Le carbone organique: Son interet dans le controle de la preozonation

The present study was performed on Seine River water and cultured water where algal growth was favoured. Multiple samples were collected during a 7-month period (November 1982–May 1983) at the Choisy-le-Roy water treatment plant. The effects of preozonation were assessed in all samples by measuring total organic carbon (TOC) and dissolved organic carbon (DOC). The latter measurements were made in ampoules on 10 ml samples after acidification and oxidation. Two different oxidation processes were tested: oxidation process No. 1 was made in the presence of 0.2 g of potassium peroxodisulphate during 5 h at 130°C; oxidation process No. 2 was made in the presence of 0.4 g of potassium peroxodisulphate during 7 h at 130°C. The CO₂ generated in the samples was measured with an infrared detector. This protocol was performed on raw water and on preozonated water. We thus had 8 variables: DOC and TOC measured in raw water and in preozonated water after two different oxidation treatments.Particular attention was paid to statistical analysis of data to improve their interpretation. Multivariate statistical analysis (principal components analysis) showed good correlations between variables (P < 0.01) (Table 5) and the importance of tested parameters on organic carbon values 98% of the total inertia is due to sampling period (75%), filtration (12.8%), different oxidation processes used for organic carbon measurement (7.5%) and preozonation (2.6%) (Table 6, Fig. 1). Representation of the samples in the principal planes (Figs 2, 3 and 4) showed gathering of points corresponding to the same sampling period (i.e. November, January, March, April, May), the points related to November and March being opposite. It seems thus they have a different behaviour with regards to the tested parameters. This was confirmed by values in Table 7 concerning mean ± SEM values of the predefined sampling periods.The univariate statistical analysis (variance analysis and paired Student test) showed the variability of the Seine River and the presence, throughout the tested period, of a significant amount of particulate organic carbon (Table 9). The influence of oxidation performed before the organic carbon measurement is generally more important for TOC evaluation than for DOC (Table 10). Table 11 confirms this result for November.The higher preozonation effect appears in DOC measured in Seine River water after the stronger oxidation (i.e. oxidation No. 2) (Table 12). Table 13 shows that on March samples this effect appears only in DOC measured after oxidation process No. 2. Increasing the preozonation rate did not reveal this effect (Table 14).The two oxidation processes tested were not sufficient for exact determination of TOC but they allowed us to discuss preozonation effect on organic matter, this effect being different in function of the sampling period.The statistical analysis used made possible the quantitative evaluation of the preozonation effect which is generally only suggested.     

Reducing the concentration of assimilable organic carbon (AOC) in treated drinking water

This study focuses on reducing the concentration of assimilable organic carbon (AOC) in treated drinking water. Experiments were conducted to evaluate the efficiency of AOC removal by biological activated carbon filters (BACF) in a pilot-scale system. The measured values of AOC in treated drinking water were approximately 59.0 ± 8.6 μg acetate-C/L. The results show that BACFs reduce the total concentration of AOC. The concentration of AOC primarily indicates microbial growth in a water supply network, and the amount of AOC in the water is significantly reduced after BACF treatment. After BACF treatment, the removal of AOC was approximately 58% after 40 min of empty-bed contact time. An AOC empirical equation was established by determining the relationship between water quality parameters, such as total organic carbon, dissolved organic carbon, UV₂₅₄, ammonia nitrogen, and total phosphorous.     

Fossil organic carbon in wastewater and its fate in treatment plants

This study reports the presence of fossil organic carbon in wastewater and its fate in wastewater treatment plants. The findings pinpoint the inaccuracy of current greenhouse gas accounting guidelines which defines all organic carbon in wastewater to be of biogenic origin. Stable and radiocarbon isotopes (¹³C and ¹⁴C) were measured throughout the process train in four municipal wastewater treatment plants equipped with secondary activated sludge treatment. Isotopic mass balance analyses indicate that 4–14% of influent total organic carbon (TOC) is of fossil origin with concentrations between 6 and 35 mg/L; 88–98% of this is removed from the wastewater. The TOC mass balance analysis suggests that 39–65% of the fossil organic carbon from the influent is incorporated into the activated sludge through adsorption or from cell assimilation while 29–50% is likely transformed to carbon dioxide (CO₂) during secondary treatment. The fossil organic carbon fraction in the sludge undergoes further biodegradation during anaerobic digestion with a 12% decrease in mass. 1.4–6.3% of the influent TOC consists of both biogenic and fossil carbon is estimated to be emitted as fossil CO₂ from activated sludge treatment alone. The results suggest that current greenhouse gas accounting guidelines, which assume that all CO₂ emission from wastewater is biogenic may lead to underestimation of emissions.     

