A Numerical and Experimental Study of Pollutant Dispersion in a Traffic Tunnel

Three-dimensional turbulent flow and dispersion of gaseous pollutants carbon monoxide (CO) and nitrogen oxides (NOx) in a road tunnel was modeled using the standard k–ε turbulence model and solved numerically using the finite volume method. Vehicle emissions were estimated from the measured traffic flow rates and modeled as banded line sources along the tunnel floor. The effects of fan ventilation and piston effect of moving vehicles on the airflow and pollutant dilution were examined. The numerical results reveal that a peak velocity exists near the tunnel floor due to the piston effect of vehicles. The cross-sectional concentrations of air pollutants are non-uniformly distributed and concentrations rise with downstream distance. The piston effect of vehicles can alone provide 25%–34% dilution of air pollutants in the tunnel, compounded 43%–70% dilution effect according to the ventilation condition.     

Assessment of river water quality during snowmelt and base flow periods in two catchment areas with different land use

River water quality was evaluated with respect to eutrophication and land use during spring snowmelt and summer base flow periods in Abashiri (mixed cropland-livestock farming) and Okoppe (grassland-based dairy cattle farming), eastern Hokkaido, Japan. Water from rivers and tributaries was sampled during snowmelt and summer base flow periods in 2005, and river flow was measured. Total N (TN), NO₃–N, and Si concentrations were determined using standard methods. Total catchment and upland areas for each sampling site were determined with ArcGIS hydrology modeling software and 1:25,000-scale digital topographic maps. Specific discharge was significantly higher during snowmelt than during base flow. In both areas, TN concentrations increased, whereas Si concentrations decreased, with increased specific discharge, and were significantly higher during snowmelt. The Si:TN mole ratio decreased to below or close to the threshold value for eutrophication (2.7) in one-third of sites during snowmelt. River NO₃–N concentrations during base flow were significantly and positively correlated with the proportion of upland fields in the catchment in both the Abashiri (r = 0.88, P < 0.001) and Okoppe (r = 0.43, P < 0.01) areas. However, the regression slope, defined as the impact factor (IF) of water quality, was much higher in Abashiri (0.025) than in Okoppe (0.0094). The correlations were also significantly positive during snowmelt in both areas, but IF was four to eight times higher during snowmelt than during base flow. Higher discharge of N from upland fields and grasslands during snowmelt and the resulting eutrophication in estuaries suggest that nutrient discharge during snowmelt should be taken into account when assessing and monitoring the annual loss of nutrients from agricultural fields.     

Numerical Modeling of Flow Fields and Dispersion of Passive Pollutants in the Vicinity of the Temelín Nuclear Power Plant

This study deals with numerical simulation of flow fields and dispersion of model passive admixtures in the planetary boundary layer in a 10 × 10 km square area, centered on the Czech Republic’s Temelín Nuclear Power Plant. Numerical calculations of three-dimensional flow fields with eight basic wind directions given for the inlet boundary of the computational domain are performed using the FLUENT CFD code with the standard k – ε turbulence model. The resultant modeling of the flow fields provides information as to probable local directions and velocities of flow vectors on a horizontal scale of 100 m, which are consistent with the data given for the boundaries of the calculation area in the framework of a scale of 10 km. The modeled flow fields generate the input data for related Lagrangian simulation of the ground concentration and deposition fields of passive particles assumedly emitted at the site of the Temelín plant. Simulated plumes describe eight cases of potential ground-level distribution of model passive admixtures in the area.     

Measurement of particulate phase polycyclic aromatic hydrocarbon (PAHs) around a petroleum refinery

