厌氧-缺氧-好氧处理出水中溶解性有机物组分的特征分析

本研究利用XAD-8大孔树脂对某城市污水处理厂的厌氧-缺氧-好氧(A2O)工艺出水中的溶解性有机物进行了组分分离,分析了各组分的溶解性有机碳(Dissolved organic carbon,DOC)、紫外-可见光谱和遗传毒性.结果表明,污水中亲水性物质和疏水酸性物质的DOC含量分别占总DOC含量的65%和24%.亲水性物质组分中的芳香族化合物含量显著高于其它组分,但是单位质量的亲水性物质、疏水酸性物质和疏水碱性物质中的芳香族化合物含量相近.污水具有一定的遗传毒性,主要遗传毒性物质为亲水性物质和疏水酸性物质,而疏水碱性物质和疏水中性物质则未检出遗传毒性.     

Formation potentials of typical disinfection byproducts and changes of genotoxicity for chlorinated tertiary e uent pretreated by ozone

The effects of ozonation on the formation potential of typical disinfection byproducts (DBPs) and the changes of genotoxicity during post chlorination of tertiary effluent from a sewage treatment plant were investigated. Ozonation enhanced the yields of all detected chlorine DBPs except CHCl3. At a chlorine dose of 5 mg/L, the three brominated THMs and five HAAs increased, while chloroform decreased with the increase of ozone dose from 0 to 10 mg/L (ozone dose in consumption base). At a chlorine dose of 10 mg/L, the two mixed bromochloro species THMs and two dominant HAAs (DCAA and TCAA) firstly increased and then decreased with the increase of ozone dose, with the turning point approximately occurring at an ozone dose of 5 mg/L. The genotoxicity detected using umu test, on the other hand, was removed from 7 μg 4-NQO/L to a negligible level by ozonation under an ozone dose of 5 mg/L. Chlorination could further remove the genotoxicity to some extent. It was found that SUVA (UV absorbance divided by DOC concentration) might be used as an indicative parameter for monitoring the removal of genotoxicity during the oxidation.     

太湖周边典型区域水体污染的遗传毒性研究

 应用SOS/umu法对太湖周边12个典型区域水体的遗传毒性进行研究,结果表明:各采样点水样的遗传毒性诱导率IR与提取物的水样体积呈较明显的剂量-效应关系,其中,T1、T2、T3、T7、T8、T9、T10水样提取物有遗传毒性效应;各区域水体遗传毒性随水情期大小排序为:汛前期>汛期,对于污染源较稳定的区域,水体遗传毒性在各水期变化较小.     

Sequential use of ultraviolet light and chlorine for reclaimed water disinfection

Several disinfection processes of ultraviolet (UV), chlorine or UV followed by chlorine were investigated in municipal wastewater according to the inactivation of Escherichia coli, Shigella dysenteriae and toxicity formation. The UV inactivation of the tested pathogenic bacteria was not affected by the quality of water. It was found that the inactivated bacteria were obviously reactivated after one day in dark. Fluorescent light irradiation increased the bacteria repair. The increase of UV dosage could cause more damage to bacteria to inhibit bacteria self-repair. No photoreactivation was detected when the UV dose was up to 80 mJ/cm² for E. coli DH5αup, and 23 mJ/cm² for S. dysenteriae. Nevertheless, sequential use of 8 mJ/cm² of UV and low concentration of chlorine (1.5 mg/L) could effectively inhibit the photoreactivation and inactivate E. coli below the detection limits within seven days. Compared to chlorination alone, the sequential disinfection decreased the genotoxicity of treated wastewater, especially for the sample with high NH₃-N concentration.     

