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171.
通过简要概述美国超级基金5年回顾政策的形成与发展、执行约束力、实施内容,分析其实施过程中面临的问题,从环境立法、强化后期风险管理、完善污染场地风险管理链条、公开修复治理信息和提高社会公众参与度等角度,为解决我国因多样性修复技术实施导致的污染场地修复后风险难题提供可借鉴的重要经验,以期为构建适宜我国国情的污染场地修复长期风险管理和污染控制制度提供理论依据,实现污染场地修复后的安全再利用。  相似文献   
172.
Pollution of antibiotics, a type of emerging contaminant, has become an issue of concern, due to their overuse in human and veterinary application, persistence in environment and great potential risk to human and animal health even at trace level. In this work, a novel adsorbent, Fe3O4 incorporated polyacrylonitrile nanofiber mat (Fe-NFM), was successfully fabricated via electrospinning and solvothermal method, targeting to remove tetracycline (TC), a typical class of antibiotics, from aqueous solution. Field emission scanning electron microscopy and X-ray diffraction spectroscopy were used to characterize the surface morphology and crystal structure of the Fe-NFM, and demonstrated that Fe-NFM was composed of continuous, randomly distributed uniform nanofibers with surface coating of Fe3O4 nanoparticles. A series of adsorption experiments were carried out to evaluate the removal efficiency of TC by the Fe-NFM. The pseudo-second-order kinetics model fitted better with the experimental data. The highest adsorption capacity was observed at initial solution pH 4 while relative high adsorption performance was obtained from initial solution pH 4 to 10. The adsorption of TC on Fe-NFM was a combination effect of both electrostatic interaction and complexation between TC and Fe-NFM. Freundlich isotherm model could better describe the adsorption isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was 315.31 mg/g. Compared to conventional nanoparticle adsorbents which have difficulties in downstream separation, the novel nanofiber mat can be simply installed as a modular compartment and easily separated from the aqueous medium, promising its huge potential in drinking and wastewater treatment for micro-pollutant removal.  相似文献   
173.
We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides(HFOs) using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents(denoted as HFO-201 and IOCCS) were employed for Sb(V) removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb(V) removal by both composites, while increasing temperature from 293 to 313 K only improved Sb(V) uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb(V) than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for IOCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb(V) adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb(V) adsorption by both hybrids was attributed to the inner sphere complexation of Sb(V) and HFO, and Ca(II) induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb(V) in the synthetic water could be effectively removed from 30 μg/L to below 5 μg/L(the drinking water standard regulated by China), and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.  相似文献   
174.
The study on population and the resource-environment by the consumption may contribute to the further cognition about their correlations and provide the policy references for natural resources use and environmental protection. This article has studied the impact status of the consumption level difference of China's 31 provinces or autonomous regions on the resource-environment in 2005 by per capita consumption expenditure and serial statistical data with unit person method and constructed consumption model and hierarchical cluster analysis. We found several trends. To the intensity that population acting on the resource-environment, four sorts of regions might be divided in 2005, furthermore, most of them were at the level of unit person. Provinces or autonomous regions, located in the developed coastal areas in China, generally have the bigger impact intensity on the resource-environment than the others. That is to say, the natural resources mainly flow from west to east and from north to south, but the environmental loads are shared in the whole China and are likely to be aggravated from east to west reversely. The main causes of imbalance of pressure on the resource-environment should be the difference of consumption level, the unmatchable resource exploitation and utilization, the imbalance of discharging pollutants, and the difference of moderate carrying capacity. To the total impact quantities that population acting on the resource-environment, four sorts of regions were divided in 2005 and the difference of them was notable. Provinces or autonomous regions, having the bigger impact quantities on the resource-environment, are generally located in the eastern and central China while the extended western China is still the weak impact area of the resource-environment consumption or terminal pressure. Provinces or autonomous regions are few, where the total impact quantities are more or less; alternately, those are many, where the total impact quantities rank the middle.  相似文献   
175.
本文以碳酸盐体系为基础提出适于区域环境水体酸化敏感性多指标评价模型,利用该模型结合各评价指标的标准化体系可进行大尺度范围水体酸化敏感性评价。  相似文献   
176.