A study on concentrations of ambient particulates viz. total suspended particulate matters (TSP), respirable suspended particulate matter (RSPM) and polycyclic aromatic hydrocarbons (PAH) were carried out at six sites around the Asia’s largest, 12 MMTPA, petroleum refinery in west coast of India. PAH concentrations are correlated with each other in these sites, suggesting that they have related sources and sinks. The present article discusses the monitoring aspects such as sample collection, pretreatment and analytical methods and compares the monitored levels for assessing the source receptor distribution pattern. The main sources of RSPM and PAHs in urban air are automobile exhaust (CPCB, Polycyclic aromatic hydrocarbons (PAHs) in air and their effects on human health. “”, 2003; Manuel et al., Environmental Science and Technology, 13: 227–231, 2004) and industrial emissions like petroleum refinery (Vo-Dinh, Chemical analysis of polycyclic aromatic hydrocarbons, Wiley: New York, 1989; Wagrowaski and Hites, Environmental Science and Technology, 31: 279–282, 1997). Polycyclic aromatic hydrocarbons (PAH) are ubiquitous constituents of urban airborne particulate mostly generated by anthropogenic activities (Li et al., Environmental Science and Technology, 37:1958–2965, 2003; Thorsen et al., Environmental Science and Technology, 38: 2029–2037, 2004; Ohura et al., Environmental Science and Technology, 32: 450–455, 2004) and some of them are of major health concern mainly due to their well-known carcinogenic and mutagenic properties (Soclo et al., Marine Pollution Bulletin, 40: 387–396, 2000; Chen et al., Environment International, 28: 659–668, 2003; Larsen and Baker, Environmental Science and Technology, 32: 450–455, 2003). Limited information is available on PAHs contributions from refineries to ambient air. Hence this study would not only create a database but also provide necessary inputs towards dose-response relationship for fixing standards. Also, since it acts as precursor to green house gas, the data would be useful for climate change assessments. The objective of this article is to find out the concentration of PAHs in particulate matter around petroleum refinery and compare with their concentrations in major Indian urban centers.     

Water quality assessment: surface water sources used for drinking and irrigation in Zaria,Nigeria are a public health hazard

We assessed the quality and pollution status of source surface waters in Zaria, Nigeria by monitoring the nature, cause and extent of pollution in Samaru stream, Kubanni River and Kubanni dam over a period of 10 months, between March and December 2002. A total of 228 water samples was collected from 12 sites and analysed for a total of ten physicochemical and one bacteriological quality indicators, using standard methods. Aesthetic water quality impairment parameters were also observed. The mean values of most water quality parameters were significantly higher (P < 0.05) in both the stream and river than in the dam. There was no significant correlation between faecal coliform counts (FCC) and water temperature (in the range 15–33°C); pH (5.77–7.32); and turbidity (1.4–567 NTU). The high FCC ranged from 2.0 × 10¹ to 1.6 × 10⁶ MPN/100 ml and exceeded the WHO standards for drinking water and water used for fresh-produce irrigation, and correlated positively (P < 0.05) with conductivity (in the range 68–1,029 μS/cm); TDS (10.0–70.0 mg/l); TSS (10.0–70.0 mg/l); Cl (7.5–181 mg/l); PO₄⁻P (0.01–0.41 mg/l); NO₃⁻N (0.6–3.8 mg/l) and BOD₅ (0.1–14.9 mg/l). The main pollution sources were municipal wastewater, stormwater runoffs, the ABU sewage treatment plant, abattoir effluents and irrigation farms treated with chemical fertilisers. We conclude that these water bodies are potentially hazardous to public health and that proper sewage treatment and river quality monitoring are needed to warn against hazards to public health.     

Heavy Metal and Trace Elements in Various Fish Samples from Sır Dam Lake, Kahramanmaraş, Turkey