Isolation and characterization of polymeric organic materials in a polluted river water

Organic matter was isolated from water samples from a river mainly polluted by domestic sewage by using Amberlite XAD-2 resin after being acidified to pH 2. The amount of the isolated organic matter comprises about 40% of the total dissolved organic matter. Measurements of elementary composition, molecular weight distribution, u.v. and i.r. spectra and GC/MS analysis of alkaline potassium permanganate oxidation products were performed for the isolated matter. The results indicate that more than a half of the isolated organic matter have apparent molecular weights higher than 5000. The chemical oxidation of the isolated organic matter produced (a) aliphatic monocarboxylic acids (C₆---C₂₄), (b) aliphatic dicarboxylic acids (C₃-C₁₂) and (c) benzene-mono-di-, tri- and tetracarboxylic acids: the latter two groups (b and c) are most abundant. The relative amounts of those three groups seem to be explained in terms of the nature and degree of pollution.     

Impact of salinity and pH on the UVC/H2O2 treatment of reverse osmosis concentrate produced from municipal wastewater reclamation

While reverse osmosis (RO) technology is playing an increasingly important role in the reclamation of municipal wastewater, safe disposal of the resulting RO concentrate (ROC), which can have high levels of effluent organic pollutants, remains a challenge to the water industry. The potential of UVC/H₂O₂ treatment for degrading the organic pollutants and increasing their biodegradability has been demonstrated in several studies, and in this work the impact of the water quality variables pH, salinity and initial organic concentration on the UVC/H₂O₂ (3 mM) treatment of a municipal ROC was investigated. The reduction in chemical oxygen demand and dissolved organic carbon was markedly faster and greater under acidic conditions, and the treatment performance was apparently not affected by salinity as increasing the ROC salinity 4-fold had only minimal impact on organics reduction. The biodegradability of the ROC (as indicated by biodegradable dissolved organic carbon (BDOC) level) was at least doubled after 2 h UVC/H₂O₂ treatment under various reaction conditions. However, the production of biodegradable intermediates was limited after 30 min treatment, which was associated with the depletion of the conjugated compounds. Overall, more than 80% of the DOC was removed after 2 h UVC/3 mM H₂O₂ treatment followed by biological treatment (BDOC test) for the ROC at pH 4-8.5 and electrical conductivity up to 11.16 mS/cm. However, shorter UV irradiation time gave markedly higher energy efficiency (e.g., EE/O 50 kWh/m³ at 30 min (63% DOC removal) cf. 112 kWh/m³ at 2 h). No toxicity was detected for the treated ROC using Microtox^® tests. Although the trihalomethane formation potential increased after the UVC/H₂O₂ treatment, it was reduced to below that of the raw ROC after the biological treatment.     

Dissolved organic compounds in reused process water for steam-assisted gravity drainage oil sands extraction

The in situ oil sands production method called steam-assisted gravity drainage (SAGD) reuses process wastewater following treatment. However, the treatment and reuse processes concentrate contaminants in the process water. To determine the concentration and dynamics of inorganic and organic contaminants, makeup water and process water from six process steps were sampled at a facility employing the SAGD process in Alberta, Canada. In the groundwater used for the makeup water, the total dissolved organic carbon (DOC) content was 4 mg/L. This significantly increased to 508 mg/L in the produced water, followed by a gradual increase with successive steps in subsequent water treatments. The concentrations and dynamics of DOC constituents in the process water determined by gas chromatography-mass spectrometry showed that in the produced water, volatile organic compounds (VOCs) such as acetone (33.1 mg/L) and 2-butanone (13.4 mg/L) predominated, and there were significant amounts of phenolic compounds (total 9.8 mg/L) and organic acids including naphthenic acids (NAs) corresponding to the formula C_nH_2n+ZO_X for combinations of n = 4 to 18, Z = 0 and −2, and X = 2 to 4 (53 mg/L) with trace amounts of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene and phenanthrene. No organic contaminants, except for saturated fatty acids, were detected in the groundwater. The concentration of DOC in the recycled water was 4.4-fold higher than that in the produced water. Likewise, the total concentrations of phenols and organic acids in the recycled water were 1.7- and 4.5-fold higher than in the produced water, whereas the total concentrations of VOCs and PAHs in the recycled water were reduced by over 80%, suggesting that phenols and organic acids are selectively concentrated in the process water treatment. This comprehensive chemical analysis thus identified organic constituents that were concentrated in the process water and which interfere with subsequent water treatments in the SAGD process.     

