Exchange pattern of gaseous elemental mercury in an active urban landfill facility

The environmental behavior of gaseous elemental mercury (Hg) in the ambient air was investigated from the center of a municipal landfill site (area approximately 0.6km(2)) located in Dae Gu, Korea in the winter of 2004. In order to provide insight on the Hg exchange processes in strong source areas, we continuously analyzed Hg concentration gradients developed across two heights between 1m and 5m over soil surfaces at hourly intervals. The results displayed Hg concentrations in the lower and upper levels in the range of 1.46-13.1ngm(-3) (3.33+/-1.29ngm(-3): N=139) and 1.20-13.7ngm(-3) (3.27+/-1.23ngm(-3): N=139), respectively. The results of our analysis, when divided separately into emission and dry deposition, showed that emission of Hg was fairly dominant in frequency (up to 58%) over dry deposition. By multiplying our Hg gradient data with the K-values predicted indirectly from the results of previous studies, the emission and deposition fluxes of Hg were estimated as 39.0+/-43.3ngm(-2)h(-1) (N=80) and -60.0+/-80.2ngm(-2)h(-1) (N=59), respectively. Although the magnitudes of exchange were moderately lower than previously investigated anthropogenic sources, the overall results of this study suggest that an active landfill site can act as an important source of Hg in an urban environment along with other man-made activities.     

Modeling of metal binding in tropical Fluvisols and Acrisols treated with biosolids and wastewater

There is growing concern about the accumulation of metals in tropical agricultural soils. In this study, experimental results from batch studies were used to test whether multi-surface geochemical models could describe metal binding in selected Vietnamese soils. The multi-surface models considered metal binding to iron hydroxides (using the diffuse layer model), organic matter (Stockholm Humic model and NICA-Donnan model), and phyllosilicate clay (Gaines-Thomas equation) as well as complexation to dissolved organic and inorganic ligands in the solution phase. We found that for total dissolved Cd, Cu and Zn the two multi-surface models being tested provided very good model fits for all soils, as evidenced by low root-mean square errors between model predictions and observations. These results suggest that organic matter is an important sorbent for many metals in these soils. However, poor fits were obtained for Cr(III), Mn and Pb for all soils. The study also suggests that the pH is the main factor that controls the solubility of metals in tropical Fluvisols and Acrisols subjected to application of biosolids and wastewater, and that advanced multi-surface models can be used to simulate the binding and release of many trace metals.     

Occurrence, fate and antibiotic resistance of fluoroquinolone antibacterials in hospital wastewaters in Hanoi, Vietnam

Occurrence and behavior of fluoroquinolone antibacterial agents (FQs) were investigated in hospital wastewaters in Hanoi, Vietnam. Hospital wastewater in Hanoi is usually not treated and this untreated wastewater is directly discharged into one of the wastewater channels of the city and eventually reaches the ambient aquatic environment. The concentrations of the FQs, ciprofloxacin (CIP) and norfloxacin (NOR) in six hospital wastewaters ranged from 1.1 to 44 and from 0.9 to 17 micrgl(-1), respectively. Total FQ loads to the city sewage system varied from 0.3 to 14 g d(-1). Additionally, the mass flows of CIP and NOR were investigated in the aqueous compartment in a small wastewater treatment facility of one hospital. The results showed that the FQ removal from the wastewater stream was between 80 and 85%, probably due to sorption on sewage sludge. Simultaneously, the numbers of Escherichia coli (E. coli) were measured and their resistance against CIP and NOR was evaluated by determining the minimum inhibitory concentration. Biological treatment lead to a 100-fold reduction in the number of E. coli but still more than a thousand E. coli colonies per 100ml of wastewater effluent reached the receiving water. The highest resistance was found in E. coli strains of raw wastewater and the lowest in isolates of treated wastewater effluent. Thus, wastewater treatment is an efficient barrier to decrease the residual FQ levels and the number of resistant bacteria entering ambient waters. Due to the lack of municipal wastewater treatment plants, the onsite treatment of hospital wastewater before discharging into municipal sewers should be considered as a viable option and consequently implemented.     

