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The character of dissolved organic matter (DOM) in source waters from two countries (Australia and China) was investigated using an extended fractionation technique by combining resin adsorption, ultrafiltration and high performance size exclusion chromatography. There are distinctive chemical characteristics associated with DOM origins. Australian sourced DOM had higher hydrophobic acid (HoA) content and exhibited a more pronounced humic character, indicating a higher influence from allochthonous organics (decayed plant bodies from vegetated catchments). The higher content of hydrophobic base and neutral components found in Chinese DOM, may be attributed to the effects of increasing pollution caused by the rapid urbanization in China. The molecular weights (MWs) of aquatic HoA are predominantly in the moderate (e.g. 1–10 kDa) or small (e.g.

The pollutants in urban storm runoff, which lead to an non-point source contamination of water environment around cities, are of great concerns. The distributions of typical contaminants and the variations of their species in short term storm runoff from different land surfaces in Xiamen City were investigated. The concentrations of various contaminants, including organic matter, nutrients (i.e., N and P) and heavy metals, were significantly higher in parking lot and road runoff than those in roof and lawn runoff. The early runoff samples from traffic road and parking lot contained much high total nitrogen (TN 6–19 mg/L) and total phosphorus (TP 1–3 mg/L). A large proportion (around 60%) of TN existed as total dissolved nitrogen (TDN) species in most runoff. The percentage of TDN and the percentage of total dissolved phosphorus remained relatively stable during the rain events and did not decrease as dramatically as TN and TP. In addition, only parking lot and road runoff were contaminated by heavy metals, and both Pb (25–120 μg/L) and Zn (0.1–1.2 mg/L) were major heavy metals contaminating both runoff. Soluble Pb and Zn were predominantly existed as labile complex species (50%–99%), which may be adsorbed onto the surfaces of suspended particles and could be easily released out when pH decreased. This would have the great impact to the environment.

Dissolved organic matter (DOM) and its potential to form disinfection by-products (DBPs) during drinking water treatment raise challenges to water quality control. Understanding both chemical and physical characteristics of DOM in source waters is key to better water treatment. In this study, the DOM from four typical source waters in China was fractionated by XAD resin adsorption (RA) and ultrafiltration (UF) techniques. The trihalomethane formation potential (THMFP) of all fractions in the DOM were investigated to reveal the major THM precursors. The fraction distributions of DOM could be related to their geographical origins in a certain extent. The dominant chemical fraction as THM precursors in the DOM from south waters (East-Lake reservoir in Shenzhen and Peal rivers in Guangzhou) was hydrophobic acid (HoA). The size fraction with molecular weight (MW)

Urea hydrolysis has always been used to prepare alumina gels and little attention has been paid to the reactive polymeric Al species that is formed before alumina sol–gels occur. Based on the hydrolysis process of aluminum in urea solution at 90 °C, speciation and transformation of the reactive hydroxyl-Al polymers obtained by urea hydrolysis was investigated with Ferron assay, solution-state and solid-state 27Al NMR spectroscopy. Unlike the traditional viewpoint, Keggin-Al13 can form in solution without localized high alkalinity. The reaction of oligomers with Al(OH)4− resulted from the dissolving of colloidal Al hydroxides is accountable for the formation of Keggin-Al13. Alp1, the defected structure of Al13, was considered as the transient species in the transformation from Al13 to crystalline Al hydroxides. Besides Al13, some other reactive polymers with hexameric ring structure also exist. The two categories of Al species have different transformation models (i.e., forced hydrolysis and spontaneous hydrolysis). The forced hydrolysis model should be the main transformation pattern for Al species under the condition of strong base addition into Al solution. Sulphate ions inhibit the formation of high polymeric Al species and affect the crystal structure of the final Al precipitate.

