三唑酮在水中的光化学降解及其影响因素

以太阳光和高压汞灯为光源,研究了水溶液中三唑酮光化学降解的影响因子。结果表明:在不同光源和透光介质下,三唑酮的降解能力从大到小依次为:石英试管 高压汞灯、玻璃试管 高压汞灯、石英试管 太阳光、玻璃试管 太阳光、暗室;水溶液中三唑酮初始浓度越高,其光降解率越低,呈负相关关系;丙酮对三唑酮在水中的光解有极显著的光敏作用,光敏效率与丙酮添加量有显著相关性;三唑酮的光解实质为光氧化作用,溶解氧含量对三唑酮光解有重大影响。     

阴-阳离子表面活性剂对啶虫脒在水溶液中光解的影响

研究了不同浓度的阴离子表面活性剂十二烷基苯磺酸钠(SDBS)和阳离子表面活性剂十六烷基三甲基溴化胺(CTAB)对啶虫脒在水溶液中光解的影响.结果表明,啶虫脒的光反应符合一级反应动力学规律,表面活性剂不直接参与啶虫脒的光反应.SDBS和CTAB对啶虫脒的光反应均有抑制作用,CTAB的抑制作用大于SDBS.当SDBS浓度低于400mg·L-1时,随着浓度的增加,SDBS的抑制作用有增强的趋势,在400mg·L-1时达到最强,而后,随着浓度的增加逐渐减弱.而CTAB的加入量为25mg·L-1时,即产生强烈的抑制作用,抑制率达到62.90%;加入量为50～150mg·L-1时,抑制作用趋于稳定,抑制率为80.36%～87.03%.     

异丙草胺光解体系中溶解氧的增强效应

研究了异丙草胺光解过程中溶解氧的协同效应,在不同初始浓度溶解氧存在时异丙草胺在水中的光解规律.随着溶解氧初始浓度的增加,光解速率和效率均有提高,其中最高和最低光解效率相差30%.初始溶解氧浓度达到7.5mg/L后,光解速率和效率出现了平台效应,并且随着溶解氧浓度增加而有所下降.伴随异丙草胺的光解,溶解氧也有消耗,可以推测溶解氧也参与了光反应.通过对降解产物的分析,发现含高浓度溶解氧和缺氧条件下的光解产物基本一致,但部分光解产物生成量不同.通过光解体系做自旋捕捉实验,推测可能是通过单线态氧¹O₂机制进行光氧化.     

铁-草酸盐配合物光分解降解对硝基苯酚的研究

研究了铁(Ⅲ)-草酸盐配合物在可见光及太阳光照射下,对对硝基苯酚的光解降解作用。结果表明,在pH=4.0、Fe(Ⅲ)/H_2C_2O_4=0.080mmol/L/0.96mmol/L(分4次加入)、光照4h的条件下,20mg/L对硝基苯酚的降解率为89％。溶液pH值,铁与草酸盐浓度比和对硝基苯酚浓度均对降解效果产生影响。     

Evaluation of nitrogen dioxide photolysis rates in an urban area using data from the 1997 Southern California Ozone Study

The photolysis of nitrogen dioxide and formaldehyde are two of the most influential reactions in the formation of photochemical air pollution, and their rates are computed using actinic flux determined from a radiative transfer model. In this study, we compare predicted and measured nitrogen dioxide photolysis rate coefficients (j_NO2). We used the Tropospheric Ultraviolet-Visible (TUV) radiation transfer model to predict j_NO2 values corresponding to measurements performed in Riverside, California as part of the 1997 Southern California Ozone Study (SCOS’97). Spectrally resolved irradiance measured at the same site allowed us to determine atmospheric optical properties, such as aerosol optical depth and total ozone column, that are needed as inputs for the radiative transfer model. Matching measurements of aerosol optical depth, ozone column, and j_NO2 were obtained for 14 days during SCOS’97. By using collocated measurements of the light extinction caused by aerosols and ozone over the full height of the atmosphere as model input, it was possible to predict sudden changes in j_NO2 resulting from atmospheric variability. While the diurnal profile of the rate coefficient was readily reproduced, j_NO2 model predicted values were found to be consistently higher than measured values. The bias between measured and predicted values was 17–36%, depending on the assumed single scattering albedo. By statistical analysis, we restricted the most likely values of the single scattering albedo to a range that produced bias on the order of 20–25%. It is likely that measurement error is responsible for a significant part of the bias. The aerosol single scattering albedo was found to be a major source of uncertainty in radiative transfer model predictions. Our best estimate indicates its average value at UV-wavelengths for the period of interest is between 0.77 and 0.85.     

