Concentrations Of Most Pollutants Research Articles

Relationships among six urban air pollutants and identification of pollution types – A case study of Chinese cities above prefecture level

Urban air pollution is caused by the interplay of urban development and natural conditions, but it's unclear which factor has a greater impact. Studying the link between air pollutants and identifying the types of pollution causes is crucial for understanding the pollution mechanisms and formulating efficient management measures. During the research period from 2015 to 2020, this study analyzed the relationships between six air pollutants, calculated the city capacity (CC) and natural condition (NC) scores of 285 cities with the help of the index system and entropy weight TOPSIS model, and employed Gaussian Mixture Model (GMM) and random forest regression model to identify air pollution types. The results show: During the study period, the concentrations of most pollutants decreased, with SO2 experiencing the largest decline, reflecting the significant effectiveness of China's recent atmospheric pollution control efforts. In terms of spatial distribution, the North China Plain (NCP) and the Loess Plateau (LP) remain focal areas of pollution. The correlation analysis results indicate a significant positive correlation among all air pollutants except O3, underscoring the necessity of coordinated pollution control efforts, but the complexity of O3 pollution should not be overlooked. High-value agglomerations of CC scores calculated by the model are predominantly located in the eastern coastal region, while NC scores exhibit two high-value agglomerations in the north and south. Utilizing the GMM, the 285 cities were classified into three categories, and the random forest regression model was employed to identify them as CC dominate, NC dominate, and intermediate types. This paper proposes a novel approach for categorizing city air pollution types, aiming to tailor prevention measures and foster sustainable urban development.

EFFICIENCY OF WASTEWATER TREATMENT WITH WATER HYACINTH EICHORNIA CRASSIPES

Prevention of pollution of effluents of water bodies and the environment in general, as well as surface water protection from pollution by untreated wastewater are priority tasks facing humanity today. To achieve an optimal solution, it is necessary to use new technologies or an effective combination of existing methods at operating sewage treatment plants. It has been established that a greater amount of wastewater occurs in the warm period of the year, respectively, and the load on treatment facilities increases. As a result of the analysis of data on wastewater composition indicators, it has been concluded that the concentrations of most pollutants increase during the warm period. Therefore, to improve the quality of purified water, it is proposed to use water hyacinth (Eichornia) together with reeds, which is used on operating biological ponds. This will make it possible to carry out additional wastewater treatment effectively, compensating for the lack of efficiency of treatment facilities. The paper presents the results of experimental studies of the higher aquatic plant Eichornii in vitro by helding a model experiment with subsequent implementation at the research object. The adaptability of water hyacinth to reservoir conditions, as well as to coastal and aquatic vegetation, have been studied. The results have proved the possibility of using reeds and Eichornia together at a wastewater treatment plant. The indicators of the qualitative composition of wastewater after treatment meet the requirements of SanPiN 2.1.3684-21.

Phosphogypsum weathering and implications for pollutant discharge into an estuary

Approximately 100 million tons of phosphogypsum were stockpiled onto marsh soils of the Tinto River estuary (Huelva, SW Spain). This study focuses on the hydraulic response of the phosphogypsum stack to the different weathering agents, as well as on the hydrochemical behavior of highly acidic and polluted effluents from its leaching during different hydrological conditions. To address these issues, a CTD-Diver was installed in a bore-hole within a phosphogypsum stack profile, which recorded the variations in the water-table of the stack, and edge outflows samples were collected around the perimeter of the stack during four sampling periods in different seasons. During dry periods, the water-table of the stack remains almost static and is controlled only by the tide oscillations. However, during rainy events this water-level rapidly increases up to 20 cm and subsequently decreases, defining peaks that coincide with the rainfalls. Having a hydraulic connection to the sea and groundwater flow in conduits, the phosphogypsum stack behaves as an anthropogenic karstic-coastal aquifer. Regarding the hydrochemical behavior of the edge outflows, the concentrations of most pollutants (e.g., PO4, Al, As, Cd or U) showed a slight decrease from the dry-warm to the rainy period. These leachates releases high concentrations of contaminants to the estuary, e.g., PO4, As and U (average values of 5000, 6.9 and 3.0 t/yr, respectively). The results obtained in this study could contribute to the development of effective treatment systems for leachates from phosphogypsum stack of Huelva and to minimize their impact on the surrounding estuarine environment.

