Estimation of internal radiation dose to the adult Asian population from the dietary intakes of two long-lived radionuclides

Daily dietary intakes of two naturally occurring long-lived radionuclides, 232Th and 238U, were estimated for the adult population living in a number of Asian countries, using highly sensitive analytical methods such as instrumental and radiochemical neutron activation analysis (INAA and RNAA), and inductively coupled plasma mass spectrometry (ICP-MS). The Asian countries that participated in the study were Bangladesh (BGD), China (CPR), India (IND), Japan (JPN), Pakistan (PAK), Philippines (PHI), Republic of Korea (ROK) and Vietnam (VIE). Altogether, these countries represent more than 50% of the world population. The median daily intakes of 232Th ranged between 0.6 and 14.4 mBq, the lowest being for Philippines and the highest for Bangladesh, and daily intakes of 238U ranged between 6.7 and 62.5 mBq, lowest and the highest being for India and China, respectively. The Asian median intakes were obtained as 4.2 mBq for 232Th and 12.7 mBq for 238U. Although the Asian intakes were lower than intakes of 12.3 mBq (3.0 ug) 232Th and 23.6 mBq (1.9 ug) 238U proposed by the International Commission on Radiological Protection (ICRP) for the ICRP Reference Man, they were comparable to the global intake values of 4.6 mBq 232Th and 15.6 mBq 238U proposed by the United Nation Scientific Commission on Effects of Radiation (UNSCEAR). The annual committed effective doses to Asian population from the dietary intake of 232Th and 238U were calculated to be 0.34 and 0.20 microSv, respectively, which are three orders of magnitude lower than the global average annual radiation dose of 2400 microSv to man from the natural radiation sources as proposed by UNSCEAR.     

Nitrogen removal from landfill leachate via ex situ nitrification and sequential in situ denitrification

Ex situ nitrification and sequential in situ denitrification represents a novel approach to nitrogen management at landfills. Simultaneous ammonia and organics removal was achieved in a continuous stirred tank reactor (CSTR). The results showed that the maximum nitrogen loading rate (NLR) and the maximum organic loading rate (OLR) was 0.65 g N l^?1 d^?1 and 3.84 g COD l^?1 d^?1, respectively. The ammonia and chemical oxygen demand (COD) removal was over 99% and 57%, respectively. In the run of the CSTR, free ammonia (FA) inhibition and low dissolved oxygen (DO) were found to be key factors affecting nitrite accumulation. In situ denitrification was studied in a municipal solid waste (MSW) column by recalculating nitrified leachate from CSTR. The decomposition of MSW was accelerated by the recirculation of nitrified leachate. Complete reduction of total oxidized nitrogen (TON) was obtained with maximum TON loading of 28.6 g N t^?1 TS d^?1 and denitrification was the main reaction responsible. Additionally, methanogenesis inhibition was observed while TON loading was over 11.4 g N t^?1 TS d^?1 and the inhibition was enhanced with the increase of TON loading.     

海洋石油工程清洁生产评估方法研究

从资源能源利用、废弃物产生、废弃物回收利用、污染物处理、环境管理效果和环境响应情况着手,建立了包括6个一级指标、29个二级指标的海洋石油工程清洁生产评估指标体系;研究利用专家调查和层次分析法确定各评估指标的权重值,探索评估指标的赋值方法、标准化方法,提出了海洋石油工程清洁生产综合指数计算方法体系。     

阿哈水库浮游植物功能群时空分布特征及其影响因子分析

为了解贵州高原阿哈水库的浮游植物功能类群时空分布特征及其影响因素,于2012年至2013年枯水期(11月)、平水期(4月)、丰水期(7月)对浮游植物与水样进行分层采样分析.研究结果表明:浮游植物可分为23个功能群,优势功能群为B、D、J、LO、P、S1和X1,其时空分布特征表现为:枯水期、平水期与丰水期分别以B+D+P+LO、S1+LO以及S1为主,其丰度由枯水期至丰水期依次递增;优势功能群主要在15 m以下水体发生变化,营养物质分布差异及人工放闸泄水是产生该特征的主要原因;采样点大坝和库中的优势功能群季节变化大致相同,但却表现出大坝多于库中,而其丰度却低于库中的特征,水动力条件是导致这一变化的主要原因.经RDA分析得出,优势功能群丰度与水温呈正相关,与总氮、透明度、磷酸盐、硝氮呈负相关,其中水温、透明度为影响浮游植物功能群时空分布的主要因子.     

通过优化环境应力筛选提高电子产品可靠性

本文对国内环境应力筛选相关的标准进行了研究,通过理论计算和实际产品的试验验证两个维度对环境应力筛选进行了优化.结合我单位电路板的实际情况,研究了组件级别温度冲击中温度保持时间,温变率,温度循环次数等因素.通过对几组电路板组件温度冲击筛选度的计算,提出了最优温度循环次数的试验设计方法.通过两箱法对我公司的通信电子产品进行...     

异丙甲草胺在氧化铝界面的亲核置换转化动力学及其影响因素

采用批处理实验的方法研究γ-Al2O3界面上亲核试剂硫化钠作用下异丙甲草胺的转化动力学及其影响因素。结果表明,硫化钠作为一种亲核试剂,能促使异丙甲草胺发生亲核置换转化,且可以进一步提高异丙甲草胺在氧化铝多相反应体系中的转化速率。结果还表明,随着硫化钠浓度的升高,异丙甲草胺降解动力学常数k值也相应增加(当硫化钠浓度为5 mmol·L 1时,k值为0.043 h 1;而当硫化钠的浓度为100 mmol·L 1时,k值上升到0.974 h 1),以速率常数k值与硫化钠初始浓度作图,发现速率常数k与硫化钠浓度成正相关线性关系,其相关系数达到0.985;多相体系中反应溶液的pH会影响异丙甲草胺的转化速率,在含有10 mmol·L 1硫化钠的γ-Al2O3体系中(温度为25℃),溶液pH值由6.0上升到10.0,异丙甲草胺降解动力学常数k由0.046上升到0.195 h 1;异丙甲草胺的转化速率与多相体系中的反应温度呈显著正相关关系,转化速率取决于体系的反应温度,温度越高,转化速率越大;热力学Arrhenius经验式求得异丙甲草胺的活化能Ea=49.9 kJ.mol 1。转化速率与温度的关系为:lnk=6.005 4×103/T+17.868。     

瑞典环境税——政策效果及其对中国的启示

文章回顾了瑞典的环境税费，特别是与能源相关的环境税的发展沿革，从环境效益、财政效益、能源结构调整效应三个方面分析了瑞典能源一环境税的效果，并展望瑞典环境税的发展前景。最后指出了瑞典环境税制度对中国的借鉴意义。