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841.
以小风和静风状态下连续点源的大气扩散模式为基础,采用与体源烟团的初始分布尺度相当的初始时间修正其扩散参数公式中的运行时间,从理论上导出了小风和静风状态下连续体源的大气扩散模式。该模式与现有的大气扩散模式体系完全相容,可以方便地应用于小风和静风状态下连续体源引起的地面浓度的预测计算。 相似文献
842.
A Pilot Study on Using Urinary 1-Hydroxypyrene Biomarker for Exposure to PAHs in Beijing 总被引:3,自引:0,他引:3
Zhang W Xu D Zhuang G Ding C Wang G Chang J Ren G 《Environmental monitoring and assessment》2007,131(1-3):387-394
To study whether the urinary 1-hydroxypyrene (1-OHP) could be the biomarker of atmospheric PAHs, a small-scale pilot study
was carried out on the relation of 1-OHP vs PAHs with the traffic policemen in Beijing of smokers and nonsmokers to be subgroups
in both the exposure and control groups. Both the PAHs and 1-OHP were analyzed with high performance liquid chromatography
(HPLC). The ambient concentrations of PAHs were different at the different sites (the average sum of PAHs (TPAH) were 12.36,
16.27, 18.37 ng/m3 at the suburban residential, police station and high traffic area, respectively.), but considerably lower than the personal-exposure
concentrations (the average TPAH were 65.84 and 47.28 ng/m3 for patrol cars and inspection station, respectively). Pyrene was correlated well with BaP and the summed PAHs (TPAH), with
the correlation coefficients (R) of 0.79, 0.87 for ambient level and 0.92, 0.96 for personal exposure, respectively. The average of 1-hydroxypyrene of smokers
and nonsmokers were 0.39, 0.15 μmol/mol creatinine in control group and 0.57, 0.33 μmol/mol creatinine in exposure group,
respectively. The better correlation of pyrene to BaP and TPAH especially for personal exposure samples indicated that the
probability of urinary 1-hydroxypyrene, the metabolite of pyrene, to be the biomarker of total PAH. Nonsmokers in the exposure
and control groups had indistinguishable levels of 1-OHP, presumably because the ambient levels of pyrene were so similar
(the average were 3.25, 3.20 ng/m3 at the police station and high traffic area, respectively.). Smokers in the control group had significantly higher 1-OHP
than that of the nonsmokers, but showed indistinguishable differences in the exposure group. These results suggested that
urinary 1-OHP could be a biomarker of PAHs only when the level of PAHs was at a relatively higher level. Smoking as an important
influencing factor need to be controlled carefully. 相似文献
843.
844.
美国的生态损害赔偿制度 总被引:2,自引:0,他引:2
<正>概述美国生态损害赔偿制度经历了从普通法到制定法的发展过程。最初,生态损害仅作为环境侵权损害的一种,由美国普通法赋予公共机构对自然资源损害赔偿的起诉权,从而实现赔偿请求。由于普通法提供的对生 相似文献
845.
本文利用模糊模式识别交叉迭代模型对分布于乌梁素海各水功能区的21个水质监测点,2009年5月~10月的富营养化等级进行了模糊模式识别研究;并利用Arcview的空间分析功能,绘制富营养化等级识别结果的空间分布月变化Grid图。将富营养化状态识别结果及其分布区域与乌梁素海同期水质监测指标浓度变化及其分布区域进行对比分析及验证。识别结果与实际水质状况相符,验证了该方法的有效性。 相似文献
846.
As a routine measurement to alleviate membrane fouling, hydraulic cleaning is of great significance for the steady operation of ultrafiltration (UF) systems in water treatment processes. In this work, a comparative study was performed to investigate the effects of the composition of backwash water on the hydraulic cleaning performance of UF membranes fouled by humic acid (HA). Various types of backwash water, including UF permeate, Milli-Q water, NaCl solution, CaCl2 solution and HA solution, were compared in terms of hydraulically irreversible fouling index, total surface tension and residual HA. The results indicated that Milli-Q water backwash was superior to UF permeate backwash in cleaning HA-fouled membranes, and the backwash water containing Na+ or HA outperformed Milli-Q water in alleviating HA fouling. On the contrary, the presence of Ca2 + in backwash water significantly decreased the backwash efficiency. Moreover, Ca2 + played an important role in foulant removal, and the residual HA content closely related to the residual Ca2 + content. Mechanism analysis suggested that the backwash process may involve fouling layer swelling, ion exchange, electric double layer release and competitive complexation. Ion exchange and competitive complexation played significant roles in the efficient hydraulic cleaning associated with Na+ and HA, respectively. 相似文献
847.
天津地区一些降尘中多环芳烃的含量与分布 总被引:13,自引:0,他引:13
采集并分析了天津地区2002~2003年16区县23个样点采暖与非采暖期降尘样品中16种优控多环芳烃(PAHs)含量.非采暖期样品16种PAHs含量总和(ΣPAH16)在1 00~48 18μg·g-1间,采暖期样品ΣPAH16在2 54~85 47μg·g-1间.采暖期降尘高含量PAHs主要为萘、菲、荧蒽、和芘,非采暖期降尘PAHs的优势成份包括萘、芴、菲、荧蒽和.除东部工业区外,同一样点采暖期降尘中高环PAHs含量普遍高于非采暖期.采暖期样品各PAHs彼此之间相关性较非采暖期显著.无论是采暖期还是非采暖期,降尘中PAHs主要都是来源于燃煤,交通污染源也占一定比例. 相似文献
848.
Luhua Jiang Shaobo Liu Yunguo Liu Guangming Zeng Yiming Guo Yicheng Yin Xiaoxi Cai Lu Zhou Xiaofei Tan Xixian Huang 《Environmental science and pollution research international》2017,24(30):23528-23537
This paper explored biochar modification to enhance biochar’s ability to adsorb hexavalent chromium from aqueous solution. The ramie stem biomass was pyrolyzed and then treated by β-cyclodextrin/poly(L-glutamic acid) which contained plentiful functional groups. The pristine and modified biochar were characterized by FTIR, X-ray photoelectron spectroscopy, specific surface area, and zeta potential measurement. Results indicated that the β-cyclodextrin/poly(L-glutamic acid) was successfully bound to the biochar surface. Batch experiments were conducted to investigate the kinetics, isotherm, thermodynamics, and adsorption/desorption of Cr(VI). Adsorption capacities of CGA-biochar were significantly higher than that of the untreated biochar, and its maximum adsorption capacity could reach up to 197.21 mg/g at pH 2.0. Results also illustrated that sorption performance depended on initial solution pH; in addition, acidic condition was beneficial to the Cr(VI) uptake. Furthermore, the Cr(VI) uptake was significantly affected by the ion strength and cation species. This study demonstrated that CGA-biochar could be a potential adsorbent for Cr(VI) pollution control. 相似文献
849.
850.
Digital technology and the conservation of nature 总被引:1,自引:0,他引:1
Digital technology is changing nature conservation in increasingly profound ways. We describe this impact and its significance through the concept of ‘digital conservation’, which we found to comprise five pivotal dimensions: data on nature, data on people, data integration and analysis, communication and experience, and participatory governance. Examining digital innovation in nature conservation and addressing how its development, implementation and diffusion may be steered, we warn against hypes, techno-fix thinking, good news narratives and unverified assumptions. We identify a need for rigorous evaluation, more comprehensive consideration of social exclusion, frameworks for regulation and increased multi-sector as well as multi-discipline awareness and cooperation. Along the way, digital technology may best be reconceptualised by conservationists from something that is either good or bad, to a dual-faced force in need of guidance. 相似文献