Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived (222Rn) decay products 214Pb and 210Pb. The samples were taken by using a single-filter technique and gamma-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214Pb and 210Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214Pb and 210Pb within the whole year was found to be 1.4+/-0.27 Bq m(-3) and 1.2+/-0.15 mBq m(-3), respectively. Different 210Pb:214Pb activity ratios during the year varied between 1.78 x 10(-4) and 1.6 x 10(-3) with a mean value of 8.9 x 10(-4) +/- 7.6 x 10(-5). From the ratio between the activity concentrations of the radon decay products 214Pb and 210Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5+/-0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air.     

Integrated Approach for Prioritizing Watersheds for Management: A Study of Lidder Catchment of Kashmir Himalayas

The Himalayan watersheds are susceptible to various forms of degradation due to their sensitive and fragile ecological disposition coupled with increasing anthropogenic disturbances. Owing to the paucity of appropriate technology and financial resources, the prioritization of watersheds has become an inevitable process for effective planning and management of natural resources. Lidder catchment constitutes a segment of the western Himalayas with an area of 1,159.38 km². The study is based on integrated analysis of remote sensing, geographic information system, field study, and socioeconomic data. Multicriteria evaluation of geophysical, land-use and land-cover (LULC) change, and socioeconomic indicators is carried out to prioritize watersheds for natural resource conservation and management. Knowledge-based weights and ranks are normalized, and weighted linear combination technique is adopted to determine final priority value. The watersheds are classified into four priority zones (very high priority, high priority, medium priority, and low priority) on the basis of quartiles of the priority value, thus indicating their ecological status in terms of degradation caused by anthropogenic disturbances. The correlation between priority ranks of individual indicators and integrated indicators is drawn. The results reveal that socioeconomic indicators are the most important drivers of LULC change and environmental degradation in the catchment. Moreover, the magnitude and intensity of anthropogenic impact is not uniform in different watersheds of Lidder catchment. Therefore, any conservation and management strategy must be formulated on the basis of watershed prioritization.     

An integrated fuzzy-stochastic modeling approach for risk assessment of groundwater contamination

An integrated fuzzy-stochastic risk assessment (IFSRA) approach was developed in this study to systematically quantify both probabilistic and fuzzy uncertainties associated with site conditions, environmental guidelines, and health impact criteria. The contaminant concentrations in groundwater predicted from a numerical model were associated with probabilistic uncertainties due to the randomness in modeling input parameters, while the consequences of contaminant concentrations violating relevant environmental quality guidelines and health evaluation criteria were linked with fuzzy uncertainties. The contaminant of interest in this study was xylene. The environmental quality guideline was divided into three different strictness categories: "loose", "medium" and "strict". The environmental-guideline-based risk (ER) and health risk (HR) due to xylene ingestion were systematically examined to obtain the general risk levels through a fuzzy rule base. The ER and HR risk levels were divided into five categories of "low", "low-to-medium", "medium", "medium-to-high" and "high", respectively. The general risk levels included six categories ranging from "low" to "very high". The fuzzy membership functions of the related fuzzy events and the fuzzy rule base were established based on a questionnaire survey. Thus the IFSRA integrated fuzzy logic, expert involvement, and stochastic simulation within a general framework. The robustness of the modeling processes was enhanced through the effective reflection of the two types of uncertainties as compared with the conventional risk assessment approaches. The developed IFSRA was applied to a petroleum-contaminated groundwater system in western Canada. Three scenarios with different environmental quality guidelines were analyzed, and reasonable results were obtained. The risk assessment approach developed in this study offers a unique tool for systematically quantifying various uncertainties in contaminated site management, and it also provides more realistic support for remediation-related decisions.     

Heavy metal contamination from mining sites in South Morocco: 1. Use of a biotest to assess metal toxicity of tailings and soils

Our work was conducted to investigate the heavy metal toxicity of tailings and soils collected from five metal mines located in the south of Morocco. We used the MetPAD biotest Kit which detects the toxicity specifically due to the heavy metals in environmental samples. This biotest initially developed to assess the toxicity of aquatic samples was adapted to the heterogeneous physico-chemical conditions of anthropogenic soils. Contrasted industrial soils were collected from four abandoned mines (A, B, C and E) and one mine (D) still active. The toxicity test was run concurrently with chemical analyses on the aqueous extracts of tailings materials and soils in order to assess the potential availability of heavy metals. Soil pH was variable, ranging from very acidic (pH 2.6) to alkaline values (pH 8.0-8.8). The tailings from polymetallic mines (B and D) contained very high concentrations of Zn (38,000-108,000 mg kg(-1)), Pb (20,412-30,100 mg kg(-1)), Cu (2,019-8,635 mg kg(-1)) and Cd (148-228 mg kg(-1)). Water-extractable metal concentrations (i.e., soil extracts) were much lower but were highly toxic as shown by the MetPAD test, except for soils from mines A, E and site C3 from mine C. The soil extracts from mine D were the most toxic amongst all the soils tested. On this site, the toxicity of soil water extracts was mainly due to high concentrations of Zn (785-1,753 mg l(-1)), Cu (1.8-82 mg l(-1)) and Cd (2.0-2.7 mg l(-1)). The general trend observed was an increase in metal toxicity measured by the biotest with increasing available metal contents in tailings materials and soils. Therefore, the MetPAD test can be used as a rapid and sensitive predictive tool to assess the heavy metal availability in soils highly contaminated by mining activities.     

