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651.
渤海和黄海北部地区海冰灾害风险评估 总被引:1,自引:0,他引:1
海冰灾害是中国海洋灾害的主要灾种之一。渤海和黄海北部地区由于受冬季风带来的寒潮天气影响成为中国最主要的结冰海域。基于灾害风险理论,将研究区海岸带上17个地级市的71个县区作为评价单元,对海冰灾害风险进行评估。选取冰期天数和最大冰厚2个指标,计算致灾因子危险度指数;选取涉海人口密度、海洋经济密度、海洋一产比重等3个指标,计算承灾体脆弱性指数;综合危险度指数与脆弱性指数计算各县区的海冰灾害风险指数,并绘制风险等级图。该风险等级图揭示了海冰灾害风险在渤海和黄海北部地区海岸带上的分布状况,为中国制定海冰灾害风险防范策略提供参考。 相似文献
652.
653.
Human breast milk samples collected from mothers (n = 110) who lived in Chengdu, Sichuan Province, southwestern China in 2009 were analyzed to determine the concentrations of 13 musk compounds. Possible relationships between musk concentrations and some personal characteristics were also studied. Only five target analytes were detected in the milk samples analyzed, with median concentration values of 16.5, 11.5, 7.85, <1.5 and <1.4 ng g−1 lipid weight for AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene), HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran), HHCB-lactone (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran-1-one), OTNE ([1,2,3,4,5,6,7,8-octahydro-2,3,8,8-tetramethylnaphthalen-2yl]ethan-1-one) and musk ketone (4-tert-butyl-2,6-dimethyl-3,5-dinitroacetophenone, MK), respectively. Mothers who reported high use of hand-cleaning agents, body-cleaning agents, shampoo and hair conditioners, hair dyes and hair gels had significantly elevated milk concentrations of HHCB whereas elevated milk concentrations of AHTN were observed among mothers reporting high use of body-cleaning agents, body lotions, shampoos, hair dyes and hair gels. Younger age showed a significantly positive effect on milk concentrations of both HHCB and AHTN whereas BMI after delivery, the number of children nursed and place of residence (urban or rural) had no significant effect. The estimated median daily intakes of synthetic musks for breast-fed infants were considerably lower than the current provisional tolerable daily intake amounts suggested for adults. 相似文献
654.
本文根据马鞍山市慈湖河流域水环境现状,结合当地政府对慈湖河的管理整治目标,选择EFDC水动力-水质模型作为慈湖河水环境模型。并根据慈湖河流域整体情况对时间空间进行概化。时间概化上,最终确定水动力学模拟时间步长为10s,水质模拟时间步长为20s;空间概化上,采用凸四边形网格概化,各网格之间为一维线性关系;通过CAD、GIS软件,将河道划分为106个网格,共计86行、24列,建立二维模型。通过研究参考文献及相似案例,最终确定本模型的参数和取值。将参数值输入程序中,对慈湖河流域2013年水质进行模拟计算。与马鞍山实际数据比对后发现,模型输出的水位、流速、水质结果在合理范围内。表明在慈湖河干流建立二维水质污染扩散模型,具有较高的拟合、预测精度和泛化能力,模型及方法可为相关水质预测研究提供参考。此外该模型可与web应用系统集成,应用于水质预警,模拟不同污染负荷情形下水质变化,模拟污染事故发生后不同应急措施对污染情况的改善效果,为污染控制和水环境管理工作提供科学依据。 相似文献
655.
酶联免疫快速检测技术在太湖流域微囊藻毒素污染调查中的应用研究 总被引:3,自引:2,他引:1
采用酶联免疫(ELISA)法对2008年5~11月环太湖水域及太湖下游嘉兴河网水体中微囊藻毒素(MC)的污染状况进行了调查.结果表明,ELISA法对环太湖水样的加标回收率为(98.0±6.5)%,相对标准偏差≤10.0%,准确性和再现性均良好,且具有通量高、检测速度快的特点,适于太湖流域MC污染的普查和初筛.环太湖水样中的MC-LR在2008年8、10月较高;太湖下游嘉兴河网水样中的MC-LR自2008年7月开始有检出,最高质量浓度出现在9月,为0.772μg/L;各饮用水源地水样中的MC-LR亦有检出,但未超过<地表水环境质量标准>(GB 3838-2002)规定的限值(1.0μg/L). 相似文献
656.
657.
