Sampling errors in the study of acid gases and anion species in atmospheric aerosols

Atmospheric acid aerosols were sampled by two annular denuder systems (ADS) and a micro-orifice uniform deposit impactor (MOUDI) at a traffic site in central Taiwan. Theoretical analysis showed that the relative artifact for HNO₃ gas sampling was about 0.53 when the initial HNO₃ concentration was under 0.2 µg/m³ and should be considered carefully. The concentrations of gaseous acid at the traffic sampling site were higher than those in the other study. The size distributions of acid aerosols were unimodal for Cl^-, NO₂^-, and NO₃^-, and bimodal for SO₄^2-. The dominant acid ions in particles less than 18 µm were SO₄^2-, NO₃^-, NO₂^- and Cl^-.     

Differential water quality in confined and free-flowing water bodies, Lebanon

Integrated management of water resources is a major critical issue to be addressed in combating water stress in developing countries, such as Lebanon. At present, surface water is not properly used in Lebanon. This emphasises the importance of assessing surface water quality as a projected means to increase water availability. This study involves two different water bodies, the freely flowing Nahr-Ibrahin River and the Qaraaoun Reservoir, an impoundment of the Litani River. Water samples were collected from 16 chosen sites of each water body at four different dates during the dry season. Measured water parameters were temperature, pH, conductivity, BOD, HCO₃^-, Ca²⁺, Mg²⁺, Cl^-, SO₄^2-, PO₄^3-, NO_{3-, NH3, Fe, Mn, Zn, Pb, and Cd. Statistical analysis of the data revealed significant differences in water quality. The differences could be attributed to the fact that whereas the Qaraaoun reservoir is receiving domestic waste discharges that lead to an increase in the CO2 content and a pH decrease, the Nahr-Ibrahim River is influenced by agricultural runoffs and industrial discharges that increase the pH values. Consequently, the water metal speciation of the two water bodies was different. The study indicated that the differential quality of the two water bodies could be attributed to the nature of the water resources and exposure to contaminants. This is crucial in recommending intervention studies to protect quality and promote the role of surface water use, as an integrated component of water management in Lebanon.}     

Influence of meteorological factors on air pollution concentration for a coastal region in India

A long-term study of measurement of concentration of NO_x, SO₂ and TSP pollutants have been done in a port and harbour region in India. Monthly measurements of gaseous and particulate pollutants were made at six monitoring stations from January 1997 to December 2000. Meteorological data was also simultaneously collected. In this study, the relationship between monitored ambient air quality data and meteorological factors, such as wind speed, temperature, is statistically analysed, using the SPSS package. The monthly mean concentrations of NO_x, SO₂ and TSP were in the range of 19.5–59.0 μg/m3, 8.6–51.3 μg/m3 and 88.2–199.3 μg/m3, respectively. The results show that TSP is strongly correlated with NO_x and SO₂ with a correlation coefficient of 0.83 and 0.82, respectively. The correlation coefficients for TSP, NO_x, and SO₂ with wind are –0.78, –0.78, and –0.88, respectively.     

Monitoring of phytoplankton biomass and nutrients in a polluted stream

The spatial and temporal variations in the concentrations of nutrients (NH₄⁺, NO₂⁻, PO₄³⁻, SiO₄⁻) and chlorophyll a were monitored simultaneously in a slow-flowing watercourse (Saricay Stream, Turkey), which runs in a rural–urban gradient. Chlorophyll a concentrations ranged between 0.044 μg l^-1 and 206.15 μg l^-1 and, in general, the higher concentrations of chlorophyll a and ammonium were measured downstream of the raw sewage outfalls. Nitrate was by far the most abundant form of inorganic nitrogen, and its concentration ranged between 411.71 μM and 87.25 μM. Silicates and phosphates were always potentially limiting to biomass relative to nitrogen. Agricultural run-off and point discharges from urban sources greatly affected the chemical composition of the water in the Saricay Stream and drove the system towards eutrophication.     

Air pollution at the Bily Kriz mountains in the Czech Republic

An evaluation of air pollution at the Bily Kriz mountains in the Czech Republic is given. Annual daily concentrations of sulphur dioxide (SO₂), nitrogen oxides (NO_x), particulate matter of size 10 mm (PM₁₀) and ozone (O₃) measured in the years 1994–2000 are presented. Air pollution at Bily Kriz is assessed with the reference to the European Union Directives and the standards adopted by the Czech Republic. In general, the concentrations of air pollutants were lower in 1996 for ozone and decreased for SO₂, NO_x and PM₁₀ from 1994. The daily values of SO₂ and PM₁₀ exceeded the European Union limits in approximately 0.0% and 5.5% of cases, respectively. The values of ozone exceeded the limits for the considered period.     