Substatiation of technological modes for effective operation of oxidative-sorption units of water treatment

The paper assessed the degree of oxidative-sorption purification of model waters on a local unit of drinking water conditioning, capacity up to 1 m³/h. It is shown that the quality of the effluent in terms of generalized indicators characterizing the total content of organic impurities, corresponds to regulatory requirements for drinking water. The replacement of ozonization with O₃/UV treatment increases the fraction of absorbed ozone and the destruction degree of organic impurities. The degree of oxidative-sorption of water treatment by all parameters being controlled is higher than the adsorption one.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments-IV Indicators of hydrocarbon pollution for waters

The ratios between organic carbons and hydrocarbon constituents were compared for polluted river waters from the Tokyo area and unpolluted river, brook, reservoir and pond waters from the Ogasawara (Bonin) Islands to derive indicators of hydrocarbon pollution fossil fuels and their products and both combustion products, and industrial products. The hydrocarbons as carbon (HCC)/total organic carbon (TOC). HCC extractable organic carbon with ethyl acetate (EOC), squalane as carbon (SgC),TOC, SqC/EOC, and unresolved complex mixture of hydrocarbons (UCMH)n-Alkane (C₁₅-C₃₃) ratios of the waters from the Tokyo area were much higher than those of the waters from the Ogasawara Islands. The values of carbon preference index (CPI₁₁) for n-alkanes (C₁₄-C₁₄) close to unity were found in all the water samples from the Tokyo area. They are considerably lower than those of the water samples from the Ogasawara Islands. These results indicate that the HCC TOC, HCC/EOC UCMH/n-Alkane and CPI₁₁ values are the important indicators of hydrocarbon pollution. Further, it was suggested that the SqC/TOC and SqC/EOC ratios are useful indicators of urban-industrial activities on water systems.     

Microscale fluctuation assay coupled with Sep-PakR concentration as a rapid and sensitive method for screening mutagens in drinking water

A sensitive short-term mutagenicity test, the microscale fluctuation test has been coupled with a concentration method based on adsorption on Sep-Pak^R C₁₈ cartridges as a method for screening drinking water mutagens. Comparison with XAD-2 concentration method showed that Sep-Pak adsorbed 5 times higher quantity of organics but was slightly less efficient for adsorbing TOX.Microscale fluctuation test was found to be more sensitive than Ames test by testing known direct-acting mutagens and concentrates of drinking water. Samples derived from conventional treatment including chlorination from eight surface water supplies in Norway were concentrated at pH 2 by adsorption on the disposable columns. The adsorbates were tested at different doses by the microscale fluctuation assay. The mutagenic properties of drinking water samples were also related to total organic carbon (TOC), total organic halogen (TOX) and trihalomethanes (THM) concentrations. Dose-related mutagenic responses were found for all the samples with S. typhimurium TA 100 and TA98 strains without metabolic activation. Good relationship was found between mutagenicity data and TOX and THM results. The method showed to be simple, rapid and suitable for routine screening of mutagens in drinking water.     

Impact of hydrogen peroxide on the destruction degree of fulvic acids and organic impurities of river water by ozone,UV radiation,and O<Subscript>3</Subscript>/UV treatment

We have investigated the impact of hydrogen peroxide on the change of the generalized indicators of water quality of the Dnieper River and model solutions of fulvic acids in UV radiation, ozonization, and O₃/UV treatment. We confirmed its involvement in the oxidation process of organic impurities by all studied methods at the pH of the medium more than 7. However, the additions of 1–5 mg/dm³ of hydrogen peroxide inhibited the destruction of fulvic acid in a weakly acidic medium (pH 6.3) and reduced the mineralization degree of water impurities of the Dnieper River during O₃/UV treatment and do note accelerate discoloration of the samples under investigation at the studied parameters of ozonization and O₃/UV treatment.     

