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331.
高斯扩散衍生公式在环境风险评价中的应用 总被引:6,自引:0,他引:6
为在大气环境风险评价中客观地确定危险源、估算各类突发性事故的危害,在高斯扩散模型基础上,通过严格的数学推导,得出一整套适用于鉴别与评估大气环境突发事故危害后果(危害区、危害期等)的定量估算公式,使用方便,结果精确。所有公式使用条件与高斯扩散模型相同,可用于直接求取任意浓度等值线精确的时、空位置及其特征点位置。作为高斯扩散模型的衍生公式,可广泛应用于风险工程设计、风险工程保险、环境风险评价、环境风险管理、环境影响评价与环境规划等各个领域 相似文献
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333.
In order to evaluate the ecological hazard of 4-tert-butylphenol (4-TBP), species abundances and physicochemical properties were monitored for 63 days in a microcosm system containing planktonic algae, rotifers, shrimps and Daphnia. The 63 days-NOEC (no observed effect concentration) of 4-TBP for this system was calculated. At the same time, species sensitivity distribution curves were constructed based on the toxicity data of EC10, EC50 and NOEC derived from laboratory single-species toxicity tests, which further gives no obvious hazard concentrations for 95% species in the ecosystem (HC5). In both the microcosm and the single-species tests, the shrimp (Neocaridina sp.) was the most sensitive species to 4-TBP exposure, while most algae species were relatively insensitive compared to the zooplankton. For the microcosm exposed to 4-TBP, significant changes occurred to the community structure instead of the community function, resulting in a NOECmicrocosm of 265.38?μg?L–1 which approached the EC10-based HC5 (0.376?mg?L–1). Nevertheless, EC50-based HC5 was higher than the NOECmicrocosm, and the NOEC-based HC5 was lower. The data showed that the EC10-based HC5 was protective at the similar level with the result of microcosm for 4-TBP, providing supportive data for chemical risk assessment. 相似文献
334.
SiO2掺杂对Ru-TiO2催化剂的结构及其对丁二酸湿式氧化活性的影响 总被引:1,自引:0,他引:1
在TiO2粉末中掺杂SiO2,制备0—20%的SiO2TiO2载体.利用浸渍法在载体上负载Ru,制备Ru/SiO2TiO2催化剂.结果表明,催化剂的晶相以锐钛矿为主,晶粒尺寸为30—50nm.掺杂的SiO2主要为无定型,以5—15nm分散于催化剂中,比表面积随SiO2掺杂量的增加显著增大,但对TiO2的晶体结构无明显影响,也未形成Si—O—Ti键.Ru因粒径细化及含量过低未产生衍射峰.在300ml间歇式反应釜中,反应温度210—270℃,初始氧分压085MPa条件下,对丁二酸(74g·l-1,COD=7000mg·l-1)的催化湿式氧化结果表明,SiO2掺杂量对COD的去除率有显著影响,掺杂10%SiO2的催化剂对COD的去除率最高.在连续十次运行中,COD的去除率保持在85%左右,活性未见降低. 相似文献
335.
主要叙述TiO2/H2O2/UV和TiO2/O3/UV体系降解对氯苯甲酸(4-CBA)和喹啉的试验研究.研究表明,(1)在TiO2/H2O2/UV体系里目标物降解速度先随过氧化氢投加量的增加而提高,但超过一定浓度之后便开始下降;(2)在TiO2/O3/UV体系中,目标降解物的反应速度都非常快,且臭氧浓度高的时候降解速度更快;(3)二氧化钛催化剂在TiO2/O3/UV体系中作为积极因素有助于提高反应速率,而在TiO2/H2O2/UV体系是消极因素,会降低反应速率. 相似文献
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337.
从1998 年长江流域发生的特大洪水说起,分析从汉代到清末2000 年间及近40 年来长江流域水旱灾害的变化趋势,认为造成长江洪水灾害的原因主要是气候异常,但也与生态环境遭到破坏有关,其中土壤侵蚀、水土流失是最重要的因素。探讨了防治长江水患的对策;基于对土壤的吸水和贮水功能主要靠地被层和土壤有机质层,而水土流失是从植被破坏、地被层消失开始的,以及对古今治水、治土正反两个方面的认识,提出了治水的同时应治土的观点及5 条有效的途径。 相似文献
338.
Li Yang Tao Chen Kai-Chong Shi Lu Zhang Ngwe Lwin Peng-Fei Fan 《Conservation biology》2023,37(1):e14045
Species shift their distribution in response to climate and land-cover change, which may result in a spatial mismatch between currently protected areas (PAs) and priority conservation areas (PCAs). We examined the effects of climate and land-cover change on potential range of gibbons and sought to identify PCAs that would conserve them effectively. We collected global gibbon occurrence points and modeled (ecological niche model) their current and potential 2050s ranges under climate-change and different land-cover-change scenarios. We examined change in range and PA coverage between the current and future ranges of each gibbon species. We applied spatial conservation prioritization to identify the top 30% PCAs for each species. We then determined how much of the PCAs are conserved in each country within the global range of gibbons. On average, 31% (SD 22) of each species’ current range was covered in PAs. PA coverage of the current range of 9 species was <30%. Nine species lost on average 46% (SD 29) of their potential range due to climate change. Under climate-change with an optimistic land-cover-change scenario (B1), 12 species lost 39% (SD 28) of their range. In a pessimistic land-cover-change scenario (A2), 15 species lost 36% (SD 28) of their range. Five species lost significantly more range under the A2 scenario than the B1 scenario (p = 0.01, SD 0.01), suggesting that gibbons will benefit from effective management of land cover. PA coverage of future range was <30% for 11 species. On average, 32% (SD 25) of PCAs were covered by PAs. Indonesia contained more species and PCAs and thus has the greatest responsibility for gibbon conservation. Indonesia, India, and Myanmar need to expand their PAs to fulfill their responsibility to gibbon conservation. Our results provide a baseline for global gibbon conservation, particularly for countries lacking gibbon research capacity. 相似文献
339.
Kunsen Lin Youcai Zhao Lina Wang Wenjie Shi Feifei Cui Tao Zhou 《Frontiers of Environmental Science & Engineering》2023,17(6):77
340.
The nuisance impact of air pollutant emissions from wastewater pumping stations is a major issue of concern to China. Hydrogen sulfide and ammonia are commonly the primary odor and are important targets for removal. An alternative control technology, biofiltration, was studied. The aim of this study is to investigate the potential of unit systems packed with compost in terms of ammonia and hydrogen sulfide emissions treatment, and to establish optimal operating conditions for a full-scale conceptual design. The laboratory scale biofilter packed with compost was continuously supplied with hydrogen sulfide and ammonia gas mixtures. A volumetric load of less than 150 gH2S/(m^3.d) and 230 gNH3/(m^3.d) was applied for about fifteen weeks. Hydrogen sulfide and ammonia elimination occurred in the biofilter simultaneously. The removal efficiency, removal capacity and removal kinetics in the biofilter were studied. The hydrogen sulfide removal efficiency reached was very high above 99%, and ammonia removal efficiency was about 80%. Hydrogen sulfide was oxidized into sulphate. The ammonia oxidation products were nitrite and nitrate. Ammonia in the biofilter was mainly removed by adsorption onto the carrier material and by absorption into the water fraction of the carrier material. High percentages of hydrogen sulfide or ammonia were oxidized in the first section of the column. Through kinetics analysis, the presence of ammonia did not hinder the hydrogen sulfide removal. According to the relationship between pressure drop and gas velocity for the biofilter and Reynolds number, non-Darcy flow can be assumed to represent the flow in the medium. 相似文献