Behavior and prediction of photochemical degradation of chlorinated polycyclic aromatic hydrocarbons in cyclohexane

The photochemical degradation of 11 chlorinated polycyclic aromatic hydrocarbons (ClPAHs) and the corresponding 5 parent PAHs was examined to simulate the compound’s fate on aerosol surfaces. All the ClPAHs and PAHs decayed according to the first-order reaction rate kinetics. The photolysis rates of ClPAHs varied greatly according to the skeleton of PAHs; the rates of chlorophenanthrenes (ClPhes) and 1-chloropyrene were higher than those of corresponding parent PAHs, whereas chlorofluoranthenes, 7-chlorobenz[a]anthracene and 6-chlorobenzo[a]pyrene were more stable under irradiation compared to respective parent PAH. Considering the photoproducts of ClPhes detected, the oxidation could occur immediately at positions of the highest frontier electron density. Finally, the quantitative structure-property relationship models were developed for direct photolysis half-lives and average quantum yields of the ClPAHs and parent PAHs, in which the significant factors affecting photolysis were E_LUMO+1, total energy and surface area, and E_LUMO, E_LUMO − E_HOMO and total energy, respectively.     

Solubility of toluene, benzene and TCE in high-microbial concentration systems

We report measurements of solubility limits for benzene, toluene, and TCE in systems that contain varying levels of biomass up to 0.13 g mL⁻¹ for TCE and 0.25 g mL⁻¹ for benzene and toluene. The solubility limit increased from 21 to 48 mM when biomass (in the form of yeast) was added to aqueous batch systems containing benzene. The toluene solubility limit increased from 4.9 to greater than 20 mM. For TCE, the solubility increased from 8 mM to more than 1000 mM. Solubility for TCE (trichloroethylene) was most heavily impacted by biomass levels, changing by two orders of magnitude as the microbial concentrations approach those in biofilms.     

Laboratory longitudinal diffusion tests: 2. Parameter estimation by inverse analysis

This study focuses on the verification of test interpretations for different state analyses of diffusion experiments. Part 1 of this study identified that steady, quasi-steady and equilibrium state analyses for the through- and in-diffusion tests with solution reservoirs are generally feasible where the tracer is not highly sorptive. In Part 2 we investigate parameter identifiability in transient-state analysis of reservoir concentration variation using a numerical approach. For increased generality, the analytical models, objective functions and Jacobian matrix necessary for inverse analysis of transient-state data are reformulated using unified dimensionless parameters. In these dimensionless forms, the number of unknown parameters is reduced and a single dimensionless parameter represents the sorption property. The dimensionless objective functions are evaluated for individual test methods and parameter identifiability is discussed in relation to the sorption property. The effects of multiple minima and measurement error on parameter identifiability are also investigated. The main findings are that inverse problems for inlet and outlet reservoir concentration analyses are generally unstable and well-posed, respectively. Where the tracer is sorptive, the inverse problem for the inlet reservoir concentration analysis may have multiple minima. When insufficient measurement data is collected, multiple solutions may result and this should be taken into consideration when inversely analyzing data including that of inlet reservoir concentration. Verification of test interpretation by cross-checking different state analyses is feasible where the tracer is not highly sorptive. In an actual experiment, test interpretation validity is demonstrated through consistency between theory and practice for different state analyses.     

海南省几种草本植物微量元素的组成

海南省位于我国热带地区,草本植物微量元素组成可反映热带区域生物地球化学特点。海南植物微量元素含量属正常范围值,仅个别植物Ｃｄ、Ｈｇ含量偏高。植物Ｚｎ、Ｃｕ、Ｍｏ含量大多在５ｍｇ／ｋｇ以上,Ｐｂ、Ｃｕ、Ｃｄ含量一般低于２ｍｇ／ｋｇ,Ｈｇ、Ａｓ、Ｎｉ通常不足１ｍｇ／ｋｇ。雀稗（Ｐａｓｐａｌｕｍｃｏｍｍｅｒｓｏｎｉ）、地胆草（Ｅｌｅｐｈａｎｔｏｐｕｓｓｃａｂｅｒ）等微量元素含量普遍较高。红裂稃草（Ｓｃｈｉｚａｃｈｙｒｉｕｍｓａｎｇｕｉｎｅｕｍ）、白茅（Ｉｍｐｅｒａｔａｃｙｌｉｎｄｒｉｃａ）等微量元素含量一般较低。植物微量元素组成与植物种类及其生境条件有关。生物吸收系数反映植物摄取元素的强度,Ｍｏ、Ｃｄ、Ｈｇ、Ｚｎ、Ｃｕ的生物吸收系数通常大于１．０,属强积聚元素,Ｐｂ、Ｃｒ、Ｎｉ、Ａｓ的生物吸收系数大多低于０．３,是弱摄取元素。     

