Removal of mercury(II) from aqueous solutions using the leaves of the Rambai tree (Baccaurea motleyana)

This study was undertaken to evaluate the biosorption potential of a natural, low-cost biosorbent, Rambai leaves (Baccaurea motleyana), to remove trace amounts of Hg(II) from aqueous solutions. It was found that the amount of Hg(II) biosorption by Rambai leaves increased with initial metal ion concentration, contact time, and solution pH but decreased as the amount of biosorbent increased. The maximum biosorption capacity was 121.95 mg/g for an initial concentration range of 5 to 120 ppb. Overall, kinetic studies showed that the Hg(II) biosorption process followed pseudo-second-order kinetics based on pseudo-first-order and intraparticle diffusion models. Isotherm data revealed that the biosorption process followed both Freundlich and Langmuir isotherms. The value of separation factor, R(L), from the Langmuir equation and rate of biosorption, n, from the Freundlich model also indicated favorable adsorption.     

Performance of an overland flow system for advanced treatment of wastewater plant effluent

Overland flow (OF) systems were evaluated and compared for advanced treatment of municipal and industrial effluents, including nutrients and nondegradable chemical oxygen demand (COD) removal. Three pilot plants were constructed at the Shahin Shahr Wastewater Treatment Plant (WWTP), Isfahan, Iran. Each pilot was assigned a specific wastewater and all were simultaneously operated for 8 months. Treatment of primary effluent, activated sludge secondary effluent, and lagoon effluent of textile wastewater was investigated at application rates (ARs) of 0.15, 0.25, and 0.35m(3)m(-1)h(-1). During 5 months of stable operation after a 3-month acclimation period, mean removals of total 5-day biochemical oxygen demand (TBOD(5)), total COD (TCOD), total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP) and turbidity were 74.5%, 54.8%, 66.2%, 39.4%, 35.8%, and 67.7% for primary effluent; 52.9%, 52.9%, 66.5%, 44.4%, 39.8%, and 50.1% for activated sludge effluent; 65.7%, 58.7%, 70.3%, 41.7%, 41.3%, and 54.9% for textile wastewater lagoon effluent, respectively. The model of Smith and Schroeder, 1985. Field studies of the overland flow process for the treatment of raw and primary treated municipal wastewater. Journal of Water Pollution Control Federation 57, 785-794] was satisfactory for TBOD(5). For all treatment parameters a standard first-order removal model was inadequate to represent the data but a modified first-order model provided a satisfactory fit to the data. Based on the results of this study, it can be concluded that an OF system as advanced treatment had the ability to meet effluent discharge permit limits and was an economical replacement for stabilization ponds and mechanical treatment options.     

Additional danger of arsenic exposure through inhalation from burning of cow dung cakes laced with arsenic as a fuel in arsenic affected villages in Ganga-Meghna-Brahmaputra plain

In arsenic contaminated areas of the Ganga-Meghna-Brahmaputra (GMB) plain (area 569,749 sq. km; population over 500 million) where traditionally cow dung cake is used as a fuel in unventilated ovens for cooking purposes, people are simply exposed to 1859.2 ng arsenic per day through direct inhalation, of which 464.8 ng could be absorbed in respiratory tract.     

Mass casualty incident after the Taba terrorist attack: an organisational and medical challenge

Two suicide bombings in and around Taba, Egypt, on 7 October 2004 created a complex medical and organisational situation. Since most victims were Israeli tourists, the National Emergency and Disaster Management Division handled their evacuation and treatment. This paper describes the event chronologically, as well as the organisational and management challenges confronted and applied solutions. Forty-nine emergency personnel and physicians were flown early to the disaster area to reinforce scarce local medical resources. Two hundred casualties were recorded: 32 dead and 168 injured. Eilat hospital was transformed into a triage facility. Thirty-two seriously injured patients were flown to two remote trauma centres in central Israel. Management of mass casualty incidents is difficult when local resources are inadequate. An effective response should include: rapid transportation of experienced trauma teams to the disaster zone; conversion of local medical amenities into a triage centre; and rapid evacuation of the seriously injured to higher level medical facilities.     

Design of on-line river water quality monitoring systems using the entropy theory: a case study

The design of a water quality monitoring network is considered as the main component of water quality management including selection of the water quality variables, location of sampling stations and determination of sampling frequencies. In this study, an entropy-based approach is presented for design of an on-line water quality monitoring network for the Karoon River, which is the largest and the most important river in Iran. In the proposed algorithm of design, the number and location of sampling sites and sampling frequencies are determined by minimizing the redundant information, which is quantified using the entropy theory. A water quality simulation model is also used to generate the time series of the concentration of water quality variables at some potential sites along the river. As several water quality variables are usually considered in the design of water quality monitoring networks, the pair-wise comparison is used to combine the spatial and temporal frequencies calculated for each water quality variable. After selecting the sampling frequencies, different components of a comprehensive monitoring system such as data acquisition, transmission and processing are designed for the study area, and technical characteristics of the on-line and off-line monitoring equipment are presented. Finally, the assessment for the human resources needs, as well as training and quality assurance programs are presented considering the existing resources in the study area. The results show that the proposed approach can be effectively used for the optimal design of the river monitoring systems.     

