Modelling the occurrence and reactivity of the carbonate radical in surface freshwater

Abstract

A model was developed to foresee the degradation kinetics of dissolved compounds for reaction with the carbonate radical in surface waters. It would contribute to the assessment of the environmental persistence of pollutants, therefore allowing a better definition of the exposure of natural ecosystems and human communities to hazardous substances. The model is a function of the water chemical composition, the water column depth, and the second-order rate constant of the reaction between the relevant compound and the carbonate radical. A comparison between the reactivity of the carbonate and the hydroxyl radical shows that the latter would often play a more important role as reactive species, but the carbonate radical could prevail in carbonate-rich waters toward the degradation of easily oxidisable molecules.

Modelling the photochemical fate of ibuprofen in surface waters

“…The same compounds could also undergo significant transformation by CO 3 −• in the environment (Vione et al, 2009b …”

A model approach to assess the long-term trends of indirect photochemistry in lake water. The case of Lake Maggiore (NW Italy)

“…The formation rate of CO 3 −• in reaction (13) is given by (Canonica et al, 2005;Vione et al, 2009a):…”

“…As far as indirect photochemical processes are concerned, they depend as molecular features, on the reactivity between the target molecule and the various photogenerated transients, and on water chemical composition and light penetration as environmental features (Hoigné, 1990). In the case of the sensitised reactions involving • OH and CO 3 −• , the role of the environmental features can be as important as, or even more important than that of molecular reactivity (Vione et al, 2009a and2010a). Therefore, it is suggested that environment-dependent parameters such as water chemical composition and column depth can play a major role in indirect photochemistry.…”

“…We modified the model to obtain the desired steady-state concentrations of the reactive transients. The original model was able to predict with very good accuracy the experimental and field data concerning the photochemical lifetime of organic xenobiotics (Albinet et al, 2010;Maddigapu et al, 2011;Vione et al, 2009a and2010a). Lake Maggiore was chosen as a case study because of the availability of long-term series of water chemical data (Mosello et al, 2001;Salmaso et al, 2007;Bertoni et al, 2010).…”

Percarbonate as a Hydrogen Peroxide Carrier in Soil Remediation Processes

“…Thus, it can be hypothesized that either PAH oxidation is carried out at the soil surface (no homogeneous scavenging of HO ) or/and radical carbonates formed in Equations (2) and (3) are capable of oxidizing the extracted PAHs in solution. Reactivity of carbonate radicals with organic molecules has been previously reported in the literature (Vione et al, 2009;Merouani et al, 2010). Alternatively, carbonate radicals can generate hydroperoxyl radicals according to:…”