道路交通拥堵与城市雾霾污染的关系研究

道路拥堵与城市雾霾是机动车行驶带来的两个负溢出效应,大量文献揭示了城市机动车行驶对二者带来的影响,却鲜有文献关注道路拥堵程度与雾霾污染之间的内在联系。这其中的缘由在于,一则道路拥堵程度与雾霾污染之间互为因果,同时有共同的影响因素,由此带来的内生性难题难以有效解决;其次,采用统一标准来测度不同城市道路拥堵程度的数据难以获得。为此利用高德地图(Amap)根据机动车定位导航系统提供的城市拥堵延时的大数据,来捕获各省会城市每日道路交通的拥堵程度,同时运用各城市每日的燃油销售价格、国际市场原油价格以及上一周同一工作日道路的拥堵程度作为工具变量,通过两阶段最小二乘法(2SLS)估计道路拥堵程度对城市雾霾污染的影响。回归结果表明:①以城市燃油价格作为工具变量时,道路拥堵程度每增加1%,会导致省会城市PM2.5、PM10分别增加6.5%和6.7%;②以国际原油价格、上一周同一个工作日拥堵程度作为工具变量,以及改用GMM方法进行估计时,基准回归的结论仍然稳健,城市的治堵举措与治霾举措能够相互协同;③进一步以省会城市新增轨道交通来实现治堵和治霾的例子表明,发展轨道交通来实现治堵与治霾的协同效应,要以有效治堵作为前提,否则减排治霾的协同效果无法实现。     

顶空气相色谱法测定水中三氯甲烷四氯化碳的参数优化及测定影响因素探讨

本文探讨了如何提高顶空气相色谱法测定三氯甲烷及四氯化碳的灵敏度、精密度与准确度。重点讨论了平衡条件的优化以及带顶空自动进器的气相色谱仪的各个关键参数的优化。     

Temperature effect on photolysis decomposing of perfluorooctanoic acid

Perfluorooctanoic acid(PFOA)is recalcitrant to degrade and mineralize.Here,the effect of temperature on the photolytic decomposition of PFOA was investigated.The decomposition of PFOA was enhanced from 34% to 99% in 60 min of exposure when the temperature was increased from 25 to 85°C under UV light(201–600 nm).The limited degree of decomposition at 25°C was due to low quantum yield,which was increased by a factor of 12 at 85°C.Under the imposed conditions,the defluorination ratio increased from 8% at 25°C to 50% at85°C in 60 min.Production of perfluorinated carboxylic acids(PFCAs,C7–C5),PFCAs(C4–C3)and TFA(trifluoroacetic acid,C2)accelerated and attained a maximum within 30 to 90 min at 85°C.However,these reactions did not occur at 25°C despite extended irradiation to180 min.PFOA was decomposed in a step-wise process by surrendering one CF2unit.In each cyclical process,increased temperature enhanced the quantum yields of irradiation and reactions between water molecules and intermediates radicals.The energy consumption for removing eachμmol of PFOA was reduced from 82.5 k J at 25°C to 10.9 k J at 85°C using photolysis.Photolysis coupled with heat achieved high rates of PFOA degradation and defluorination.     

Probabilistic approaches in the effect assessment of toxic chemicals. What are the benefits and limitations?

There is an ongoing discussion whether in the environmental risk assessment for chemicals the so called 'deterministic' approach using point estimates of exposure and effect concentrations is still appropriate. Instead, the more detailed and scientifically sounder probabilistic methods that have been developed over the last years are widely recommended. Here, we present the results of a probabilistic effect assessment for the aquatic environment performed for the pesticide methyl parathion and compare them with the results obtained with the common deterministic approach as described in the EU Technical Guidance Document. Methyl parathion was chosen because a sufficient data set (acute toxicity data for about 70 species) was available. The assumptions underlying the probabilistic effect assessment are discussed in the light of the results obtained for methyl parathion. Two important assumptions made by many studies are: (i) a sufficient number of ecologically relevant toxicity data is available, (ii) the toxicity data follow a certain distribution such as log-normal. Considering the scarcity of data for many industrial chemicals, we conclude that these assumptions would not be fulfilled in many cases if the probabilistic assessment was applied to the majority of industrial chemicals. Therefore, despite the well-known limitations of the deterministic approach, it should not be replaced by probabilistic methods unless the assumptions of these methods are carefully checked in each individual case, which would significantly increase the effort for the assessment procedure.     