Effect of fertilizer application on soil heavy metal concentration

A large amount of chemicals is annually applied at the agricultural soils as fertilizers and pesticides. Such applications may result in the increase of heavy metals particularly Cd, Pb, and As. The objective of this study was to investigate the variability of chemical applications on Cd, Pb, and As concentrations of wheat-cultivated soils. Consequently, a study area was designed and was divided into four subareas (A, B, C, and D). The soil sampling was carried out in 40 points of cultivated durum wheat during the 2006–2007 periods. The samples were taken to the laboratory to measure their heavy metal concentration, soil texture, pH, electrical conductivity, cationic exchange capacity, organic matter, and carbonate contents. The result indicated that Cd, Pb, and As concentrations were increased in the cultivated soils due to fertilizer application. Although the statistical analysis indicates that these heavy metals increased significantly (P value < 0.05), the lead and arsenic concentrations were increased dramatically compared to Cd concentration. This can be related to overapplication of fertilizers as well as the pesticides that are used to replant plant pests, herbs, and rats.     

Modeling of Hydrodynamics and Cohesive Sediment Processes in an Estuarine System: Study Case in Danshui River

The Danshui River estuarine system is the largest estuarine system in northern Taiwan and is formed by the confluence of Tahan Stream, Hsintien Stream, and Keelung River. A comprehensive one-dimensional (1-D) model was used to model the hydrodynamics and cohesive sediment transport in this branched river estuarine system. The applied unsteady model uses advection/dispersion equation to model the cohesive sediment transport. The erosion and deposition processes are modeled as source/sink terms. The equations are solved numerically using an implicit finite difference scheme. Water surface elevation and longitudinal velocity time series were used to calibrate and verify the hydrodynamics of the system. To calibrate and verify the mixing process, the salinity time series was used and the dispersion coefficient of the advection/dispersion equation was determined. The cohesive sediment module was calibrated by comparing the simulated and field measured sediment concentration data and the erosion coefficient of the system was determined. A minimum mean absolute error of 4.22 mg/L was obtained and the snapshots of model results and field measurements showed a reasonable agreement. Our modeling showed that a 1-D model is capable of simulating the hydrodynamics and sediment processes in this estuary and the sediment concentration has a local maximum at the limit of salinity intrusion. Furthermore, it was indicated that for Q ₅₀ (the flow which is equaled or exceeded 50% times), the turbidity maximum location during neap tide is about 1 km closer to the mouth compared to that during spring tide. It was found that deposition is the dominant sediment transport process in the river during spring–neap periods. It was shown that, while sediment concentration at the upstream depends on the river discharge, the concentration in the downstream is not a function of river discharge.     

活性氮和人类健康:眼前和长远的意义

活性氮对人类健康的影响表现在许多有益和不利的方面.有益方面,最为重要的是活性氮不断增加全球和区域性的食物供给,并提高了可利用食物的营养质量.在贫困、干旱、洪涝、战争以及难民涌入等因素造成食物紧缺时,膳食中氨基酸和蛋白质的摄入量不足是引起营养不良的主要原因.已掌握的大量数据即便还是有限的,也足以表明环境中活性氮流通量的增加通过其他一些作用途径对人类健康产生了显著的影响.职业原因和广大人群室内和户外生活所接触到的空气污染中的活性氮对人类的健康产生了不良影响.活性氮还可通过水污染和全球变暖影响人类健康,其产生的水污染包括地下水污染产生的高铁血红蛋白血症以及使鱼类死亡和对人体有毒的赤潮富营养化.环境中活性氮类的污染物普遍存在,因此,很难界定活性氮对人们健康产生特定影响的程度.鉴于活性氮影响到全人类,为了确定氮相关污染物及其衍生物对人类健康产生的有利和不良影响的程度和性质,需要多学科合作,进行长期的研究.     

Predicting the effects of urbanization on runoff after frequent rainfall events

Urbanization dynamics are commonly subjected to powerful market forces, only partly managed by land-use plans. The density, location and pattern of urbanized areas affect rainfall-runoff relations. Consequently, it is essential to understand future impacts of urbanization on runoff and produce focused regulation. The goal was to analyze land-cover scenarios and their impact on runoff in an urbanized watershed in Israel. Present and predicted land-cover scenarios in a densely populated watershed were produced. The runoff response to rainfall was then simulated using a hydrological model. The impact of implementing afforestation and quarrying national outline plans was considered. By the year 2050, 50% of the watershed will be urbanized with a linear increase in runoff response. Afforestation and quarrying plans show little effect on runoff, although quarries may decrease runoff through percolation. As urbanization is expected to continue spreading in adjacent watersheds, statutory measures should be applied to mitigating runoff.     

Dechlorane Plus as an emerging environmental pollutant in Asia: a review

Environmental Science and Pollution Research - Dechlorane Plus (DP) is an unregulated, highly chlorinated flame retardant. It has been manufactured from past 40&nbsp;years but its presence in...