Estimating the biogenic emissions of non-methane volatile organic compounds from the North Western Mediterranean vegetation of Catalonia, Spain

An estimation of the magnitude of non-methane volatile organic compounds (NMVOCs) emitted by vegetation in Catalonia (NE of the Iberian Peninsula, Spain), in addition to their superficial and temporal distribution, is presented for policy and scientific (photochemical modelling) purposes. It was developed for the year 2000, for different time resolutions (hourly, daily, monthly and annual) and using a high-resolution land-use map (1-km2 squared cells). Several meteorological surface stations provided air temperature and solar radiation data. An adjusted mathematical emission model taking account of Catalonia's conditions was built into a geographic information system (GIS) software. This estimation uses the latest information, mainly relating to: (1) emission factors; (2) better knowledge of the composition of Catalonia's forest cover; and (3) better knowledge of the particular emission behaviour of some Mediterranean vegetal species. Results depict an annual cycle with increasing values in the March-April period with the highest emissions in July-August, followed by a decrease in October-November. Annual biogenic NMVOCs emissions reach 46.9 kt, with monoterpenes the most abundant species (24.7 kt), followed by other biogenic volatile organic compounds (e.g. alcohols, aldehydes and acetone) (16.3 kt), and isoprene (5.9 kt). These compounds signify 52%, 35% and 13%, respectively, of total emission estimates. Peak hourly total emission for a winter day could be less than 10% of the corresponding value for a summer day.     

Intraparticle diffusion and adsorption of arsenate onto granular ferric hydroxide (GFH)

Porous iron oxides are being evaluated and selected for arsenic removal in potable water systems. Granular ferric hydroxide, a typical porous iron adsorbent, is commercially available and frequently considered in evaluation of arsenic removal methods. GFH is a highly porous (micropore volume approximately 0.0394+/-0.0056 cm(3)g(-1), mesopore volume approximately 0.0995+/-0.0096 cm(3)g(-1)) adsorbent with a BET surface area of 235+/-8 m(2)g(-1). The purpose of this paper is to quantify arsenate adsorption kinetics on GFH and to determine if intraparticle diffusion is a rate-limiting step for arsenic removal in packed-bed treatment systems. Data from bottle-point isotherm and differential column batch reactor (DCBR) experiments were used to estimate Freundlich isotherm parameters (K and 1/n) as well as kinetic parameters describing mass transfer resistances due to film diffusion (k(f)) and intraparticle surface diffusion (D(s)). The pseudo-equilibrium (18 days of contact time) arsenate adsorption density at pH 7 was 8 microg As/mg dry GFH at a liquid phase arsenate concentration of 10 microg As/L. The homogeneous surface diffusion model (HSDM) was used to describe the DCBR data. A non-linear relationship (D(S)=3.0(-9) x R(p)(1.4)) was observed between D(s) and GFH particle radius (R(P)) with D(s) values ranging from 2.98 x 10(-12) cm(2)s(-1) for the smallest GFH mesh size (100 x 140) to 64 x 10(-11) cm(2)s(-1) for the largest GFH mesh size (10 x 30). The rate-limiting process of intraparticle surface diffusion for arsenate adsorption by porous iron oxides appears analogous to organic compound adsorption by activated carbon despite differences in adsorption mechanisms (inner-sphere complexes for As versus hydrophobic interactions for organic contaminants). The findings are discussed in the context of intraparticle surface diffusion affecting packed-bed treatment system design and application of rapid small-scale column tests (RSSCTs) to simulate the performance of pilot- or full-scale systems at the bench-scale.     

