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.     

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^-.     

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.     

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.     

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.     

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.}     

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.     

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.     

Dye wastewater treatment by using ceramic membrane bioreactor

Performance of a Micro-filtration Membrane Bioreactor (MMBR) for treatment of dye wastewater was investigated. The experimental results indicated that the removal efficiency for COD, TOC and colour was 85%, 85-90% and 70%, respectively, the effluent COD was below 70 mgl⁻¹ on average. Gel layer resistance of COD was 10%. Particle size distribution of sludge in MMBR was 1-150 μm, and the average particle diameter was 20-40 μm. The activity of dehydrogenase of activated sludge in MMBR was 36-42 mgTTC (gVSS) ⁻¹h⁻¹, while active dehydrogenase enzyme content was 7.95 mgVSS⁻¹.     

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.     

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.     

Enhanced stabilisation and methane potential of MSWs in a field-scale landfill with leachate recirculation

This study was carried out on two field scale test cells constructed at Odayeri Sanitary Landfill (OSL) located at the European side of Istanbul city. Approximately 11,000 tons of municipal solid wastes (MSW) were filled at equal quantities to each cell (C1 and C2). Leachate was periodically recirculated to one (C2) of the test cells in various quantities. These cells are compared in terms of leachate quality (pH, BOD and COD), methane potential (MP) of wastes and surface settlement for a monitoring period of 0–400 days. Experimental results showed that optimum pH for anaerobic decomposition was reached in a shorter period of time in C2 compared to C1. Moreover, BOD and COD concentrations were decreased more rapidly in C2 cell than in C1 cell. BOD/COD ratio was determined as 0.25 and 0.17 for C1 and C2 cells consequently after 380 days from placement of refuse to the test cells. In MP tests, first order rate constants for cell C1 and C2 were found be 0.145 year^-1 and 0.222 year^-1, respectively. Topographic measurements revealed that cumulative settlements after 12 months from refuse placement were 0.49 and 0.70 m for C1 and C2 cells, respectively. According to results obtained from this study, it can be concluded that appropriate conditions can cause enhance in the decomposition rate of MSW.     

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.     

Lead and zinc content of cows' milk affected by varying traffic density

This study was conducted to investigate the influence of vehicle emissions on zinc and lead content of cow's milk, grazing at 15 different locations near to roadsides in Sakarya, Turkey. The results obtained for zinc were between 1262 μg kg⁻¹ and 6566 μg kg⁻¹. An acceptable range of zinc content from various sides confirmed the absence of possible toxicological risks in this region. The lead levels ranged from 3.24 μg kg⁻¹ to 80.69 μg kg⁻¹. The levels of lead in milk samples collected from roadside pastures were higher than the regulatory limits and pose a health risk.     

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.     

The benzene problem: impact of three-way catalyst technology: potential for further improvement

Chemical ionisation mass spectrometry (CI-MS) was applied to study the benzene emission characteristics of a TWC-vehicle at a time resolution of one Hertz. Three important operating conditions with increased emissions were identified: at vehicle start; at extended stop-and-go situations; and whenever a catalyst-induced benzene formation occurs. The cold start influence was detectable for about 200 seconds of driving corresponding to a distance of 1.2 km. At hot engine/catalyst mean pre- and post-catalyst emission rates of 25–150 mg km^-1 and 0.1–135 mg km^-1 were determined. Catalyst conversion varied from 0.07 to >0.99. Even negative conversion efficiencies were observed at several occasions, indicating that benzene can be formed de novo in a TWC. It is of importance to lower benzene emissions at these critical operating conditions to further reduce ambient air levels in cities and with it the cancer risk for large proportions of our population.     

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).