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711.
沸石强化A/O生物脱氮实验研究表明,沸石对配水氨氮具有良好的吸附性能,其吸附特征可以通过Frend lich和Langmu ir吸附等温线表征,但对污水中氨氮的吸附较配水吸附要复杂。由于沸石能与微生物构成沸石-生物复合体,从而增加了系统的硝化细菌和反硝化细菌数量,改善了A段的反硝化作用和O段的硝化作用。吸附饱和的铵沸石在硝化细菌和电导率的协同作用下,经好氧曝气4.5 h,能再生69.8%。在A段,进水氨氮浓度较高,沸石吸附氨氮,提高污水碳氮比,促进生物反硝化;进入O段,在盐度和微生物的协同作用下,混合液氨氮浓度因为生物降解而逐渐降低,不断打破铵沸石的吸附-脱附平衡,铵沸石不断释放氨氮而得到充分的再生。 相似文献
712.
Radiological hazards of TENORM in the wasted petroleum pipes 总被引:1,自引:0,他引:1
Disposal petroleum pipes containing sludge and scale as a technically enhanced natural occurring radioactive material (TENORM) leads to internal and external radiation hazards and then a significant radiation dose to the workers. In order to contribute to a future waste management policy related to the presence of TENORM in the disposal sites of wasted petroleum pipes, scale and sludge as TENORM wastes are collected form these disposal pipes for radiometric analysis. These pipes are imported from onshore oilfields at south Sinai governorate, Egypt. The highest mean 226Ra and 228Ra concentrations of 519 and 50 kBq/kg respectively, were measured in scale samples. Sludge lies within the normal range of radium concentration. The average absorbed dose caused by the exposure to the wasted pipes equal to 4.09 μGy h−1 from sludge and 262 μGy h−1 from scale. This is much higher than the acceptable level of 0.059 μGy h−1. Due to radon inhalation, important radon related parameters are calculated which advantage in internal dose calculation. Fairly good correlation between real radium content and radon exhalation rate for sludge samples is obtained. The hazards from sludge come from its high emanation power for radon which equal to 3.83%. The obtained results demonstrate the need of screening oil residues for their radionuclide content in order to decide about their final disposal. 相似文献
713.
基于集约评价的城市开发区规模计量研究——以南京市省级以上开发区为例 总被引:1,自引:0,他引:1
随着开发区集约利用评价工作的全面开展,合理界定其用地规模成为研究的重点。本文以南京市为例,首先运用多目标决策法评价开发区集约利用等级,然后采用逐步回归法选取与集约利用相关度较大的因素作为预测依据,进而计量其合理的规模。研究结果表明:其一,A、B和C开发区集约等级为II级,可以适当扩大开发区规模;D、E、F和G开发区集约等级为III级,应该维持开发区规模;而H和I开发区集约等级为IV级,应适当缩小开发区规模。其二,当B开发区、A开发区和其他开发区地均工业总产值增长率分别达到23.10%、18.18%和15%时,可以充分发挥土地利用潜力。其三,即使实现土地集约利用,B开发区仍需扩充6.08 km2。最后,本文提出通过科学设定地均工业总产值增长率来提升开发区集约利用水平的政策建议。 相似文献
714.
This paper reports a meta-analysis of studies using the New Environmental Paradigm (NEP) Scale over the last 30 years. A review of 69 studies from 36 countries (including 58,279 participants from 139 samples) shows that there is considerable variation in the way the NEP Scale is used, particularly with regards to the number of items used and the number of points on the Likert scale employed. Results from weighted regression analyses reveals that variations in sample type and scale length have a significant effect on NEP scores. In particular, environmentalist and white-collar samples scored significantly higher on the NEP Scale than nationally or regionally representative samples, while blue-collar samples scored significantly lower; and participants scored higher on 6-item versions of the scale than on the revised 15-item version, and lower on versions of the scale containing 5, 7, 8 or 10 items. Implications of this research for the comparability of previous studies using the NEP Scale are discussed and guidelines for future research are presented. 相似文献
715.
通过AT89C51单片机控制地衡自动采集运材车的称重量,自动检测车辆的上、下衡和自动识别车号,并通过计算机网络将数据信息安全地传送到管理部门。目前,此系统已成功地、安全地应用于伊春市、加格达奇地区部分林业局的数字化木材生产安全管理中。 相似文献
716.
717.