Nutrient cycling at the sediment-water interface and in sediments at Chiricahueto marsh: a subtropical ecosystem associated with agricultural land uses

A study was conducted to examine the potential role to accumulate and transform nitrogen and phosphorus of a common wetland type marsh; the site is located in a subtropical environment that receives agricultural pollutants. Chiricahueto marsh effectively removes N and P from surface waters. It is clear that the diagenetic processes are mainly controlled by the exponential decomposition of organic matter that takes place at the sediment-water interface and in the sedimentary column, under oxic and suboxic-anoxic conditions, respectively. Mass balances indicated a net sedimentation of 11.3 g Nm(-2)x yr (-1) and 3.9 g Pm(-2) x yr (-1), which results in an annual regeneration of 1.7 g Nm(-2) and 0.8 g Pm(-2) at the sediment-water interface under oxic conditions. A major remineralization rate was estimated in 6.4 g Nm(-2) x yr (-1) and 1.1g Pm(-2) x yr (-1) into the sedimentary column where suboxic to anoxic conditions occur by the utilization of nitrate, Fe and Mn as electron acceptors. The estimated burial fluxes in the deeper sediments (>50 cm) were 1.5 g Nm(-2) x yr (-1) and 0.4 g Pm(-2) x yr (-1).     

Phosphorus cycling through phosphine in paddy fields

Phosphine emission fluxes from paddy fields, phosphine ambient levels in air, and the vertical profile of matrix-bound phosphine in soil have been measured throughout the growing season of rice in Beijing, China. It was found that both the seasonal and diurnal emission fluxes and ambient levels fluctuate significantly. During the drainage period, phosphine released from the soil with the highest diurnal average flux on the first period of drainage (approx. 17.7 ng m(-2) h(-1)), whereas its highest ambient level (approx. 250 ng m(-3)) occurred at 06.00 h. During the flooded period, phosphine emission was low, and the peaks of phosphine emissions occurred at midnight. The average flux of PH3 emission for the whole season was found to be approximately 1.78 ng m(-2) h(-1). The mass fraction of matrix-bound phosphine is approximately 0.18 approximately 1.42 x 10(-7) (m/m) part of organic phosphorus or 3.4 approximately 9.2 x 10(-9) (m/m) part of total phosphorus in paddy soil. The amount of phosphine emitted to the atmosphere was only a small fraction of the phosphine that remained in the soil in the matrix-bound form. Soil serves both as the source and the sink of PH3.     

Particle and carbon dioxide emissions from passenger vehicles operating on unleaded petrol and LPG fuel

A comprehensive study of the particle and carbon dioxide emissions from a fleet of six dedicated liquefied petroleum gas (LPG) powered and five unleaded petrol (ULP) powered new Ford Falcon Forte passenger vehicles was carried out on a chassis dynamometer at four different vehicle speeds--0 (idle), 40, 60, 80 and 100 km h(-1). Emission factors and their relative values between the two fuel types together with a statistical significance for any difference were estimated for each parameter. In general, LPG was found to be a 'cleaner' fuel, although in most cases, the differences were not statistically significant owing to the large variations between emissions from different vehicles. The particle number emission factors ranged from 10(11) to 10(13) km(-1) and was over 70% less with LPG compared to ULP. Corresponding differences in particle mass emission factor between the two fuels were small and ranged from the order of 10 microg km(-1) at 40 to about 1000 microg km(-1) at 100 km h(-1). The count median particle diameter (CMD) ranged from 20 to 35 nm and was larger with LPG than with ULP in all modes except the idle mode. Carbon dioxide emission factors ranged from about 300 to 400 g km(-1) at 40 km h(-1), falling with increasing speed to about 200 g km(-1) at 100 km h(-1). At all speeds, the values were 10% to 18% greater with ULP than with LPG.     

On-road vehicle emission inventory and its uncertainty analysis for Shanghai, China

As vehicle population and activity increase, vehicle emissions are becoming the most predominant source of air pollution in Shanghai, China. It has become important to accurately estimate the traffic emissions in this city. This paper presents a bottom-up approach based on the International Vehicle Emission (IVE) model to develop the vehicle emission inventory for Shanghai. The results show that the total emissions of CO, VOC, NO(X) and PM from vehicles in Shanghai in 2004 were 57.06 x 10(4) t, 7.75 x 10(4) t, 9.20 x 10(4) t and 0.26 x 10(4) t, respectively. About 20% of the total emissions were emitted during the cold start period. Heavy-duty vehicles such as trucks and buses contributed over half of NO(X) and PM. Motorcycles and mopeds provided 45.0% of VOC and 36.3% of PM. Light-duty vehicles are the main source of CO emissions. An assessment of vehicle emissions by time of day and road type was also discussed. The three peak emission periods accounted for 54% to 56% of the total emissions during the day and more than 50% of the total emissions were emitted on the arterial roads. Finally, the study focused on the uncertainty analysis of two critical factors: emission factors and the estimate of the total Vehicle Kilometers Traveled (VKT). The analysis indicates that the emission factors calculated in this paper are close to those factors measured during on-road testing, and the difference between the VKT used in this paper and other calculations is less than 10%.     

