钙镁钾离子混合物对水体中几种重金属离子毒性的影响及作用机理

为明确水体中常见的钙镁钾离子混合物对重金属离子Cu^(2+)、Zn^(2+)、Cr^(6+)、Cd^(2+)和Fe^(3+)毒性的影响,以明亮发光杆菌T3(Photobacterium phosphoreum T3)为受试生物,进行急性毒性测试并通过生化指标及核心发光基因表达量变化进行机理解析。结果表明:单一重金属离子对明亮发光杆菌T3的毒性大小为Zn^(2+)>Cd^(2+)>Cu^(2+)>Fe^(3+)>Cr^(6+),在添加不同浓度Ca^(2+)-Mg^(2+)-K^(+)混合液后重金属离子的毒性降低,当Ca^(2+)、Mg^(2+)和K^(+)质量浓度分别为13.40、8.00和26.20 mg/L时,联合毒性最弱;重金属离子质量浓度较低(<2.0 mg/L)时,重金属离子与Ca^(2+)-Mg^(2+)-K^(+)混合液之间呈拮抗作用,并出现明显的兴奋刺激效应;随着重金属离子质量浓度的增加,联合作用逐渐转为加和作用;Ca^(2+)-Mg^(2+)-K^(+)混合液的加入使细胞内活性氧质量下降,超氧化物歧化酶活性以及还原型烟酰胺腺嘌呤二核苷酸质量上升,使得菌体抗氧化能力增强,并刺激氧化还原反应来提升能量供应水平,从而降低金属离子的毒性。该研究可为实际水体中混合重金属离子的毒性评估和调控提供数据参考。

聚丙烯酰胺类油田添加剂生物毒性测试方法

为了有效解决明亮发光细菌T3价格暴涨且供货不稳定的问题,采用费氏弧菌为测试菌种,ZnSO4·7H2O为参比毒物,通过单因素实验探讨了不同时间内费氏弧菌的稳定性,考察了不同浓度的参比毒物对菌种发光强度和抑制率的影响,研究了费氏弧菌在油田添加剂生物毒性测试中的应用.结果表明:费式弧菌在测试过程中存活性高、稳定性好;参比毒物ZnSO4·7H2O浓度越大,发光强度越低,抑制率越高;费氏弧菌测得的降滤失剂的毒性大于包被剂,最佳测试时间为15~30 min.

土壤浸提液中重金属对发光杆菌T_3的毒性效应

通过测定掺杂Pb2+、Zn2+、Cd2+、Cu2+和Cr3+的土壤浸提液中明亮发光杆菌T3的抑制率,研究重金属复合污染对明亮发光杆菌T3的生物毒性效应。按照重金属离子等效应浓度配比的原理,设计均匀试验,用逐步多元回归法构建土壤水浸提液中重金属(Pb2+、Zn2+、Cd2+、Cu2+和Cr3+)浓度(Xi)与发光菌抑制率(Y)的响应关系:Y=(-39.596±15.811)-(6.633±0.802)×(-lgXCu)(-lgXZn)+(59.466±8.731)×(-lgXCd)(-lgXCr)。该模型具有较好的拟合优度(F检验和t检验的P<0.05),模型校正后的决定系数(R2adj)为0.933。内部样本验证表明,发光菌抑制率的预测值与试验值相对偏差最大为8.6%,说明该模型具有较好的预测能力。机理分析显示,Cu2+和Zn2+交互体现为拮抗作用,Cd2+和Cr3+交互体现为协同作用,故在重金属复合污染控制方面,有必要进一步研究Cu2+和Zn2+拮抗作用对降低复合毒性的贡献。

Identification and ecotoxicity assessment of intermediates generated during the degradation of clofibric acid by advanced oxidation processes

The aim of this study was to identify the intermediates in clofibric acid degradation under various advanced oxidation processes, namely ultraviolet （UV）, UV/H2O2, vacuum ultraviolet （VUV）, VUV/H2O2, and solar/TiO2 processes, as well as to assess the toxicity of these intermediates. Eleven intermediates have been detected by gas chromatography-mass spectrometer, most of which were reported for the first time to our best knowledge. Combining the evolution of the dissolved organic carbon, CF and specific ultraviolet absorption at 254 nm, it could be deduced that cleavage of aromatic ring followed by dechlorination was the mechanism in solar/ TiO2 process, while dechlorination happened first and accumulation of aromatic intermediates occurred in the other processes. Different transformation pathways were proposed for UV-, VUV-assisted and solar/TiO2 processes, respectively. The acute toxicity was evaluated by means of Photobacterium phosphoreurn T3 spp. bioassay. It was believed that aromatic intermediates increased the toxicity and the ring-opening pathway in solar/TiO2 process could relieve the toxicity.