化学品足迹:概念、研究进展及挑战

化学品污染被联合国环境规划署列为影响人类生存与发展的全球重大环境问题之一。为实现可持续的化学品管理,需定量评价产品生命周期内由化学品排放造成的生态影响。然而,当前的化学品风险评价指标体系往往指向零碎的危害性或毒性终点,未能综合出整体性指标来定量表征生态系统所承受的损害,亦不能衡量人类活动排放的化学品总量与环境承载容量的相对大小。作为环境足迹一员,化学品足迹继承了"足迹"指标的特点,可定量表征生态系统受化学品影响的程度,并结合生态阈值及环境承载容量,有助于评价人类活动对环境可持续性的影响,有望成为公众、企业、决策者及利益相关者之间相互交流的重要工具。本文概述了化学品足迹的基本概念及其发展历程,介绍了现有的化学品足迹计算方法及其应用于不同空间尺度下的案例研究,讨论了化学品足迹研究中存在的问题与挑战,并对其应用前景进行了展望。     

二苯甲酮类紫外防晒剂发光菌急性毒性及QSAR研究

二苯甲酮类化合物广泛用于防晒剂、塑料添加剂、香味剂等。随着紫外防晒产品的大量使用,其环境及健康风险越来越受到人们的关注。为揭示二苯甲酮类污染物的毒性特征,选择了14种二苯甲酮类化合物作为目标化合物,测试了它们对发光细菌的急性毒性效应。分别运用二维、三维定量构效相关技术和分子对接技术探讨了目标化合物的分子结构特征对毒性效应的影响。结果表明14种二苯甲酮类化合物对发光菌急性毒性的EC50值在17.67到243.82 mg·L-1范围内,其中2-羟基-4-甲氧基-5-磺酸基二苯甲酮的急性毒性最低,2,2',4,4'-四羟基二苯甲酮的毒性最高。羟基取代的二苯甲酮化合物的急性毒性随着分子中羟基数量的增加而升高;具有相同羟基数量的二苯甲酮类化合物,羟基位于苯环4-位时毒性最高,3-位时次之,2-位时毒性最低。QSAR结果表明,运用静电场、氢键受体场和氢键供体场能很好解释这类化合物的毒性特征,若在苯环4-位引入带正电荷的官能团、在苯环2-,4-位引入氢键受体,都将导致毒性升高。上述研究结果将为科学评价该类化合物的潜在生态风险提供基础数据。     

污水再生处理工艺中卡马西平的去除过程模拟及其生态风险评价

卡马西平在污水和水环境中广泛存在,且对水生生态系统安全构成风险,因此成为目前研究较多的药品之一。以北京清河再生水厂为例,研究"超滤—臭氧氧化—氯消毒"处理工艺中卡马西平的去除特性,并针对臭氧氧化和氯消毒工艺建立模拟卡马西平去除过程的机理模型。同时,利用美国环境保护署ECOTOX数据库,获取卡马西平对北京市水生生物物种的毒性数据,并基于毒性数据建立物种敏感度分布(species sensitivity distribution,SSD)模型,评价再生水厂出水补给地表水体时卡马西平产生的生态风险。臭氧氧化和氯消毒模型对卡马西平、总有机碳、氨氮等指标的模拟误差总体低于20%,模型的灵敏参数均可以被较好地识别,且其不确定性显著下降。对比7种SSD模型发现,对数正态分布和对数Logistic分布模型较好地拟合了北京市6个物种的卡马西平毒性数据,二者预测得到的总体生态风险期望值分别为7.4%和8.5%。     

Trends in vehicular emissions in China's mega cities from 1995 to 2005

Multiyear inventories of vehicular emissions in Beijing, Shanghai and Guangzhou from 1995 through 2005 have been developed in this paper to study the vehicle emissions trends in China's mega cities during the past decade. The results show that the vehicular emissions of CO, HC, NO_x and PM₁₀ have begun to slow their growth rates and perhaps even to decline in recent years due to the implementation of measures to control vehicular emissions in these cities. However, vehicular CO₂ emissions have substantially increased and still continue to grow due to little fuel economy improvement. Passenger cars and large vehicles (including heavy duty trucks and buses) are the major sources of vehicular CO₂ and CO emissions while large vehicles were responsible for nearly 70% and 80% of the vehicular NO_x and PM₁₀ emissions in these mega cities. Motorcycles are also important contributors to vehicular emissions in Guangzhou and Shanghai.     