Vertical variations in the concentration of mercury in soils around Sakurajima Volcano,Southern Kyushu,Japan

In an effort to estimate the influence of mercury emitted from Sakurajima Volcano, Southern Kyushu, Japan, on the accumulation of mercury in soil, the vertical distribution of total mercury in soils was investigated together with organic matter content and grain size. The soils were sampled at a thickness of 1 cm from the surface to depth of 1 m at five locations on Sakurajima and two control locations, i.e. Takatoge approximately 11 km southeast and Suzuyama 22 km southwest of the volcano. The concentration in soils increased with the distance from the volcano and was 6.5+/-1.9 ngg(-1) (n=335), 29.0+/-15.6 ngg(-1) (n=100) and 229+/-105 ngg(-1) (n=103) for Sakurajima, Takatoge and Suzuyama, respectively. The concentration of mercury correlated with the amount of organic matter, but not with grain size distribution. The sedimentation rate for Sakurajima, Takatoge and Suzuyama was estimated from geological data to be approximately 1.3, 0.083 and 0.0048 cmyear(-1), respectively. The relatively fast sedimentation of Sakurajima soil was caused by the frequent precipitation of volcanic ash. The annual deposition of mercury estimated for Sakurajima, Takatoge and Suzuyama from the mercury concentration, sedimentation rate and soil density was 9 x 10(4), 3 x 10(4) and 2 x 10(4) ngm(-2)year(-1), respectively. Although the soil of Sakurajima had the lowest concentration among the three sites, it received the largest amount of mercury.     

Time and space patterns of volatile organic compounds in a sewage treatment plant

47 regulated and non-regulated volatile organic compounds (VOCs) were characterised by closed-loop stripping analysis (CLSA) and high resolution gas chromatography coupled to mass spectrometry (HRGC/MS) in 28 aqueous samples from 4 sampling points along a sewage treatment plant in Manresa, Catalonia, Spain. A 4 x 2(2) factorial design (16 samples) was first prepared for the sampling, and reinforced with 12 additional samples at the plant influent. The total analyte weighted mean concentration was 232 microg x l(-1) at the plant influent, with a mass flow of 2231 kg x yr(-1). Petroleum solvents and terpenic compounds accounted for 79% of the influent analyte concentration. VOC concentration in influent was clearly higher for most VOCs from 12 to 22 h (high organic load hours), and lower from 24 to 10 h (lower organic load). Differences between time bands were confirmed through t tests. Differences between weekdays and the weekend were not so clear, and could not be confirmed through t tests. VOC concentrations along the plant are discussed. Overall analyte removal in the plant was 89%.     

Removal of carbon and nutrients from domestic wastewater using a low investment, integrated treatment concept

