Natural Water Photochemistry

Yaron B, Saltzman S (1978) Soil-parathion surface interactions. Residue Rev 69 1-34 Zafiriou OC (1984) A bibliography of references in natural waters photochemistry. Tech. Mem. 

Zafiriou, O. C., Natural water photochemistry . In Chemical Oceanography, Vol. 8, Academic Press, London, 1983, pp. 339-379. 

Keywords Environmental processes Iron Natural waters Photochemistry... 

Surface mediated processes are also an Important consideration in natural water photochemistry. In aqueous media, two different surface/Interfaces may occur that result In heterogeneous reactions. The two Interfaces considered here are liquid-solid and liquid-liquid. Surface processes In geochemistry and aquatic envlroments have been covered In more detail In two recent books and the reader is referred to these volumes for more details (24,25). 

Zafiriou, O. C., J. Joussot-Dubien, R. G. Zepp, and R. G. Zika, Photochemistry of natural waters , Environ. Sci. Technol., 18, 358A-371A (1984). 

Nitrate photolysis is a relevant source of hydroxyl in natural waters. A study carried out on the Greifensee Lake water indicates that nitrate photolysis is a much more important source of hydroxyl when compared with the photolysis of hydrogen peroxide or the Fenton reaction [12]. Nitrate photochemistry can thus lead to a steady-state hydroxyl concentration around 5 x 10 16 M [8]. 

DOM, and in particular dissolved humic substances give, depending on their concentration, a yellowish or brown colour to the natural waters. To underline the fact that the light-absorbing components, and, thus, those that are photochemically active, are also responsible for the colour, the term coloured (or chromophoric) dissolved organic matter (CDOM) [24,25] has been proposed for use in environmental photochemistry literature, and will be used here. 

Cooper W. J., Zika R. G., Petasne R. G., and Fischer A. M. (1989) Sunlight-induced photochemistry of humic substances in natural waters major reactive species. In Aquatic Humic Substances Influence on Fate and Treatment of Pollutants. Advances in Chemistry Series 219 (eds. I. H. Sufifet and P. MacCarthy). American Chemical Society, Washington, DC, pp. 333-362. 

This section has called attention to some ways that vertical mixing complicates the photochemistry of natural waters. On the other hand, if the rates of CDOM absorption and photochemistry can be quantified, then the steady state profile of a photochemical product (i.e. dissolved hydrogen peroxide) can be used to infer vertical mixing rates. This was possible in freshwater systems (Canadian Lakes and the St. Lawrence River) that accumulate higher levels of peroxide due to their CDOM content [36,46]. A similar attempt to model the depth-time variation of hydrogen peroxide in the ocean (where CDOM is much lower) was only partially successful in reproducing the observed distribution [47,48]. 

J.M.C. Plane, R.G. Zika, R.G. Zepp, L.A. Burns (1987). Photochemical modeling applied to natural waters. In R.G. Zika, W.J. Cooper (Eds). Photochemistry of Environmental Aquatic Systems (pp. 250-267). American Chemical Society. 

Photochemistry of chromophoric dissolved organic matter in natural waters... 

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