Investigation of organic pollutants in wastewater-irrigated soil and its DNA damage and oxidative damage on mice

This work aimed to determine the DNA and oxidative damage on mice by mixtures of organic contaminants in wastewater-irrigated soil, in order to assess their usefulness as markers for this kind of pollution. Wastewater-irrigated soil samples in the vicinity of an industrial area in Tangshan, China were collected, and soil irrigated by underground water satisfying drinking water standards was used as control group. Organic pollutants were extracted from the soil using ultrasonic oscillation, and analyzed by gas chromatography–mass spectrometry (GC-MS). Meanwhile, DNA damage on mice was determined by the Comet assay after oral gavage with the extracts, and changes in total superoxide dismutase (T-SOD) activity, glutathione peroxidase glutathione, GSH peroxidase (GSH-P_X) activity and malondialdehyde content in serum of mice were investigated. The number of categories and concentrations of organic compounds in the wastewater-irrigated soil is more than those in groundwater-irrigated soil, as identified by the GC-MS. The toxicity test of mice showed that compared with reagent control group, the activities of T-SOD and GSH-P_X decreased; the tailing rate of peripheral blood lymphocyte of mice increased and was more than that of the control group. This shows that mammalian toxicity end points can be used to determine the joint toxicity of organic pollutants in soil. When there is no means to identify each and every pollutant in soil, it is feasible to evaluate the combined effects of various pollutants to determine the extent to which the soil is polluted.     

基于机器视觉的鱼类行为特征提取与分析

近年来,水污染问题备受关注。生物式水质监测成为目前国家环境保护工作的重要任务之一。为准确监测水质污染情况,本文以青鳉鱼(Oryzias latipes)为研究对象,采用非接触式的机器视觉监测技术,提取青鳉鱼的生理特征(呼吸频率)和运动特征(胸鳍和尾鳍的摆动频率),并分析这些特征与水质之间的关系。本文采用支持向量机(Support Vector Machine,SVM)准确提取鱼鳃,并根据鱼鳃呼吸面积大小变化计算出鱼的呼吸频率。基于形态学细化算法提取青鳉鱼骨架,求出胸鳍和尾鳍的摆动频率。结果显示:不同浓度铜离子暴露实验测得的青鳉鱼生理特征和运动特征与实际情况一致;通过对不同铜离子浓度下的毒性实验数据对比,发现了青鳉鱼的生理特征和运动特征会随不同的铜离子浓度发生相应变化,可以作为水质监测的评价标准。     

Role of illumination intensity in microcystin development using Microcystis aeruginosa as the model algae

Environmental Science and Pollution Research - Microcystis aeruginosa (M. aeruginosa) is one of the most common genera of cyanobacteria in algal blooms. In the present work, the impact of the...     

基于白碳黑的水化硅酸钙制备及其磷回收特性简

以白碳黑、硅灰、硅藻土和硅胶筛选硅质原料,并与钙质原料电石渣制备了水化硅酸钙。借助XRF、BET、FTIR等表征手段,通过多次重复除磷实验,研究了硅质原料特性对水化硅酸钙回收磷性能的影响。结果表明,白碳黑具有极高的反应活性,因此可作为制备具有磷回收特性的水化硅酸钙的硅质原料。结合XRD等表征发现,白碳黑的有效利用率是影响水化硅酸钙回收磷性能的关键,该利用率取决于白碳黑与电石渣的摩尔配比以及水热反应温度。当电石渣与白碳黑的摩尔比为1.6：1,反应温度为170℃时,白碳黑具有最佳的利用效率。该条件制备的水化硅酸钙可作为晶种,在其表面结晶形成羟基磷灰石,从而达到磷回收的目的,磷回收后固体物质中的磷含量为19.05%。     

Biodegradation of methyl red by Bacillus sp. strain UN2: decolorization capacity,metabolites characterization,and enzyme analysis

Azo dyes are recalcitrant and refractory pollutants that constitute a significant menace to the environment. The present study is focused on exploring the capability of Bacillus sp. strain UN2 for application in methyl red (MR) degradation. Effects of physicochemical parameters (pH of medium, temperature, initial concentration of dye, and composition of the medium) were studied in detail. The suitable pH and temperature range for MR degradation by strain UN2 were respectively 7.0–9.0 and 30–40 °C, and the optimal pH value and temperature were respectively 8.0 and 35 °C. Mg²⁺ and Mn²⁺ (1 mM) were found to significantly accelerate the MR removal rate, while the enhancement by either Fe³⁺ or Fe²⁺ was slight. Under the optimal degradation conditions, strain UN2 exhibited greater than 98 % degradation of the toxic azo dye MR (100 ppm) within 30 min. Analysis of samples from decolorized culture flasks confirmed biodegradation of MR into two prime metabolites: N,N′dimethyl-p-phenyle-nediamine and 2-aminobenzoic acid. A study of the enzymes responsible for the biodegradation of MR, in the control and cells obtained during (10 min) and after (30 min) degradation, showed a significant increase in the activities of azoreductase, laccase, and NADH-DCIP reductase. Furthermore, a phytotoxicity analysis demonstrated that the germination inhibition was almost eliminated for both the plants Triticum aestivum and Sorghum bicolor by MR metabolites at 100 mg/L concentration, yet the germination inhibition of parent dye was significant. Consequently, the high efficiency of MR degradation enables this strain to be a potential candidate for bioremediation of wastewater containing MR.     

