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.     

Measurement of atmospheric fluxes of radionuclides at a UK site using both direct (rain) and indirect (soils) methods

Direct measurements of radionuclide tracers are useful tools for correcting proxy fluxes that are subject to post depositional changes. An analytical methodology was designed for the measurement of ²¹⁰Pb and ⁷Be in rainwater. Atmospheric inputs of the radionuclides to Cumbria (UK) were recorded. Rainwater fluxes were then compared with measurements from soil cores. The annual deposition from April 1997 to March 1998 of ²¹⁰Pb and ⁷Be was 165 ± 8 Bq m^-2 and 3912 ± 120 Bq m^-2, respectively, compared to an indirect ²¹⁰Pb flux of 148 ± 7 Bq m^-2 yr^-1 calculated from soil core records.     

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.}     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Synthesis of Na-Pc zeolite from perlite and study of its ability to remove cyanide from liquid wastes

With the aim of the economic upgrading of natural resources, this investigation examined the hydrothermal synthesis of zeolite from perlite, and the ability of the synthetic zeolite to adsorb and retain cyanide. The hydrothermal treatment of perlite with aqueous sodium hydroxide results in the formation of Na-P_c zeolite. The cation-exchange capacity of zeolite for zinc, copper and silver was respectively 2.26, 1.86 and 2.44 meq g^-1. The exchange was incomplete, but equilibrium was rapidly attained. Cyanide adsorption isotherms, constructed at three different temperatures, showed that the zeolite was very selective for cyanide. The solubility products of the cyanide precipitate and the exchange capacity of zeolite for individual cations governed the adsorption capacity of the zeolite. The method also remains selective in the presence of some other anions. Kinetic data for cyanide desorption in water and sodium chloride solution indicated that zeolite retains most of the adsorbed cyanide.     

Comparison of PDFs, closure schemes and turbulence parameterisations in Lagrangian stochastic models

Six one-dimensional models, based on the Ito-type stochastic equation, are presented and compared. Four of these take into account up to the fourth order moment of vertical velocity fluctuations, and two up to the third order moment. Four models make use of a bi-Gaussian probability density function (PDF) and the other two are based on a Gram-Charlier series expansion truncated to the third or fourth order. All the models were run with a parameterisation of input turbulence (i.e. w², w³, and τ profiles). Concerning the fourth order moment w⁴, two different parameterisations were considered. Comparisons are made between ground-level concentrations, plume height and plume width observed in the Willis and Deardorff water tank experiments and those predicted by the different models here considered. The goal of this study was to find the models that give greater confidence in their applicability in dispersion studies and to verify the importance of considering the fourth order moment. The main conclusions are: simulation results largely depend on the turbulence parameterisation chosen; the Gram-Charlier PDF gives the best agreement with observations; some combinations of models and turbulence parameterisations perform well in simulating the shape of the ground-level concentration (g.1.c.) trend but fail in correctly simulating the form of the plume (plume height and vertical width); in the case of the Gram-Charlier PDF, the fourth order model reproduced the vertical plume width better than the third order one, whereas the two schemes yielded similar g.1.c. distributions.     

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.     

Impact of plant harvesting on nitrogen and phosphorus removal in constructed wetlands treating agricultural region wastewater

Agricultural region wastewater near Dianchi Lake, China increases eutrophication of the lake. Thus nitrogen and phosphorus removal from the wastewater by Phragmites australis and Zizania caduciflora in two Constructed Wetlands (CWs) was studied. South CW and North CW have areas of 2800 and 4200 m², respectively. From January 2003 to December 2003, the input loads were 5.31 (2.89) and 0.68 (0.37) kg P ha⁻¹ day⁻¹ in SCW (NCW). The removal amounts of N and P via plant harvesting accounted for 32 (58) and 37 (51)% of the corresponding removal load in SCW (NCW).     

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.     

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).     

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.     

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.     

Time-resolved ammonia measurement in vehicle exhaust

The objective of this study was to identify the influence of sampling and analytical approach on the quality of NH3 emission data of a gasoline-fuelled three-way catalyst vehicle. NH₃ concentration measurements have been performed in the tailpipe and in the diluted exhaust after a constant volume sampling (CVS) system during five different test cycles. Chemical ionisation mass spectrometry (CI-MS) and Fourier transform infrared spectroscopy (FTIR) were used to acquire ammonia concentrations in real-time. Independently, NH₃ emission rates were determined by continuous absorption of a flow-proportional sample of exhaust gas in diluted sulphuric acid and subsequent ion chromatography (IC). Ammonia emission rates ranged from 22–94 mg km^-1. The results of the three compared techniques are in good agreement. Furthermore, time-resolved ammonia emission profiles recorded by CI-MS and FTIR coincided with respect to emission levels as well as emission dynamics. However, in the dilution tunnel, severe ammonia adsorption was observed leading to long lasting memory effects or even analyte loss. Therefore, neither ammonia real-time emission data nor NH₃ emission rates should be acquired after a CVS system.