Temporal variability of the precipitation chemistry in the forest area of Istanbul, Turkey

The chemical compositions of precipitation show temporal and spatial variability. It is important to determine the temporal variation of the chemical composition of rainwater for estimating the impacts of pollutants on the forest. In this study, the 34 rainwater samples are collected using, for the first time, the specially designed collectors between November 1997 and March 1998 in Istanbul University, Faculty of Forestry at Bahcekoy, Istanbul in Belgrad Forest. The sequentially collected samples are analysed for major ions concentrations and pH estimations. The pH values for all samples vary from 5.1-7.6. In general, the concentration of all rainwater samples decrease with time. Furthermore, it is estimated that the average Ca²⁺) (1943.0 µeql^-1) and SO₄^2- (887.3 µeql^-1) concentrations are extremely high during the first ten minutes of the precipitation event.     

A structural decomposition analysis of air pollution from fossil fuel combustion in India

During the last decade, there has been worldwide concern with global climate change, which has been induced by greenhouse gases (GHGs) due to the use of fossil fuels. The CO₂ emissions from fossil fuel combustion have been identified as the single most significant source of GHG emissions into the atmosphere. Realising the need to control and regulate emissions of pollutants, the objective of the present study estimates the trend of CO₂, SO₂ and NO_x between the periods 1991-92 and 1996-97. An input-output structural decomposition analysis approach is used to determine their sources of change. It also provides a set of alternative scenarios for the year 2001-2 and 2006-7. The sources of changes in the amount of CO₂, SO₂ and NO_x emissions are categorised into four factors: the ecoefficiency, the structure of production, the structure of demand, and the volume of demand. Results indicate that the electricity sector contributes more towards direct, as well as indirect, emission coefficients. The petroleum product sector also contributes more in this respect. The dominant role is played by the structure of demand and the volume of demand.     

Sustainable urban transportation: impact of CO2 mitigation strategies on local pollutants

This paper assesses CO₂ mitigation strategies in Delhi and Mumbai against the dynamics of local pollutants. After testing against techno-economic feasibility, compressed natural gas (CNG) technology, four-stroke two-wheelers and battery-operated vehicles (BOV) were selected as candidate options for Mumbai and Delhi. Multiple constrained optimisation for finding out the optimal mix of vehicles to meet the travel demand under the business-as-usual scenario for the period of CO₂ mitigation targets of 5, 10, 15, 20, 25% resulted in reduced stock of diesel and petrol vehicles, with the reduction spanning over different points of the above time period. In the case of Mumbai, battery-operated three-wheelers dominated the vehicular mix, with the share of CNG vehicles remaining at a standard level. CO₂ reduction targets did not influence the CNG option significantly. CO₂ mitigation influenced the dynamics of local pollutants considerably in both Delhi and Mumbai. In Delhi, TSP and SOx reduction levels against the CO₂ mitigation target were found to be significant. In Mumbai, the percentage reduction in local pollution (TSP in particular) was higher than the target CO₂ reduction. Local pollutants other than TSP and SO_x showed an increasing trend against the CO₂ mitigation strategies in Delhi. In the case of Mumbai, all non-target pollutants showed a falling trend against the CO₂ mitigation strategies, though insignificantly for pollutants other than TSP and SO_x.     

Air pollution and the influence of sources on Paulinia (Brazil) and surroundings

The air quality in the industrial area and surroundings of the city of Paulinia (state of Sao Paulo, Brazil) has been investigated by analysing the concentration of air pollutants (SO₂, PM₁₀, NO, NO₂, CO and ozone) and identifying the main sources of air pollution. A mobile pollutant monitoring unit was used to collect the data at five different sites from November 2000 to July 2002. Critical pollutants were determined based on air quality standards, and sources were identified by principal component analysis. Photochemical reactions play an important role in Paulinia's air pollution: three out of five monitored sites showed levels exceeding the standard air quality of ozone. SO₂ and PM₁₀ appeared as pollutants deserving special attention. All the monitored sites showed vehicles and industrial plants (which release SO₂) to be significant sources of pollution. Depending on the location, ozone was related mainly with vehicular or industrial sources.     

