The widely used antimicrobial agent triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) readily reacts with free chlorine under drinking water treatment conditions. Overall second-order kinetics were observed, first-order in free chlorine and first-order in triclosan. Over the pH range of 4-11.5, the kinetics were pH sensitive as a result of the pH dependent speciation of both triclosan and free chlorine. Using a Marquardt-Levenberg routine, it was determined that this pH effect indicates that the dominant reaction in this system is between the ionized phenolate form of triclosan and hypochlorous acid (HOCl). The overall second-order rate coefficient was determined to be kArO- = 5.40 (+/- 1.82) x 10(3) M(-1) s(-1). Three chlorophenoxyphenols and two chlorophenols were identified by gas chromatographic-mass spectroscopic analysis. The chlorophenoxyphenol compounds include two monochlorinated triclosan derivatives (5,6-dichloro-2-(2,4-dichlorophenoy)phenol and 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol) and one dichlorinated derivative (4,5,6-trichloro-(2,4-dichlorophenoxy)phenol); these species form via bimolecular electrophilic substitution of triclosan. 2,4-Dichlorophenol was detected under all reaction conditions and forms via ether cleavage of triclosan. In experiments with excess free chlorine, 2,4,6-trichlorophenol was formed via electrophilic substitution of 2,4-dichlorophenol. Chloroform formation was observed when an excess of free chlorine was present. A Hammett-type linear free-energy relationship (LFER) using Brown-Okamoto parameters (sigma+) was established to correlate the reactivity of HOCI and the phenolate forms of triclosan and other chlorophenols (log kArO- = -(10.7 +/- 2.2)Sigmasigma(+)o,m,p + 4.43). This LFER was used to obtain estimates of rate coefficients describing the reactivity of the intermediates 5,6-dichloro-2-(2,4-dichlorophenoy)phenol (kArO- approximately equal to 6 x 10(2)), 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol (kArO- approximately equal to 3 x 10(2)), and 4,5,6-trichloro-(2,4-dichlorophenoxy)phenol (kArO- approximately equal to 4 x 10(1)).

Triclosan is a widely used antibacterial agent found in many personal hygiene products. Although it has previously been established that pure triclosan and free chlorine readily react, interactions between triclosan-containing consumer products and free chlorine have not previously been analyzed in great depth. Sixteen double-blinded solutions including both triclosan-containing (1.14-3.12 mg triclosan/g product) and triclosan-free products were contacted with free chlorine at pH 7. Products detected included (chlorophenoxy) phenols, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and chloroform. The daughter product yields were found to be highly variable and were dependent on the antimicrobial product investigated, the free chlorine to triclosan ratio, and the temperature at which the study was conducted. Lowering the temperature from 40 to 30 degrees C resulted in a decreased average chloroform yield from 0.50 to 0.37 mol chloroform/mol triclosan consumed after 1 min of reaction time for an initial free chlorine concentration of 4.0 mg/L as Cl2. At 40 degrees C the average molar chloroform yields decreased to 0.29 and <0.1 when the initial free chlorine concentration was decreased to either 2.0 or 1.0 mg/L as Cl2, respectively. Field experiments, in which Atlanta, GA and Danville, VA tap waters were augmented with various soap products, exhibited results varying from the laboratory experiments in that different productyields were observed. These differences are attributed to the chlorine demand of constituents in the tap water. A simple exposure model suggests that exposure to chloroform can be significant under some conditions.

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A rapid surface-enhanced resonance Raman spectroscopy (SERRS) method has been developed for the detection of two waterborne pathogens, Cryptosporidium parvum and Giardia lambia. Raman labels were prepared by conjugating gold nanoparticles with commercial antibodies and dye molecules. After incubation with the immunogold labels, C. parvum oocysts and G. lamblia could easily be measured and differentiated by Raman spectroscopy. The immunogold signal intensities were optimized by testing several sizes of gold nanoparticles, four different commercially available dye molecules, and two Raman excitation wavelengths. Raman maps were collected across fixed and labeled Cryptosporidium oocysts and Giardia cysts, and the maps were used to determine which C. parvum and G. lamblia antibodies exhibited the best specificities and organism coverages. Ultimately, 40 nm gold nanoparticles were conjugated with rhodamine B isothiocyanate and malachite green isothiocyanate for the C. parvum and G. lamblia immunogold syntheses, respectively. C. parvum monoclonal IgM antibodies and G. lamblia monoclonal IgG1 antibodies resulted in the best immunogold coverage. The research presented here demonstrates the feasibility of utilizing SERRS labeling for sensitive multipathogen monitoring strategies.

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Crude influent sewages were collected from 30 English wastewater treatment works representing rural, urban and industrial catchments as part of a screening study to assess the significance of the concentrations of substances from the Water Framework Directive priority pollutants list in crude sewage. Composite samples were analysed for a range of determinands including metals and organic compounds. Of the determinands quantified, the pesticides were almost exclusively below the limit of detection. Most trace metals (with the exception of mercury) were detectable in all wastewaters, reflecting their ubiquitous nature. Organic determinands detected in the influent at μg/L levels included surfactants (linear alkylbenzene sulphonates and nonylphenol ethoxylates), phthalates (diethylhexyl phthalate), polynuclear hydrocarbons and solvents. Trace concentrations of trichlorobenzene, tributyltin and polychlorinated biphenyl 153 were detected in a limited number of works. Little correlation was observed between runoff or trade effluent inputs entering the works and determinand concentration (chromium being the only exception).

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Ratios of analyte mass to total organic carbon (OC) mass (µg/ g) for the PM1.8 and the PM0.1 size fractions are shown in Tables 1 and 2, respectively. Ratios of analyte mass to total elemental carbon (EC) mass (µg/g) for the PM1.8 and PM0.1 size fractions are shown in Tables 3 and 4, respectively. The PM0.1 values published in the original manuscript did not incorporate the pyrolysis correction in the OC and EC values used to normalize the mass of each analyte. The PM1.8 values published in the original manuscript did not incorporate correction for adsorption artifacts measured with a downstream filter. The authors apologize for these errors.The revised values shown in Tables 1-4 confirm all of the conclusions made in the original manuscript with a single exception. The abundance of PAHs relative to OC in the ultrafine size fraction and the PM1.8 size fraction are approximately equal. There is not an enhancement of the relative PAH concentration in the ultrafine size fraction as was stated in the original manuscript.