南京北郊地区黑碳气溶胶对光解系数的影响

采用2018年6月以及2017年10月南京黑碳气溶胶（BC）垂直观测数据和Mie散射理论计算BC光学厚度（AOD_BC）,并将结果输入TUV辐射传输模型,探讨BC对光解系数J[O¹D]和J[NO₂]日变化及垂直变化的影响.结果表明,在地面,J[O¹D]和J[NO₂]日变化均呈单峰型分布,峰值在正午12：00,但BC对J[O¹D]和J[NO₂]的衰减作用正午时最小,在6：00和18：00左右较大,最大分别可达-13.7%和-19.0%.AOD_BC与光解系数呈非线性负相关,BC对光解系数的衰减能力随着AOD_BC增大而下降.当天顶角为0°时,光解系数对AOD_BC的变化最敏感.在边界层0~1km内,光解系数与高度呈线性正相关,这与紫外辐射密切相关,J[O¹D]和J[NO₂]在垂直高度上与紫外辐射的相关系数R均高达0.99.BC对光解系数的衰减程度随高度下降而增大,但幅度较小,距平的最大值仅0.1%.     

Photodegradation of the organophosphorus pesticides chlorpyrifos,fenamiphos and vamidothion in water

The photodegradation of the pesticides chlorpyrifos, fenamiphos and vamidothion in water containing 2–4% methanol was examined. Acetone (5%) was added as photosensitizer in the photolysis of vamidothion. A suntest apparatus equipped with a xenon arc lamp which exhibits a radiation very close to natural sunlight was employed. Analyses were performed by direct injection of the water samples containing the photoproducts into a liquid chromatograph with diode array and thermospray mass spectrometric detection. The major photodegradation products were identified by matching their diode‐array spectra with the corresponding spectra of the authentic standards, their retention times and the spectra obtained using positive and/or negative thermospray mass spectrometry. 3,5,6‐trichloro‐2‐pyridinol, fenamiphos sulfoxide and vamidothion sulfoxide were the major photodegradation products from chlorpyrifos, fenamiphos and vamidothion, respectively.     

Phototransformation of chlorimuron-ethyl on leaf surface

Chlorimuron-ethyl, a post-emergent herbicide selectively used in soybean and maize, degrades mainly through chemical hydrolysis. Photolysis has also an important role in the degradation of this compound. Phototransformation of chlorimuron-ethyl takes place through the cleavage of the sulfonylurea bridge, dechlorination, de-esterification and cyclization. Enzymatic de-esterification usually takes place in plant system to liberate the free acid, chlorimuron, which, in fact, inhibits the acetolactate synthase enzyme. In the non-enzymatic environment, de-esterification generally does not occur at normal pH and in moisture-free medium. But on the leaf surface of maize crop de-esterification of chlorimuron-ethyl takes place. The moisture deposited on leaf surfaces by virtue of evapo-transpirational loss of water may cause the de-esterification of chlorimuron-ethyl to the free acid, chlorimuron.     

水环境中抗生素的光降解研究进展

抗生素的大量使用已经成为了全球环境问题.由于其在环境水体中难以被微生物降解,且能导致细菌抗药性越来越受到关注.光降解是污染物在水环境中非常重要的非生物降解途径.本文介绍了水环境中抗生素的直接、间接和自敏化光降解动力学,着重阐述了抗生素的光降解过程的影响因素、降解产物和可能降解途径等最新研究成果,指出抗生素光降解产物的分离提取与结构鉴定,以及预测抗生素降解过程的动力学模型构建将成为今后主要的研究方向和趋势.