Measurement of atmospheric particles and anionic species across central Taiwan

The ambient air concentrations and fluxes of various anionic species were sampled by MOUDI, TSP and dry deposition plates at a traffic sampling site in Taichung, central Taiwan. In the sampling period, from September to December 2000, the ambient air particle concentrations (PM₁, PM_2.5, PM₁₀ and TSP) were lower in the September than in the other three months (October to December). The reason is that the northwest wind brought more particles (diameter less than 10 μm) and the higher wind speed caused higher dry deposition fluxes and TSP concentrations in the last three months. The anion species percentages of TSP were 0.24%, 13.7%, 0.52%, 12.0%, 18.9'% and 54.6% for F^-, Cl^-, Br^-, NO₂^-, NO₃^- and SO₄^2-, respectively. The results revealed that SO₄^2-, NO₃^-, Cl^- and NO₂^- were the dominant species at the traffic sampling site. The ion-size distributions of Cl^-, NO₂^- and NO₃^- were unimodal, the main peak being between 3.2 and 5.6 μm. In contrast, the size distribution of SO₄^2- was bimodal, with the main peaks in the particle size ranges 0.32.0.56 μm and 3.2.5.6 μm. The ambient average particle dry deposition flux was 6.28 μg/m2/s, and the dry deposition fluxes were 0.01, 94.6, 0.05, 34.7, 72.2 and 376.4 ng/m2/s for F^-, Cl^-, Br^-, NO₂^-, NO₃^- and SO₄^2-, respectively. The dry deposition velocities were 3.10, 0.03, 3.67, 0.05, 1.54, 2.03 and 3.67 cm/s for F^-, Cl^-, Br^-, NO₂^-, NO₃^- and SO₄^2-, 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.     

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^-.     

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.     

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.     

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.}     

Analysis of radioisotope concentrations in sediments using γ-ray spectrometry

The concentrations of some naturally occurring radioisotopes in sediments of the Kufranja river basin in Jordan were determined by means of γ-ray spectrometry with precise calibration of energy and efficiency. The nuclides' concentrations were found by either direct measurement of their activities, as in the case of ²²⁶Ra and ⁴⁰K, or through the measurements of the activities of their daughters with short half-lives, as in the case of ²³⁸U and ²³²Th. Furthermore, the hazard index, the radium equivalent activity and the absorbed dose rate for each of these nuclides had been calculated. It turned out that the concentrations of radioisotopes in sediments of the studied area were below the standard limits and the human effective dose equivalent ranged from 23.8 to 35.7 μSv/yr.     

Heavy metal speciation and mobility assessment of arid soils in the vicinity of Al Ain landfill, United Arab Emirates

Sixty-four surface soil samples taken in the vicinity of Al Ain landfill were analysed for cadmium, chromium, copper, nickel, lead and zinc by inductively coupled plasma spectroscopy. Extraction techniques were used to establish the association of the total concentrations of the six metals in the soil samples with their contents in the exchangeable, carbonate, iron/manganese oxides, and residual fractions. In the investigated soils, the recorded concentrations were as follows: 0.043 mg kg^-1 for cadmium, 19.1 mg kg^-1 for chromium, 53.3 mg kg^-1 for copper, 60 mg kg^-1 for nickel, 13.7 mg kg^-1 for lead, and 117 mg kg^-1 for zinc. Cadmium, chromium, nickel, lead and zinc concentrations in the investigated soil samples reflect the natural background values in shale, whereas copper is slightly enriched. I-geo (geoaccumulation index) values of the metals in the soils under study indicate that they are uncontaminated with cadmium, chromium, nickel, lead and zinc, but contaminated to moderately contaminated with copper. Heavy metal contents in the sediments were found to be significantly influenced by different physico-chemical parameters. The effect of these parameters can be arranged in the following order: clay fraction > carbonate fraction > silt fraction > organic matter fractions. A sequential extraction procedure showed that the total concentrations of the heavy metals are largely bound to the residual phase (retained 71.4% of cadmium, 77.8% of chromium, 75% of copper, 47% of nickel, 62.8% of lead, and 75.8% of zinc). A likely sequence of mobility in the investigated soils is as follows: chromium > lead > nickel > cadmium > zinc > copper.     

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.     

Measurement of ammonia emissions using various techniques in a comparative tunnel study

A field-based intercomparison study for ammonia measurements was conducted using seven analytical methods. It included sulphuric acid impinger, citric acid denuder, differential optical absorption spectroscopy (DOAS), Fourier transform infrared spectroscopy (FTIR), photoacoustic spectroscopy (PAS), and continuous aqueous extraction followed by measurement of conductivity (Airrmonia). Measurements were done at the entrance and the exit of the Gubrist highway tunnel near Zurich, Switzerland. For DOAS, FTIR, PAS and Airrmonia, 24 hour means were calculated based on a time resolution of 10 minutes. At the tunnel exit, all 24 hour averages were within 13%, and the continuous data of the time-resolved methods agreed well. At the tunnel entrance, a slightly reduced method comparison included four methods, and daily mean values agreed within 23%. Ammonia emission factors, based on 4 weeks of continuous measurements with the Airrmonia, were 31 ± 4 mg km^-1 for light-duty vehicles and 14 ± 7 mg km^-1 for heavy-duty vehicles.     