Achanthobrama marmid (thorn-bream) (n:24), Chondrostoma regium (nose-carp) (n:33) and Silurus glanis (wels) (n:21), and Cyprinus carpio (carp) (n:30) were collected from Sır Dam Lake in Kahramanmaraş Province. The iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), and lead (Pb) levels were determined in the total of 108 fish samples by Atomic Absorption Spectrophotometer. The concentrations of heavy metals were expressed as mg kg⁻¹ wet weight of tissue. The mean Fe and Mn levels of muscle and gill of C. carpio were 0.8–5.71 and 0.30–1.96, respectively. The mean of the Fe and Mn levels of muscle and gill of A. marmid were 1.22, 5.07 and 0.38, 0.85 mg kg⁻¹, respectively. The ranges of mean concentrations of Fe and Mn levels in muscle and gill of C. regium were 0.91, 5.61 and 0.27, 3.42 mg kg⁻¹, respectively. The mean value of Fe in S. glanis gill was 1.03, which of Mn was 0.17 mg kg⁻¹. Fe, Mn, Co, Ni, and Pb were not detected in the muscle of S. glanis. The mean values for Co in muscle of thorn-bream, carp, and nose-carp were 0.005, 0.01, 0.0 mg kg⁻¹, respectively. Nickel values in the muscle were ranged between 0.38 and 1.93 in thorn-bream, 0.06 and 1.34 in carp, 0.14 and 1.89 in nose-carp, in that order. The mean Pb levels of muscle and gill of A. marmid were 0.14 and 0.29 mg kg⁻¹, respectively. The mean values of Pb concentration of muscle and gill for C. carpio were 0.13 and 0.50 mg kg⁻¹, respectively. In C. regium mean values for Pb in muscle and gill were 0.06 and 0.06 mg kg⁻¹, respectively. The mean value of Pb in S. glanis gill was 0.42, ranged between 0.0–0.92 mg kg⁻¹.     

Fecal source tracking by antibiotic resistance analysis on a watershed exhibiting low resistance

The ongoing development of microbial source tracking has made it possible to identify contamination sources with varying accuracy, depending on the method used. The purpose of this study was to test the efficiency of the antibiotic resistance analysis (ARA) method under low resistance by tracking the fecal sources at Turkey Creek, Oklahoma exhibiting this condition. The resistance patterns of 772 water-isolates, tested with nine antibiotics, were analyzed by discriminant analysis (DA) utilizing a five-source library containing 2250 isolates. The library passed various representativeness tests; however, two of the pulled-sample tests suggested insufficient sampling. The resubstitution test of the library individual sources showed significant isolate misclassification with an average rate of correct classification (ARCC) of 58%. These misclassifications were explained by low antibiotic resistance (Wilcoxon test P < 0.0001). Seasonal DA of stream E. coli isolates for the pooled sources human/livestock/deer indicated that in fall, the human source dominated (P < 0.0001) at a rate of 56%, and that human and livestock respective contributions in winter (35 and 39%), spring (43 and 40%), and summer (37 and 35%) were similar. Deer scored lower (17–28%) than human and livestock at every season. The DA was revised using results from a misclassification analysis to provide a perspective of the effect caused by low antibiotic resistance and a more realistic determination of the fecal source rates at Turkey Creek. The revision increased livestock rates by 13–14% (0.04 ≤ P ≤ 0.06), and decreased human and deer by 6–7%. Negative misclassification into livestock was significant (0.04 ≤ P ≤ 0.06). Low antibiotic resistance showed the greatest effect in this category.     

Desorption Kinetics of Benzene in a Sandy Soil in the Presence of Powdered Activated Carbon

Desorption kinetics of benzene was investigated with a modified biphasic desorption model in a sandy soil with five different powdered activated carbon (PAC) contents (0, 1, 2, 5, 10% w/w) as sorbents. Sorption experiments followed by series dilution desorption were conducted for each sorbent. Desorption of benzene was successively performed at two stages using deionized water and hexane. Modeling was performed on both desorption isotherm and desorption rate for water-induced desorption to elucidate the presence of sorption–desorption hysteresis and biphasic desorption and if present to quantify the desorption-resistant fraction (q _irr) and labile fraction (F) of desorption site responsible for rapid process. Desorption isotherms revealed that sorption–desorption exhibited a severe hysteresis with a significant fraction of benzene being irreversibly adsorbed onto both pure sand and PAC, and that desorption-resistant fraction (q _irr) increased with PAC content. Desorption kinetic modeling showed that desorption of benzene was biphasic with much higher (4–40 times) rate constant for rapid process (k ₁) than that for slow process (k ₂), and that the difference in the rate constant increased with PAC content. The labile fraction (F) of desorption site showed a decreasing tendency with PAC. The experimental results would provide valuable information on remediation methods for soils and groundwater contaminated with BTEX.     