POPs concentrations in cetaceans stranded along the agricultural coastline of SE Spain show lower burdens of industrial pollutants in comparison to other Mediterranean cetaceans

Despite the Mediterranean Sea being one of the world's marine biodiversity hotspots, it is a hotspot of various environmental pollutants. This sea holds eight cetacean with resident populations whose numbers are considered to decline in the last decades and which are particularly susceptible to POPs bioaccumulation due to their peculiar characteristics. In this work, we studied blubber concentration of various OCPs and several PCBs and PBDEs congeners in cetaceans stranded in the northern coast of the Gulf of Vera (Region of Murcia, SE Spain) between 2011 and 2018. Most compounds and congeners were above the limit of detection in most samples, although some pesticides like endosulfan stereoisomers or endrin were never detected. DDT and its metabolites, PCBs and metoxychlor appear as the dominant compounds while PBDEs shows concentrations of lower magnitude. Striped dolphin was the species accounting for higher concentrations of most pollutants. There were differences in concentrations and profiles between species which could be partially explained by differences on diet and feeding behavior. We also observed differences based on life history parameters suggesting maternal transfer for most POPs, in accordance with other works. DDE/ ΣDDT ratio suggest no recent exposure to these pesticides. Despite showing lower concentrations than some previous works, PCB concentrations accounted for higher total TEQ than many studies. According to toxicity thresholds in the literature, we cannot guarantee the absence of health consequences on populations studied, especially for those caused by PCBs. These findings are of major importance considering the relevance of the study area in the conservation of Mediterranean cetaceans.

Effects of chronic exposure to ambient air pollutants, demographic, and socioeconomic factors on COVID-19 morbidity: The Israeli case study

BackgroundRecent studies conducted in several OECD countries have shown that chronic exposure to elevated levels of air pollutants (especially PM2.5, PM10 and NOx), might negatively impact COVID-19 morbidity and mortality rates. The aim of this study was to examine the association between chronic exposure to air pollution in Israeli cities and towns, their demographic and socioeconomic status, and COVID-19 morbidity, during the three local morbidity waves. MethodsWe examined the associations between: (a) annual average concentrations of NOx, CO, PM10, PM2.5 and SO2 in 2016–2019, and demographic and socioeconomic parameters, and (b) COVID-19 positive cases in 279 Israeli cities and towns, in the four state-wide morbidity peaks: 1st wave peak: March 31st, 2020; 2nd wave peaks: July 24th and September 27th, 2020, and the 3rd wave peak: January 17th, 2021, which occurred after the beginning of the nationwide vaccination campaign. These associations were calculated using both Spearman correlations and multivariate linear regressions. ResultsWe found statistically significant positive correlations between the concentrations of most pollutants in 2016–19 and COVID-19 morbidity rate at the first three timepoints but not the 4th (January 17th, 2021). Population density and city/town total population were also positively associated with the COVID-19 morbidity rates at these three timepoints, but not the 4th, in which socioeconomic parameters were more dominant - we found a statistically significant negative correlation between socioeconomic cluster and COVID-19 morbidity. In addition, all multivariate models including PM2.5 concentrations were statistically significant, and PM2.5 concentrations were positively associated with the COVID-19 morbidity rates in all models. ConclusionsWe found a nationwide association between population chronic exposure to five main air pollutants in Israeli cities and towns, and COVID-19 morbidity rates during two of the three morbidity waves experienced in Israel. The widespread morbidity that was related to socioeconomic factors during the 3rd wave, emphasizes the need for special attention to morbidity prevention in socioeconomically vulnerable populations and especially in large household communities. Nevertheless, this ecological study has several limitations, such as the inability to draw conclusions about causality or mechanisms of action. The growing body of evidence, regarding association between exacerbated COVID-19 morbidity and mortality rates and long-term chronic exposure to elevated concentrations of air pollutants should serve as a wake-up call to policy makers regarding the urgent need to reduce air pollution and its harmful effects.