An integrated chemical-physical-biological treatment concept for the low-cost treatment of domestic wastewater is proposed. Domestic wastewater was subjected to a chemically enhanced primary treatment (CEPT), followed by treatment in an upflow anaerobic sludge blanket (UASB) reactor. In addition, a regenerable zeolite was used to remove NH4+, either after CEPT pretreatment or after biological treatment in the UASB reactor. The CEPT pretreatment consisted of the addition of a coagulant (FeCl3) and an anionic organic flocculant and removed on average 73% of the total chemical oxygen demand (COD(t)), 85% of the total suspended solids, and 80% of PO4(3-) present in the wastewater. The UASB system, which consequently received a low COD(t) input of approximately 140 mg/L, was operated using a volumetric loading rate of 0.4 g COD(t)/L. d (hydraulic retention time [HRT]=10 h) and 0.7 g COD(t)/L. d (HRT=5 h). For these conditions, the system removed about 55% of the COD(t) in its influent, thus producing an effluent with a low COD(t) of approximately 50 mg/L. The zeolite, when applied in batch mode before the UASB reactor, removed approximately 45% of the NH4+, whereas its application as a post-treatment cartridge resulted in almost 100% NH4+ removal. The simple design and relatively low operating costs, due to low costs of added chemicals and low energy input (estimated at Euro 0.07-0.1 per m3 wastewater treated), combined with excellent treatment performance, means that this system can be used as a novel domestic wastewater treatment system for developing countries. Therefore, the system is called a Low Investment Sewage Treatment (LIST) system.     

UV disinfection of RBC-treated light greywater effluent: kinetics, survival and regrowth of selected microorganisms

The microbial quality of raw greywater was found to be much better than that of municipal wastewater, with 1.6 x 10(7)cfu ml(-1) heterotrophic plate count (HPC), and 3.8 x 10(4), 9.9 x 10(3), 3.3 x 10(3) and 4.6 x 10(0)cfu 100 ml(-1) faecal coliforms (FC), Staphylococcus aureus sp., Pseudomonas aeruginosa sp. and Clostridium perfringes sp., respectively. Further, three viral indicators monitored (somatic phage, host: Escherichia coli CN(13) and F-RNA phages, hosts: E. coli F+(amp), E. coli K12) were not present in raw greywater. The greywater was treated by an RBC followed by sedimentation. The treatment removed two orders of magnitude of all bacteria. UV disinfection kinetics, survival and regrowth of HPC, FC, P. aeruginosa sp. and S. aureus sp. were examined. At doses up to 69 mW s cm(-2) FC were found to be the most resistant bacteria, followed by HPC, P. aeruginosa sp. and S. aureus sp. (inactivation rate coefficients: 0.0687, 0.113, 0.129 and 0.201 cm2 mW(-1)s(-1), respectively). At higher doses (69-439 mW s cm(-2)) all but HPC (which exhibited a tailing curve) were completely eliminated. Microscopic examination showed that FC self-aggregate in the greywater effluent. This provides FC an advantage at low doses, since the concentration of suspended matter (that can provide shelter from UV radiation) in the effluent was very low. FC, P. aeruginosa sp. and S. aureus sp. did not exhibit regrowth up to 6h after exposure to increasing UV doses (19-439 mW s cm(-2)). HPC regrowth was proven to be statistically significant in un-disinfected effluent and after irradiation with high UV doses (147 and 439 mW s cm(-2)). At these doses regrowth resulted from growth of UV-resistant bacteria due to decreased competition with other bacteria eliminated by the irradiation.     

Batch foam separation of a soluble protein

Removal of protein dissolved in water by batch foam separation was conducted with using ovalbumin (OA) as a model protein in the light of wastewater treatment reducing organic loading. The removal efficiency had a maximum value near the i.e.p. of OA (pH 4.6); thus, most experiments were conducted at pH 4.6. Typical experimental conditions; superficial gas velocity, U(g): 1.97 x 10(-2)-5.37 x 10(-2)cm/s; initial bulk concentration of OA, C(i): ca. 0.05-0.25 g/L; liquid volume, V: 600 cm(3). A model estimating bulk concentration profile was proposed by taking into account a mass balance of the present system. The model predicted that OA could be removed perfectly, however, was not all removed experimentally. The residual OA concentration of the bulk liquid within the column reached plateau value, which correspond to ca. 18% of the initial OA concentration. The plateau value of the bulk concentration was attained for ca. 100-500 min with U(g)=1.97 x 10(-2)-5.37 x 10(-2)cm/s. Foaming ability test revealed that the foaming limit concentration of OA at pH 4.6 was 9.72 x 10(-3)g/L. These results suggested that OA molecules could be damaged by interaction of bubble surface in the dispersed phase, since there were the residual OA concentrations over the limit concentration. To take account of this phenomena and correct the model, average surface density, X(d), which should convert protein molecule into the denatured protein molecule, was introduced. The corrected model could explain well the time profile of OA bulk concentration.     