地震作用下土‐深埋地下结构相互作用的高效时程分析方法∗

基于黏弹性边界和将场地地震反应转化为等效荷载的有限元直接法是目前进行地震作用下土-结构相互作用分析的常用时程分析方法之一。当结构埋深较深时,整个土-结构系统的有限元模型自由度数目较多,尤其对于三维问题,计算效率低。提出一种高效分析方法,即一维场地反应分析仍然针对整个深厚土层,在后续的土-结构相互作用分析中将土-结构计算模型的自由表面向下移动、底边界面向上移动到接近结构的位置,通过缩减土-结构相互作用模型尺寸来提高计算效率。采用理论分析与数值算例,通过与采用整个深厚土层的传统土-结构相互作用分析结果对比,说明提出的高效分析方法能够满足精度要求,并且针对不同结构尺寸、结构埋深和围岩等级给出上、下人工边界位置的建议。     

基于无人机的施工扬尘污染源自动监测系统设计与实现

施工扬尘是大气污染物的主要来源和施工环境监测的重点对象,但传统监测手段的效率和效果有限。为此,综合使用无人机和图像识别技术,以HSV特征提取、直方图对比、非零像素点计算为核心,设计了施工扬尘污染源自动监测系统的结构、功能及运行流程,并对运行效果进行了测试。研究和测试表明:该系统可实现监测区航拍、污染源特征提取、污染源存在性检验、污染源种类判定和污染源分布区面积计算;该系统污染源存在性检验正确率为71%,污染源面积计算效率较高,污染源特征比对效果相对稳定,基本满足施工扬尘污染源监测需求。     

Hotspots analysis and perspectives of Prussian blue analogues (PBAs) in environment and energy in recent 20 years by CiteSpace

Environmental Science and Pollution Research - Prussian blue analogs (PBAs), a type of metal–organic frameworks (MOFs), have attracted much attention because of their large specific surface...     

Effect of phosphate and silicate on selenite uptake and phloem-mediated transport in tomato (Solanum lycopersicum L.)

Environmental Science and Pollution Research - The ambiguous mechanism that selenite seems to be absorbed by roots via phosphorus (P) and silicon (Si) transporters signifies P and Si may affect...     

Source apportionment of PM2.5 during different haze episodes by PMF and random forest method based on hourly measured atmospheric pollutant

Environmental Science and Pollution Research - Hourly measured PM2.5-bound species, gases, and meteorological data were analyzed by the PMF receptor model to quantify source contributions, and by...     

Identification of important precursors and theoretical toxicity evaluation of byproducts driving cytotoxicity and genotoxicity in chlorination

• NOM formed more C-DBPs while amino acids formed more N-DBPs during chlorination • Aspartic acid and asparagine showed the highest toxicity index during chlorination • Dichloroacetonitrile might be a driving DBP for cytotoxicity and genotoxicity • Dichloroacetonitrile dominated the toxicity under different chlorination conditions Chlorination, the most widely used disinfection process for water treatment, is unfortunately always accompanied with the formation of hazardous disinfection byproducts (DBPs). Various organic matter species, like natural organic matter (NOM) and amino acids, can serve as precursors of DBPs during chlorination but it is not clear what types of organic matter have higher potential risks. Although regulation of DBPs such as trihalomethanes has received much attention, further investigation of the DBPs driving toxicity is required. This study aimed to identify the important precursors of chlorination by measuring DBP formation from NOM and amino acids, and to determine the main DBPs driving toxicity using a theoretical toxicity evaluation of contributions to the cytotoxicity index (CTI) and genotoxicity index (GTI). The results showed that NOM mainly formed carbonaceous DBPs (C-DBPs), such as trichloromethane, while amino acids mainly formed nitrogenous DBPs (N-DBPs), such as dichloroacetonitrile (DCAN). Among the DBPs, DCAN had the largest contribution to the toxicity index and might be the main driver of toxicity. Among the precursors, aspartic acid and asparagine gave the highest DCAN concentration (200 g/L) and the highest CTI and GTI. Therefore, aspartic acid and asparagine are important precursors for toxicity and their concentrations should be reduced as much as possible before chlorination to minimize the formation of DBPs. During chlorination of NOM, tryptophan, and asparagine solutions with different chlorine doses and reaction times, changes in the CTI and GTI were consistent with changes in the DCAN concentration.