Modeling the air pollutant concentration near a cement plant co-processing wastes.

In this study, for the first time, we conducted full life-cycle studies on pollutants in a cement plant co-processing hazardous waste (HW) via the combined use of thermodynamic equilibrium calculations and the American Meteorological Society/Environmental Protection Regulatory Model. Results showed that the potential toxic elements (PTEs) can be classified into three categories: (1) non-volatized elements, Co; (2) semi-volatized elements, Cr and Ni; and (3) volatized elements, Cd, Pb and As. Besides, the spatial distributions of pollutants were strongly influenced by the prevalent wind direction and the size of the particulate matter they were absorbed on. The highest concentrations of most pollutants tended to be centralized at a distance in the range of 400 to 800 m away from the cement plant. Finally, validated results indicated that there is good agreement between the simulated and observed concentrations in this study. These findings can facilitate and assist local government authorities and policy makers with the management of urban air quality.

Spatiotemporal variations of air pollutants in western China and their relationship to meteorological factors and emission sources

We have carried out a comprehensive analysis of six air pollutants (particles with an aerodynamic diameter less than 2.5 μm (PM2.5) and less than 10 μm (PM10), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3)) in western China, including the spatiotemporal characteristics of air pollutants, their relationship with meteorological factors and emission sources, and the efficiency of emission control strategies for the region. Based hourly observations at 23 sites in western China from June 2016 to May 2017, concentrations of most pollutants were higher outside the Tibetan Plateau, lowest in summer and highest in winter, the exception being O3. This was partially because meteorological conditions in winter were found to the most unfavorable to pollutant dispersion and dilution than other seasons. Pollutant concentrations at most sites were correlated with the residential emissions which were higher in winter, but anti-correlated with the industrial emissions which were lower during the winter holiday period. The Weather Research and Forecasting with Chemistry (WRF-Chem) simulations of four pollution control strategies indicated that reduction of residential emissions is crucial to alleviate PM2.5, PM10, and CO pollution in western China, although reduction of industrial and transport emissions can reduce SO2 and NO2, respectively. Since PM2.5 and PM10 were also found to be the species most and next frequently responsible for extremely serious pollution in western China, respectively, we recommend pollution control regulations that target residential emissions.

Assessing how spatial variations of land use pattern affect water quality across a typical urbanized watershed in Beijing, China

Understanding the relationship between land use patterns and water quality in urbanized areas can provide insight into urban water quality management. In this study, a self-organizing map (SOM) and a linear mixed effects (LME) model were applied to explore the spatiotemporal patterns of nutrients and their relationship with land use characteristics in the highly urbanized Beiyun River watershed. The SOM classified 324 sampling data from 2014 to 2015 at 25 typical river sampling sites into nine clusters, with differences in land use patterns and seasonal (rainy and dry seasons) distributions. In the urbanized upstream reach of the river, concentrations of most pollutants were low, while in downstream sites the concentrations were higher for these pollution parameters. Nitrate-N (NO3−-N), however, exhibited the opposite pattern, probably due to the sources of pollutants and biochemical processes. The explanatory ability of the LME model in the established urbanized area and newly developed area in the upstream portion of the watershed was much better than in the downstream area, probably due to the influence of upstream nutrient contributions and the point source inputs in the downstream area. These statistical results indicated that sewage disposal and the main urbanized land use types were the most important drivers of river contamination. Forest land positively or negatively influenced river water quality depending on its spatial location as well as the water quality indicators. Therefore, sewage disposal as well as spatial non-stationarity of land-use impacts should be taken into consideration to reduce water pollution in the Beiyun River watershed.

