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Florfenicol (FF, CHClFNOS), an emerging halogenated organic contaminant of concern was effectively degraded in water by sulfidized nanoscale zerovalent iron (S-nZVI). Sulfidized nZVI (62.5 m g) that was prepared using a one-step method resulted in small Fe/Fe-sulfide particles that were more stable against aggregation than unsulfidized nZVI (10.2 m g). No obvious removal of FF was observed by unsulfidized nZVI. S-nZVI degraded FF, having a surface area normalized reaction rate constant of 3.1 × 10 L m min. The effects of the S/Fe molar ratio, initial FF concentration, initial pH, temperature, and water composition on the removal of FF by S-nZVI, and on the formation of reaction products, were systematically investigated. Both dechlorination and defluorination were observed, resulting in four degradation products (CHClFNOS, CHFNOS, CHNOS, and CHNOS). High removal efficiencies of FF by S-nZVI were achieved in groundwater, river water, seawater, and wastewater. The reactivity of S-nZVI was relatively unaffected by the presence of both dissolved ions and organic matter in the waters tested.

Recent epidemiological evidence support the hypothesis that health effects from inhalation of air particles are governed by more than just particle mass, since specific chemical components have been identified as important contributors to mortality and hospitality admissions. We studied the chemical composition and the oxidative potential (OP) of total suspended particle (TSP) samples from Milan at two sites with different traffic loads: a site in the low emission zone (LEZ) and a traffic site (TR) outside. Two a-cellular assays; dithiothreitol (OP DTT) and 2',7' dichlorofluorescin (OP DCFH) were used to characterize the OP of the soluble fraction of TSP. TSP samples from LEZ showed significantly lower concentrations of traffic-related chemical components compared to TR. The decrease in the concentrations from TR to LEZ was maximum for EC, with a LEZ/TR ratio of 0.64 (±0.18), and a significant reduction (p<0.01) was also observed for PAHs (LEZ/TR= 0.73± 0.16), elements (Mn, Cu, Zn, Cd, Pb: LEZ/TR ranged between 0.64-0.82), OC (LEZ/TR= 0.85± 0.12) and NH4 + (LEZ/TR= 0.92± 0.07). OP measures, expressed as OP/m 3 or OP/mg, were comparable between sites both for OP DTT and OP DCFH , thus not showing any significant impact of local traffic on OP values at sites. OP DTT and OP DCFH showed contrasting seasonal and daily trends, indicating that the two a-cellular assays gave complementary information on the OP of particles in Milan. The two OP assays resulted to be sensitive to different chemical properties of PM samples. OP DTT correlated positively only with Global Radiation (Spearman's rs= 0.38, p<0.05), which could be considered as a proxy for high concentrations of secondary oxidizing organics, while OP DCFH was related to various PM chemical species, mainly correlated with total mass (rs= 0.65; p<0.01), elements (e.g. Zn, rs=0.67; As, rs=0.65; p<0.01) and the sum of sulfate and nitrate (rs= 0.63; p<0.01), a proxy for secondary aerosol.

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