美国高校实验室废弃物安全管理浅析

实验室废弃物的收集、管理不当会造成严重的环境污染甚至人员伤害,这已经引起国内外相关部门的高度重视。美国高校在实验室废弃物安全管理方面积累了科学、规范的管理经验：通过对实验室科研人员的专业培训保证废弃物的安全分类收集;通过专业环境健康安全管理部门人员的科学管理实现对废弃物的安全收集与存放;通过专业废弃物收集处置公司来实现废弃物的安全转移运输和最终无害化处理。为加强国内高校实验室废弃物的安全管理,在对美国高等院校实验室废弃物的收集、储藏、运输和处理等方面调查研究的基础上,结合国内实验室废弃物安全管理的现状,对国内外高校实验室废弃物的安全管理进行了对比分析,以期为国内高校实验室废弃物的安全管理工作提供有益的借鉴。     

Plotting formula for pearson type III distribution considering historical information

Most of the existing plotting position formulas have been proposed for use in the analysis of systematic flood records, but little has been reported on the plotting formulas for historical or non-systematic flood samples. In particular, no previous investigations have specifically examined the probability plots for the Pearson type III (P3) distribution in the analysis of historical flood information. The present paper suggests a new plotting position formula for the P3 distribution for use with both systematic and historical flood records. The proposed formula has a simple structure as do most existing formulas, but it is more flexible because in can take explicitly into account the skewness coefficient of the underlying distribution. Further, results of graphical and numerical comparisons have demonstrated that the suggested formula provided the least bias in flood quantile estimation as compared with many available plotting formulas, including the well-known Weibull formula. Finally, results of a numerical example using actual flood data have indicated the practica convenience of the proposed plotting formula. It can be concluded that the formula developed in this study is the most appropriate for the P3 distribution in the analysis of flood records considering historical information.     

Risk evaluation with waste scenario: lead emissions in solder waste treatment

In this work, an estimate of the elevation of airborne lead concentrations via the lead solder contained in domestic electricity installations and an investigation into the effects of human exposure were conducted using a simulation method. The elevation of airborne lead concentrations due to incineration was calculated to be 0.001 µg/m³ maximum. The simulation results of the calculations indicated that blood lead concentrations could reach as high as 10⁻⁵ µg/dl. These concentrations could primarily be attributed to the inhalation of airborne lead particles. In addition, we discuss the influences of lead solder disposal on the ecosystem via soil and water.     

Community concerns about landfills: A case study of Hanoi,Vietnam

This paper examines the nature of community concerns about a landfill in Hanoi, Vietnam and compares these concerns to those found in studies of North American landfills. Based on a survey of 174 households living near Hanoi's landfill, it was found that concerns were uniformly high within the study area. Although the community initially believed the proponent's claims that the landfill would not pollute the environment, their faith in those claims disappeared once the landfill opened and began to produce numerous negative impacts on the community. Residents called for a variety of technical, management and economic measures to mitigate these impacts.     

Sustainable solutions for solid waste management in Southeast Asian countries

Human activities generate waste and the amounts tend to increase as the demand for quality of life increases. Today’s rate in the Southeast Asian Nations (ASEANs) is alarming, posing a challenge to governments regarding environmental pollution in the recent years. The expectation is that eventually waste treatment and waste prevention approaches will develop towards sustainable waste management solutions. This expectation is for instance reflected in the term ‘zero emission systems’. The concept of zero emissions can be applied successfully with today’s technical possibilities in the agro-based processing industry. First, the state-of-the-art of waste management in Southeast Asian countries will be outlined in this paper, followed by waste generation rates, sources, and composition, as well as future trends of waste. Further on, solutions for solid waste management will be reviewed in the discussions of sustainable waste management. The paper emphasizes the concept of waste prevention through utilization of all wastes as process inputs, leading to the possibility of creating an ecosystem in a loop of materials. Also, a case study, focusing on the citrus processing industry, is displayed to illustrate the application of the aggregated material input–output model in a widespread processing industry in ASEAN. The model can be shown as a closed cluster, which permits an identification of opportunities for reducing environmental impacts at the process level in the food processing industry. Throughout the discussion in this paper, the utilization of renewable energy and economic aspects are considered to adapt to environmental and economic issues and the aim of eco-efficiency. Additionally, the opportunities and constraints of waste management will be discussed.