Effects of untreated hospital effluents on the accumulation of toxic metals in sediments of receiving system under tropical conditions: Case of South India and Democratic Republic of Congo

Physicochemical and ecotoxicological analyses have been performed to assess the quality of sediments receiving untreated hospital effluents from Indian and Democratic Republic of Congo (DRC) hospitals. The sediments were collected monthly and characterized for grain size, organic matter, total organic carbon, total carbon, nitrogen, phosphorus, toxic metals and ecotoxicity. The results highlight the high concentration of toxic metals from the Indian hospital effluent receiving systems, especially for Cr, Cu, As, Zn and Hg. On the other hand, the metal concentrations in the sediment receiving system from DRC are low (e.g. maximum Hg and Zn concentration were 0.46 and 48.84 mg kg⁻¹ respectively). Ostracods exposed to sediment samples H2 (September month sample) and H3 (June and September month samples) were found dead after 6 d of exposure whereas the higher mortality rate for Congo sediments was 23% but was accompanied with 33 ± 7% of growth inhibition. The results of this study show the variation of sediment composition on toxic metal levels as well as toxicity related to both, the type of hospitals and the sampling period. Additionally, hospital effluent disposal practices at the study sites can lead to the pollution of water resources and may generate risks for aquatic organisms and human health.     

Effect of ZnCl<Subscript>2</Subscript> impregnation ratio on pore structure of activated carbons prepared from cattle manure compost: application of N<Subscript>2</Subscript> adsorption-desorption isotherms

Activated carbons were prepared from cattle manure compost (CMC) by ZnCl₂ activation with various ZnCl₂/CMC mass ratios. Based on the N₂ adsorption-desorption isotherms, mathematical models including the Dubinin-Radushkevich (DR) equation, the α_s plot, and the Horvath-Kawazoe method were used to analyze the pore structural characteristics of the prepared activated carbons. It was found that for carbons possessing both micro-and mesopores, the DR method provided a more accurate estimation than the α_s method for the extent of microporosity. The effect of the ZnCl₂ impregnation ratio on the pore structure was discussed using the DR method. The results revealed that pore evolution involved three distinct regions with increases in the amount of impregnated ZnCl₂: raising the ZnCl₂/CMC mass ratio from 0.00 to 0.50 resulted in a 19-fold increase in micropore volume (V_me ^D) but caused no change in the mesopore volume (V_me ^D); increasing the ZnCl₂/CMC mass ratio from 0.50 to 1.00 led to an increment in V_mi ^D of about 50% and in V_me ^D of 170%; while raising the ratio from 1.50 to 2.50 caused a slight decrease in V_mi ^D but a 200% increment in the value of V_me ^D.     

飞机外场腐蚀损伤检测方法研究

目的研究飞机外场条件下适用的腐蚀损伤检测方法。方法针对某型飞机铝合金和结构钢的腐蚀损伤特点,采用X射线CR(计算机放射成像系统,Computed Radiography,简称CR)、X射线DR(Digital Radiography,简称DR)、红外热波检测等无损检测方法对铝合金和结构钢的典型腐蚀损伤件进行检测,优选及并验证适合用于飞机腐蚀损伤的外场检测方法。结果 X射线CR检测方法可检测铝合金和结构钢单层隐蔽腐蚀损伤和多层隐蔽裂纹,X射线DR检测方法可检测铝合金和结构钢单层/多层隐蔽腐蚀损伤/裂纹,红外热波检测方法只可检测铝合金和结构钢单层隐蔽腐蚀损伤。结论相较于X射线CR和红外热波检测方法,X射线DR成像检测方法能够更可靠、便捷地检测铝合金和结构钢单层/多层结构隐蔽腐蚀/裂纹损伤,更适于飞机结构腐蚀损伤的外场检测。     

中国“人口流动-经济增长收敛谜题”——基于新古典内生经济增长模型的分析与检验

大规模人口从中西部向东部发达地区流动必将对区域经济产生重要影响。人口流动是否促进区域经济增长,区域经济增长是发散还是收敛对促进区域经济协调发展具有重要的现实意义。本文从人均产出出发,以Barro and Sala-i-Martin国际人口迁移模型为理论基础,用数理分析方法推演出携带人力资本的人口流动新古典内生经济增长收敛机制。在稳态邻域内,发达地区经济增长收敛速度加快,同时欠发达地区经济增长收敛速度减慢,最终导致区域经济相对发散。随后,本文借鉴DR模型建立动态面板数据模型,该模型既能预测内生经济增长发散性,又可以预测新古典经济增长收敛性。通过利用2005—2014年中国29个省份面板数据,采用系统GMM方法对区域经济增长收敛性进行实证检验。实证结果显示:1人口流动促进了区域经济增长;2以2008年为时间节点,西部大开发政策的实施加速了西部地区经济增长;3中国区域经济具有新古典经济增长收敛机制和内生经济增长收敛机制。这意味着理论模型和实证检验相矛盾,从而产生"人口流动-经济增长收敛谜题"。"收敛谜题"产生的原因可能有政策效应、追赶效应、人力资本效应、收入转移效应和干中学效应。"收敛谜题"告诉我们,要使区域经济协调发展,从根本上解决区域差距扩大的矛盾,发挥新古典经济收敛机制和内生经济收敛机制的作用,就必须提高国民整体人力资本水平、解决好就业市场体制问题和流动人口福利待遇问题。     

利用DR／2010分光光度计构建水环境应急监测平台

介绍了DR／2010分光光度计在水环境应急监测中的应用,对氨氮、六价铬、磷酸盐、COD等常规项目进行比色测定,操作简便、快捷,结果准确、可靠。     

Atmosphere Watersphere Disaster Reduction System

ＴｈｅｔｏｔａｌｌｏｓｓｃａｕｓｅｄｂｙＣｈｉｎａ＇ｓｎａｔｕｒａｌｄｉｓａｓｔｅｒｓａｍｏｕｎｔｓ３％～６％ｏｆｔｈｅｃｏｕｎｔｒｙ＇ｓｇｒｏｓｓｎａ－ｔｉｏｎａｌｐｒｏｄｕｃｔｉｏｎ（ＧＮＰ）,ｗｈｉｃｈｉｍｐｌｉｅｓｔｈａｔｔｈｅｎａｔｕｒａｌ...     

重铬酸钾比色法测定水中化学需氧量

对重铬酸钾比色法测定水中化学需氧量(COD)的方法进行了验证性研究。结果显示,该方法检出限为6mg/L,化学需氧量浓度低于24mg/L时,测定误差比较大。运用过程表明,该方法具有简单、稳定、快速、成本低廉、监测仪器便于携带等优点。