Tracking natural organic matter (NOM) in a drinking water treatment plant using fluorescence excitation-emission matrices and PARAFAC

Natural organic matter (NOM) in water samples from a drinking water treatment train was characterized using fluorescence excitation emission matrices (F-EEMs) and parallel factor analysis (PARAFAC). A seven component PARAFAC model was developed and validated using 147 F-EEMs of water samples from two full-scale water treatment plants. It was found that the fluorescent components have spectral features similar to those previously extracted from F-EEMs of dissolved organic matter (DOM) from diverse aquatic environments. Five of these components are humic-like with a terrestrial, anthropogenic or marine origin, while two are protein-like with fluorescence spectra similar to those of tryptophan-like and tyrosine-like fluorophores. A correlation analysis was carried out for samples of one treatment plant between the maximum fluorescence intensities (F_max) of the seven PARAFAC components and NOM fractions (humics, building blocks, neutrals, biopolymers and low molecular weight acids) of the same sample obtained using liquid chromatography with organic carbon detection (LC-OCD). There were significant correlations (p < 0.01) between sample DOC concentration, UVA₂₅₄, and F_max for the seven PARAFAC components and DOC concentrations of the LC-OCD fractions. Three of the humic-like components showed slightly better predictions of DOC and humic fraction concentrations than UVA_254. Tryptophan-like and tyrosine-like components correlated positively with the biopolymer fraction. These results demonstrate that fluorescent components extracted from F-EEMs using PARAFAC could be related to previously defined NOM fractions and that they could provide an alternative tool for evaluating the removal of NOM fractions of interest during water treatment.     

Effects of ozonation and ultraviolet irradiation on biodegradability of oil shale wastewater organic solutes

Ozonation and u.v. irradiation were evaluated for their abilities to (1) mineralize organic solutes that remained in a biooxidized oil shale process wastewater and (2) effect sufficient structural modification of the remaining biorefractory organic solutes to promote secondary biooxidation. Full-spectrum u.v. radiation (5 h, total dose of 10.2 × 10⁶ J l⁻¹) failed to mineralize or effect the biooxidation of any of the biorefractory carbon. Although ozonation (5 h, total dose of 1.6 g O₃ l⁻¹) directly mineralized only 8% of the biorefractory carbon, it enhanced secondary biooxidation; 26% of the refractory carbon was mineralized by an acclimated microbial inoculum. When u.v. irradiation and ozonation were combined simultaneously, a synergistic effect was observed; 3 h of combined treatment (5.9 × 10⁶ J l⁻¹ and 0.83 g O₃ l⁻¹) was as effective a pretreatment for secondary biooxidation as was 5 h of ozonation. Sequential application of primary biooxidation, 6 h of combined u.v./ozonation, and secondary biooxidation removed only 59% of the dissolved organic carbon; total reduction of 87% was achieved by using a culture in the secondary biooxidation step that was specifically adapted to this oxidized water. Each time-course sample was analyzed for the distribution of polar and nonpolar organic solutes. In general, ozonation and combined u.v./ozonation mineralized carbon from the nonpolar fraction; biooxidation of formerly refractory carbon was promoted by oxidation of nonpolar carbon to yield more polar or lower-molecular-weight species.     

Measurements of dissolved organic nitrogen (DON) in water samples with nanofiltration pretreatment

Dissolved organic nitrogen (DON) measurements for water samples with a high dissolved inorganic nitrogen (DIN, including nitrite, nitrate and ammonia) to total dissolved nitrogen (TDN) ratio using traditional methods are inaccurate due to the cumulative analytical errors of independently measured nitrogen species (TDN and DIN). In this study, we present a nanofiltration (NF) pretreatment to increase the accuracy and precision of DON measurements by selectively concentrating DON while passing through DIN species in water samples to reduce the DIN/TDN ratio. Three commercial NF membranes (NF90, NF270 and HL) were tested. The rejection efficiency of finished water from the Yangshupu drinking water treatment plant (YDWTP) is 12%, 31%, 8% of nitrate, 26%, 28%, 23% of ammonia, 77%, 78%, 82% of DOC (dissolved organic carbon), and 83%, 87% 88% of UV₂₅₄ for HL, NF90 and NF270, respectively. NF270 showed the best performance due to its high DIN permeability and DON retention (∼80%). NF270 can lower the DIN/TDN ratio from around 1 to less than 0.6 mg N/mg N, and satisfactory DOC recoveries as well as DON measurements in synthetic water samples were obtained using optimized operating parameters. Compared to the available dialysis pretreatment method, the NF pretreatment method shows a similar improved performance for DON measurement for aqueous samples and can save at least 20 h of operating time and a large volume of deionized water, which is beneficial for laboratories involved in DON analysis. DON concentration in the effluent of different treatment processes at the YDWTP and the SDWTP (Shijiuyang DWTP) in China were investigated with and without NF pretreatment; the results showed that DON with NF pretreatment and DOC both gradually decreased after each water treatment process at both treatment plants. The advanced water treatment line, including biological pretreatment, clarification, sand filtration, ozone-BAC processes at the SDWTP showed greater efficiency of DON removal from 0.37 to 0.11 mg N L⁻¹ than that at the YDWTP, including pre-ozonation, clarification and sand filtration processes from 0.18 to 0.11 mg N L⁻¹.     