Studies of air quality predictors based on neural networks

In recent years, urban air pollution has emerged as an acute problem because of its negative effect on health and living conditions. Regional air quality problems, in general, are linked to violations of specified air quality standards. The current study aims to find neural network based air quality predictors, which can work with a limited number of datasets and are robust enough to handle data with noise and errors. A number of available variations of neural network models, such as the Recurrent Network Model (RNM), the Change Point Detection Model with RNM (CPDM), the Sequential Network Construction Model (SNCM), the Self Organising Feature Model (SOFM), and the Moving Window Model (MWM), were implemented using MATLAB software for predicting air quality. Developed models were run to simulate and forecast based on the annual average data for 15 years from 1985 to 1999 for seven parameters, viz. VOC, NO_x, CO, SO₂, PM₁₀, PM_2.5 and NH₃ for one county of California, USA. The models were fitted with first nine years of data to predict data for remaining six years. The models, in general, could predict air quality patterns with modest accuracy. However, the SOFM model performed extremely well in comparison with the other models for predicting long-term (annual) data.     

The application of the RAINS model for Greece

In order to comply in 2010 with the emission ceilings proposed by European commission under the convention on transboundary air pollution, Greece has to develop and implement a cohesive strategy affecting all the sectors of the economy. The RAINS model was used for the evaluation of the environmental and economic impacts arising from the use of a number of control technologies under alternative energy scenarios. To this purpose a number of modifications regarding the input databases of RAINS were made. The analysis clearly reveals that the reduction of SO₂ emissions can be achieved in a lower cost compared to the reduction of NO_x emissions. Moreover, the complementarity of CO₂ abatement policies and the SO₂/NO_x abatement policies is also accented.     

Short-term prediction of means of artificial neural urban NO2 pollution by networks

A neural network model for the short-term prediction of concentrations of urban pollutants was developed and applied to the Turin (Northern Italy) air quality network. In particular, the study was focused on NO₂ concentrations measured at five stations; t + 3 and t + 24 hour NO₂ concentration forecasting based on hourly meteorological and concentration data gave good agreement with observed concentrations. This is particularly true for the mean concentration values and concentration distribution. The time of occurrence of peak values was correctly forecast but the amounts were generally underestimated. To reduce this underestimation, an empirical step function was applied in the t + 24 case. This allowed an accurate estimate to be obtained of the few cases in which 50% of the air quality monitoring stations exceeded the attention level (200 μg m^-3) during the following day for at least one hour.     

Spatial and diurnal variations in concentration of atmospheric NOx along urban-rural roadways in Nanjing, Southeastern China

Atmospheric NO_x concentrations (including NO₂ and NO) on the roadside environments of urban trunk, belt highway and suburban road as well as a reference in a forest area were measured. NO_x concentrations on roadside environments tended to be higher than that on the reference. With the exception of suburban road, NO_x concentrations over both of the urban trunk and belt highway exceeded the limited value of National Air Environmental Quality Standards. Gradient measurement of NO_x on the downwind side of the belt highway shows that it declined to background level over 100 m from the road edge.     

Mechanism and kinetics of Zn(II) removal from wastewater by immobilised beads of SRB sludge

The treatment of Zn(II)-bearing wastewater by immobilised Sulfate Reducing Bacteria (SRB) sludge beads of inner cohesive nutrient source was investigated, by which the traditional problems in SRB methods were resolved. The mechanism and kinetics model on Zn(II) removal were studied. The results showed that SO₄²⁻ was reduced to S²⁻ on the surface of SRB sludge beads, and Zn(II) precipitated outside beads. The effect of internal diffusion could be neglected, and the chemical reaction was the rate determining step. The reaction kinetics was followed by Micaelis-Menten formula, and the constants, K_s and v_max were 8.99 mg⋅L⁻¹ and 0.018 mg⋅L⁻¹⋅s⁻¹, respectively.     

Atmospheric particulate matter in the city of Sao Carlos/SP, Brazil

This paper presents experimental data and source apportionment simulations on particulate matter (PM₁₀ and PM_2.5) in the atmosphere of Sao Carlos/SP, Brazil. Both a Hi-vol sampler equipped with glass fibre filters and a Dichotomous sampler with nucleopore filters were used. The collected material was analysed for total carbon, using a thermometric method, and for traces of several chemical species, using X-ray fluorescence spectroscopy. Source apportionment estimations were made with a chemical mass balance receptor model software (CMB8), with source profiles taken and adapted from the literature. The results indicate that both PM₁₀ concentration and source apportionment vary seasonally, and that vegetative burning can be a significant source of PM₁₀ in the dry season     

Effects of organic loading and oil-grease for the treatment of edible oil effluent in a pilot-scale upflow anaerobic sludge blanket process

In this study, Karadeniz Birlik Dogan Erdil vegetable oil factory, Elazig City, Turkey, was selected as representative of this sector. During the first part of the test programme, the quality of raw effluents was investigated. The removals of COD and oil-grease were above 85% at organic loadings between 1.62 and 7.83 kg COD m^-3 d^-1 at hydraulic retention times of 2.0 and 2.5 days. The conversion rates of the removed COD into methane gas were between 0.24 and 0.361 g CH₄ (g COD)^-1.     