Influence of UV radiation on chlorophyll,and antioxidant enzymes of wetland plants in different types of constructed wetland

A surface- and vertical subsurface-flow-constructed wetland were designed to study the response of chlorophyll and antioxidant enzymes to elevated UV radiation in three types of wetland plants (Canna indica, Phragmites austrail, and Typha augustifolia). Results showed that (1) chlorophyll content of C. indica, P. austrail, and T. augustifolia in the constructed wetland was significantly lower where UV radiation was increased by 10 and 20 % above ambient solar level than in treatment with ambient solar UV radiation (p?C. indica, P. australis, and T. angustifolia by elevated UV radiation of 10 % was higher in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland. The sensitivity of MDA, SOD, POD, and CAT activities of C. indica, P. austrail, and T. augustifolia to the elevated UV radiation was lower in surface-flow-constructed wetland than in the vertical subsurface-flow-constructed wetland, which was related to a reduction in UV radiation intensity through the dissolved organic carbon and suspended matter in the water. C. indica had the highest SOD and POD activities, which implied it is more sensitive to enhanced UV radiation. Therefore, different wetland plants had different antioxidant enzymes by elevated UV radiation, which were more sensitive in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland.     

负载纳米TiO_2凹凸棒黏土的制备表征及对Mn~(2+)的吸附性能

以溶胶-凝胶法制备了负载纳米TiO2凹凸棒黏土吸附剂,采用SEM、XRD等分析方法对负载纳米TiO2凹凸棒黏土前后的结构进行了表征,并对Mn2+进行了吸附性能的研究。结果表明:经过高温焙烧后的负载纳米TiO2凹凸棒黏土吸附剂较负载前的凹凸棒黏土,因其结构中的结晶水和沸石水脱失,内部孔道面积和表面积增加,活性吸附位点的数量增大,吸附能力有了明显提高。在室温条件下(20~25℃),pH为5~6,吸附平衡时间为120 min时,负载纳米TiO2凹凸棒黏土吸附剂对Mn2+有较好的吸附效果。     

The fate of recombinant plasmids during composting of organic wastes

Composting was investigated as a means for safe disposal of organic waste containing bacteria that carry transgenes in recombinant plasmids. To generate model recombinant plasmids, a mobile IncQ plasmid, RSF1010, and a non-mobile plasmid, pGFP, were genetically modified to carry a DNA segment encoding both green fluorescent protein and kanamycin resistance and were designated as RSF1010-GFPK and pGFPK. Escherichia coli (E. coli) C600 harboring these plasmids were inoculated into chicken manure specimens that were placed in compost at 20 and 60 cm from the bottom of a 1.0-m high compost bin. Control specimens were held at ambient temperature. By day 10, compost temperatures at the lower and upper levels of the bin had reached 45.3 and 61.5°C, respectively, and at both levels the target E. coli had been inactivated and the plasmids had lost their capacity to be transformed or mobilized. Furthermore, based on real time Polymerase chain reaction (PCR), the transgene fragments along with the host chromosomal DNA fragment from specimens at the upper level had been degraded beyond the detection limit. However, at the lower level where temperatures remained below 48°C these fragment persisted to day 21. At ambient temperatures (0–8°C), the E. coli, plasmids and the transgene fragments persisted in manure specimens throughout the 21 day test period. The study showed the potential for composting as a safe procedure for disposal of bacteria carrying transgenes in recombinant plasmids.     

可旋转径向式微粒捕集器消声特性影响因素灰色关联分析

为降低可旋转径向式微粒捕集器中的排气噪声,采用有限元法建立可旋转径向式微粒捕集器声学特性模型,分析得到了其消声特性和传递损失曲线,并采用灰色关联分析方法研究可旋转径向式微粒捕集器结构参数对消声特性的影响程度。结果表明,可旋转径向式微粒捕集器具有降噪能力,且对高频噪声消声效果明显好于低频噪声,平均消声量为20 dB左右;直径比和扩张管锥角是影响可旋转径向式微粒捕集器消声特性的2个主要因素,适当选用小的直径比和扩张管锥角,有利于提高可旋转径向式微粒捕集器的消声性能。     

电镀综合废水对DF膜的污染

江苏某电镀厂的电镀综合废水在采用DF膜进行预处理时,膜易受到污染。针对这一问题,采用DF膜生产厂家提供的小试装置,研究探索了膜污染的原因及其具体特征。实验结果表明,在处理电镀综合废水时,DF膜的污染速率较快,而酸洗对DF膜的恢复性较好,研究还证实电镀综合废水中的无氰沉锌水洗液是造成DF膜污染的主要原因。