Photocatalytic destruction of fulvic acids by oxygen in the TiO<Subscript>2</Subscript> suspension

The paper presents a short review of the published data dealing with the photocatalytic (O₂/TiO₂/UV) oxidation of humic and fulvic acids that represent main organic impurities of natural waters. The possibility of achieving a deep destruction (≥ 90% in terms of TOC) of fulvic acids separated from the water of the Dnieper River during the process of photocatalytic oxidation by oxygen was shown for a wide interval of pH (3–8). The photocatalytic activity of a series of commercial TiO₂ samples in different isomorphic states was estimated and the impact of certain parameters of photocatalytic oxidation on the degree of complete destruction of fulvic acids was determined.     

Water disinfection by joint effects of ozone and UV radiation in a flow-through mode

We have investigated the efficiency of disinfection and destruction of organic impurities of model and natural waters separately and together by ozone and UV radiation in the flow-through mode on a laboratory unit with the capacity 0.02 m³/h. We agreed on the parameters of ozonization and O₃/UV treatment of the Dnieper water in the flow-through mode making for the degree of its decontamination and discoloration corresponding to the standards for drinking water. It has been shown that the use of O₃/UV treatment raises the degree of disinfection and purification of the Dnieper water from organic impurities compared with ozonization or UV radiation.     

Automated determination of carbon in natural waters

An automated method for determining inorganic carbon and organic carbon in water is described. The sample is acidified and the CO₂ from inorganic carbonate is removed in a packed column and measured with an i.r. analyzer. The stripped liquid is pumped to a furnace containing cobalt oxide catalyst at 950°C where the organic carbon is oxidized; the resulting CO₂ is measured with an i.r. analyzer. Operating as a “two-channel” system, inorganic carbon and organic carbon are measured simultaneously at 20 samples per hour. If used in a “single-channel” mode, inorganic and organic carbon are measured separately, inorganic carbon at 60 samples per hour, organic carbon at 20 samples per hour. The coefficients of variation at 1 and 5 mg l⁻¹ organic carbon are 5.1 and 2.8% respectively. The detection limit is 200 μg l⁻¹C.     

Biosorption processes in biomembrane systems during water treatment of surface water sources

The characteristics of a system with bioactive powdered activated carbon and microfiltration have been studied under conditions of the aerobic treatment of natural water from the water storages of Guan Ting (China), the Moskva River, and the Yauza River (Russia). The removal of organic matter in the system was estimated in terms of the permanganate oxidizability and UV absorption at λ = 254 nm (UV₂₅₄) and λ = 410 nm (UV₄₁₀). The average removal efficiency amounted to 68.42, 75.61, and 87.50%, respectively, at water temperature 10°C. The water treatment process (at 20°C) began immediately after the start-up of the plant at the expense of the adsorption on activated carbon that guaranteed a high speed of removal of organic pollutants in the absence of mature microflora. By the time the adsorption capacity of carbon was exhausted, the microflora was able to mature ensuring in combination with the powdered activated carbon a high speed of removal. In order to guarantee the biological stability of water, the removal degree of assimilable organic carbon amounted to 60.2% and the purified water met the requirements of the recommended criterion (100 mg acetate-C/dm³).     

The impact of increased oxygen conditions on metal-contaminated sediments part I: effects on redox status, sediment geochemistry and metal bioavailability

