随着压实度的增加由棱边接触、支架镶嵌向面接触逐渐过渡;较高压实度通过改变土体孔隙尺度特征和形态分布以改善土体抗剪特性,主要表现为随着压实度的增加孔隙分布范围内微、小孔隙的含量增加,中、大、特大孔隙含量减小,孔隙形状也相对变得圆滑。     

农药在土壤－水环境中归宿的主要支配因素──吸附和脱附

综述了近年来农药在土壤－水环境中吸附－脱附研究的实验方法、影响因素、数学描述、作用机理等方面的工作。重点讨论了农药与土壤粘土矿物、有机物（腐殖酸、富菲酸等）的物理化学键合机理。