Transformation of tetracycline during chloramination: Kinetics,products and pathways

To assess the potential adverse effects stemming from tetracycline (TC) in drinking water or disinfected wastewater, the kinetics of the chloramination of TC was investigated at room temperature, the transformation products and pathways of their generation were elucidated, and their growth inhibiting properties towards sludge bacteria were assessed. The chloramination of TC exhibited pseudo-first-order kinetics with the rate constants (k_obs) ranging from 0.0082 to 0.041 min^?1 at pH of 6–8. Chloramination of TC generated at least 13 discernible products, and the structures of 12 products, including five chlorinated compounds, were identified using LC–ESI–MS. Two main pathways for the generation of these products were proposed: (1) chlorine substitution reactions followed by dehydration; and (2) oxidization by chloramine. The chlorinated products were proposed to be further degraded to small molecules via the scission of benzene rings of TC, and two oxidization products (2,11a-dihydroxy-keto-TC and 6,11-epoxy-2,11a-dihydroxy-TC) were the final products obtained under the experimental conditions. The chlorinated solution, even without detection of TC, exhibited greater than 80% of TC inhibitory effects towards sludge bacteria, suggesting potential effects on microorganisms in aquatic environment.     

3M测试片法在膜法水处理技术中的应用

采用3M测试片法测定膜法水处理系统的细菌总数,找出双膜系统的微生物污染环节,并采用正交实验筛选出适宜的杀菌剂种类、杀菌剂加入量和杀菌时间。实验结果表明：3M测试片法的测定结果数据准确可靠,且操作简便,节省时间,可以替代常规的平皿培养法用于评价膜的微生物污染情况;某炼化公司双膜系统的反渗透膜已受到微生物的污染,确定的适宜杀菌条件为杀菌剂Trsea 380、杀菌剂加入量50 mg/L、杀菌时间2.0 h,在此条件下杀菌率可达100%。     

Simazine degradation in bioaugmented soil: urea impact and response of ammonia-oxidizing bacteria and other soil bacterial communities

The objective of this study was to investigate the impact of exogenous urea nitrogen on ammonia-oxidizing bacteria (AOB) and other soil bacterial communities in soil bioaugmented for simazine remediation. The previously isolated simazine-degrading Arthrobacter sp. strain SD1 was used to degrade the herbicide. The effect of urea on the simazine degradation capacity of the soil bioaugmented with Arthrobacter strain SD1 was assessed using quantitative PCR targeting the s-triazine-degrading trzN and atzC genes. Structures of bacterial and AOB communities were characterized using terminal restriction fragment length polymorphism. Urea fertilizer could affect simazine biodegradation and decreased the proportion of its trzN and atzC genes in soil augmented with Arthrobacter strain SD1. Bioaugmentation process could significantly alter the structures of both bacterial and AOB communities, which were strongly affected by urea amendment, depending on the dosage. This study could provide some new insights towards s-triazine bioremediation and microbial ecology in a bioaugmented system. However, further studies are necessary in order to elucidate the impact of different types and levels of nitrogen sources on s-triazine-degraders and bacterial and AOB communities in bioaugmented soil.     

An integrated assessment of seawater intrusion in a small tropical island using geophysical,geochemical, and geostatistical techniques

In this study, geophysics, geochemistry, and geostatistical techniques were integrated to assess seawater intrusion in Kapas Island due to its geological complexity and multiple contamination sources. Five resistivity profiles were measured using an electric resistivity technique. The results reveal very low resistivity <1 Ωm, suggesting either marine clay deposit or seawater intrusion or both along the majority of the resistivity images. As a result, geochemistry was further employed to verify the resistivity evidence. The Chadha and Stiff diagrams classify the island groundwater into Ca-HCO₃, Ca-Na-HCO₃, Na-HCO₃, and Na-Cl water types, with Ca-HCO₃ as the dominant. The Mg²⁺/Mg²⁺+Ca²⁺, HCO₃ ^?/anion, Cl^?/HCO₃ ^?, Na⁺/Cl^?, and SO₄ ^2?/Cl^? ratios show that some sampling sites are affected by seawater intrusion; these sampling sites fall within the same areas that show low-resistivity values. The resulting ratios and resistivity values were then used in the geographical information system (GIS) environment to create the geostatistical map of individual indicators. These maps were then overlaid to create the final map showing seawater-affected areas. The final map successfully delineates the area that is actually undergoing seawater intrusion. The proposed technique is not area specific, and hence, it can work in any place with similar completed characteristics or under the influence of multiple contaminants so as to distinguish the area that is truly affected by any targeted pollutants from the rest. This information would provide managers and policy makers with the knowledge of the current situation and will serve as a guide and standard in water research for sustainable management plan.     