In vitro cytotoxicity of CdSe/ZnS quantum dots with different surface coatings to human keratinocytes HaCaT cells

Quantum dots (QD) nanoparticles have been widely used in biomedical and electronics fields, because of their novel optical properties. Consequently it confers enormous potential for human exposure and environmental release. To increase the biocompatibility of QDs, a variety of surface coatings or functional groups are added to increase their bioactivity and water solubility. Human adult low calcium high temperature (HaCaT) cells are the epithelial cells derived from adult human skin that exhibits normal differentiation capacity and a DNA fingerprint pattern that is unaffected by long-term cultivation, transformation, or the presence of multiple chromosomal alternations. Human keratinocytes, HaCaT cells were used to systematically evaluate the cytotoxicity of biocompatible QD made of CdSe metal core and ZnS shell with three different coatings and at three different wavelengths (530, 580 and 620 nm). In terms of half- maximal inhibitory concentration, QSA-QDs with amine-polyethyleneglycol coating and QSH-QDs with amphiphilic polymer coating were not cytotoxic, while QEI-QDs with polyethylenimine coating were highly toxic to the HaCaT cells in comparison to a reference CuInS2/ZnS. QEI-QDs led to significant increase in reactive oxygen species, decrease in mitochondrial membrane potential and DNA damage in HaCaT cells. The mechanisms of toxicity of QEI-530 and QEI-580 can be attributed to the combination of intracellular reactive oxygen species production and loss of MMP. The QDs toxicity can be attributed to the polyethylemimine surface coating which was highly toxic to cells in comparison with amine-polyethyleneglycol, but not due to the release of cadmium ions.     

杀虫剂三唑磷对沼水蛙（Hylarana guentheri）蝌蚪的遗传毒性研究

采用微核试验和单细胞凝胶电泳技术(彗星试验)检测了不同浓度(0、0.2、0.4、1.2、2.0、2.8mg·L-1)的三唑磷溶液对沼水蛙蝌蚪遗传毒性的影响.结果表明,当三唑磷染毒24h(≥1.2mg·L-1)及72h(≥0.2mg·L-1)后,蝌蚪微核率和核异常率比对照组均有极显著的提高.在同一时间下,随着三唑磷浓度的增大,蝌蚪微核率和核异常率总体上随之增加;在同一浓度下,随着染毒时间的增加,低浓度组(≤0.4mg·L-1)微核率出现逐渐升高趋势;高浓度组(≥1.2mg·L-1)微核率则先增加后降低.染毒24h后,彗星试验的各项指标Tail Length、Comet Length、Tail Moment和Olive Tail Moment均随三唑磷浓度的增加而增加,并呈现极显著的剂量-效应关系.当三唑磷浓度达到0.2mg·L-1时,与对照组相比,DNA总体损伤水平(Comet Assay Tail Factor)显著提高.实验表明三唑磷对蛙类蝌蚪会造成一定的遗传损伤,微核试验和彗星试验在检测污染物对蝌蚪的遗传毒性方面具有较大的应用价值.     

甲苯二异氰酸酯(TDI)致癌性的综合评估

甲苯二异氰酸酯(TDI)被数家机构分类为可能的人类致癌物,其主要依据为动物实验发现对啮齿动物经灌胃暴露TDI后肿瘤发生率升高。基于研究结果的可靠性以及一致性,综合评估了现有研究数据是否支持这一分类。结果显示现有的流行病学数据不足以有力证明TDI为人类致癌物。动物实验研究表明,吸入接触TDI并不导致肿瘤发生。经灌胃暴露后观察到的肿瘤很可能是由于TDI转化为已知的啮齿动物致癌物甲苯二胺(TDA)所致。在TDI吸入暴露的体内实验中,当由TDI转化生成的TDA不能达到具有显著生物学效应的浓度时,TDI对啮齿动物或人类都没有遗传毒性。由于哺乳动物在生理性接触条件下TDI不能转变成TDA,所以对人类而言,TDI接触与致癌效应之间无直接的显著因果关系。因此虽然在如灌胃等非生理暴露的条件下,TDI可能的人类致癌物的分类是正确的,但本文对其致癌研究数据的合理评估和正确理解有助于将产品监管力度集中于与职业暴露更相关的有害健康效应上。     

