Microbial biodegradation of microcystin-RR by bacterium Sphingopyxis sp. USTB-05

A strain,USTB-05,isolated from Lake Dianchi,China,degraded the cyanobacterial toxin microcystin-RR(MC-RR) at the rate of 16.7 mg/L per day.Analysis of 16S rDNA sequence showed that the strain was Sphingopyxis sp.Enzymatic degradation pathways for MC-RR by Sphingopyxis sp.USTB-05 were identified.Adda-Arg peptide bond of MC-RR was cleaved and then a hydrogen and a hydroxyl were combined onto the NH 2 group of Adda and the carboxyl group of arginine to form a linear molecule as intermediate product within the ...     

甲硫醇降解菌群筛选及其降解特性研究

从处理甲硫醚(DMS)和丙硫醇(PT)混合废气的生物滴滤塔中富集出一组能够有效降解甲硫醇(MT)的混合菌群,并对其特性进行了系列研究.结果表明,该混合菌群能有效降解MT,菌群较为适宜的生长和降解条件为30℃、p H=7.0,在该条件下能将初始浓度为20 mg·L~(-1)的MT在70 h内降解完全.添加酵母膏(YE)后,MT降解速率进一步提高,降解所需时间缩短10 h.利用高通量测序技术分析混合菌群的群落结构,发现其中优势菌属为Pseudomonas sp.、Thiobacillus sp.和Acinetobacter sp.,所占比例分别为33.78%、21.91%和17.01%.中间产物检测结果表明,混合菌群降解MT的过程中产生了甲醛、H_2S、二甲基二硫醚(DMDS)等物质,推断MT的降解途径可能有如下2条:(1)MT在MT氧化酶作用下形成甲醛和H2S,随后氧化为SO_4~(2-);(2)MT依次转化为DMDS、DMS、二甲基亚砜(DMSO)和二甲基砜(DMSO_2),最后经甲基磺酸(MSA)可生成SO_4~(2-).     

Employing the shared socioeconomic pathways to predict CO2 emissions

Predicting CO₂ emissions is of significant interest to policymakers and scholars alike. The following article contributes to earlier work by using the recently released “shared socioeconomic pathways” (SSPs) to empirically model CO₂ emissions in the future. To this end, I employ in-sample and out-of-sample techniques to assess the prediction accuracy of the underlying model, before forecasting countries’ emission rates until 2100. This article makes three central contributions to the literature. First, as one of the first studies, I improve upon the Representative Concentration Pathways (RCPs) by incorporating the SSPs, which did not exist when the RCPs have been released. Second, I calculate predictions and forecasts for a global sample in 1960–2100, which circumvents issues of limited time periods and sample selection bias in previous research. Third, I thoroughly assess the prediction accuracy of the model, which contributes to providing a guideline for prediction exercises in general using in-sample and out-of-sample approaches. This research presents findings that crucially inform scholars and policymakers, especially in light of the prominent 2 °C goal: none of the five SSP scenarios is likely to be linked to emission patterns that would suggest achieving the 2 °C goal is realistic.     

噻吩磺隆降解菌Staphylococcus sp.的分离及其降解特性与途径

采用富集培养技术从磺酰脲类除草剂污染土壤中筛选得到1株降解噻吩磺隆的细菌,命名为ZWS13.经形态特征和16S rRNA基因序列分析,初步鉴定为葡萄球菌属(Staphylococcus sp.).采用HPLC研究了初始底物浓度、温度、接种量、pH等因素对菌株ZWS13降解噻吩磺隆的影响.结果表明,菌株ZWS13对噻吩磺隆的降解具有较广的底物浓度范围,在7 d内对初始浓度5.0~100.0 mg·L~(-1)噻吩磺隆的降解率达到60%以上;菌株ZWS13降解噻吩磺隆的较适pH为8.0,较适温度为40℃,较适接种量为1%;其中,菌株培养温度为40℃时,菌株在10 d内对50.0mg·L~(-1)噻吩磺隆的降解率达到99%以上.降解谱测定结果表明,菌株对烟嘧磺隆、吡嘧磺隆和甲磺隆亦具有良好的降解效果.采用HPLC-MS分析确定了菌株对噻吩磺隆的5个降解产物,推测菌株对噻吩磺隆的降解途径主要为磺酰脲桥C—N键的断裂、脱甲基作用或脱酯作用的甲基丢失及三嗪环的开裂.研究表明,菌株ZWS13能够有效地降解噻吩磺隆,具有生物修复噻吩磺隆污染的潜力.     

Mass balance approach to estimating radionuclide loads and concentrations in edible fish tissues using stable analogues

Humans can consume a number of types of biota tissues, which have varying propensities to accumulate radionuclides. As a result, depending upon the biota species, the radionuclide and the tissue under consideration, it may be necessary to estimate the percent radionuclide load in specific edible tissues, and in cases where whole organisms are consumed, to estimate the radionuclide load in the whole body of an organism, based on data that have been collected for individual tissues. To accomplish this, data were compiled that can be used to estimate the partitioning patterns and percent loads of various groups of elements in edible tissues of freshwater fishes. General trends in partitioning, such as those provided in this paper, can be used to predict radionuclide transfer to humans and the corresponding potential radiological dose to humans via dietary pathways, in this case following the consumption of fish.     