Artificial neural network based carbon monoxide persistence models for episodic urban air quality management

This paper describes the development of artificial neural network (ANN) based carbon monoxide (CO) persistence (ANNCOP) models to forecast 8-h average CO concentration using 1-h maximum predicted CO data for the critical (winter) period (November–March). The models have been developed for three 8-h groupings of 10 p.m. to 6 a.m., 6 a.m. to 2 p.m. and 2–10 p.m., at two air quality control regions (AQCRs) in Delhi city, representing an urban intersection and an arterial road consisting heterogeneous traffic flows. The result indicates that time grouping of 2–10 pm is dominantly affected by inversion conditions and peak traffic flow. The ANNCOP model corresponding to this grouping predicts the 8-h average CO concentrations within the accuracy range of 68–71%. The CO persistence values derived from ANNCOP model are comparable with the persistence values as suggested by the Environmental Protection Agency (EPA), USA. This work demonstrates that ANN based model is capable of describing winter period CO persistence phenomena.     

Accuracy assessment of a small-area method for estimating the spatial distribution of the degree of tree damage

Tree damage, gauged by the amount of defoliation, is one of the basic criteria used to determine treatments for protected and economic forests. Monitoring should include an assessment of the degree of tree damage in different spatial scales. Therefore, in addition to the commonly applied large-area methods, small-area methods should be used. The aim of the paper is to present the results of the accuracy assessment of a small-area method, proposed by Podlaski (2005) [Podlaski, R. (2005). Inventory of the degree of tree defoliation in small areas. Forest Ecology and Management, 215, 361–377], for monitoring the degree of tree damage. The degree of tree damage was shown in sub-blocks P₃ of the system of information on natural environment (SINUS). To estimate the spatial distribution of the degree of tree defoliation, survey sampling, based on simple random sampling with replacement (SRSWR), was used. The degree of damage to fir (Abies alba Mill.) and beech (Fagus sylvatica L.) was analysed in the Święty Krzyż forest section in the Świętokrzyski National Park. The maximum total estimation errors for the proportion of trees with a degree zero of damage, and with second and third degrees of damage together (for α = 0.05) were at most 30.8% for fir and 24.3% for beech trees. For standard, small-area evaluations, these are satisfactory values. In the Święty Krzyż forest section, the number of P₃ sub-blocks with 0.00–5.00% of undamaged trees and with 80.01–100.00% of moderately- or severely-damaged trees was significantly greater for fir than for beech. These results indicate that the fir population was unhealthier than the beech group in the study area. P₃ sub-blocks of the SINUS system, in which the proportion of the healthiest trees was highest, were situated at the forest margin, bordering on meadows and arable fields (in the case of fir) and forming dense patches consisting of several sub-blocks, or occurring singly in the whole study area (in the case of beech). The results show the significant differentiation of forest tree health in small areas.     

Heavy metals and PCDD/Fs in solid waste incinerator fly ash in Zhejiang province,China: chemical and bio-analytical characterization

Fly ash samples were taken from solid waste incinerators with different feeding waste, furnace type, and air pollution control device in six cities of Zhejiang province. The solid waste incinerators there constitute one fifth of incinerators in China. Heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in the fly ash. Moreover, the fly ash samples were extracted by toxicity characteristic leaching procedure (TCLP). The biotoxicity of the leachate was evaluated by Chlorella pyrenoidosa. High variation and contents were found for both the heavy metals and PCDD/Fs. The contents of Zn, Cu, As, Pb, Cd, Cr, Ni, and Hg in the fly ash samples varied from 300 to 32,100, 62.1–1175, 1.1–57, 61.6–620, 0.4–223, 16.6–4380, 1.2–94.7, and 0.03–1.4 μg g⁻¹ dw, respectively. The total contents of 17 PCDD/Fs varied from 0.1128 to 127.7939 μg g⁻¹ dw, and the 2,3,7,8-TeCDD toxic equivalents (TEQ) of PCDD/Fs ranged from 0.009 to 6.177 μg g⁻¹ dw. PCDF congeners were the main contributor to the TEQ. The leachate of the fly ash showed biotoxicity to C. pyrenoidosa. A significant correlation was found between the Cd and EC₅₀ values. Further research is required to investigate the environmental impact of the various pollutants in the fly ash.     

