Speciation and persistence of doxycycline in the aquatic environment: Characterization in terms of steady state kinetics

The aim of the present work was to establish the kinetics for the degradation of doxycycline in the aquatic environment with a view to arriving at a kinetic model that can be used to predict the persistence of antibiotic with confidence. The degradation of doxycycline in both water and sediment phases of aquatic microcosm experiments, as well as in distilled water control experiments, was studied over a period of 90 days. An initial 21% loss due to adsorption by the sediment was observed in the microcosm experiment soon after charging. Biphasic zero-order linear rates of degradation, attributed to microbial degradation of the free and sediment or colloidal particle-adsorbed antibiotic, were observed for both water phase (2.3 × 10^?2 and 4.5 × 10^?3 μgg^?1 day^?1) and sediment phase (7.9 × 10^?3 and 1.5 × 10^?3 μgg^?1 day^?1) of the microcosm experiment. The covered distilled water control experiment exhibited a monophasic zero-order linear rate (1.9 × 10^?3 μgg^?1 day^?1) attributed to hydrolysis, while the distilled water experiment exposed to natural light exhibited biphasic liner rates attributed to a combination of hydrolysis and photolysis (2.9 × 10^?3 μgg^?1 day^?1) and to microbial degradation (9.8 × 10^?3 μgg^?1 day^?1). A kinetic model that takes into account hydrolysis, photolysis, microbial degradation as well as sorption/desorption by colloidal and sediment particles is presented to account for the observed zero-order kinetics. The implications of the observed kinetics on the persistence of doxycycline in the aquatic environment are discussed.     

表面活性剂修复重金属污染土壤的研究

本文探讨了3种常用表面活性剂,十二烷基苯磺酸钠(SDBS)、十二烷基硫酸钠(SDS)、聚山梨脂(Tween-80)对被重金属铬、镉污染了的土壤的修复洗脱作用,以及被污染土壤对3种表面活性剂的吸附作用。淋洗实验结果表明,3种表面活性剂对土壤中的铬、镉有明显去除效果,聚山梨脂(Tween-80)对污染土壤中铬和镉的去除率分别为61.2%和37.06%。实验表明,土壤对3种表面活性剂均有较强的吸附作用,这种吸附作用对土壤重金属的去除会产生不利的影响。     

长江入海口北支沿海滩涂养殖区底泥重金属污染特征及趋势评价

对长江入海口北支沿海滩涂养殖区底泥重金属污染的总体水平进行调查,结果表明,滩涂养殖区底泥重金属含量满足海洋沉积物质量一类标准要求,污染程度属于安全Ⅰ级水平,重金属潜在生态危害属轻微级别,6种重金属潜在生态危害由大到小排序依次为Cd﹥Hg﹥Cu﹥Cr﹥Pb﹥As,2005年～2011年,底泥重金属污染程度均处于安全的Ⅰ级水平。     

浅析规模化畜禽集中养殖环境污染现状及防治对策——以安居区玉丰镇为例

通过实地调查取样分析,结果表明:玉丰镇鸡头寺村和金龟村规模化畜禽集中养殖实际出栏量是土地环境容量1.3倍,土壤中含锌、铜、锰、砷量分别为163.05mg/kg、156.00mg/kg、101.13mg/kg和9.19mg/kg,已造成土壤污染,农田灌溉用水化学需氧量超标准限值503%,地下水和大气受到一定程度的污染。     

渠县近5年大气污染特征及预测分析

本文应用污染损害综合指数法,分析了四川省渠县近5年来的大气变化及其危害程度,并运用GM(1,1)模型对渠县未来8年的大气状况作预测。结果表明,渠县大气环境主要污染物为可吸入微粒,其浓度变化呈逐年下降趋势,从2008年开始TSP有明显下降,SO2与NO2含量较低并且比较稳定。通过GM(1,1)模型对渠县空气质量进行预测得知,SO2、NO2逐渐下降,TSP的浓度将大幅度下降,在未来的8年里渠县的空气环境质量得到大幅度的提高。     