双极膜电渗析技术处理稀土钠皂化废水回收液

采用双极膜电渗析（BMED）技术处理稀土钠皂化废水回收液,使回收液中的氯化钠转化为氢氧化钠溶液（简称碱）和盐酸（简称酸）而回用。考察了电流和初始酸碱浓度对膜对电压、回收的酸和碱的浓度、电流效率和能耗的影响。实验结果表明,随电流的增大,膜对电压升高,回收的酸和碱的浓度也明显增加,电流效率和能耗均提高;随初始酸碱浓度的增加,膜对电压、电流效率和能耗均下降,回收的酸和碱的浓度逐渐增加;综合考虑各方面因素并侧重考虑回收的酸和碱的浓度,本实验适宜的工艺条件为：电流25 A、初始酸碱浓度0.3 mol/L。在此条件下反应150 min,回收酸的浓度为1.24 mol/L,回收碱的浓度为1.55 mol/L。     

Immobilization of Cd in landfill-leachate-contaminated soil with cow manure compost as soil conditioners: A laboratory study

Introducing cow manure compost as an amendment in landfill-leachate-contaminated soils is proved to be an effective technique for the immobilization of Cd in this study. Landfill-leachate-contaminated soil was collected from an unlined landfill in China and amended with a different blending quantity of cow manure compost (0, 12, 24, 36, and 48 g per 200 g soil), which was made by mixing cow manure and chaff at a ratio of 1/1 and maturing for 6 months. pH values of five different blending quantity mixtures increased by 0.2–0.4, and the organic matter levels increased by 2.5–7%, during a remediation period of 5 weeks. Four fractions of Cd named exchangeable Cd, reducible Cd, oxidizable Cd, and residual Cd in soil were respectively analyzed by a sequential extraction procedure. Introducing the cow manure compost application resulted in more than 40% lower exchangeable Cd but a higher concentration of oxidizable Cd in soils, and mass balance results showed nearly no Cd absorption by applied material, indicating that transformation of exchangeable Cd into oxidization forms was the main mechanism of Cd immobilization when cow manure compost was used as an amendment. The Pearson correlation showed that increasing of pH values significantly improved the efficiency of Cd immobilization, with a correlation coefficiency of 0.940 (p < 0.05). This is the first attempt at heavy metal immobilization in landfill-leachate-contaminated soil by cow manure compost, and findings of this work can be integrated to guide the application.

Implications: Addition of cow manure compost (CMC) was effective in reducing exchangeable Cd in landfill-leachate-contaminated soils (LLCS). The immobilization effect of Cd was mainly assigned to the redistribution of labile soil Cd. Organic matter (OM) and pH value increased with CMC application. The pH values were more sensitive to Cd immobilization efficiency. It was proved that CMC can be safely and effectively used for the restoration of LLCS.     

Atrazine biodegradation by Arthrobacter strain DAT1: effect of glucose supplementation and change of the soil microbial community

The objective of this study was to investigate the impact of glucose supplementation on the soil microbiota inoculated with the atrazine-degrading Arthrobacter strain DAT1. Soil microcosms with different treatments were constructed for biodegradation tests. The impact of glucose supplementation on atrazine degradation capacity of the strain DAT1 and the strain’s survival and growth were assessed. The densities of the 16S rRNA gene and the atrazine-metabolic trzN gene were determined using quantitative PCR. The growth of the strain DAT1 and the bacterial community structure were characterized using terminal restriction fragment length polymorphism. Glucose supplementation could affect atrazine degradation by the strain DAT1 and the strain’s trzN gene density and growth. The density of the16S rRNA gene decreased during the incubation period. Glucose supplementation could alter the bacterial community structure during the bioaugmentation process. Glucose supplementation could promote the growth of the autochthonous soil degraders that harbored novel functional genes transforming atrazine. Further study will be necessary in order to elucidate the impact of exogenous carbon on autochthonous and inoculated degraders. This study could add some new insights on atrazine bioremediation.     

磁性膨润土的制备、表征及类Fenton催化降解橙黄Ⅱ

以铝柱撑膨润土和铁盐为原料,采用共沉淀法制备纳米Fe3O4负载的磁性膨润土复合材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和比表面孔隙分析(BET)对样品进行表征,研究了磁性膨润土对橙黄Ⅱ的类Fenton催化降解性能,并考察了催化剂用量、温度和初始pH、H2O2初始浓度等因素对降解效果的影响。结果表明,Fe3O4均匀负载在膨润土表面,未发生明显团聚,并且改善了膨润土的孔隙结构,增加了其比表面积。在磁性膨润土用量为0.6 g/L,温度为40℃,pH为3.0,H2O2初始浓度为21 mmol/L的条件下,0.5 mmol/L橙黄Ⅱ溶液在180 min内色度去除率和UV254去除率分别达到100%和97%,且催化剂重复使用4次效果稳定。     

植物-微生物联合修复石油污染土壤的实验研究

筛选高效石油降解菌并考察菌株的石油降解能力,通过植物-微生物联合修复石油污染土壤室内实验,在修复过程中测定了土壤中细菌和固氮菌,碱解氮、速效磷和速效钾的含量变化,同时采用傅立叶变换离子回旋共振质谱(ESI FT-ICR MS)考察了植物-微生物联合修复效果。结果表明,菌株3#、4#的生长适应性较强,其混合菌的降解效果最好,将其混合菌液与植物进行植物-微生物联合修复不同浓度的石油污染土壤,经过150 d的温室降解,最高降解率达到73.47%。ESI FT-ICR MS分析结果表明,与空白组相比,植物组的O1、O2和N1类等化合物相对丰度都发生了显著变化,石油污染物得到一定程度的生物降解。     

环保标识与区域性可持续发展评估

从“商品环境影响评估”的角度,探讨环境标识与可持续发展的因果关系。世界各地现已因应环境保法例及商品的市场需求,循“品质圈”的模式革新产品。虽然生命周期评价（ＬＣＡ）是环保标识的重要支柱,可惜迄今对估并需强化它在环境安全与健康资源运用、公众咨询、环境管理和审核（ＥＭ＆Ａ）、环境补偿和生态修复等重要领域的工作,确立它在区域性可持续发展中的战略作用。文章以香港为例案,探讨推动环境标识所面对的困难和解决方