Implications of climate change for evaporation from bare soils in a Mediterranean environment

The purpose of this study was to predict quantitative changes in evaporation from bare soils in the Mediterranean climate region of Turkey in response to the projections of a regional climate model developed in Japan (hereafter RCM). Daily RCM data for the estimation of reference evapotranspiration (ET _r) and soil evaporation were obtained for the periods of 1994–2003 and 2070–2079. Potential evaporation (E _p) from bare soils was calculated using the Penman–Monteith equation with a surface resistance of zero. Simulation of actual soil evaporation (E _a) was carried out using Aydin model (Aydin et al., Ecological Modelling 182:91–105, 2005) combined with Aydin and Uygur (2006, A model for estimating soil water potential of bare fields. In Proceedings of the 18th International Soil Meeting (ISM) on Soils Sustaining Life on Earth, Managing Soil and Technology, Sanliurfa, 477–480pp.) model of predicting soil water potential at the top surface layer of a bare soil, after performances of Aydin model (R ² = 94.0%) and Aydin and Uygur model (R ² = 97.6) were tested. The latter model is based on the relations among potential soil evaporation, hydraulic diffusivity, and soil wetness, with some simplified assumptions. Input parameters of the model are simple and easily obtainable such as climatic parameters used to compute the potential soil evaporation, average diffusivity for the drying soil, and volumetric water content at field capacity. The combination of Aydin and Aydin and Uygur models appeared to be useful in estimating water potential of soils and E _a from bare soils, with only a few parameters. Unlike ET _r and E _p projected to increase by 92 and 69 mm (equivalent to 8.0 and 7.3% increases) due to the elevated evaporative demand of the atmosphere, respectively, E _a from bare soils is projected to reduce by 50 mm (equivalent to a 16.5% decrease) in response to a decrease in rainfall by 46% in the Mediterranean region of Turkey by the 2070s predicted by RCM, and consequently, to decreased soil wetness in the future.     

Determination of cobalt,nickel and iron at trace level in natural water samples by in-column chelation-reversed phase high-performance liquid chromatography

This paper reports the utilization of 4-(2-pyridylazo) resorcinol (PAR) as a chelating reagent for in-column derivatization and the determination of trace Co, Fe, and Ni ions by reversed-phase high-performance liquid chromatography with photodiode array detector. A good separation of Co, Fe, and Ni chelates were achieved by using an Inertsil ODS-3 column and a mobile phase, consisted of methanol–THF–water mixture (50:5:45) containing ammonium acetate buffer (pH 5.0) and PAR. After full optimization, good repeatability of retention times (relative standard deviation (RSD) < 0.05%) and peak areas (RSD < 1.7%) was achieved as well as a good linearity (r ² > 0.9991). The detection limits (S/N = 3), expressed as micrograms per liter, were 0.50 (Co), 9.07 (Fe), and 2.00 (Ni). The applicability and the accuracy of the developed method were estimated by the analysis of spiked water samples and certified reference material BCR 715 wastewater-SRM.     

Integral assessment of climate impact on the transboundary Mesta River flow formation in Bulgaria

The present work considers the section of the Mesta River on Bulgarian territory using the integral method for evaluation of climate and anthropogenic impact on the river flow. The level of this impact is determined by the index K _i (flow module), the coefficient C _i for the deviation of the average annual water volume Q _i from the flow norm Q _o and the index h _i for the deviation of the average annual rainfall volume H _i from the average multi-annual rainfall volume H _o . The dynamics of the average annual flow Q _i at two typical hydrometric stations – Yakoruda and Khadzhidimovo, as well as the dynamics of the average annual rainfall for the Yakoruda station was examined for the period 1955–2003. The data for the considered period 1955–2003 exhibit a decreasing trend of the average annual water volumes dynamics for both stations due to the impact of climate changes in the Mesta River catchment.     

