Characteristics of organic precursors and their relationship with disinfection by-products

The molecular weight distribution and chemical composition of precursors and their relationship with disinfection by-products (DBPs) were investigated. Most of the organic matter responsible for the major DBP precursors in the Pan-Hsin water are small compounds with a molecular weight less than 1 kDa. The hydrophobic acids display the greatest ability to produce DBP. Therefore, effective removal of small molecules or hydrophobic acidic organics prior to disinfection process will significantly reduce the DBP concentration in the finished water. Although the coagulation process is effective in removing large organic precursors and the removal efficiencies of CHCl3 formation potential and organic carbon increase proportionally to the molecular weight of the precursors, the conventional treatment methods have limited efficiency in eliminating small precursors, which have high DBP formation potential.     

Dust Storms are an Indication of an Unhealthy Environment in East Asia

Dust storms frequently occur in Mongolia and in northern China. Each year there are 30 to 120 dusty days in source regions of Mongolia and 14–20 dusty days on the Korean Peninsula. Intense sand storms and associated dust falls produce environmental impacts in East Asia. This paper discusses the environmental degradation in Mongolia and the social, economic and atmospheric impacts of dust storms in the sink area. The impact of dust storms on environmental compartments as well as their direct and indirect consequences to basic resources like water and energy demand and supply is explained. Governments are encouraged to take appropriate action in specified regions. For monitoring dust storms there is a need for international cooperation to combat growing environmental and human security concerns.     

基于航空摄影测量的填埋堆体动态重构精度及影响因素

填埋堆体表面形变监测是填埋场库容管理和堆体失稳等风险分析的核心,其时空高分辨率监测研究近年来引起广泛关注。基于航空摄影的地表测量技术具有采集速度快、时空分辨率高等优点,但在填埋场特殊环境下,面对高频填埋活动、显著的堆体变化以及防雨膜覆盖等干扰时,要同时满足高时空分辨率和耗时短的动态监测要求,无人机的最佳飞行参数设定亟待研究。为此,该研究模拟中等规模危险废物填埋场的规模和日填埋量,利用专业级无人机获取模拟区域图像,空三加密处理生成三维点云数据,利用Arcmap叠加分析多期监测数据,从点位坐标、重构尺度、重构体积、体积差分精度4个角度分析重构误差。结果表明:三维重构的坐标精度可以达到米级;重构尺度误差为2~3 cm,重构体积误差为0.16~0.17 m³,差分体积误差为0.16~0.17 m³;进一步研究发现,高度为25~55 m时,高度越高精度越低,相机倾角为[-53°,-60°]时,精度最高,旁向重叠率大于80%时,误差骤减且基本稳定。考虑到填埋场的填埋作业间隔、无人机续航能力等对飞行时间的约束,为获得最佳精度,建议无人机飞行高度为37 m、相机倾斜角度为[-53°,-60°]、旁向重叠率为80%。     

Numerical study on the ozone formation inside street canyons using a chemistry box model

Tropospheric ozone is a secondary air pollutant produced in the presence of nitrogen oxides (NO_x),volatile organic compounds (VOCs),and solar radiation.In an urban environment,ground-level vehicular exhaust is the major anthropogenic source of ozone precursors.In the cases of street canyons,pollutant dilution is weakened by the surrounding buildings that creates localized high concentration of NO_x and VOCs,and thus leads to high potential of ozone formation.By considering the major physical and chemica...     

Testing the performance of European diatom indices for evaluating the ecological status in the Kızılırmak basin,Turkey: flowing waters

Environmental Science and Pollution Research - The K?z?l?rmak River is the longest river (1.355 km) in Turkey and flows into the Black Sea. Main pressures in the basin are waste...     

Guinea worm control: Assessing the effectiveness of drum-lined water holes

Summary The purpose of the paper is to examine the feasibility of used oil drums as a lining material for shallow rural wells. The discussion focuses upon the comparison of the water quality in the oil drum-lined holes with other local water sources. The response to the innovation, from a range of guinea worm prone rural environments in Ibarapa district, Oyo State, Nigeria, was encouraging. The study noted substantial reductions in cyclop population (potential for guinea worm infection) and improved water quality in the sanitary wells as compared to rural ponds. Investigations also reveal substantial saving in costs in using oil drum-lining as opposed to concrete. Findings point to the need for this kind of water scheme as opposed to sophisticated boreholes, and deep well programmes, especially in situations of limited funds and technical skills necessary to install and maintain water supply systems.Dr Abimbola Y. Sangodoyin obtained his first degree in Agricultural Engineering at the University of Ibadan. He subsequently obtained a MSc in Water Resources Technology and a PhD in Civil Engineering at the University of Birmingham, UK. He is currently a lecturer in the Department of Agricultural Engineering, University of Ibadan where his research has focused on rural water systems and urban solid waste disposal and pollution problems.Mr Miebaka J. Ayotamuno has trained to Master's level as an Agricultural Engineer at the University of Ibadan. He is currently a member of staff at the Department of Agricultural Engineering, River State University of Science and Technology, Port Harcourt, Nigeria.     

Histopathological lesions in the body organs of cat-fish (Heteropneustes fossilis) following mercury intoxication

Light microscopic study of different body organs of cat-fish following exposure to HgCl2 0.2 mg/L in water for 30 days revealed that focal degeneration of liver cells and disorganization of hepatic cords occurred at places. Furthermore, centrilobular atrophy and compensatory hypertrophy of some hepatic cells were also observed. In the kidneys disintegration of renal epithelium along with displacement of nuclei, shrinkage of glomeruli, breakdown of Bowman's capsule and heavy infiltration by inflammatory cells were observed. The histopathological changes noted in the intestine included degeneration of lining epithelium, and diminution of goblet cells. Microscopic section of ovaries exhibited reduction of ooplasm leading to formation of atypical oocytes. An increase in the occurrence of atretic oocytes and interfolicular spaces was also discernible. No histopathological lesions could be detected in testes of male fish probably because of the difference in the maturity of the control and experimental groups. The pathomorphological alterations in relation to mercury toxicity in spleen were associated with the disorganization of the splenic cords resulting in the displacement of lymphatic tissue cells within the substance of splenic pulp. Marked depletion of the red pulp was noticeable.