Sulfate reduction processes in salt marshes affected by phosphogypsum: Geochemical influences on contaminant mobility

Sulfate reduction and its associated contaminant immobilization in marsh soils supporting a phosphogypsum stack was examined by pore-water and solid analysis, selective extractions, microscopy and sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy. The negative impact of this stack on estuarine environments is a concerning problem. In the weathering profile, total concentrations of most pollutants increase with depth; instead, dissolved contents in pore-waters increase to middle of the saturated zone but then decrease drastically down to reach the marsh due to sulfide precipitation. Excess of acid-volatile sulfide plus pyritic sulfur over metals bound to the oxidizable fraction indicates that sulfide precipitation is the main mechanism responsible for metal removal in the marsh. Thus, abundant pyrite occurred as framboidal grains, in addition to other minor sulfides of As, Zn and Cu as isolated particles. Moreover, high contents of elemental sulfur were found, which suggest partial sulfide oxidation, but marsh may have capacity to buffer potential release of contaminants. The importance of sulfur species was quantitatively confirmed by XANES, which also supports the accuracy of selective extraction schemes. Accordingly, managing pore-water quality through organic carbon-rich amendments over phosphogypsum stacks could lead to a decrease in contaminant loading of leakages resulting from weathering.

Biomonitoring of chemicals in biota of two wetland protected areas exposed to different levels of environmental impact: results of the "PREVIENI" project.

The PREVIENI project (funded by the Ministry of Environment) investigated the exposure to endocrine disrupters in samples of human population and environmental biota in Italy. The environmental biomonitoring considered two Italian WWF Oasis, with the aim to compare the presence and effects of endocrine disruptors in organisms from two protected natural areas, respectively, upstream and downstream a chemical emission site. Chemical analysis of pollutants' tissue levels was made on tissues from earthworm, barbell, trout, and coot, selected as bioindicator organisms. The contaminants considered were as follows: the perfluorinated compounds perfuoroctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), polychlorinated biphenyls (PCBs 58 congeners), polybrominated diphenyl ethers (PBDEs, 13 congeners), polycyclic aromatic hydrocarbons (PAHs, 16 compounds), toxic trace elements, the phthalate di-2-ethylexyl phthalate (DEHP) and its primary metabolite, bisphenol A, synthetic musk compounds (musk xylene, musk ketone, tonalide, and galaxolide), and p-nonylphenol. The analyses showed low concentrations of most pollutants in all species from both areas, compared to available literature; noticeable exceptions were the increases of DEHP's primary metabolite, PBDE, PAHs, Hg, and Pb in barbells, and of PCB and Cd in earthworms from the downstream area. The results showed the presence of endocrine disruptors, including those considered as "non-persistent," in bioindicators from protected areas, albeit at low levels. The results provide a contribution to the evaluation of reference values in biota from Mediterranean Europe and support the relevance of monitoring exposure to pollutants, in particular for freshwater environment, also in protected areas.

Spatial variation of VOCs and inorganic pollutants in a university building

Indoor concentrations of 34 volatile organic compounds (VOCs), sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) were measured at 32 sampling points in classes, offices and hallways of the Environmental Engineering Department (ENVE) in the Middle East Technical University (METU) in Ankara. Outdoor samples were also collected around the department during the sampling campaigns. Two passive sampling campaigns, one in summer and the other one in winter, were conducted. Indoor concentrations of most pollutants were higher than their outdoor concentrations owing to the presence of indoor sources. The notable exception to this general pattern is O3. The average indoor/outdoor concentration ratio (I/O) was 10.9 in winter and 3.7 in summer. For most of the VOCs, the winter concentrations were higher than their summer concentrations due to more effective ventilation of the building and variation of emissions during summer months. Compounds with higher concentrations in the summer samples were the ones that were strongly affected by solvent evaporation in laboratories.