Flow and Pollutant Dispersion in Street Canyons using FLUENT and ADMS-Urban

This paper is devoted to the study of flow within a small building arrangement and pollutant dispersion in street canyons starting from the simplest case of dispersion from a simple traffic source. Flow results from the commercial computational fluid dynamics (CFD) code FLUENT are validated against wind tunnel data (CEDVAL). Dispersion results from FLUENT are analysed using the well-validated atmos pheric dispersion model ADMS-Urban. The k − ε turbulence model and the advection-diffusion (AD) method are used for the CFD simulations. Sensitivity of dispersion results to wind direction within street canyons of aspect ratio equal to 1 is investigated. The analysis shows that the CFD model well reproduces the wind tunnel flow measurements and compares adequately with ADMS-Urban dispersion predictions for a simple traffic source by using a slightly modified k − ε model. It is found that a Schmidt number of 0.4 is the most appropriate number for the simulation of a simple traffic source and in street canyons except for the case when the wind direction is perpendicular to the street canyon axis. For this last case a Schmidt number equal to 0.04 gives the best agreement with ADMS-Urban. Overall the modified k − ε turbulence model may be accurate for the simulation of pollutant dispersion in street canyons provided that an appropriate choice for coefficients in the turbulence model and the Schmidt number in the diffusion model are made.     

The determination of ambient formaldehyde using a dual coil system and an assessment of dominant factors that influence its abundance in Korea

An enhanced dual coil 2,4-dinitrophenylhydrazine (DNPH) derivatization method (dual coil/DNPH) allowed the quantitative determination of formaldehyde (HCHO) in ambient air. In this method, traceable HCHO was collected using a coil sampler connected in series and lacking a long sampling tube. It was then analyzed using liquid chromatography followed by UV detection of the DNPH derivatives. The method is based on the reaction of formaldehyde with DNPH to produce 2,4-dinitrophenylhydrazone. The detection limits (3σ) were 0.10–0.40 ppbv with a precision ranging from 0.84 to 4.09% RSD. The results of dual coil/DNPH and conventional DNPH cartridge methods were generally well correlated: HCHO (dual coil/DNPH) = 0.97 (±0.13) vs. HCHO (DNPH Cartridge) + 0.33 (±0.33), r = 0.82. The dual coil/DNPH method was used to measure gaseous HCHO in the atmosphere of Metropolitan Seoul during the summer 2000 and 2001, and in Gwangju during the fall of 2001 and 2002. The daytime mean concentration of HCHO was 4.52 (±5.69) and 3.21 (±1.27) ppbv in Metropolitan Seoul for 10–12 August 2000 and 29–31 May 2001, respectively, and 1.73 (±0.98), 3.04 (±2.25), 2.70 (±1.70), and 2.01 (±2.28) ppbv in Gwangju City during 22–27 September 2001, 17–24 October 2001, 9–13 October 2002, and 28 October to 2 November 2002, respectively. The HCHO in Seoul from 10–12 August 2000 was mainly the result of photochemical processes, while direct emissions from vehicles and long-range transport of air from China contributed during 29–31 May 2001. During 22–27 September 2001, 17–24 October 2001, and 9–13 October 2002 in Gwangju, the HCHO came primarily from photochemical processes, although some air affected by biomass burning admixed in the late afternoon. The increase in the HCHO concentration on 20 October 2001 and from 28 October to 2 November 2002 was attributed mainly to direct emissions from biomass burning in farmland near the measurement site.     

Risk Assessment of Organic Pesticides Pollution in Surface Water of Hangzhou

Advances in research on pollution of organic pesticides (OPs) in surface water, pollution survey and risk assessments of organochlorine pesticides (OCPs) and organophosphorus pesticides (OPPs) of surface water in Hangzhou are conducted. Total concentrations of dichloro-diphenyl-trichloroethane (DDT) and hexachloride-benzene (HCH) in surface water were observed to be 0–0.270 μg/L and 0–0.00625 μg/L respectively. DDE, as a metabolite of DDT and many species of OPP_S were determined in some samples of surface water. Parathion, the main pollutant among OPPs in surface water of Hangzhou, was observed to be 0–0.445 μg/L. Based on these experimental results, health risk assessments on the organic pollution are developed. It is observed that the total risk “R ^T” at present time of surface water in Hangzhou is mainly contributed by organophosphorus pesticides, especially Parathion; HCH and DDT are not the main contaminants; on the contrary, organophosphorous pesticides, especially Parathion, must be of concern at the present time.     

