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971.
Michael G. Dosskey Zeyuan Qiu Yang Kang 《Journal of the American Water Resources Association》2013,49(6):1270-1283
Targeted placement of vegetative buffers may increase their effectiveness for improving water quality in agricultural watersheds. The use of digital elevation models (DEMs) enables precise mapping of runoff pathways for identifying where greater runoff loads can be intercepted and treated with buffers. Five different DEM‐based targeting indexes were compared and contrasted for the degree to which they identify similar locations in watersheds: Flow Accumulation [S.K. Jenson and J.O. Domingue (1988). Photogrammetric Engineering and Remote Sensing 54:1593], Wetness Index [I.D. Moore, R.B. Grayson, and A.R. Ladson (1991). Hydrological Processes 5:3], Topographic Index [M.T. Walter, T.S. Steenhuis, V.K. Mehta, D. Thongs, M. Zion, and E. Schneiderman (2002). Hydrological Processes 16:2041], and the Water Inflow and Sediment Retention Indexes [M.G. Dosskey, Z. Qiu, M.J. Helmers, and D.E. Eisenhauer (2011b). Journal of Soil and Water Conservation 66:362]. The indexes were applied in two different watersheds, one in New Jersey and one in Missouri. Results showed that they all tend to target similar locations in both watersheds which traces to the importance of larger contributing area to the rankings by each index. Disagreement among indexes traces to other variables which enable more accurate targeting under particular hydrologic circumstances. Effective use of these indexes poses special challenges, including selecting an index that better describes the hydrologic circumstances in a watershed and is simple enough to use, ensuring the accuracy of the DEM, and determining a maximum index value for the appropriateness of vegetative buffers. When properly applied, each index can provide a standardized basis and effective spatial resolution for targeting buffer placement in watersheds. 相似文献
972.
北京作为"国家首都、世界城市、文化名城和宜居城市",近两年加快了应急避难场所建设的步伐。针对北京市应急避难场所管理过程中存在的问题,在详细介绍ArcGIS Server的体系结构和内部运行机制的基础上,结合北京市应急避难场所的实际情况,开发了基于ASP.Net Ajax和Arcgis Server北京市应急避难场所信息管理平台。系统采用了Oracle数据库存储空间和业务数据,通过ArcSDE实现Arcgis Server和Oracle数据库的连接,实现了属性数据和空间数据的一体化存储。不仅有利于提供及时、直观、形象的应急避难场所属性信息和空间信息,同时在事故发生后抢险救灾、伤员疏散以及最大限度的减少事故损失方面起到了关键作用。 相似文献
973.
Cheong YW Yim GJ Ji SW Kang SS Skousen J 《Environmental monitoring and assessment》2012,184(1):503-513
The objective of this study was to assess the changes in mine water quality as an underground mine flooded from July 2005
to October 2008. The effect of air injection with a blower into the water was used to evaluate the potential to convert ferrous
to ferric iron and to provide in situ treatment and precipitation. Mine flooding averaged 31 cm/day with a linear shape until
November 2007, when it flattened out due to outflow. During flooding, mine water pH remained around 6, but Eh shifted from
200 to −150 mV. After the mine water level stabilized, contents of elements such as Fe and SO4 tended to decrease as time passed. Air was injected by diffusers (150 L/min/each) at three different depths of 2, 3, and
5 m below the water level in the shaft. Dissolved oxygen eventually increased to 4 or 5 mg/L depending on the depth of the
diffusers. Aeration caused conversion of ferrous iron to ferric iron and about 30 mg/l of iron was removed from the mine water.
Therefore, air injection shows potential as a semi-active treatment or part of conventional treatment to precipitate iron
in the mine pool. 相似文献
974.
975.
从实际操作层面出发,总结和分析污染源排污核算现状和存在的问题,提出适合排污权交易的污染源排污核算方法体系,力求准确掌握污染源排污情况和监控排污权使用情况,为科学建立排污权交易制度、维护公平和公正的排污权交易秩序、有效推进各项环境经济政策提供技术支撑. 相似文献
976.