Removal Efficiencies of a Bioretention System for Trace Metals, PCBs, PAHs, and Dioxins in a Semiarid Environment

AbstractThe negative effects of urbanization on water quantity and quality and the performance of bioretention for treating runoff and reducing concentrations and loads of sediment, nutrients, pathogens, and selected trace metals have been well documented. This study evaluated the efficiency of a bioretention system installed in semiarid Daly City, California, for a large suite of pollutants, including some that have been rarely evaluated in such systems. Stormwater flow and pollutant concentrations were measured before and after the construction of a bioretention system consisting of rain gardens and a bioswale. After installation, concentrations of most pollutants were reduced and met water quality guidelines. Water quality improvements (concentration or load reductions) were demonstrated for total Hg, polychlorinated biphenols (PCBs) and dioxins ranging between 18 and 100%, and a suite of more conventional pollutants [SSC, Cd, Cu, Ni, Pb, Zn, and polycyclic aromatic hydrocarbons (PAHs)] ranging between...

Study of a large scale powdered activated carbon pilot: Removals of a wide range of emerging and priority micropollutants from wastewater treatment plant effluents

The efficacy of a fluidized powdered activated carbon (PAC) pilot (CarboPlus®) was studied in both nominal (total nitrification + post denitrification) and degraded (partial nitrification + no denitrification) configuration of the Seine Centre WWTP (Colombes, France). In addition to conventional wastewater parameters 54 pharmaceuticals and hormones (PhPHs) and 59 other emerging pollutants were monitored in influents and effluents of the pilot. Thus, the impacts of the WWTP configuration, the process operation and the physico-chemical properties of the studied compounds were assessed in this article.Among the 26 PhPHs quantified in nominal WWTP configuration influents, 8 have high dissolved concentrations (>100 ng/L), 11 have an intermediary concentration (10–100 ng/L) and 7 are quantified below 10 ng/L. Sulfamethoxazole is predominant (about 30% of the sum of the PhPHs). Overall, 6 PhPHs are poorly to moderately removed (<60%), such as ibuprofen, paracetamol or estrone, while 9 are very well removed (>80%), i.e. beta blockers, carbamazepine or trimethoprim, and 11 are well eliminated (60–80%), i.e. diclofenac, naproxen or sulfamethoxazole.In degraded WWTP configuration, higher levels of organic matter and higher concentrations of most pollutants are observed. Consequently, most PhPHs are substantially less removed in percentages but the removed flux is higher. Thus, the PAC dose required to achieve a given removal percentage is higher in degraded WWTP configuration. For the other micropollutants (34 quantified), artificial sweeteners and phthalates are found at particularly high concentrations in degraded WWTP configuration influents, up to μg/L range. Only pesticides, bisphenol A and parabens are largely eliminated (50–95%), while perfluorinated acids, PAHs, triclosan and sweeteners are not or weakly removed (<50%). The remaining compounds exhibit a very variable fate from campaign to campaign.The fresh PAC dose was identified as the most influencing operation parameter and is strongly correlated to performances. Charge and hydrophobicity of compounds have been recognized as crucial for the micropollutant adsorption on PAC, as well as the molecular weight. Finally, a PAC dose of 10 mg/L allows an average removal of 72–80% of the sum of the PhPHs in nominal WWTP configuration. The comparaison of the results with those from the scarce other studies tends to indicate that an extrapolation of them to different PAC processes and to other WWTPs could be possible and relevant, taking into account the differences of water quality from WWTP to WWTP.

