水溶性有机物电子转移能力与荧光峰强度的关系研究

以不同来源的水溶性有机物（DOM）为供试材料,采用电化学方法和荧光光谱法研究了DOM电子转移能力及其与荧光峰强度的关系.采用库仑安培法测定DOM电子转移能力,其中测得的电子接受能力为635.6～1 049.3μmol.（g.C）-1,电子供给能力为27.3～42.3μmol.（g.C）-1.利用循环伏安法研究DOM电化学活性,发现其氧化还原电位在-731～-996 mV（vs.Ag/AgCl）之间.经过电位跃阶法三次氧化还原循环后电子转移能力仍可维持在232.1～897.2μmol.（g.C）-1之间,电子循环率为36.7%～78.2%,说明DOM具有重复利用、反复转移电子的特性.采用荧光激发发射光谱法（EEMS）测定DOM的类富里酸荧光峰强度并比较其与DOM电子转移能力的关系,发现DOM的类富里酸荧光峰强度与DOM的电子循环率具有显著相关（r2=0.92）.实验结果为理解DOM在元素循环、污染物降解以及生物地球化学循环中的作用提供科学依据.     

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.     

Transcervical chorionic villus biopsy with a brush

A brush delivered to the biopsy site by a metal introducer and cannula set was tested as an alternative implement for transcervical collection of chorionic villi. This implement was easy to use and readily identified by ultrasound. With only one attempt at sampling, the overall collection rate for 83 patients was 65 per cent. With practice 84 per cent successful collection was achieved. Gestations between 8 and 11 weeks was the best time for collection of chorionic villi. A single sampling can produce adequate material (15 mg wet weight) suitable for diagnostic purposes. No gestation sac was perforated but some slight bleeding followed the procedure. Appreciable success following a single sampling attempt coupled with the low complication rate suggests that this technique may have clinical application and deserves further investigation.     

US Energy Conservation and Efficiency: Benefits and Costs

With increased energy conservation plus the adoption of diverse energy efficient technologies, the US economy could save about 32 quads or about 33% of its current energy consumption, if sound conservation energy use policies were implemented over approximately 10 years. This potential of 32 quads is slightly greater than the current US oil imports. The systems that have the greatest potential to provide major energy savings are transportation, residential energy use, and the food system. Not only saving energy has merit in itself, but it would save US citizens approximately $438 billion per year, helping support the US economy, a high standard of living, and energy security. In addition, this analysis suggests that reducing the $40 billion in taxpayer money spent on subsidies of the energy industries would further increase conservation.