In order to evaluate the effect of improved oxygen concentrations in overlying surface water on the redox status, sediment geochemistry and metal bioavailability in metal-polluted sediments a 54 days lab experiment with two different experimental treatments was conducted (90% and 40% O₂). Changes in redox potential (Eh) in the sediment were monitored over time. At 6 different time points (after 0, 2, 5, 12, 32 and 54 days) and at 4 sediment depths (0-1, 1-4, 4-8 and 8-15 cm), acid volatile sulfides (AVS), simultaneously extracted metals (SEM) and total organic carbon (TOC) were measured and metal release to overlying surface water was determined. Labile metal species in both water and sediment were measured using Diffusive Gradients in Thin films (DGT). Our results showed that elevated oxygen levels in overlying surface water led to an Eh increase in the sediment of the 90% O₂ treatment from 0 to ±200 mV while AVS concentrations in the upper sediment layer decreased by 70%. Following AVS oxidation metal availability in the pore water was highly elevated after 54 days. However, Cu remained strongly bound to the sediment during the whole experiment. Only a limited metal release to the overlying surface water was noticed, which was due to the fact that SEM_tot concentrations in the sediment did not yet exceeded AVS levels ([SEM_tot − AVS]/f_OC = 0) after 54 days. Additionally, adsorption on Fe and Mn hydroxides and particulate organic carbon also slowed down any potential metal release. Our results indicated that increasing oxygen concentrations due to general water quality improvements can enhance the mobility of trace metals which may result in the leaching of sediment-bound metals to overlying surface water, even in undisturbed watercourses.     

Performing a microfiltration integrated with photocatalysis using an Ag-TiO2/HAP/Al2O3 composite membrane for water treatment: Evaluating effectiveness for humic acid removal and anti-fouling properties

Membrane filtration has been increasingly used for water treatment and wastewater reclamation in recent years. To further improve the effectiveness of membrane process and reduce membrane fouling, a highly reactive photocatalytic membrane, Ag-TiO₂/hydroxiapiate (HAP, Ca₁₀(PO₄)₆(OH)₂)/Al₂O₃, was employed to realize microfiltration (MF) coupling photocatalysis for surface water treatment. The effectiveness on the potential of membrane was investigated by removing humic acid (HA) test under different feed total organic carbon (TOC), light intensity and transmembrane pressure (TMP). The HA removal and anti-fouling property of as-prepared membrane was improved under UV irradiation, likely due to photocatalytic degradation of foulants along with filtration simultaneously. Under given feed water composition, increasing the light intensity resulted in increased removal of HA from aqueous solution. However, a limiting TMP seems to exist beyond which the increased HA removal cannot be sustained. Fouling behavior analysis indicated that the transition in fouling mode from initial pore blocking to cake filtration occurred much slower as UV irradiated. Furthermore, a superior efficiency on removal of trace organic contaminants, as well as milder flux reduction, was presented from surface water treatment, which demonstrated that the integrated system with enhanced performance is foreseen as an emerging technique for water treatment.     

Characterisation of atmospheric deposition as a source of contaminants in urban rainwater tanks

To characterise atmospheric input of chemical contaminants to urban rainwater tanks, bulk deposition (wet + dry deposition) was collected at sixteen sites in Brisbane, Queensland, Australia on a monthly basis during April 2007-March 2008 (N = 175). Water from rainwater tanks (22 sites, 26 tanks) was also sampled concurrently. The deposition/tank water was analysed for metals, soluble anions and selected samples were additionally analysed for PAHs, pesticides, phenols, organic & inorganic carbon. Flux (mg/m²/d) of total solids mass was found to correlate with average daily rainfall (R² = 0.49) indicating the dominance of the wet deposition contribution to total solids mass. On average 97% of the total mass of analysed components was accounted for by Cl⁻ (25.0%), Na (22.6%), organic carbon (20.5%), NO₃⁻ (10.5%), SO₄²⁻ (9.8%), inorganic carbon (5.7%), PO₄³⁻ (1.6%) and NO₂⁻ (1.5%). For other minor elements the average flux from highest to lowest was in the order of Fe > Al > Zn > Mn > Sr > Pb > Ba > Cu > Se. There was a significant effect of location on flux of K, Sb, Sn, Li, Mn, Fe, Cu, Zn, Ba, Pb and SO₄²⁻ but not other metals or anions. Overall the water quality resulting from the deposition (wet + dry) was good but 10.3%, 1.7% and 17.7% of samples had concentrations of Pb, Cd and Fe respectively greater than the Australian Drinking Water Guidelines (ADWG). This generally occurred in the drier months. In comparison 14.2% and 6.1% of tank samples had total Pb and Zn concentrations exceeding the guidelines. The cumulative mean concentration of lead in deposition was on average only 1/4 of that in tank water over the year at a site with high concentrations of Pb in tank water. This is an indication that deposition from the atmosphere is not the major contributor to high lead concentrations in urban rainwater tanks in a city with reasonable air quality, though it is still a significant portion.