Transport of persistent organic pollutants across the human placenta

Prenatal life is the most sensitive stage of human development to environmental pollutants. Early exposure to persistent organic pollutants (POPs) may increase the risk of adverse health effects during childhood. The mechanisms of transference of POPs during pregnancy are still not well understood. The present study is aimed to investigate the transfer of POPs between mother and fetus. The concentrations of 14 organochlorine pesticides, 7 polychlorinated biphenyls (PCBs) and 14 polybromodiphenyl ether (PBDEs) congeners have been measured in 308 maternal serum samples, their respective umbilical cords and 50 placental tissues from a mother–infant cohort representative of Spanish general population. In general, the adjusted lipid-basis concentrations were higher in maternal serum than in cord serum and placenta. The concentrations of most pollutants between maternal serum and cord serum and between maternal serum and placenta were significantly correlated. These distributions were consistent with a predominant maternal source that transfers the pollutants into the placenta and the fetus. However, this distribution did not correspond to passive diffusion of these compounds between these tissues according to lipid content. The compounds more readily metabolized were higher in newborns, which suggest that differences in metabolic capabilities may be responsible of the observed variations in POP distributions between mother and newborns. Prenatal exposure to 4,4′-DDT and some PBDEs such as BDE 99 and BDE 209 is much higher than it could be anticipated from the composition of maternal serum. POP exposure assessment studies of newborns may overlook the effects of some of these pollutants if they only consider maternal determinations.

Malondialdehyde in exhaled breath condensate and urine as a biomarker of air pollution induced oxidative stress

Underlying mechanisms by which air pollutants adversely affect human health remain poorly understood. Oxidative stress has been considered as a potential mechanism that may promote lipid peroxidation by reactive oxygen species, leading to the formation of malondialdehyde (MDA) that is excreted in biofluids (e.g., urine and exhaled breath condensate (EBC)). A panel study was conducted to examine whether concentrations of MDA in EBC and urine were associated, respectively, with changes in air pollution levels brought by the Beijing Olympic air pollution control measures. EBC and urine samples from 125 healthy adults were collected twice in each of the pre-, during-, and post-Olympic periods. Period-specific means of MDA and changes in MDA levels associated with increases in 24-h average pollutant concentrations were estimated using linear mixed-effects models. From the pre- to the during-Olympic period, when concentrations of most pollutants decreased, EBC MDA and urinary MDA significantly decreased by 24% (P<0.0001) and 28% (P=0.0002), respectively. From the during-Olympic to the post-Olympic period, when concentrations of most pollutants increased, EBC MDA and urinary MDA increased by 28% (P=0.094) and 55% (P=0.046), respectively. Furthermore, the largest increases in EBC MDA associated with one interquartile range (IQR) increases in all pollutants but ozone ranged from 10% (95% CI: 2%, 18%) to 19% (95% CI: 14%, 25%). The largest increases in urinary MDA associated with IQR increases in pollutant concentration ranged from 9% (95%: 0.3%, 19%) to 15% (95% CI: 3%, 28%). These findings support the utility of EBC MDA as a biomarker of oxidative stress in the respiratory tract and urinary MDA as a biomarker of systemic oxidative stress in relation to air pollution exposure in healthy young adults. Both EBC and urine samples can be collected noninvasively in the general population.

System design and treatment efficiency of a surface flow constructed wetland receiving runoff impacted stream water

This study reported the efficiency of a free water surface flow constructed wetland (CW) system that receives runoff impacted stream water from a forested and agricultural watershed. Investigations were conducted to examine the potential effect of hydraulic fluctuations on the CW as a result of storm events and the changes in water quality along the flow path of the CW. Based on the results, the incoming pollutant concentrations were increased during storm events and greater at the near end of the storm than at the initial time of storm. A similar trend was observed to the concentrations exiting the CW due to the wetland being a relatively small percentage of the watershed (<0.1%) that allowed delays in runoff time during storm events. The concentrations of most pollutants were significantly reduced (p < 0.05) except for nitrate (p = 0.5). Overall, this study suggests that the design of the system could feasibly function for the retention of most pollutants during storm events as the actual water quality of the outflow was significantly better by 21-71% than the inflow and the levels of pollutants were reduced to appreciable levels.