Predictions of nitrate diffusion in sediment using horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry

Using a novel and simple method based on horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry, the effective diffusion coefficient, De, of nitrate in a contaminated anthropogenic sediment was estimated as 7.34 x 10(-6)cm2 s(-1). This method, which requires as little as 1 mL of sediment sample, was able to measure the De of a chemical species with a reproducibility of +/-3% in about 5h. Based on this De and a pre-determined nitrate reduction rate, the profiles of nitrate concentration in two sediment columns were satisfactorily predicted from a mathematical model. Results showed that the profile in this aged sediment depended mainly on the diffusion of nitrate and, only to a much lesser degree, the rate of nitrate reduction. Measurements in 55 anthropogenic sediment samples collected from five locations and various depths of a contaminated site further showed that the De of nitrate increased linearly with the water content of the sediment, but decreased with the sediment density. The technique demonstrated in this study shall be applicable for the risk assessment of toxic pollutants in contaminated sediments, and for planning the spatial and time intervals of nitrate injection strategy in bioremediation.     

Release of organic matter in a discontinuously chlorinated drinking water network

The effects of discontinuous chlorination on the characteristics of the water in a pilot drinking water distribution network were investigated. The release or consumption of organic matter (as dissolved organic carbon, DOC) following chlorination and non-chlorination periods were estimated, as were changes in bacterial cell production. In each unchlorinated network 0.3 mg DOCl(-1) was consumed and the average cell production was approximately 1.3 x 10(5) cells ml(-1). In discontinously chlorinated networks (chlorine treatment: 3.3 mg Cl2l(-1), chlorine residual: 0.1 mg Cl2l(-1)) the DOC release (DOCout-DOCin) was between 0.1 and 0.2 mg Cl(-1). Biomass production (cells(out)-cells(in)) during this chlorination period was lower (approximately 2 x 10(4) cells ml(-1)). The delay before DOC was released in chlorinated networks appeared to be less than 24 h, which corresponds to one hydraulic residence time. Likewise, when chlorination was stopped, 24 h or less were required before an efficient DOC removal was resumed. When chlorination was prolonged the observed release of DOC was progressively reduced from 0.2 mg l(-1) to zero, thus after 6 weeks of continuous chlorination the DOCin was equivalent to the DOCout.     

Estimation of mercury emission from different sources to atmosphere in Chongqing, China

This investigation presents a first assessment of the contribution to the regional mercury budget from anthropogenic and natural sources in Chongqing, an important industrial region in southwest China. The emissions of mercury to atmosphere from anthropogenic sources in the region were estimated through indirect approaches, i.e. using commonly acceptable emission factors method, which based on annual process throughputs or consumption for these sources. The natural mercury emissions were estimated from selected natural sources by the dynamic flux chamber technique. The results indicated that the anthropogenic mercury emissions totaled approximately 8.85 tons (t), more than 50% of this total originated in coal combustion and 23.7% of this total emission in the industrial process (include cement production, metal smelting and chemical industry). The natural emissions represented approximately 17% of total emissions (1.78 t yr(-1)). The total mercury emission to atmosphere in Chongqing in 2001 was 10.63 t.     

Emissions of mercury and other trace elements from coal-fired power plants in Japan