电磁辐射污染投诉原因分析及解决办法探讨

近年来,随着经济的发展,高压输变电工程和移动通信基站越来越多地落户于大型居民小区,由此引发的环境投诉和纠纷呈快速上涨趋势。电磁辐射污染投诉产生的原因主要是:电磁辐射环境管理法制不健全,思想上不重视,项目环保审批环节脱节,环保与规划部门信息交流不畅,公众维权意识增强,寻求其他经济利益;针对原因提出的预防和解决办法为:加强法制建设、强化现场监管,理顺项目审批和监管程序,建立与规划部门的联动机制,加强宣传,引导司法解决。     

基于WebGIS和粒子系统的空气污染预测动态可视化展示技术

在完成国家"863"项目"重点城市群大气复合污染综合防治技术与集成示范"(3c-star)的过程中,我们研发了具有自主知识产权的"区域大气环境综合管理和辅助决策系统",其中创造性地利用NetCDF、Silverlight、WebGIS、粒子系统、多媒体等技术实现了空气污染预测动态可视化数据展示。本文阐述了工作的背景、技术要点及成果。     

基于BP人工神经网络的城市PM2.5浓度空间预测

针对PM2.5日均质量浓度,采用BP人工神经网络模型,预测研究区空气中PM2.5浓度的空间变异,通过与普通克里格(Ordinary Kriging)插值方法对比验证BP人工神经网络预测模型的精度.结果表明:BP人工神经网络预测模型下研究区检验样本点位置的PM2.5仿真浓度与观测浓度之间的均方差、平均绝对误差、平均相对偏差和相关系数分别为0.296 μg2/m6、0.412 μg/m3、1.650％和0.851;而与此同时,普通克里格插值方法下的对应结果分别为1.041 μg2/m6、0.689 μg/m3、11.910％、0.638.研究成果在肯定BP人工神经网络预测模型可用于揭示PM2.5浓度空间变异特征的同时,也证实了其相对于普通克里格插值方法在固定空间点位准确预测PM2.5浓度方面的优势.     

太湖表层沉积物重金属污染评价与来源分析

对太湖湖区表层沉积物中11种重金属的总量进行调查分析,借助地累积指数法和潜在生态风险指数法分析了重金属的污染程度和生态风险,并利用主成分分析-绝对主成分分数-多元线性回归受体模型对重金属来源进行解析.结果显示太湖沉积物中Cd、Sb含量平均值分别为江苏省土壤背景值的4.29倍和3.18倍,地累积指数表明Cd和Sb为偏中度...     

Analyzing the cost effectiveness of Santiago, Chile's policy of using urban forests to improve air quality

Santiago, Chile has the distinction of having among the worst urban air pollution problems in Latin America. As part of an atmospheric pollution reduction plan, the Santiago Regional Metropolitan government defined an environmental policy goal of using urban forests to remove particulate matter less than 10 microm (PM(10)) in the Gran Santiago area. We used cost effectiveness, or the process of establishing costs and selecting least cost alternatives for obtaining a defined policy goal of PM(10) removal, to analyze this policy goal. For this study, we quantified PM(10) removal by Santiago's urban forests based on socioeconomic strata and using field and real-time pollution and climate data via a dry deposition urban forest effects model. Municipal urban forest management costs were estimated using management cost surveys and Chilean Ministry of Planning and Cooperation documents. Results indicate that managing municipal urban forests (trees, shrubs, and grass whose management is under the jurisdiction of Santiago's 36 municipalities) to remove PM(10) was a cost-effective policy for abating PM(10) based on criteria set by the World Bank. In addition, we compared the cost effectiveness of managing municipal urban forests and street trees to other control policies (e.g. alternative fuels) to abate PM(10) in Santiago and determined that municipal urban forest management efficiency was similar to these other air quality improvement measures.