Cheng-Hsun Lai Chih-Chung Chang Chieh-Heng Wang Min Shao Yuanhang Zhang Jia-Lin Wang 《Atmospheric environment (Oxford, England : 1994)》2009,43(7):1456-1463
Continuous on-site measurements of 50 speciated volatile organic compounds (VOCs) were conducted in downtown Guangzhou to characterize the sources and concentration profiles of ambient VOCs. The synchronicity in diurnal variation between the VOCs and NO suggests that traffic emissions were responsible for the observed VOCs in downtown Guangzhou.It was found that the three major constituent species of liquefied petroleum gas (LPG), i.e., propane, iso-butane, and n-butane, together termed LPG alkanes, contributed, on average, 24% of the total VOCs (TVOCs). Their high correlation and synchronized diurnal variations between NO and the LPG alkanes suggest that their origin lies in LPG fueled car exhaust in Guangzhou. LPG buses and taxis were likely to be responsible for the bulk of ambient LPG species. Using propane and 3-methyl pentane (3MC5A) as the indicators for the LPG and gasoline emissions, respectively, the emissions of the LPG fleet were found to increase more than those of the gasoline fleet during the morning and evening rush hours, as well the noontime break in downtown Guangzhou.Although LPG alkanes account for 24% of the TVOC, their contribution to the total ozone forming potential (OFP) is only about 7%. Ethylene and propylene contribute about 26% to the total OFP despite their lower contribution of 16% to the TVOC. 相似文献
658.
Houhu Zhang Pinjing He Liming Shao 《Atmospheric environment (Oxford, England : 1994)》2009,43(16):2623-2631
Municipal solid waste landfills are the significant anthropogenic sources of N2O due to the cooxidation of ammonia by methane-oxidizing bacteria in cover soils. Such bacteria could be developed through CH4 fumigation, as evidenced by both laboratory incubation and field measurement. During a 10-day incubation with leachate addition, the average N2O fluxes in the soil samples, collected from the three selected landfill covers, were multiplied by 1.75 (p < 0.01), 3.56 (p < 0.01), and 2.12 (p < 0.01) from the soil samples preincubated with 5% CH4 for three months when compared with the control, respectively. Among the three selected landfill sites, N2O fluxes in two landfill sites were significantly correlated with the variations of the CH4 emissions without landfill gas recovery (p < 0.001). N2O fluxes were also elevated by the increase of the CH4 emissions with landfill gas recovery in another landfill site (p > 0.05). The annual average N2O flux was 176 ± 566 μg N2O–N m?2 h?1 (p < 0.01) from sandy soil–covered landfill site, which was 72% (p < 0.05) and 173% (p < 0.01) lower than the other two clay soil covered landfill sites, respectively. The magnitude order of N2O emissions in three landfill sites was also coincident by the results of laboratory incubation, suggesting the sandy soil cover could mitigate landfill N2O emissions. 相似文献
659.
The irrigation of a plant-soil system with landfill leachate should promote the formation of N2O due to the introduction of organic carbon and mineralized-N and the elevation of the moisture content. Laboratory incubation was performed to minimize N2O emissions from a leachate irrigated plant-soil system by manipulating leachate NH(4)(+)-N loading, moisture content, and soil type. A field investigation, consisting of three plots planted with Cynodon dactylon, Nerium indicum Mill, and Festuca arundinacea Schreb, was then conducted to select plant species. There was almost no difference in N2O emissions between soil moisture contents of 46% and 55% water-filled pore space (WFPS), while a sharp increase occurred at 70% WFPS. N2O fluxes were significantly correlated with leachate NH4(+)-N loading. Amongst the physiochemical characteristics of the selected nine soils, only soil pH was significantly correlated with N2O fluxes. Compared with fertilizers application in other ecosystems, N2O turnover rate from the plant-soil system under leachate irrigation was relatively lower. Therefore, avoiding high NH4(+)-N loadings and excessively wet conditions (<60% WFPS) and cultivating conifer plants of stronger sunlight penetration with less litter deposit on acidic sandy soil could minimize potential N2O emissions under leachate irrigation. 相似文献
660.
One aerobic and two combined bio-drying processes were set up to investigate the quantitative relationships of sorting efficiency and combustion properties with organics degradation and water removal during bio-drying. Results showed that the bio-drying could enhance the sorting efficiency of municipal solid waste (MSW) up to 71% from the initial of 34%. The sorting efficiency was correlated with water content negatively (correlation coefficient, r = −0.89) and organics degradation rate positively (r = 0.92). The higher heating values (HHVs) were correlated with organics degradation negatively for FP (i.e. the sum of only food and paper) (r = −0.93) but positively for the mixing waste (MW) (r = 0.90), whereas the lower heating values (LHVs) were negatively correlated with water content for both FP (r = −0.71) and MW (r = −0.96). Other combustion properties depended on organics degradation performance, except for ignition performance and combustion rate. The LHVs could be greatly enhanced by the combined process with insufficient aeration during the hydrolytic stage. Compared with FP, MW had higher LHVs and ratios of volatile matter to fixed carbon. Nevertheless, FP had higher final burnout values than MW. 相似文献