Identification of mangrove water quality by multivariate statistical analysis methods in Pondicherry coast,India

Different multivariate statistical analysis such as, cluster analysis, principal component analysis, and multidimensional scale plot were employed to evaluate the trophic status of water quality for four monitoring stations. The present study was carried out to determine the physicochemical parameters of water and sediment characteristics of Pondicherry mangroves—southeast coast of India, during September 2008–December 2010. Seasonal variations of different parameters investigated were as follows: salinity (10.26–35.20 psu), dissolved oxygen (3.71–5.33 mg/L), pH (7.05–8.36), electrical conductivity (26.41–41.33 ms⁻¹), sulfide (1.98–40.43 mg/L), sediment texture sand (39.54–87.31%), silt (9.89–32.97%), clay (3.06–31.20%), and organic matter (0.94–4.64%). pH, temperature, salinity, sand, silt, clay, and organic matter indicated a correlation at P < 0.01. CA grouped the four seasons in to four groups (pre-monsoon, monsoon, post-monsoon, summer) and the sampling sites in to three groups. PCA identified the spatial and temporal characteristics of trophic stations and showed that the water quality was worse in stations 3 and 4 in the Pondicherry mangroves.     

Seasonal Variation of the Particle Size Distribution of n-Alkanes and Polycyclic Aromatic Hydrocarbons (PAHs) in Urban Aerosol of Guangzhou, China

Seasonal aerosol samples have been collected by Andersen Hi-Vol pumping system equipped with a five stage cascade impactor and a backup filter (size range: 10–7.2 μ m, 7.2–3.0 μ m, 3.0–1.5 μ m, 1.5–0.95 μ m, 0.95–0.49 μ m, ≤0.49 μ m) in the Liwan district, Guangzhou. n-Alkanes were measured using gas chromatography and PAHs were measured using gas chromatography/mass spectrometry analysis. The bimodal log-normal distributions of n-alkanes and semi-volatile PAHs were found, while for non-volatile PAHs that was unimodal, so much as the mode of semi-volatile PAHs was similar with that of the particles. The n-alkanes and PAHs were preferably associated with fine particles. C _max (carbon number maximum) (C₂₂–C₂₆), CPI (carbon preference index) (1.12–1.21), U/R (unresolved to resolved components ratio) (7.42–10.7), wax% (0.9–3.12%) and the diagnostic ratios for PAHs revealed that vehicular emission was the major source of these organic compounds during the study periods, while the contribution of epicuticular waxes emitted by terrestrial plants was minor. CPI₂ (values for petrogenic hydrocarbons), CPI₃ (values for biogenic n-alkanes) and wax% revealed that the natural preferentially accumulated in the larger aerosol while the anthropogenic in the smaller. In addition, the different MMDs (mass median diameters) for n-alkanes and PAHs were observed in different seasons. The MMDs for n-alkanes and PAHs were higher in autumn/winter than those in spring/summer. The seasonal effect was related to the hydrocarbon content in the individual particulate fractions, showing a preferential association of n-alkanes and PAHs with larger particles in the autumn/winter season.     

Analysis of gross alpha, gross beta activities and beryllium-7 concentrations in surface air: their variations and statistical prediction model

Measurement of gross α, gross β activities and cosmogenic beryllium-7 (⁷Be) concentrations were made both daily and weekly during the years 2001–2004 from samples of atmospheric aerosols filtered from the air at Tehran Nuclear Research Center (35 41′ N) and Zahedan (28 29′ N). Weekly aerosol samples collected with the high-volume air samplers on cellulose filters were used to determine the ⁷Be contents of samples, using a semiconductor gamma spectrometer. Airborne dust samples were collected daily on fiber glass filters and used to determine the gross β and gross α activities with automatic beta analyzer and a ZnS(Ag) counter, respectively. In this work, the concentration and meteorological data were used to determine models for gross α, gross β and ⁷Be. The air concentrations of gross β and gross α activities and ⁷Be concentrations displayed lognormal distributions during the study period. Both β and ⁷Be have maximum activity concentrations during warm mid-year months.