Inorganic polymeric Al coagulants have been being widely used in water treatment due to their advantages of applicability within broad pH and temperature ranges, high capacity of charge neutralization as well as less alkalinity consumption. However, the removal of dissolved organic matter (DOM) by such kind of coagulants has not been well understood because of the complexity of natural organic matter and the diversity of such polymeric Al coagulants. In this paper, coagulants with different Al speciation characteristics were prepared to conduct coagulation of humic acid (HA). The humic acid used was peat origin and was characterized physicochemically. The results showed that coagulants with preformed Al species were less effective than conventional Al salt in removing humic acid with large molecular and hydrophobic properties. The floes formed by preformed Al species were smaller than those formed by conventional Al salt. Decreasing pH could improve the coagulation performance of all coagulants. Coagulation of humic acid might not follow the same charge neutralization rules associated with coagulation of mineral colloids. In the presence of humic acid, Al-13 could be decomposed during coagulation process. (c) 2006 Elsevier B.V. All rights reserved.

The pollutants in urban storm runoff, which lead to non-point source contamination of water environment around cities, are of great concerns. The distributions of typical contaminants and the variations of their species in short term storm runoff from different land surfaces in a seaside city in South China were investigated. The concentrations of various contaminants, including organic matter, nutrients (i.e., N and P) and heavy metals, were significantly higher in parking lot and road runoff than those in roof and lawn runoff. The early runoff samples from traffic road and parking lot contained much high total nitrogen (TN 6–19 mg/L) and total phosphorus (TP 1–3 mg/L). A large proportion (around 60%) of TN appeared as the species of total dissolved nitrogen (TDN) in most kinds of runoff. The percentage of TDN (%TDN) or percentage of total dissolved phosphorus (%TDP) remained relatively stable in runoff during the rain events and did not decrease as dramatically as TN or TP. In addition, only parking lot and road runoff were contaminated by heavy metals, in which only Pb (25–120 μg/L) and Zn (0.1–1.2 mg/L) were the significant heavy metal contaminants. Soluble Pb and Zn were predominantly existed as labile complex species (50%–99%), which are adsorbed on the surface of suspended particles and could be easily re-released out when ambient pH decreased. This indicates that the labile complex pb and Zn in urban runoff would have the largest impact on the aquatic environment.

Iron oxides coated on Fe-0 core-shell nanospheres (nIOCl) were synthesized through the reduction of ferrous sulfate aqueous solution by sodium borohydride at ambient atmosphere. The catalyst was highly effective for the degradation of humic acid (HA) in the presence of H2O2 and UVA at neutral pH. Under deoxygenated conditions in the dark, the generation of hydroxyl radicals in aqueous nIOCl dispersion verified its galvanic cell-like performance, which enhanced the interfacial electron transfer and led to its higher reactivity. By the total organic carbon, the absorbance Of UV254, FTIR, the molecular weight distribution and the chemical fractional character analysis, the degradation process of HA was shown to proceed by the disappearance of aromaticity, the increase of hydrophilic fraction and aromatic ring openings into CO2 and small organic acid. The treated HA showed much lower reactivity toward chlorine and the disinfection byproduct (DBP) formation potential was also greatly reduced. Moreover, it was found that the DBP formation potential more depended on the structure of the intermediates of HA degradation than TOC removal. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

Dissolved organic matter (DOM) and its potential to form disinfection by-products (DBPs) during water treatment are of great public health concern. Understanding the seasonal changes in DOM composition and their reactivity in DBP formation could lead to a better treatment of drinking water and a more consistent water quality. DOM from the East-Lake, a reservoir in the south-China, was fractionated and characterized by XAD resin adsorption (RA) and ultrafiltration (UF) techniques during different seasons within a year. The properties of chemical fractions (isolated by RA) appeared more stable than those of physical fractions (separated by UF) throughout the sampling period. The relative contribution of each chemical fraction to the total dissolved organic carbon (DOC), UV254 absorbance and trihalomethane formation potential (THMFP) remained relatively constant across the sampling period. However, the physical (molecular weight) fractions of the DOM exhibited large seasonal changes in UV254 and THMFP. Compared to the parameter of DOC, the THMFP and specific THMFP (STHMFP) of either chemical or physical fractions were more variable. In terms of DOC concentration, the hydrophobic acids (HoA) and hydrophilic matter (HiM) dominated in the DOM in most of the seasons; while the components with molecular weight of 10-30 kDa and less than I kDa were the predominant physical fractions. (c) 2007 Published by Elsevier B.V.