矿区土壤中重金属元素含量异常的调查 总被引:3,自引:0,他引:3
对某金矿区下游土壤重金属元素含量异常区进行了调查,研究了异常元素的空间分布和相态组成.通过对土壤、水、农产品、大气沉降物等的采样分析表明,土壤中重金属元素含量异常是由于矿山开采,废水排放,下游引水灌溉造成的.对异常元素的环境影响进行了分析评价,并提出了土壤治理建议. 相似文献
977.
978.
Mutagenicity, genotoxicity and carcinogenic risk assessment of indoor dust from three major cities around the Pearl River Delta 总被引:1,自引:0,他引:1
The mutagenicity and genotoxicity of workplace dust including commercial office, secondary school, shopping mall, hospital, electronics factory and manufacturing plant in Hong Kong and settled house dust from Hong Kong, Shenzhen and Guangzhou were measured. Results indicated that indoor dust contained both frameshift and base pair substitution mutagens. Dust from manufacturing plant showed highest mutagenic potency on TA98±S9 and TA100±S9 activation, whereas, electronics factory showed highest genotoxicity with and without S9 activation. TA100 (-S9) mutagenic potency was significantly correlated with genotoxicity expressed as SOSIP (-S9) of workplace dust (r(2)=0.37, p<0.01). The total PAHs concentration of settled house dust from PRD ranged from 1.63 to 29.2μg/g. Linear regression analyses indicated that the PAHs likely accounted for about 45% of the TA98 with S9 mutagenic activity of workplace dust. TA98 (-S9) mutagenicity (r(2)=0.27, p<0.05) and SOSIP (-S9) of house dust (r(2)=0.41, p<0.01) were both significantly correlated with the number of inhabitants in the house. To achieve a more accurate cancer risk assessment, the oral bioaccessibility of B(a)A, Chry, B(b+k)F, B(a)P, D(ah)A and I(cd)P in different dust ranging from 1.3% to 17% was taken into account. Risk assessments indicated that about 26% of house dust samples resulted in unacceptable cancer risk (>1×10(-6)) for preschool children. 相似文献
979.
980.
Daiwen Kang Rohit Mathur S. Trivikrama Rao 《Atmospheric environment (Oxford, England : 1994)》2010,44(18):2203-2212
The National Air Quality Forecast Capacity (NAQFC) system, which links NOAA’s North American Mesoscale (NAM) meteorological model with EPA’s Community Multiscale Air Quality (CMAQ) model, provided operational ozone (O3) and experimental fine particular matter (PM2.5) forecasts over the continental United States (CONUS) during 2008. This paper describes the implementation of a real-time Kalman Filter (KF) bias-adjustment technique to improve the accuracy of O3 and PM2.5 forecasts at discrete monitoring locations. The operational surface-level O3 and PM2.5 forecasts from the NAQFC system were post-processed by the KF bias-adjusted technique using near real-time hourly O3 and PM2.5 observations obtained from EPA’s AIRNow measurement network. The KF bias-adjusted forecasts were created daily, providing 24-h hourly bias-adjusted forecasts for O3 and PM2.5 at all AIRNow monitoring sites within the CONUS domain. The bias-adjustment post-processing implemented in this study requires minimal computational cost; requiring less than 10 min of CPU on a single processor Linux machine to generate 24-h hourly bias-adjusted forecasts over the entire CONUS domain.The results show that the real-time KF bias-adjusted forecasts for both O3 and PM2.5 have performed as well as or even better than the previous studies when the same technique was applied to the historical O3 and PM2.5 time series from archived AQF in earlier years. Compared to the raw forecasts, the KF forecasts displayed significant improvement in the daily maximum 8-h O3 and daily mean PM2.5 forecasts in terms of both discrete (i.e., reduced errors, increased correlation coefficients, and index of agreement) and categorical (increased hit rate and decreased false alarm ratio) evaluation metrics at almost all locations during the study period in 2008. 相似文献