To evaluate trace element emissions from modern coal-fired power plants into the atmospheric environment in Japan, trace elements in the coal used in electric utility boilers, stack concentrations, emission rates and emission ratios of coal-fired power plants, and proportions of trace elements in coal-fired power plants were studied. The elements were As, B, Be, Cd, Co, Cr, F, Hg, Mn, Ni, Pb, Sb, Se and V, which are designated in the Law of Pollutant Release and Transfer Register. The particulate trace elements were collected in an electrostatic precipitator and a wet desulfurization scrubber. Emissions into the atmosphere were lower than 1% of the quantity in coal, but the volatile trace elements showed somewhat higher emission ratios. For mercury, the mean concentration in coal was 0.045 ppm, the mean emission rate was 4.4 microg/kW h, and the mean emission ratio was 27%, the highest ratio among all elements in this study. The total annual emission of mercury from coal-fired power plants of the electric power industry in Japan was estimated to be 0.63 t/y. On the basis of these data, the atmospheric environment loads from a coal-fired power station were investigated. The calculation of stack gas dispersion showed that maximum annual mean ground level concentrations were in the order of 10(-2) to 10(-5) of the background concentrations, and that the adverse effect of the emissions from the coal-fired power station was small.     

Assessing the human health risks from exposure of inorganic arsenic through oyster (Crassostrea gigas) consumption in Taiwan

This study estimated the human health risk associated with ingesting inorganic arsenic through consumption of farmed oysters in Taiwan. Two hundred fifty-four samples of oyster (Crassostrea gigas) were collected from four townships in southwest coastal areas, where 90% of Taiwan's oysters are produced. The concentrations of total arsenic and arsenic species including As(V), As(III), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) were analyzed. The analytical results reveal that the ratio of mean concentration among the four townships of inorganic As to total concentration of As in oysters is approximately 1.64%. The mean concentrations of As(III) and As(V) in oysters from the four townships range from 0.071 to 0.145 microg/g, and 0.032 to 0.062 microg/g respectively. The estimated target cancer risks (TR), based on a 95% occurrence probability from ingesting inorganic As by consuming oysters at a rate of 18.6-56 g/day, range from 1.26 x 10(-5) to 3.82 x 10(-5). The probabilities of TR fell within the range 10(-6)-10(-4), suggesting that inorganic As uptake from farmed oysters is associated with a potential cancer risk. Moreover, a target hazard quotient (THQ) was used to evaluate the non-carcinogenic risk associated with ingesting inorganic As through oyster consumption at a rate of 18.6-56 g/day. The THQ values based on a 95% probability of exposure range from 0.071 to 0.214. All THQ values are below unity, indicating that farmed oyster consumption contributes only a little to the non-carcinogenic risk. Based on the estimation of the TR model, an ingestion rate of 1.6 g/day is recommended to meet the 95th percentile of carcinogenic risk, 10(-6), for exposure to inorganic As through the consumption of oysters in Taiwan.     

Recycled water: potential health risks from volatile organic compounds and use of 1,4-dichlorobenzene as treatment performance indicator

Characterisation of the concentrations and potential health risks of chemicals in recycled water is important if this source of water is to be safely used to supplement drinking water sources. This research was conducted to: (i) determine the concentration of volatile organic compounds (VOCs) in secondary treated effluent (STE) and, post-reverse osmosis (RO) treatment and to; (ii) assess the health risk associated with VOCs for indirect potable reuse (IPR). Samples were examined pre and post-RO in one full-scale and one pilot plant in Perth, Western Australia. Risk quotients (RQ) were estimated by expressing the maximum and median concentration as a function of the health value. Of 61 VOCs analysed over a period of three years, twenty one (21) were detected in STE, with 1,4-dichlorobenzene (94%); tetrachloroethene (88%); carbon disulfide (81%) and; chloromethane (58%) most commonly detected. Median concentrations for these compounds in STE ranged from 0.81 μg/L for 1,4-dichlorobenzene to 0.02 μg/L for carbon disulphide. After RO, twenty six (26) VOCs were detected, of which 1,4-dichlorobenzene (89%); acrylonitrile (83%) chloromethane (63%) and carbon disulfide (40%) were the more frequently detected. RQ(max) were all below health values in the STE and after RO. Median removal efficiency for RO was variable, ranging from −77% (dichlorodifluoromethane) to 91.2% (tetrachloroethene). The results indicate that despite the detection of VOCs in STE and after RO, their human health impact in IPR is negligible due to the low concentrations detected. The results indicate that 1,4-dichlorobenzene is a potential treatment chemical indicator for assessment of VOCs in IPR using RO treatment.     

