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701.
Factors affecting HCH and DDT in soils around watersheds of Beijing reservoirs,China 总被引:3,自引:0,他引:3
Wenyou Hu Yonglong Lu Tieyu Wang Wei Luo Xiang Zhang Jing Geng Guang Wang Yajuan Shi Wentao Jiao Chunli Chen 《Environmental geochemistry and health》2010,32(2):85-94
The factors that influence the dynamics of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) in soils
around the watersheds of Beijing reservoirs were examined. Compared with other studies on HCH and DDT in soils and established
reference values, the concentrations of HCH and DDT in soils around our study area were relatively low. The relationships
between HCH and DDT concentrations and land use, soil texture, and soil properties were discussed. HCH and DDT concentrations
were higher in arable soils than those in uncultivated fallow soils. Although land use was the most important factor affecting
HCH and DDT residues, additional factors such as soil texture and soil total organic carbon were also involved in pesticide
retention in soils. The results indicated that the historical agricultural applications of HCH and DDT were the major source
of their residues. Atmospheric deposition, as well as long-distance transportation and inputs from surrounding weathered agricultural
soils may also serve as important sources of HCH and DDT residues in the watersheds. 相似文献
702.
Minghong Wu Wenyan Shi Haijiao Zhang Zheng Jiao Jie Chen Side Yao Guoji Ding Jiamo Fu 《Environmental Chemistry Letters》2010,8(1):25-31
A wide range of pharmaceutical compounds have been identified in the environment, and their existence is a topic of growing
concern, both for human and ecological health. The work described here has investigated the photolytic properties of L(+)-α-phenylglycine
(L-α-PG-H) in aqueous solution as it can be degraded by photo-catalysis. In 266 nm laser flash photolysis of aqueous solution
of L-α-PG-H saturated with nitrogen, two transient absorption bands are observed at 280–330 nm and 450–800 nm, respectively,
due to L-α-PG-H radical cation and hydrated electrons (eaq−). Then eaq− reacts with L-α-PG-H to form the L-α-PG-H radical anion. Decaying rate constants of eaq− observed at 720 nm is to be 8.9 × 108 dm3 mol−1 s−1. The rate constant for oxidation of L-α-PG-H by SO4
− is calculated as 4.5 × 108 and 4.3 × 108 s−1 mol−1 dm3, respectively. The dissociation constants (pKa) of L-α-PG-H is 3. Excited triplet of L-α-PG-H in solution is formed by laser
flash photolysis. The quench rate constant of L-α-PG-H excited triplet (k
s) is determined to be 1.3 × 107 dm3 mol−1 s−1 and k
0 is equal to 1.7 × 105 s−1. 相似文献
703.
704.
705.
Zhou Yan Huijun He Chunping Yang Guangming Zeng Le Luo Panpan Jiao Huiru Li Li Lu 《环境科学学报(英文版)》2017,29(7):211-220
In this study,the performance of 3,5-dimethyl-2,4-dichlorophenol(DCMX) degradation by a screened strain was investigated.18 S r DNA and the neighbor-joining method were used for identification of the isolated strain.The results of phylogenetic analysis and scanning electron micrographs showed that the most probable identity of the screened strain should be Penicillium sp.Growth characteristics of Penicillium sp.and degradation processes of DCMX were examined.Fourier transform infrared spectroscopy of the inoculated DCMX solution was recorded,which supported the capacity of DCMX degradation by the screened Penicillium sp.Under different salinity conditions,the highest growth rate and removal efficiency for DCMX were obtained at p H 6.0.The removal efficiency decreased from 100%to 66% when the DCMX concentration increased from 5 to 60 mg/L,respectively.Using a Box–Behnken design,the maximum DCMX removal efficiency was determined to be 98.4%.With acclimation to salinity,higher removal efficiency could be achieved.The results demonstrate that the screened Penicillium sp.has the capability for degradation of DCMX. 相似文献
706.
利用卫星遥感MODIS数据研究区域大气PM_(2.5)浓度分布是环境管理的有效方法。获取美国国家航空航天局MODIS L1B1KM数据,采用暗目标法反演阜新市大气气溶胶厚度AOD数据;提取阜新市5个大气监测站点位2014年3月至5月、2015年3月至4月期间PM_(2.5)浓度数据进行相关性分析,建立PM_(2.5)浓度-AOD之间的线性、一元二次、对数函数、幂函数及指数函数5种相关性模型;引用湿度影响因子建立大气PM_(2.5)浓度订正模型,采用PM_(2.5)浓度订正模型、Peterson模型分别订正PM_(2.5)浓度及AOD标高,应用阜新市环保局5个监测点位2014年6~12月、2015年5~12月期间PM_(2.5)的月平均浓度进行模型检验。对比分析订正后的5种相关性模型拟合优度,检验结果表明:订正方法提高了PM_(2.5)浓度-AOD相关性;线性相关性模型R2为0.633 6,相对误差为12.41%,相对其他4种模型相对误差较小。利用阜新市大气AOD预测PM_(2.5)浓度具有良好环境指示意义。 相似文献
707.
708.
从IPCC第四次评估报告看全球气候变化及防灾减灾对策 总被引:9,自引:0,他引:9
本文介绍了IPCC第四次评估报告提出的全球气候变化情况,概述了全球气候变化的原因、影响和灾害,提出了相应的防灾减灾应对措施。 相似文献
709.
710.
大同火山群位于大同盆地的东部,是火山活动的典型遗存.从30年代开始,国内外学者对火山群进行了地貌背景等方面的研究,初步认定大同火山为第四纪火山.近年来,随着对火山活动时期研究的不断深入,火山活动的年代逐步精确.本文对大同火山的研究现状进行了简要概述,并提出了对大同火山研究的进一步思路. 相似文献