利用大型蚤和斑马鱼评价腈纶废水好氧-厌氧处理过程的急性毒性和遗传毒性变化

腈纶废水毒性较强且难以去除,对腈纶废水毒性及污水处理过程毒性削减能力进行评价,可为开发该类废水毒性减排技术提供科学依据。利用大型蚤及斑马鱼评价某腈纶废水的急性毒性和遗传毒性,及厌氧-好氧工艺对该废水毒性的削减能力。采用大型蚤活动抑制率和斑马鱼致死率表征废水急性毒性,采用斑马鱼肝细胞彗星尾矩表征废水遗传毒性。腈纶废水处理前对大型蚤和斑马鱼的急性毒性单位(TU)分别为1.2和2.9,经厌氧-好氧工艺处理后分别降至0.4和0.5。遗传毒性结果表明腈纶废水对斑马鱼肝细胞造成DNA损伤作用,经处理后遗传毒性仍显著高于阴性对照组。理化指标与毒性指标相关性分析表明,该废水氨氮与毒性显著相关,推测氨氮可能是该废水中的重要致毒因子之一。研究结果表明该腈纶废水采用现有厌氧-好氧工艺无法有效削减毒性,对受纳水体水生态环境造成潜在危害。     

Responses of oxidative stress,genotoxicity and immunotoxicity as biomarkers in Theba pisana snails dietary exposed to silver nanoparticles

Silver nanoparticles (AgNPs) are now being of a great interest by ecotoxicological researchers. Their potential hazards to humans and other non-target organisms had led to crucial concerns. In this research, white radish leaf extract was used for the green synthesis of AgNPs. UV–Vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) have been utilised to characterise the biosynthesised AgNPs. Furthermore, the present study aimed to investigate the ecotoxicological effects of 1?mM biosynthesised AgNPs on the land snail, Theba pisana after two weeks of exposure and one week recovery with respect to oxidative stress parameters; lipid peroxidation (LPO), reduced glutathione (GSH), catalase (CAT) and glutathione-S-transferase (GST), cytogenetic parameters; DNA content and micronucleus test, as well as immunological parameters; cell death, phagocytosis, lysosomal membrane stability (LMS), lectins, superoxide anion (O₂^?) generation, phenoloxidase (PO), peroxidase (POD) and haemocyanin (Hc) were examined. AgNPs have been biosynthesised successfully; the UV–vis spectrum exhibited a single and broad absorption band located between 375 and 415?nm, TEM image shows AgNPs formed were nearly spherical in shape with a mean size of 2.18–19.87?nm and the crystalline nature of nanoparticles was confirmed by XRD. After two weeks exposure, the result showed that AgNPs significantly increased LPO level as well as CAT and GST activities, cell death, cell abnormalities and Hc level, whereas, significant decline was found in DNA and GSH contents, phagocytic activity, LMS, lectins, O₂^? generation, POD and PO activities compared to the controls. After a week of recovery, most of the tested biomarkers in AgNP-exposed snails did not completely return to the control levels. The multiple measured parameters could be effectively used as sensitive biomarkers in the risk assessment of contaminants in the terrestrial ecosystem.     

Ecotoxicological assessment of metalworking fluids using the Allium cepa test procedure

Metalworking fluids (MWFs), which have a long history of use in industry and are in constant and ever-increasing use in parallel with advancements in mechanisation, are emulsions prepared with water. MWFs prepared as a 1/20 (MWF: water) mixture in practice, contain a large amount of water within their structure, and may become an aquatic toxic mixture in an ecosystem. In this study, half maximal effective concentration (EC₅₀) values for MWFs were determined using the Allium cepa test, an accepted ecotoxicological biomonitor, and test solutions were prepared (1/250, 1/500 and 1/1000). Depending on the MWF ratio at each concentration, a decrease in the mitotic index (MI), irregularities in the phase distribution and aberrations in the chromosomes were observed. When the amount of MWF in the water increased, chromosomal abnormalities such as stickiness were observed to occur; whereas abnormalities such as c-mitosis, fragments, bridges, vagrants and micronucleus increased as the amount of the MWF decreased. Over a second 24-h period, it was observed that values, in particular MI, showed a tendency to return to normal.