MOBILE汽车源排放因子计算模式研究

在盆栽条件下，研究了土壤中Ｐｂ、Ｈｇ及其相互作用对烟草叶片活性氧代谢的影响．实验结果表明：随着Ｐｂ、Ｃｄ处理浓度的增加，ＰＯＤ活性逐渐增加，ＳＯＤ开始上升后转而下降，ＣＡＴ活性逐渐下降．它既诱导了活性氧的生成，又影响活性氧清除系统对活性氧的清除能力，结果造成活性氧的产生和清除之间的不平衡，致使相关的生理生化过程紊乱，加速了叶片衰老的进程．Ｐｂ、Ｈｇ对烟草叶片抗氧化酶代谢的影响，两者之间存在着一定的协合作用．     

Photodegradation and volatility of pesticides

BACKGROUND AND OBJECTIVES: Among the factors affecting the environmental fate of surface-applied pesticides several biological as well as abiotic factors, such as volatilization and photochemical transformations are of particular interest. Whereas reliable measurement methods and models for estimating direct photodegradation are already available for the compartments of water and atmosphere and individual subprocesses have already been described in detail, there is still a need for further elucidation concerning the key processes of heterogeneous photodegradation of environmental chemicals on surfaces. METHODS: In order to systematically examine the direct and indirect photodegradation of 14C-labeled pesticides on various surfaces and their volatilization behavior, a new laboratory device ('photovolatility chamber') was designed according to US EPA Guideline 161-3. Model experiments under controlled conditions were conducted investigating the impact of different surfaces, i.e. glass, soil dust and radish plants, and environmental factors, i.e. irradiation and atmospheric ozone (O3), on the photodegradation and volatilization of surface-deposited [phenyl-UL-14C]parathion-methyl (PM). RESULTS AND DISCUSSION: Depending on the experimental conditions, parathion-methyl was converted to paraoxon-methyl, 4-nitrophenol, unknown polar products and 14CO2. With respect to the direct photodegradation of PM (experiments without O3), the major products were polar compounds and 14CO2, due to the rapid photochemical mineralization of 4-nitrophenol to 14CO2. Paraoxon-methyl and 4-nitrophenol formation was mainly mediated by the combination of light, O3, and *OH radicals. In radish experiments PM photodegradation was presumably located in the cuticle compartment, which exhibited a sensitized photodegradation, as more unknown products were yielded compared to the glass and soil dust experiments. This could be explained by intensifying the inherent PM degradation in the dark with the same product spectrum. Due to photochemical product formation, which is an antagonistic process to the volatilization of parent compound, the volatilization of unaltered parathion-methyl from each surface generally decreased in the presence of light, particularly in combination with increasing O3 concentrations and *OH radical production rates. CONCLUSION: First results demonstrated that the photovolatility chamber provides a special tool for the systematic evaluation of (a) photodegradation of surface-located pesticide residues, i.e. measuring qualitative aspects of direct and indirect photodegradation together with relative photodegradation rates, and (b) volatilization of pesticides on surfaces by including and optionally varying relevant parameters such as light, atmospheric O3 concentration, surface temperature, air temperature, air flow rate. OUTLOOK: The experimental facility represents an important complement to lysimeter and field studies, in particular for experiments on the volatilization of pesticides using the wind tunnel system. With the photovolatility chamber special experiments on photodegradation, volatilization and plant uptake can be conducted to study key processes in more detail and this will lead to a better understanding of the effects of certain environmental processes on the fate of released agrochemicals contributing to an improved risk assessment.     