Migration Pathways and Remediation of Urban Runoff for PAH Control

The migration pathways for polyaromatic hydrocarbons (PAH) and the associated active attenuating mechanisms within the urban environment are examined. The interest in developing an improved understanding of PAH migration/attenuation is focused toward quantification of the cost-effectiveness of urban runoff control strategies for mitigation of PAH inputs to receiving water bodies.A case study application to the City of Sault Ste Marie demonstrates that snow removal from sub-basins with the largest deposition rates, and relatively small wet and/or dry stormwater management ponds, are the most cost-effective remediation strategies.     

双酚AF诱导乳腺癌细胞增殖的分子机制

从细胞水平上研究不同浓度双酚AF(BPAF)对MCF-7人乳腺癌细胞系的细胞增殖能力、细胞凋亡、细胞周期等终点的影响;以新型雌激素膜受体GPER1介导的PI3K/Akt和ERK1/2信号通路为靶点,研究低浓度BPAF对该信号通路相关基因表达的影响,以及其在诱导乳腺癌细胞增殖中的作用,评估其增殖效应机制.结果表明,低浓度...     

常州市臭氧污染传输路径和潜在源区

利用NCEP全球再分析资料和HYSPLIT4模式,计算了2013—2015年常州市臭氧(O_3)超标日的气流后向轨迹。结合聚类分析方法和常州市PM2.5、PM10、SO2、NO2、O_3数据,分析了O_3超标日不同类型气团来源对各污染物浓度的影响,并利用引入权重因子后的潜在污染源贡献函数分析了影响常州市O_3超标的潜在污染源区分布特征。结果表明:常州市O_3超标期间易受到东南和西南方向气流影响,其中从东海和黄海途经浙江东北部、上海、江苏南部等地的东南气流占比达50%以上。自内陆途经黄山-湖州-宜兴到常州的气流对应的O_3平均质量浓度最高,为116μg/m3。自山东经枣庄-宿迁-淮安-泰州-苏州-无锡到常州的气流对应的O_3平均质量浓度最低,为78μg/m3,但该气流对应的SO2和NO2平均值为各聚类中的最高。影响常州市O_3的潜在污染源区主要在常州周边200 km以内的区域,且集中在从南京至上海的长江下游沿线区域和杭州湾区域;其中太湖湖区为重点污染源源区之一。O_3超标日影响常州NO2的潜在污染源区主要集中在江苏南部、浙江东北部和上海3个区域,太湖周边的常州、无锡、苏州和湖州等几个临近城市为潜在的重点污染源区。与影响常州O_3的WPSCF高值区相比,影响NO2的高值区分布范围更大、距离更远。影响常州O_3的潜在污染源区分布,与长江三角洲地区人为源大气污染物的高排放区域较为一致,说明长江三角洲地区的O_3污染与本区域的人为源大气污染物排放有着极为密切的关联。     

吉非罗齐在热活化过硫酸盐体系中的降解机制研究

以降血脂药物吉非罗齐(GEM)为目标污染物,研究其在热活化过硫酸盐体系中的降解机制.结果表明,GEM的降解过程符合准一级反应动力学规律,增加过硫酸盐初始浓度或升高反应溶液温度都可以显著提高GEM的降解速率常数(kobs),其反应的表观活化能Ea为133.14k J·mol~(-1).酸性和中性条件下GEM的降解效果要好于碱性条件.自然水体中的腐植酸(HA)和HCO_3~-对GEM的降解有明显的抑制作用.自由基清除实验表明,在酸性和中性条件下,SO_4~(·-)对GEM的降解起主导作用,而在碱性条件下,HO·成为体系主要的氧化物种.利用HPLC-MS/MS技术共检测到11种中间产物,推测GEM的降解路径涉及苯环的羟基化和醛基化反应、苯环侧链的环化作用和脱羧反应以及醚支链的断裂.     

孟加拉国饮用水砷污染控制策略与方向

孟加拉国是“一带一路”重要节点国家,经济社会快速发展,正从“最不发达国家”进入到“发展中国家”行列。同时,孟加拉国是全世界砷污染最严重的国家之一,其地下水砷污染形成过程与环境地球化学机制、人群砷暴露途径与风险水平、砷中毒机制与控制原理等在全球范围内具有重要研究价值。此外,孟加拉国政府和国际社会为控制饮用水砷污染开展了大量工作,已取得很好的成效。以饮用水砷污染及其健康风险控制为目标,制定科学、合理、有效的砷污染控制策略,对于孟加拉国在全国范围内从根本解决饮用水安全问题具有重要意义。