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591.
Tongwan City is one of the most famous and best-researched archaeological sites in China. By using palaeoclimatology proxy records from China over the last 2,000 years and archaeological/historical documents, we analyse the possible effect of climate on the collapse of Tongwan City, an ancient urban city of the Daxia state (AD 407–427). During Tongwan City’s existence (AD 413–994), two severe cold and drought stages were recorded by both natural proxy data and the synthesis compiled from the historical documents. The first cold and drought stage occurred at about AD 420–550, with the lowest point centred at about AD 500. The second cold and drought stage occurred at about AD 780–950. These periods correspond to the times of climate deterioration, especially weak summer monsoons, which eventually resulted in the intensive desertification and collapse of Tongwan City. 相似文献
592.
Yali Liu Jianqing Du Boyang Ding Yuexian Liu Wenjun Liu Anquan Xia Ran Huo Qinwei Ran Yanbin Hao Xiaoyong Cui Yanfen Wang 《Frontiers of Environmental Science & Engineering》2022,16(3):28
593.
Li Ziyue Chen Yongliang Meng Fanlei Shao Qi Heal Mathew R. Ren Fengling Tang Aohan Wu Jiechen Liu Xuejun Cui Zhenling Xu Wen 《Environmental science and pollution research international》2022,29(38):57190-57203
Environmental Science and Pollution Research - While intensive peach production has expanded rapidly in recent years, few studies have explored the environmental impacts associated with specific... 相似文献
594.
Cui Yuanpei Wei Zikun Xue Qinglin Sohail Sidra 《Environmental science and pollution research international》2022,29(30):45612-45622
Environmental Science and Pollution Research - The primary focus of this study is to evaluate the impact of various levels of education on CO2 emissions in China. Moreover, the study also tested... 相似文献
595.
Eatough DJ Cui W Hull J Farber RJ 《Journal of the Air & Waste Management Association (1995)》2006,56(12):1694-1706
The concentration of fine particulate nitrate, sulfate, and carbonaceous material was measured for 12-hr day-night samples using diffusion denuder samplers during the Project Measurement of Haze and Visibility Effects (MOHAVE) July to August 1992 Summer Intensive study at Meadview, AZ, just west of Grand Canyon National Park. Organic material was measured by several techniques. Only the diffusion denuder method measured the semivolatile organic material. Fine particulate sulfate and nitrate (using denuder technology) determined by various groups agreed. Based on the various collocated measurements obtained during the Project MOHAVE study, the precision of the major fine particulate species was +/- 0.6 microg/m3 organic material, +/- 0.3 microg/m3 ammonium sulfate, and +/- 0.07 microg/m3 ammonium nitrate. Data were also available on fine particulate crustal material, fine and coarse particulate mass from the Interagency Monitoring of Protected Visual Environments sampling system, and relative humidity (RH), light absorption, particle scattering, and light extinction measurements from Project MOHAVE. An extinction budget was obtained using mass scattering coefficients estimated from particle size distribution data. Literature data were used to estimate the change in the mass scattering coefficients for the measured species as a function of RH and for the absorption of light by elemental carbon. Fine particulate organic material was the principal particulate contributor to light extinction during the study period, with fine particulate sulfate as the second most important contributor. During periods of highest light extinction, contributions from fine particulate organic material, sulfate, and light-absorbing carbon dominated the extinction of light by particles. Particle light extinction was dominated by sulfate and organic material during periods of lowest light extinction. Combination of the extinction data and chemical mass balance analysis of sulfur oxides sources in the region indicate that the major anthropogenic contributors to light extinction were from the Los Angeles, CA, and Las Vegas, NV, urban areas. Mohave Power Project associated secondary sulfate was a negligible contributor to light extinction. 相似文献
596.
The effect of ageing on the bioaccessibility and fractionation of cadmium in some typical soils of China 总被引:9,自引:0,他引:9
Ingestion of contaminated soil has been recognized as an important exposure pathway of cadmium (Cd) for humans, especially for children through outdoor hand-to-mouth activities. The effect of ageing process following the input of Cd into soil on the bioaccessibility of Cd in five typical soils of China was investigated using physiologically based in vitro test in this study. A sequential extraction procedure was employed with attempt to identify the bioaccessible fraction(s) of Cd in soils. The bioaccessibility of Cd in strongly acidic (approximately pH 4.5) soils reached nearly steady levels (76.5-76.9% and 52.0-52.6% in the gastric and small intestinal phases, respectively) after a sharp decline in the first week of ageing. In contrast, the bioaccessibility of Cd in higher pH (>6.0) soils was found to be much lower (53.3-72.7% and 29.9-43.4% in gastric and small intestinal phases, respectively) and took 2 weeks of ageing to reach steady levels. The freshly spiked Cd was more labile than native Cd. The main proportion of spiked Cd was found in exchangeable Cd which was higher in strongly acidic soils (68.6-71.8%) than in higher pH soils (53.4-61.4%) at day 120 after a sharp decline to the nearly steady state in the first 1 and 2 weeks, respectively. Significant correlations between Cd bioaccessibility and either water soluble and exchangeable Cd individually, or the sum of water soluble and exchangeable Cd throughout the incubation period for all soils, indicate that these forms of Cd are likely to constitute the main proportion of bioaccessible Cd in soils. 相似文献
597.
TiO2光催化处理水中苯酚的环境风险研究 总被引:2,自引:0,他引:2
利用薄膜水循环TiO2光催化反应器(TiO2-WFCPR)处理水中苯酚的实验数据,分析了不同处理条件下苯酚光催化降解过程中间产物的降解规律和出水的环境风险.研究结果表明,即使苯酚已达<污水综合排放标准>(GB 8978-1996)一级排放标准,但出水中还不同程度地存在有害的中间产物,排放时会对环境造成危害,因此应以残留苯酚及其中间产物的浓度及影响确定该工艺最终的反应时间.足够的反应时间和偏碱性条件是降低苯酚及其中间产物环境风险的关键因素.苯酚初始浓度及进水pH越高,苯酚达标的反应时间会越长,处理的经济性就越差.所以,从环境风险与经济性综合考虑,该工艺适用于处理苯酚初始质量浓度≤60.00 mg/L的水,适宜的pH为6.0~8.0. 相似文献
598.
介绍了传统评分法的基本计算步骤,在此基础上,运用评分法对大连市五区地下水质量进行了系统的评价,以此指导大连市区地下水开采方案的设计和地下水资源的规划与管理. 相似文献
599.
600.
太原市大气污染防治战略研究 总被引:2,自引:0,他引:2
以太原市2003年-2013年大气中主要污染物SO2、NO2、PM10为依据,分析了其季节、年度变化特征和外源输入的影响。2013年污染物的季节变化显示,SO2在冬季较高是受采暖排放影响;PM10在春季由于扬尘使其浓度最高。2003年-2012年间SO2和PM10浓度呈显著下降趋势,但仍较严重。重污染天气受来自西南、西北和东南方向的气团影响。太原市城区SO2和氮氧化物的排放总量已超过大气环境容量,其中主要是工业排放。对重点工业企业搬迁的方向也将对太原市空气质量改善产生影响。 相似文献