Inhibition of photosensitized degradation of organic contaminants by copper under conditions typical of estuarine and coastal waters

Dissolved organic matter (DOM) driven-photochemical processes play an important role in the redox cycling of trace metals and attenuation of organic contaminants in estuarine and coastal ecosystems. In this study, we evaluate the effect of Cu on 4-carboxybenzophenone (CBBP) and Suwannee River natural organic matter (SRNOM)-photosensitized degradation of seven target contaminants (TCs) including phenols and amines under pH conditions and salt concentrations typical of those encountered in estuarine and coastal waters. Our results show that trace amounts of Cu(II) (25  500 nM) induce strong inhibition of the photosensitized degradation of all TCs in solutions containing CBBP. The influence of TCs on the photo-formation of Cu(I) and the decrease in the lifetime of transformation intermediates of contaminants (TC & BULL;+/ TC & BULL;(-H)) in the presence of Cu(I) indicated that the inhibition effect of Cu was mainly due to the reduction of TC & BULL;+/ TC & BULL;(-H) by the photo-produced Cu(I). The inhibitory effect of Cu on the photodegradation of TCs decreased with the increase in Cl concentration since less reactive Cu(I) Cl complexes dominate at high Cl concentrations. The impact of Cu on the SRNOM-sensitized degradation of TCs is less pronounced compared to that observed in CBBP solution since the redox active moieties present in SRNOM competes with Cu(I) to reduce TC & BULL;+/ TC & BULL;(-H). A detailed mathematical model is

Automated summary

Dissolved organic matter (DOM) driven-photochemical processes are important in the redox cycling of trace metals and attenuation of organic contaminants in estuarine and coastal ecosystems. This study examined the effect of Cu on the photosensitized degradation of seven target contaminants (TCs) under typical pH and salt conditions. The results showed that trace amounts of Cu(II) strongly inhibit the degradation of TCs in solutions containing certain compounds. The inhibitory effect of Cu decreases with increasing Cl  concentration. Overall, Cu has a significant impact on the degradation of TCs. Rating: 8/10.