Temporal variability of bioavailable Cd,Hg, Zn,Mn and Al in an upwelling regime

Monthly variability of Cd, Hg, Zn, Mn and Al concentrations in mussels (Mytilus californianus) soft tissue and brown seaweed (Macrocystis pyrifera) was studied at a pristine rocky shore off San Quintin Bay, Baja California, México. The results were related to climatic and hydrographic conditions and to the physiological state of the mussels (condition index) by correlation analysis and principal component analysis (PCA). A "normalization" to account for the variability induced by the physiological state of the mussel was performed. The PCA was performed in two ways to relate the environmental variables and the condition index to: (1) the metal concentrations in mussels, and (2) the "normalized" mussel concentrations. The association of the variability of Cd with the upwelling season was revealed in both PCAs. The temporal variability of this metal in mussels was highly correlated to that in seaweed, suggesting that the dissolved phase determined the variability of Cd in mussels. However, for Hg, Zn, Mn and Al the results from both PCAs were different. The first PCA showed the relationship of these metals to pluvial precipitation and to the condition index. The PCA for the normalized mussel concentrations showed that, after eliminating the effect of the condition index, only Al was related to pluvial precipitation. Manganese, and to a less degree Zn, were related to these metals in seaweed. Because zinc is an essential element in mussels, some regulation of their internal concentrations is likely. Mercury was not detected in seaweed, but because of its reactive nature, it is not expected that the dissolved fraction could be a significant pathway; therefore, it can be concluded that its temporal variability was determined by the variability in the condition index only.     

Hg2+胁迫下两优培九和武运粳7号水稻幼苗抗性差异的研究

以三叶期的水稻幼苗为材料 ,比较了Hg2 污染对杂交稻两优培九和常规稻武运粳 7号的叶绿素含量、类囊体膜光系统Ⅰ (PSⅠ )和光系统Ⅱ (PSⅡ )电子传递活性、细胞膜透性、过氧化物酶 (POD)、过氧化氢酶 (CAT)活性和脯氨酸含量的影响。结果表明 ,随着Hg2 处理浓度的增加 ,两优培九和武运粳 7号的叶绿素含量、PSⅠ和PSⅡ的电子传递活性降低 ,而 2者的细胞膜透性、脯氨酸含量升高 ,两优培九的CAT活性、武运粳 7号的POD和CAT活性呈现先升后降的趋势 ,但两优培九的POD活性则呈现升高的趋势。两优培九对Hg2 污染的抗性明显大于武运粳 7号。     

Hg2+、Cu2+胁迫下茶菱保护酶系统的防御作用

研究了不同ρ（Hg^2 )、ρ(Cu^2 ）对茶菱（Trapella sinenisis Olive）叶片和根部保护酶系统的影响，结果表明：随ρ（Hg^2 )、ρ(Cu^2 ）的增加，膜透性增加，根部μ（O2^-）、b（H2O2）上升，λ（SOD)、λ（POD）、λ（CAT）先升后降，Hg^2 胁迫下，叶片μ（O2^-）、b（H2O2）、λ（SOD）、λ（POD）先升后降，而λ（CAT）下降；Cu^2 胁迫下，λ（SOD）先降后升，λ（POD）逐渐下降，茶菱保护酶系统对Hg^2 的防御作用弱于Cu^2 ，叶的防御作用弱于根。     

地下水中VOC挥发因子模型的研究

建立了一个计算地下水中挥发性有机物（VOC）挥发因子的模型.选用半挥发性的1,2,4-三氯苯和挥发性的四氯乙烯为VOC的代表,分别计算了非饱和区土壤为砂土和粘土时的挥发因子.结果表明：蒸发使VOC的挥发因子增大,而下渗则使VOC的挥发因子减小;不论VOC的挥发性强弱,蒸发（下渗）对挥发因子的影响均比较明显;蒸发情况下,非饱和区土壤性质对挥发因子的影响不明显,而下渗情况下,非饱和区土壤性质对挥发因子的影响则趋于明显;此外,当非饱和区土壤为粘土时,VOC的挥发因子受蒸发（下渗）的影响更明显.     