A statistical model for predicting carbon monoxide levels

This paper presents a statistical model that is able to predict carbon monoxide (CO) concentrations as a function of meteorological conditions and various air quality parameters. The experimental work was conducted in an urban atmosphere, where the emissions from cars are prevalent. A mobile air pollution monitoring laboratory was used to collect data, which were divided into two groups: a development group and a testing group. Only the development dataset was used for developing the model. The model was determined by using a stepwise multiple regression modelling procedure. Thirteen independent variables were selected as inputs: non-methane hydrocarbon (NMHC), methane (CH₄), suspended dust, carbon dioxide (CO₂), nitrogen oxide (NO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), wind speed, wind direction, temperature, relative humidity and solar energy. It was found that NO has the most effect on the predicted CO concentration. The contribution of NO to the CO concentration variations was 91.3%. Adding in the terms for NO₂), NMHC and CH₄ improved the model by only a further 2.3%. The derived model was shown to be statistically significant, and model predictions and experimental observations were shown to be consistent.     

Preliminary studies of the oxidation of arsenic(III) by potassium ferrate

The Pollutant Standards Index (PSI) was developed in the USA to give the public an overall assessment of the air quality on a regular basis. Currently, the PSI does not include the synergistic effects of the major air pollutants. Synergism applies when the damage caused by two or more pollutants, either to human health or property, is greater than the effect or damage caused by each individual pollutant acting alone. The purpose of this work is to develop a methodology that would take into account the synergistic effects of the priority air pollutants, and therefore give us a better understanding of the severity of the damage caused by these pollutants. The equation suggested is D(P1,P2,P3,P4,P5) = C1^A C2^B C3^C C4^D C5^E. If it is assumed that the weight constants A to E are equal to one (all pollutants contribute equally to the damage), the equation becomes D (P1,P2,P3,P4,P5) = K·C1·C2·C3·C4·C5 where the constant K represents a conversion factor between the PSI scale and the new Synergistic Theory scale. The value of K is to be determined experimentally by finding the threshold value in the synergistic scale and dividing the threshold value of the PSI scale (100) by this number K = 100/SSC1_threshold where SS_threshold is the Synergistic Scale threshold value.     

Source contribution of atmospheric aerosols in Bangkok metropolitan area by CMB8 receptor model

The CMB₈ model was applied for source apportionment of particulate matter in Bangkok area. The 24 h of ambient data were collected and analysed for elemental composition during December 1996 to January 1997 by high volume air samplers at a station in Bangkok, Thailand. Seven source profiles and the average mass concentrations of 42 ambient data were used to run the chemical mass balance (CMB₈) model. The source apportionment by CMB₈ gave similar results comparing with factor analysis – multiple regression (FA–MR) model of the same data. The results revealed that major sources of particulate matter in Bangkok were: soil (33%), road dust (33%) and automobile (15%). The minor source contributions were: sea salt (4.34%), refuse incineration and biomass burning (0.84%), steel mill (0.62%) and fuel oil combustion (0.35%). The lack of source profile for biomass or open burning in Bangkok resulted in much lower predicted contribution of this source when compared to that from FA–MR. When apply this CMB₈ model with daily ambient data, the result revealed that one fourth of daily CMB₈ source apportionment had high value of ² (>4). These exceedance values of Chi² also point out that one of the selected sources (biomass burning) may not be the true contributing sources. Presumably, accurate biomass burning source profile is needed to improve the CMB calculation of source contributions for particulate matter in Bangkok metropolitan area.     

Nitrification of centrate from dewatering of anaerobically digested sludge

Nitrification of anaerobically digested sludge centrate was studied in bench-scale suspended growth and fixed film enhanced suspended growth systems at temperatures of 10.5-28.5°C and pH values of 6.0-9.1. Nitrification followed zero-order kinetics in both systems, and ammonia removals in excess of 99% were observed. The temperature dependency of the suspended growth nitrification rate observed under not fully acclimated biomass conditions at pH between 6.8 and 8.5, was expressed as k_T = k₂₀θ^T-20where k₂₀ and θ were found to be 0.34 mg NH₃-N/MLVSS-d and 1.033, respectively. The nitrification rate in the fixed film enhanced suspended growth system involving styrofoam pads ranged from 0.11 to 0.13 mg NH₃-N/mg MLVSS-d at temperatures of 21.5-25°C and pH values of 7.8-8.6. The process contained suspended solids in the range of 10-20 mg/l.