Feasibility of Assessing Public Health Impacts of Air Pollution Reduction Programs on a Local Scale: New Haven Case Study

BackgroundNew approaches to link health surveillance data with environmental and population exposure information are needed to examine the health benefits of risk management decisions.ObjectiveWe examined the feasibility of conducting a local assessment of the public health impacts of cumulative air pollution reduction activities from federal, state, local, and voluntary actions in the City of New Haven, Connecticut (USA).MethodsUsing a hybrid modeling approach that combines regional and local-scale air quality data, we estimated ambient concentrations for multiple air pollutants [e.g., PM2.5 (particulate matter ≤ 2.5 μm in aerodynamic diameter), NOx (nitrogen oxides)] for baseline year 2001 and projected emissions for 2010, 2020, and 2030. We assessed the feasibility of detecting health improvements in relation to reductions in air pollution for 26 different pollutant–health outcome linkages using both sample size and exploratory epidemiological simulations to further inform decision-making needs.ResultsModel projections suggested decreases (~ 10–60%) in pollutant concentrations, mainly attributable to decreases in pollutants from local sources between 2001 and 2010. Models indicated considerable spatial variability in the concentrations of most pollutants. Sample size analyses supported the feasibility of identifying linkages between reductions in NOx and improvements in all-cause mortality, prevalence of asthma in children and adults, and cardiovascular and respiratory hospitalizations.ConclusionSubstantial reductions in air pollution (e.g., ~ 60% for NOx) are needed to detect health impacts of environmental actions using traditional epidemiological study designs in small communities like New Haven. In contrast, exploratory epidemiological simulations suggest that it may be possible to demonstrate the health impacts of PM reductions by predicting intraurban pollution gradients within New Haven using coupled models.

Indoor air pollution levels in public buildings in Thailand and exposure assessment

Levels of pollutants including PM2.5 and PM2.5 composition (black carbon and water soluble ions), SO(2), NO(2), CO, CO(2), and BTEX (benzene, toluene, ethylbenzene, xylene) were monitored for indoor and outdoor air at a university campus and a shopping center, both located in the Northern suburb of Bangkok. Sampling was done during December 2005-February 2006 on both weekdays and weekends. At the university, indoor monitoring was done in two different air conditioned classrooms which shows the I/O ratios for all pollutants to be below 0.5-0.8 during the weekends. However, on weekdays the ratios for CO(2) and most detected BTEX were above 1.0. The concept of classroom occupancy was defined using a function of the student number in a lecture hour and the number of lecture hours per day. Classroom 2, which had a higher occupancy than classroom 1, was characterized by higher concentrations of most pollutants. PM2.5 was an exception and was higher in classroom 1 (37 microg/m(3), weekdays) as compared to classroom 2 (26 microg/m(3), weekdays) which was likely linked to the dust resuspension from the carpeted floor in the former. Monitoring was also done in the shopping mall at three different sites. Indoor pollutants levels and the I/O ratios at the shopping mall were higher than at the university. Levels of all pollutants measured at the car park, except for toluene and CO(2), were the highest. I/O ratios of the pollutants at the mall were above 1.0, which indicates the relatively higher influence of the indoor sources. However, the black carbon content in PM2.5 outdoor is higher than indoor, which suggest the important contribution from outdoor combustion sources such as the traffic. Major sources of outdoor air pollution in the areas were briefly discussed. Exposure modeling was applied using the time activity and measured pollutant concentrations to assess the exposure of different groups of people in the study areas. High exposure to PM2.5, especially for the people working in the mall, should be of health effect concern.