1961~2010年中国大尺度区域暴雨时空分布特征研究 总被引:1,自引:0,他引:1
长时间大范围的区域暴雨作为一种极端天气气候事件,是人民生产生活的一大威胁,已成为社会和学界的关注焦点之一,亟需研究中国长时间序列区域暴雨的时空演变特征。通过定义的区域暴雨事件,选取持续天数、影响站点数、最大日降雨量和最大累积降雨量4项指标,统计分析了1961~2010年中国区域暴雨的时空变化格局。结果表明:在空间格局上,1961~2010年中国区域暴雨主要分布在黑龙江漠河至云南腾冲一线以东的东部沿海季风区,而西北内陆则无区域暴雨发生;在省际分布上,多集中发生在以广东为首的东部沿海省市;在时间序列上,中国区域暴雨存在准10a(6.5a和13a)的周期振荡,以1997年前后年份发生次数较多,年内多集中在5~9月,且4项指标均在6月份达到最高。 相似文献
718.
以港口货物吞吐量和港口集装箱吞吐量为指标,运用首位度、位序-规模法则和Kernel密度估计对长三角地区港口规模分布进行研究。结果表明:(1)长三角地区港口等级规模分布由首位分布向位序-规模分布演变;港口货物运输与集装箱运输的首位分布特征演变具有内在一致性,但演变态势、具体时点等方面存在差异;港口体系结构由单核枢纽演变为双核枢纽,并有望形成三足鼎立新格局;(2)长三角地区港口规模分布逐步优化,等级结构不断趋于合理,港口体系基本满足位序-规模法则,但还没有达到理想状态;港口体系呈现分散化发展态势,集装箱技术的应用减缓了港口体系的分散化发展;(3)港口货物吞吐量与港口集装箱吞吐量的核密度曲线由多峰结构分别变为双峰结构和单峰结构,货物运输和集装箱运输均向协调态势发展。 相似文献
719.
Distribution of Selected Soil and Water Conservation Practices in the U.S. as Identified with Google Earth
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Michael White Leighton Haglund Marcus Gloe Katrin Bieger Brandon Namphong Marilyn Gambone Eric Hardy Jungang Gao Haw Yen Jeff Arnold 《Journal of the American Water Resources Association》2017,53(5):1229-1240
The proper representation of conservation practices on agricultural lands is an important factor in large‐scale assessments of water quality in the United States. Unfortunately, there are few publicly available data sources at the local level and even fewer at the national scale. In this research, randomly selected points within agricultural lands were examined for selected conservation practices using Google Earth aerial imagery by a team of interpreters. In total, 13,530 points had field boundaries digitized, and were subsequently examined and classified. The presence of terraces, grassed waterways, contour farming, center pivot irrigation, strip cropping, ponds, riparian vegetation, filter strips, and land cover were noted. Subjectivity among interpreters was evaluated using duplicate samples and was found to be similar to image misclassification rates in other research. Conservation practice adoption rates for selected major river basins compared favorably with data collected by the Conservation Effects Assessment Project. The frequency of occurrence of each conservation practice was summarized and presented by ecoregion. To facilitate future research, point level data and software source code developed in this research are available via the web at http://nlet.brc.tamus.edu/Conservation . Aerial imagery was found to be a powerful, inexpensive, and easily accessible tool to assess large‐scale conservation practice implementation for certain conservation practices. 相似文献
720.
The Impact of Projected Climate Change Scenarios on Nitrogen Yield at a Regional Scale for the Contiguous United States
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Md Jahangir Alam Jonathan L. Goodall Benjamin D. Bowes Evan H. Girvetz 《Journal of the American Water Resources Association》2017,53(4):854-870
Improved understanding of the potential regional impacts of projected climatic changes on nitrogen yield is needed to inform water resources management throughout the United States (U.S.). The objective of this research is to look broadly at watersheds in the contiguous U.S. to assess the potential regional impact of changes in precipitation (P) and air temperature (T) on nitrogen yield. The SPAtially Referenced Regression On Watershed attributes model and downscaled P and T outputs from 14 general circulation models were used to explore impacts on nitrogen yield. Results of the analysis suggest that projected changes in P and T will decrease nitrogen yield for the majority of the contiguous U.S., including the watersheds of the Chesapeake Bay and Gulf of Mexico. Some regions, however, such as the Pacific Northwest and Northern California, are projected to face climatic conditions that, according to the model results, may increase nitrogen yield. Combining the projections of climate‐driven changes in nitrogen yield with projected changes in watershed nitrogen inputs could help water resource managers develop regionally specific, long‐term strategies to mitigate nitrogen pollution. 相似文献