海水中溶解有机磷化合物的生态效应

介绍了海水中溶解有机磷的生物效应及其分析方法。有机磷农药在农业中得到广泛应用并被雨水冲刷进入海水中。农药生产企业排放的污染物已经严重污染近海水体。讨论了有机磷农药的毒性机理和有效利用的方法。     

The internal barriers of rotation for the 209 polychlorinated biphenyls

The internal barrier of rotation (Erot) was calculated for all 209 polychlorinated biphenyls (PCBs) by using a semi-empirical method, viz. the Austin Model 1 (AMI) Hamiltonian. The difference in total energy between a forced planar state and an optimised twisted structure was defined as Erot. The Erot values were in the range of 8.33 to 483 kj/mol, and were significantly influenced by the number of chlorine atoms inortho position. An additional structural characteristic of the PCBs influencing Erot ofortho substituted congeners was substitution by chlorine atoms in vicinalmeta positions, which is assumed to prevent outward bending ofortho substituents. This so-called buttressing effect contributed with 4 to 31 kj/mol per added chlorine atom. In conclusion, the internal barrier of rotation, calculated for all 209 PCBs, provides an important structure dependent physico-chemical parameter for multivariate modelling of future quantitative structure-activity and structure-property relationships (QSARs/QSPRs).     

生物膜的研究进展

本文综述了近年来生物膜研究成果,包括生物膜的发育形成、形态结构、组成、物理－ 化学特征、抗性等;生物膜在污水处理方面的作用和微生物组织腐蚀性的负效应     

环境中氟化物的迁移和转化及其生态效应

本文对环境中氟化物的迁移和转化及其对人体、动物、植物的污染生态效应作一简要的综述,主要包括以下几方面：１．环境中氟化物的来源及其地球化学特征;２．土－水－气－食物链中氟化物的迁移和积累与地方性氟流行病;３．土－水－气中氟的迁移和积累与植物氟毒效应;４．土－水－气中氟的迁移和积累与蚕桑氟化物污染;５．环境中氟污染的防治对策。     

生物质炭添加量对BDE-47在土壤中吸附和解吸行为的影响

研究了添加生物质炭对2,2’,4,4’-四溴联苯醚(BDE-47)在土壤中吸附和解吸行为的影响。结果表明,在受试天然土壤中添加不同量的生物质炭,土壤对BDE-47吸附能力的变化程度也将不同,当生物质炭添加量为2.0%(质量分数,下同)以下时,随着生物质炭添加量的增加,土壤对BDE-47吸附能力的提高程度越明显,BDE-47的解吸滞后性则呈现先上升后下降的趋势。当生物质炭添加量为0.1%、0.5%时,土壤单点分配系数分别为原土壤的0.98~1.39、1.02~1.50倍;当生物质炭添加量为1.0%、2.0%时,土壤单点分配系数分别为原土壤的1.44~1.68、3.25~3.27倍;生物质炭添加量为1.0%时,BDE-47的解吸滞后性最显著。     

盐城蟒蛇河饮用水源原水水质及盐龙湖工程水质净化效果评价

蟒蛇河是盐城市区主要的地表饮用水源地,其水质通常在Ⅳ~Ⅴ类标准。为改善原水水质,中国首个平原上开挖的饮用水源生态净化湖——盐龙湖于2012年6月建成启用。通过水质监测,分析了近年来蟒蛇河原水水质及其污染特征,并对盐龙湖工程水质的净化效果进行了评价。研究表明:(1)蟒蛇河原水在春、秋、冬季水质主要指标基本能满足《地表水环境质量标准》(GB3838-2002)Ⅲ类标准,但夏季水质相对较差;(2)蟒蛇河原水呈现出典型的有机污染特征,营养盐类多是以有机形态存在,但TN与TP的主要污染来源并不一致,在不同季节原水污染特性存在波动规律;(3)近年来蟒蛇河原水中有机物及营养盐浓度有升高趋势;(4)盐龙湖工程水质净化效果在夏季最佳,春、秋季次之,冬季则一般;(5)近一年来,盐龙湖工程累计削减原水高锰酸盐指数、氨氮、TN、TP、SS的量分别达到56.6、35.6、59.8、8.9、1 000.0t(干质量)。