垂直面绿化植物遮阳系数与叶面积指数研究

比较、分析了农业研究中提出的叶面积指数LAI与用于建筑节能领域的垂直面绿化植物叶片遮阳系数SCPVW两个概念的异同和各自的应用范围。指出城市绿化采用水平或垂直绿化方式时,由于下垫面差异,植物叶片的遮阳系数应当分别采用LAI和SCPVW进行计算。     

CBERS-2B数据提取平原区细小地物系数的方法探讨

利用Landsat TM等中等分辨率影像对区域生态环境进行监测与评价时,由于影像分辨率的局限性,仍有许多地物无法解译出来,如农田中的道路、水渠等,文章主要研究了利用图像融合增强和人机交互式解译等技术方法,对CBERS-2B的CCD影像和HR影像进行处理,提取平原区农田中道路面积比系数,从而将农田中未解译的地物扣除。结果表明,CCD影像与HR影像经过融合增强处理后,可以进行平原地区村级及以上道路的提取。     

基于灰关联分析的天津市气溶胶消光特征研究

根据天津市秋季(2006年10月10日～20日)消光系数(bext)、PM2.5、SO2、NOX、NO2、O3质量浓度及相对湿度监测结果,利用灰色关联分析法分析大气消光系数同空气中的几种主要污染要素的相关性。结果表明,与消光系数有关的几种主要指标的灰关联度序为PM2.5NOXRHNO2O3,其中PM2.5与消光系数的灰关联系数达到0.905,远高于其他相关指标。同时对PM2.5和消光系数相关分析表明,监测期间天津市PM2.5质量消光系数为6.04m2/g。     

四川省毛河流域污染综合治理方案探讨

分析了四川省毛河流域各类污染源分布状况及水质现状,采用一维稳态单组分水质模型、多宾斯-坎普稳态模型,引入水文数据、水质监测数据、环境统计数据、社会统计公报数据,以Excel作为数据平台,对毛河水环境进行了动态模拟,反演出主要污染物降解系数。总结了毛河水环境目前存在的问题,并模拟计算了2种污染综合治理方案实施后对毛河水质的影响,确定了毛河流域水污染综合治理的重点以及制约因子。     

珠三角秋冬季节长时间灰霾污染特性与成因

利用珠三角大气超级站2012年10月与2013年1月能见度、不同粒径颗粒物与BC质量浓度、气溶胶光散射系数、O3、相对湿度等在线监测数据,分析秋冬季节2次持续时间超过10 d的长时间灰霾过程污染特性与成因。结果表明,冬季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为13%和67%;PM2.5、PM1占PM10质量浓度分别为66%和39%;较高的PM2.5与BC日均浓度相关系数(R2=0.88)体现了一次排放对颗粒物质量浓度及能见度的显著影响。秋季灰霾过程中气溶胶吸光系数和光散射系数对大气总消光系数的贡献分别为11%和69%,由BC导致的吸光效应较冬季下降了约20%;PM2.5和PM1占PM10质量浓度比例分别为68%和45%,均高于冬季;O3浓度日最大小时值的平均值接近冬季的2倍;二次来源对PM2.5浓度升高和能见度下降起主导作用。来自不同方向的2种气团在珠三角僵持,大气扩散条件差是导致这2次灰霾过程的重要外在条件,应成为灰霾预报预警的重点关注对象。     

燃煤电厂在线监测系统颗粒物浓度排放系数影响因素的探讨

选取上海市7家未安装气-气换热器的国控燃煤电厂作为研究对象,从煤质、除尘器、脱硫协同脱除作用以及锅炉工况负荷等方面探讨对颗粒物浓度排放系数 K值产生的影响,得出上述因素通过改变脱硫进口颗粒物浓度值影响 K值,当脱硫进口颗粒物浓度较低、波动范围较小时,其 K值也维持相对稳定的状态;当脱硫进口颗粒物浓度较高、波动范围较大时,其 K值也会发生较大的变化等结论。