Determination of nickel in blood and serum samples of oropharyngeal cancer patients consumed smokeless tobacco products by cloud point extraction coupled with flame atomic absorption spectrometry

Oropharyngeal cancer is a significant public health issue in the world. The incidence of oropharyngeal cancer has been increased among people who have habit of chewing smokeless tobacco (SLT) in Pakistan. The aim of present study was to evaluate the concentration of nickel (Ni) in biological samples (whole blood, serum) of oral (n?=?95) and pharyngeal (n?=?84) male cancer patients. For comparison purposes, the biological samples of healthy age-matched referents (n?=?150), who consumed and did not consumed SLT products, were also analyzed for Ni levels. As the Ni level is very low in biological samples, a preconcentration procedure has been developed, prior to analysis of analyte by flame atomic absorption spectrometry (FAAS). The Ni in acid-digested biological samples was complexed with ammonium pyrrolidinedithio carbamate (APDC), and a resulted complex was extracted in a surfactant Triton X-114. Acidic ethanol was added to the surfactant-rich phase prior to its analysis by FAAS. The chemical variables, such as pH, amounts of reagents (APDC, Triton X-114), temperature, incubation time, and sample volume were optimized. The resulted data indicated that concentration of Ni was higher in blood and serum samples of cancer patients as compared to that of referents who have or have not consumed different SLT products (p?=?0.012–0.001). It was also observed that healthy referents who consumed SLT products have two to threefold higher levels of Ni in both biological samples as compared to those who were not chewing SLT products (p? Figure

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Heavy metal contamination from mining sites in South Morocco: Monitoring metal content and toxicity of soil runoff and groundwater

The aim of the present work is the assessment of metal toxicity in runoff, in their contaminated soils and in the groundwater sampled from two mining areas in the region of Marrakech using a microbial bioassay MetPLATE™. This bioassay is based on the specific inhibition of the β-galactosidase enzyme of a mutant strain of Escherichia coli, by the metallic pollutants. The stream waters from all sampling stations in the two mines were all very toxic and displayed percent enzyme inhibition exceeding 87% except SWA₄ and SWB₁ stations in mine C. Their high concentrations of copper (Cu) and zinc (Zn) confirm the acute toxicity shown by MetPLATE. The pH of stream waters from mine B and C varied between 2.1 and 6.2 and was probably responsible for metal mobilization, suggesting a problem of acid mine drainage in these mining areas. The bioassay MetPLATE™ was also applied to mine tailings and to soils contaminated by the acidic waters. The results show that the high toxicity of these soils and tailings was mainly due to the relatively concentration of soluble Zn and Cu. The use of MetPLATE™ in groundwater toxicity testing shows that, most of the samples exhibited low metal toxicity (2.7–45.5% inhibition) except GW3 of the mine B (95.3% inhibition during the wet season and 82.9% inhibition during the dry season). This high toxicity is attributed to the higher than usual concentrations of Cu (189 μg Cu l⁻¹) and Zn (1505 μg Zn l⁻¹). These results show the potential risk of the contamination of different ecosystems situated to the vicinity of these two metalliferous sites. The general trend observed was an increase in metal toxicity measured by the MetPLATE with increasing total and mobile metal concentrations in the studied matrices. Therefore, the MetPLATE bioassay is a reliable and fast bioassay to estimate the metals toxicity in the aquatic and solids samples.     

The effects of socioeconomic parameters on household solid-waste generation and composition in developing countries (a case study: Ahvaz,Iran)

Environment problems associated with the generation of waste are part of societal changes where households play an important role. These societal changes influence the size, structure and characteristic of given households. For the effective planning of solid-waste handling infrastructure, it is essential to know the quantity of waste generation and its composition. This paper presents the findings of a study carried out in an urban municipal area in Iran to determine the household solid-waste generation rate and waste composition based on field surveys and to determine the related socioeconomic parameters. The dependent variables were waste generation and composition, and independent variables were family size, family employment, age, number of room and education. Over 400 sample households were selected for the study using a stratified random sampling methodology and from five different socioeconomic groups. Waste collected from all groups of households were segregated and weighted. Waste generation rate was 5.4 kg/household/day. Household solid waste comprised of ten categories of wastes and with the largest component (76.9%). The generation and composition of household solid waste were correlated with family size, education level and households income. This paper adequately suggests new insights concerning the role of socioeconomic parameters in affecting the generation of household waste.     

Performance of a small-scale solar-powered adsorption cooling system

In this study, an experimental investigation on the performance of a small-scale residential-size solar-driven adsorption (silica gel-water) cooling system that was constructed at Assiut University campus, Egypt is carried out. As Assiut area is considered as hot, arid climate, field tests for performance assessment of the system operation during the summer season are performed under different environmental operating conditions. The system consists of an evacuated tube with a reflective concentration parabolic surface solar-collector field with a total area of 36 m², a silica gel-water adsorption chiller of 8 kW nominal cooling capacity, and hot and cold water thermal storage tanks of 1.8 and 1.2 m³ in volume, respectively. The results of summer season field test show that under daily solar insolation varying from 21 to 27 MJ/m², the solar collectors employed in the system had high and almost constant thermal efficiency. The daily solar-collector efficiency during the period of system operation ranged from about 50% to 78%. The adsorption chiller performance shows that the chiller average daily coefficient of performance (COP) was 0.41 with the average cooling capacity of 4.4 kW when the cooling-water and chilled-water temperatures were about 31°C and 19°C, respectively. As the chiller cooling water is cooled by the cooling tower in the hot arid area, the cooling water is at a higher temperature than the design point of the chiller. Therefore, an experiment was carried out using the city water for cooling. The results show that an enhancement in the chiller COP by 40% and the chilling power by 17% has been achieved when the city water was 27.7°C.