Aluminium accumulation in Pteris cretica and trace element uptake in vegetation growing on an abandoned aluminium smelter site in Knoxville, TN, USA

Smokey Mountain Smelters in Knoxville, Tennessee USA is an abandoned aluminium smelter where smelter waste (slag) was dumped on site. ICP analyses indicated the highest slag metal concentrations were 223,000 mg kg⁻¹ Al, 281 mg kg⁻¹ As, 132 mg kg⁻¹ Se, and 2910 mg kg⁻¹ Cu. Metal uptake was quantified in plants growing on slag. Our data indicates that P. cretica accumulates Al in high concentrations, but not As, when grown in slag. Metal concentrations in vegetation grown on slag were lower than controls grown in uncontaminated soil, suggesting low metal availability or root exclusion mechanisms.     

Adsorption of molybdate ion by natrolite and clinoptilolite-rich tuffs

Natural clinoptilolite-rich tuffs and natrolite from Iranian deposits and their different ion-exchanged forms were used for the adsorption of ⁹⁹Mo as molybdate ion. The effect of pH, contact time, initial molybdate concentration, and some cationic and anionic interferences were also studied. To investigate the selectivity of zeolites and their exchanged forms, the isotherms of adsorption were constructed at room temperature. Desorption experiments were carried out to examine the ability of zeolite to retain adsorbed molybdate. It was concluded that molybdate could be considerably adsorbed by some of the exchanged forms of the zeolites (Ag⁺, Cd²⁺ and Pb²⁺ exchanged forms) whereas the uptake by the natural forms was negligible.     

Estimation of dry deposition of atmospheric nitrogen to coastal waters of de la Plata River in front of Buenos Aires city

The deposition of atmospheric nitrogen (N) to surface waters of de la Plata River downwind of Buenos Aires city has been estimated using atmospheric dispersion-deposition models. The CALPUFF model has been applied to point source emissions and the DAUMOD-RD model has been developed to evaluate the area source emission contributions. Annual N dry deposition is 31,763 kg-N yr⁻¹ (≈ 18 kg-N km⁻² yr⁻¹). Nitrogen dioxide contribution to this value is 54% and nitric acid contribution is 46%. The maximum monthly N dry deposition fluxes vary between 7 kg-N km⁻² month⁻¹ (in February) and 13 kg-N km⁻² month⁻¹ (in December).     

Manganese levels and chemical fractionation in street dust in South Africa

Mn in street dust and soil from selected roads was studied to assess the contribution of combustion of vehicular methylcyclopentadienyl manganese tricarbonyl (MMT) to Mn levels and distribution in Pretoria, South Africa. Total Mn concentrations ranged from (329.1-863.9 μg g⁻¹) for dust and (215.8-450.6 μg g⁻¹) for soil. These values were significantly higher than the mean value (278.9 μg g⁻¹) found on soil from a rural environment in Pretoria. The lowest value for the dust sample (329.1 μg g⁻¹) was close to the mean background level of 330 μg g⁻¹ for Mn in soil. Mn distribution in the samples was most in the residual fraction (178.18-487.50 μg g⁻¹) and (140.76-293.40 μg g⁻¹) for dust and soil respectively. Mn in the other fractions were 56.45-202.60 μg g⁻¹ oxides, 90.71-45.34 μg g⁻¹ organic, 45.36-12.65 μg g⁻¹ carbonates and 1.98-6.72 μg g⁻¹ exchangeable for dust and 32.54–167.31 μg g⁻¹ oxides, 34.23–70.45 μg g⁻¹ organic, 10.98-30.45 μg g⁻¹ carbonate and 1.0-4.87 μg g⁻¹ exchangeable for soil. Major source of Mn determined was mainly from the combustion of vehicular MMT.     

Observation based analysis for the determination of equilibrium time constant between ammonia, acid gases, and fine particles

Experimental measurements of ammonia, acid gases, and the inorganic components of atmospheric aerosols were made at a commercial hog farm in eastern North Carolina from May 1998 to June 1999 by an annular denuder system (ADS). The ADS consisted of a cyclone separator, one diffusion denuder coated with sodium carbonate, another diffusion denuder with citric acid, and a filter pack containing Teflon and nylon filters in series. The equilibrium time constant for transfer between ammonia, acid gases, and aerosol phase of ammonium nitrate and ammonium chloride was determined based on kinetic rate constants (k_N as the rate constant of ammonium nitrate aerosol: 2.04 × 10^-4 m³/µmole/sec; k_Cl as the rate constant of ammonium chloride aerosol: 3.44 × 10^-4 m³/µmole/sec) and the observed inorganic components of atmospheric aerosols. The equilibrium time constant was determined based on kinetic rate constants and the observed inorganic components of atmospheric aerosols. The equilibrium time constant has a wide range of values, with an average value of 15.26 (±10.94) minutes for ambient equilibrium time between ammonia, nitric acid gas and ammonium nitrate aerosol; and 8.22 (±6.81) minutes for ammonia, hydrochloric acid, and ammonium chloride. Significant correlations were determined between comparisons of equilibrium time constant estimates with meteorological parameters, such as ambient temperature and relative humidity. The predicted chemical compositions in the particle by EQUISOLV II Model are in good agreement with the observed chemical composition at the experimental site.     

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.     

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.     

Treatment of distillery anaerobic effluent in a hybrid biological reactor

The treatability of anaerobic effluent from a molasses-based distillery was studied in a shaft-type hybrid bioreactor under purely suspended growth and hybrid system containing 5 mm tyre-tube beads. The Ks, k, Y and k found as 111.29 mg/l, 0.026/h, 0.4607 and 0.0040/h respectively. The maximum COD removal was 51.7% at a loading rate of 5.250 kg d⁻¹ m⁻³. The overall removal rate was 0.0431, 0.0452, 0.0484 and 0.053/h under 0, 10, 20 and 30 g/l of beads respectively. When attached biomass increased, the cell synthesis part of oxygen utilisation coefficient gradually decreased and that for endogenous respiration increased.     

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.     

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.