A comparative study of Cyperus papyrus and Miscanthidium violaceum-based constructed wetlands for wastewater treatment in a tropical climate

The treatment efficiencies of constructed wetlands containing Cyperus papyrus L. (papyrus) and Miscanthidium violaceum (K. Schum.) Robyns (synonymous with Miscanthus violaceum (K. Schum) Pilg.) were investigated in a tropical climate (Kampala, Uganda). Papyrus showed higher ammonium-nitrogen and total reactive phosphorus (TRP) removal (75.3% and 83.2%) than Miscanthidium (61.5% and 48.4%) and unplanted controls (27.9% ammonium-nitrogen). No TRP removal was detected in control effluent. Nutrients (N and P) were significantly higher (p<0.015) in papyrus than Miscanthidium plant tissues. Plant uptake and storage was the major factor responsible for N and P removal in treatment line 2 (papyrus) where it contributed 69.5% N and 88.8% P of the total N and P removed. It however accounted for only 15.8% N and 30.7% P of the total N and P removed by treatment line 3 (Miscanthidium violaceum). In addition, papyrus exhibited a significantly larger (p=0.000) number of adventitious roots than Miscanthidium. Nitrifying bacteria attached to papyrus (2.15 x 10(6)+/-1.53 x 10(5) MPN/g DW) and Miscanthidium roots (1.30 x 10(4)+/-8.83 x 10(2) MPN/g DW) and the corresponding nitrification activities were consistent with this finding. Epiphytic nitrifiers appeared more important for total nitrification than those in peat or suspended in water. Papyrus root structures provided more microbial attachment sites, sufficient wastewater residence time, trapping and settlement of suspended particles, surface area for pollutant adsorption, uptake, assimilation in plant tissues and oxygen for organic and inorganic matter oxidation in the rhizosphere, accounting for its high treatment efficiency.     

Estimating national exhaust emissions from railway vehicles in Turkey

The estimated exhaust emissions from railway vehicles in Turkey were presented. The emissions of nitrogen oxides (NO(X)), hydrocarbon compounds (HC), carbon monoxide (CO), particulate matter (PM), sulfur dioxide (SO(2)) and carbon dioxide (CO(2)) from the diesel locomotives and railcars were calculated using the railway traffic data recorded by Turkish State Railways (TSR) for the period of 2000-2005. EPA emission factors were used for different vehicle types and operation modes such as shunting and line-hauling. Total emissions from railway vehicles in Turkey were estimated as 384 t y(-1) for HC, 1016 t y(-1) for CO, 6799 t y(-1) for NO(X), 256 t y(-1) for PM, 357 t y(-1) for SO(2) and 383 537 t y(-1) for CO(2) for the year 2005. The distribution of emissions with respect to type of railway vehicles shows that the mainline locomotives contribute approximately 91% to the total emissions. The increases of 22%, 39% and 49% in the current numbers of mainline locomotives, shunting locomotives and diesel railcars, respectively corresponding to the full capacity of railway network in Turkey will increase the annual emissions to 431 t y(-1) for HC, 1121 t y(-1) for CO, 7399 t y(-1) for NO(X), 342 t y(-1) for PM, 552 t y(-1) for SO(2) and 420 256 t y(-1) for CO(2). Total railway emissions constitute 0.15%, 0.08% and 4.21% of total Turkish traffic emissions for HC, CO and NO(X), respectively.     

Groundwater contamination potential from stormwater infiltration practices

The potential effects of stormwater on groundwater quality was estimated based on the likely presence of problem constituents in the stormwater, their mobility through soils, the type of treatment received before infiltration, and the infiltration method used. The constituents of most concern include chloride, certain pesticides (lindane and chlordane), organic toxicants (1,3-dichlorobenzene, pyrene and fluoranthene), pathogens, and some heavy metals (nickel and zinc). Reported instances of groundwater contamination associated with stormwater was rare in residential areas where infiltration occurred through surface soils (except for chloride), but was more common (especially for toxicants) in commercial and industrial areas where subsurface infiltration was used.