Effects of organic acids on copper and cadmium desorption from contaminated soils

A study was conducted to investigate the effect of organic acids on Cd and Cu desorption from natural contaminated soils (NCS) with permanent contamination by metal smelters and from artificial contaminated soils (ACS) derived from an artificial amendment of Cd to three representative zonal soils in Central China. Results showed that the desorption of Cd in either NCS or ACS, with the increment of tartrate or citrate concentration in desorption solution, can be characterized as a valley-like curve. The presence of tartrate or citrate at a low concentration (< or =0.5 mmol/l) inhibited Cd desorption from these two types of soils, whereas the presence of organic acids at high concentrations (> or =2 mmol/l for citrate and about > or =15 mmol/l for tartrate) apparently promoted Cd desorption. The desorption curve of Cu by tartrate solution with different tartrate concentrations can also be characterized as a valley-like curve, while the desorption of Cu in the presence of citrate was directly enhanced with the increment of citrate concentration. With the enhancement of initial pH value from 2 to 8 in the presence of citrate, Cu desorption ratio decreased at the first stage, then increased, and then decreased again. A valley and a peak sequentially appeared in the Cd or Cu desorption curve with initial pH value increment. Compared with citrate, the desorption ratio of Cd or Cu from NCS or ACS was directly decreased in the presence of tartrate, with the enhancement of the pH value from 2 to 8. Cd or Cu desorption was clearly enhanced when the electrolyte concentration of KNO3 or KCl increased in the presence of 2 mmol/l tartrate. Moreover, a higher desorption ratio of Cd or Cu was shown with KCl electrolyte than with KNO3 electrolyte with the same concentration. Based on these observations, we suggest that bioavailabilities of heavy metal can be promoted with selected suitable types and concentrations of organic acid amendment and reasonable field condition.     

烟台市近海海域水质污染研究

烟台市海洋渔业资源丰富,水产业在该市农业经济中占有重要的地位,但近海海域存在石油、无权氮和活性磷酸盐的污染,水质污染对水力业构成了严重危害．为控制该市近海海域水质污染,本文建议当地政府加强对工业污染源的管理,尽快兴建新的污水处理工程,加强海上船舶排污的监督与管理力度,以及引导农民合理应用化肥．     

武汉市可持续发展的主要问题和对策

阐述了武汉市可持续发展战略提出的背景和可持续发展的远景目标,全面分析了影响武汉市可持续发展的六个主要问题：城市经济发展不够,产品市场不大;城市人口增长过快,人口素质仍然不高;管理城市水平有限,城市规划起点较低;交通设施建设滞后,居民住房严重不足;污染治理任务艰巨,生态环境不尽人意;洪涝威胁仍然较大,城市发展受长江制约。并就解决这些问题提出了对策措施,重点是转变政府职能,加快交通设施建设,贯彻“科教     

Calculation of the stability criterion in the reaction of energetic materials

The stability in the energetic materials' thermal decomposition reaction is developed from both transient mass and heat transfer equations simultaneously. The derived equation is the sufficient and necessary condition for the reaction system's stability, which was expressed as:

In this stability equation, a modified Semenov number φ is the expressed function of three kinetic parameters, i.e., n, and β and two variables, i.e., x and θ, respectively. A reaction system is stable if its evaluated modified Semenov number satisfies this stability criterion. In the case of the minimum modified Semenov number φ_m, we can deduce the stability equation at critical condition as

The criteria of stability for the explosives TNT, RDX, PETN and HMX were evaluated using this formula, which was expressed θ_c as function of x at given n, η and various β as parameters.     

1996年7月湖南益阳特大水灾分析

全面科学地分析了1996年7月湖南益阳夏季特大水灾的历史背景、特点及防御对策，对综合治理洞庭湖提供了科学依据。     

社会主义市场经济体制下的区域规划

建立社会主义市场经济体制，就是要使市场在国家宏观调控下对资源配置起基础性作用。经济体制的改革对区域规划提出了新的要求．它决不意味着取消或削弱区域规划，而是要更好地发挥区域规划在发展区域经济中的宏观调控作用。区域规划是区域经济发展的超前研究，其价值在于具有比较准确的发展预见性，能够提出正确的发展方向和战略。区域规划的核心内容是指导资源优化配置，但它并不具有直接的资源流动机制，只能作为资源流动的信息机制。区域规划发挥宏观调控作用的必要条件是政府立法，公益性设施列入国家或地方的计划，在实施中争取社会舆论和社会投资的支持，对经济落后区域的开发采取国家扶持的政策。     

煤矿灾害及防御对策

本文根据调查统计及遥感资料，对我国近４０年以来煤矿主要灾害类型、特征、灾情等进行了系统分析研究，并针对煤矿生产现状与环境问题提出了相应减灾防御对策。     

山东日照市东港区震害损失动态初步预测

本文以山东省日照市东港区为例，以其１９９０年基础数据和１９９０年静态震害人员、财产损失预测为基础，以未来５年预测的房屋、人口、财产变化结果为变量，给出了动态震害人员、财产损失预测的方法及其初步预测结果。该方法还可以根据房屋、人口、财产的实际变化情况，实现“滚动式”的震害人员、财产损失预测。     

农业害虫的综合防治

病虫害造成农作物的严重损失，而大量施用农药又造成对环境的污染和人体的危害，本文在收集实例的基础上，论述了综合防治在病虫害防治方面的作用和意义。     

人发中微量钴的分光光度测定

本文应用显色剂5-(2＇-噻唑偶氮)-2,4-二氨基甲苯(简称2,4-TADAT)测定了人发中的钴,方法操作方便、选择性好,获得满意结果.