植物叶片氨挥发研究进展

氨是大气污染的一个重要组成部分,植物叶片氨挥发是大气氨污染的来源之一。植物氨挥发的强弱与植株氮素利用效率有很好的相关性,很多研究表明,植株收获时的总氮量一般显著小于植株氮素最大累积量,植株生长后期体内含氮化合物的水解和氨的挥发可能是其重要原因。因此,研究植物体的氨挥发对于大气环境保护和提高氮肥利用率具有非常重要的意义。本文对植物叶片氨挥发的主要测定方法、机理和影响因素进行了综述,对植物叶片氨挥发研究中的一些问题进行了讨论。     

Hg、Cd对莼菜越冬芽光合膜光化学活性及多肽组分的影响

研究了重金属Ｈｇ＾２＋、Ｃｄ＾２＋对水生植物莼菜越冬芽光合膜叶绿素含量、多肽组分及光化学特性的影响。实验结果表明，经１ｍｍｏｌ／Ｌ浓度Ｈｇ＾２＋处理后，叶片光合膜叶绿素含量、叶绿素ａ／ｂ值、室温吸收光谱、荧光发射光谱、光系统电子传递活性呈下降趋势；当Ｈｇ＾２＋处理浓度超过２ｍｍｏｌ／Ｌ时，叶片光合膜叶绿素含量及其它化光学活性显下降，光合膜多肽组分也产生降解。茎光合膜对Ｈｇ＾２＋的敏感程度比叶片低     

上海典型燃烧源铅和汞大气排放趋势分析

上海百年来快速的城市化进程导致资源能源的大量消耗,并向城市环境中排放了大量有毒有害污染物.为探寻上海典型燃烧源重金属大气排放历史及趋势,基于上海化石燃料(煤炭和汽油)的历史消耗量及其大气铅(Pb)和汞(Hg)的排放因子,估算了上海主要燃煤部门(燃煤电厂、工业部门和居民生活)和机动车燃油大气Pb和Hg的历史排放量.结果表明,1949~2015年间大气Pb和Hg的燃煤排放量随时间推进均呈现先增长后下降趋势,即1949年解放后快速增长的煤炭消耗和较少的烟尘控制措施使其排放量出现急剧地波动式增长,至20世纪80~90年达到高峰,此后上海采取了各种减排和控制措施,使得目前三大燃煤源的大气Pb和Hg排放量出现大幅度下降.1980~2015年间上海大气Hg的燃煤排放比例一直占据主导地位(87.5%~99.7%).含铅汽油自1997年完全退出上海市场之后,燃煤排放替代其成为大气Pb的主要贡献源(78.2%~83.5%),然而自2005年起随着汽油消耗的急速增长,汽油燃烧排放又成为其主要贡献源(55.5%~79.1%).     

Watershed characteristics and climate factors effect on the temporal variability of mercury in the southern Baltic Sea rivers

Mercury(Hg) is a neurotoxic metal which can enter into the human organism mainly by fish consumption, skin and transpiration. In the coastal zone of the southern Baltic Sea, rivers are the main source of Hg. The Polish region represents the largest proportion of the Baltic Sea catchment and this research included four rivers of the Baltic watershed: the Reda,Zagórska Struga, Kacza and Gizdepka. The samples were collected in the years 2011–2013.Total and particulate Hg concentration in these rivers were measured. Due to intensive rain,deposited mercury on the catchment area was washed out into the riverines water and introduced into the Baltic Sea. Consequently, the load of Hg increased three times.Additionally, the intensive dry atmospheric deposition during heating season caused the increase of the concentration of particulate Hg in the river water even by 85%. The research confirmed the role of the river flow magnitude in the load of mercury introduced into the sea by rivers. Moreover, a high variability of mercury concentration was connected to the additional sources such as the chemicals containing Hg and no municipal sewage system.The analysis of stable isotopes indicated that the SPM contained terrestrial organic matter;however, there was no clear correlation between Hgtot, Corgand Ntotconcentrations and δ~(13)C, δ~(15)N, C/N in particulate matter.