放射源测井技术是当今石油勘探和开发中必不可少的手段,开展对测井人员的屏蔽防护研究十分必要。将聚乙(丙)烯与碳化硼和氧化铝等以不同比例混合后制成的板材和织物具有良好的热中子、中能中子和快中子屏蔽效果,加工成屏蔽装置后,可使镅-铍源中子的屏蔽率达到62.06%,γ射线屏蔽率达到32.43%,结合中子辐射防护服和防护围裙等的使用,可较好地解决测井人员的辐射防护问题。  相似文献   
177.
Desertification directly threatens more than 250 million people and one third of the earths land surface. Although it is well known that desertification could be reversed in most cases if the intensity of land use were reduced, there have been no studies on how to achieve this reversed desertification on a large scale. We conducted a case study in Hunshandak Sandland of North China, exploring how creation of a nature reserve might aid restoration of a degraded ecosystem. Experimental data indicated that desertified regions, if designated as a nature reserve, could be restored with conservation of biodiversity. The buffer zones in moderately desertified lands could serve as a base for forage production and/or ecotourism industry. The construction of ecologically designed towns (ecotowns) in transition zones could accommodate migrants moved from core zones so as to develop stock production, related industry, and ecotourism, enabling both economic and environmental development. Up to now, 5778 local inhabitants in the core zones of Zhenglan Banner (county) in the Hunshandak Sandland have been moved out of the severely degraded areas with the financial assistance of the central government. Those people have been moved into three eco-towns of the Banner with an objective of greatly enhancing the economic and social status while restoring the degraded sandlands.  相似文献   
178.
利用雄黄尾矿制备药用雄黄   总被引:2,自引:0,他引:2  
在分析比较现有提炼富集雄黄工艺的基础上,提出了利用雄黄尾矿制备药用雄黄的“湿法”工艺流程,并对其中的关键工艺-雄黄除杂工艺进行了试验研究,结果表明,较佳的工艺条件为:盐酸浓度2mol/L,温度45℃,液固比2.5L:1kg,反应时间90min,研磨时间0.5h,在此条件下除杂,可制得符合药典要求和雄黄。  相似文献   
179.

The ecological footprint value (abbreviated as EF) is the quantitative indicator on evaluating the sustainable development status of a region. How to simulate the EF’s trend with a long-time data series has been heatedly discussed. The economic development of Suzhou, one of the most developed cities in Yangtze Delta, China, has been accelerated in the past 20 years, and it is necessary to evaluate the influence of the socioeconomic growth on local natural resources. The EF values of Suzhou from 1999 to 2018 were calculated and simulated using both the ARIMA model and the GM(1,1) model. The ARIMA model has been used in the prediction of EF values in several cases. However, the EF data series of the city consisted of white noise and could not be fitted by the ARIMA model. The GM(1,1) model, an approach forecasting nonlinear data series, was not found in the studies of the EF simulation. Through the model precision test, the GM(1,1) model introduced fit the EF data series well and was considered to be appropriate to simulate the EF values for Suzhou. The fitting performance was accurate, and the EF values of the city could be forecasted by the model in short term. With the proposed model, the ecological sustainability status of the city was analyzed.

  相似文献   
180.
超声波处理剩余污泥有机物、氮和磷的释放特性研究   总被引:10,自引:1,他引:9  
以生活污水处理厂污泥为研究对象.采用超声波技术研究了污泥破解过程中有机物、氮和磷的释放规律.结果表明,在声能密度为0.167、0.330、0.500 W/mL的条件下,污泥中的有机物、氮和磷的释放均随超声时间而增加;破解后污泥释放出的有机物以分子量(MW)≤2 000的物质为主,且上清液BOD5/COD>0.33;所释放的氮以有机氮为主,其次是氨氮,污泥破解液COD/凯氏氮平均值为11,适合于生物法脱氮;污泥破解所释放的正磷酸盐约占污泥总磷质量的6.0%~18.2%.利用沉淀结晶法将其回收,可减轻原污水处理工艺的磷负荷.  相似文献   
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