Organohalogenated pollutants in human serum from Iassy, Romania and their relation with age and gender

Human serum samples ( n = 142) from Iassy county (Eastern Romania) collected in 2005 were analyzed for p, p′-DDT and its metabolites, hexachlorobenzene, hexachlorocyclohexane (HCH) isomers, chlordane and metabolites and 14 polychlorinated biphenyl (PCB) congeners. In all samples, p, p′ -DDE (principal metabolite of p, p′ -DDT) and β-HCH (most persistent HCH isomer) were the most abundant organochlorine pesticides (OCPs) with median concentrations of 1975 and 923 ng/g lipid weight (lw), respectively. Hexachlorobenzene and p, p′ -DDT were also detected in all samples, but at a lower median concentration of 30 and 340 ng/g lw, respectively. The large variation of the ratio p, p′ -DDT/ p, p′ -DDE (range between 0.02 and 0.80) suggests various degrees of exposure to DDT, including recent exposure, at least to some subgroups of the population. Chlordane and its metabolites were in most cases close to the limit of quantification suggesting a very low use of chlordane formulations in Eastern Romania. Unexpectedly, PCBs were present in all samples at sometimes considerable levels (up to 4970 ng/g lw for sum of 14 PCB congeners) indicating a higher exposure of the Romanian population than previously reported. The PCB profile consisted of persistent congeners such as 138, 153, 170 and 180 which contributed for approximately 75% to the sum PCBs. Concentrations of most pollutants correlated significantly with age ( r > 0.86, p < 0.01). Except for p, p′ -DDT and γ-HCH, the mean levels of OCPs in females were statistically higher than in males, while, except for octa-CBs, no gender differences were found for PCBs. Levels of p, p′ -DDE, penta-CBs, hexa-CBs and hepta-CBs were significantly higher in individuals with a rural main residence. In a pooled serum sample, 6 polybrominated diphenyl ether (PBDE) congeners were measured at a level of 1.04 ng/g lw. Compared to results available from Central and Eastern European countries, human serum samples from Romania contained higher levels of contamination. This emphasizes that an extensive and rigorous program for the monitoring of OCPs and PCBs in Romanian population is highly needed in the light of possible adverse health effects acknowledged for these pollutants.

Treatment of tar pond sludge in a circulating fluidized bed combustor

A series of tests to burn mixtures of tar pond sludge and coal was carried out using a mini-circulating fluidized bed combustor (mini-CFBC). During the tests, carbon dioxide, oxygen, carbon monoxide, sulfur dioxide, and nitrogen oxides in the flue gas were monitored continuously. Stack gas sampling was carried out for hydrochloric acid, metals, particulate matter, volatile organic compounds (VOCs), total hydrocarbons, semivolatile organic compounds (SVOCs), dioxins and furans (PCDD/Fs), and polychlorinated biphenyls (PCBs). Results showed that hydrochloric acid, mercury, particulate matter, PCDD/F, and metal concentrations were all below both the current limits and the gas-release limits to be implemented in 2008 in Canada. The new 2008 emissions limits will reduce the maximum allowable concentrations of most pollutants by half. Thus, the maximum concentration for particulate matter will be 5 mg/m3 (from the current maximum concentration of 10 mg/m3);the maximum concentration for hydrochloric acid will be 5 mg/m3 (from 10 mg/m3); and the-maximum concentration for dioxins and furans will be 0.032 ng/m toxic equivalent (from 0.08 ng/mcurrently). Sulfur capture efficiency was 89–91 percent. The percentage of fuel nitrogen converted to nitrogen oxides was of the order of 4.7 to 6.1, which is significantly lower than that of conventional pulverized coal-fired boilers and well within the normal range for fluidized bed combustors (FBCs). PCB and polycyclic aromatic hydrocarbon (PAH) emissions levels were comparable or lower than levels reported in the literature for industrial-scale FBCs. VOC concentrations were low except for benzene, for which the concentration was higher than that reported for pulverized coal-fired utility boilers. In addition, carbon monoxide concentration was high at 1,200 to 2,200 parts per million. However, these carbon monoxide concentrations are typical of the mini-CFBC firing coal. The trials showed that for 10 percent by weight tar pond sludge mixed with 90 percent by weight coal, the combustion was both stable and efficient. The tests demonstrated that CFBC technology is an environmentally sound option for eliminating tar pond waste sludge. © 2005 Wiley Periodicals, Inc.