The influence of the structure of humic substances extracted from different soils and peats on their capacity to photosensitize 1-naphthol

This study compares the photosensitizing properties of a variety of humic substances (hs) extracted from soils (kaldenkirchen,bouzule,scheyern and belle fontainerendzine) and peats (w1,w9b and w9c). all the hs under consideration induced the photodegradation of 1-naphthol (2.10-6 m) at 365 nm. the results revealed that 1-naphthol is oxidized into naphthoquinones and hydroxynaphthoquinones. generally,humic (has) and fulvic (fas) acids of both w9b and w9c peat were the least effective. significant correlations between the photosensitizing properties and the structural features of the examined humic substances were established. thus,the pollutant phototransformation rate increased with the increase in n/c fraction,but decreased with the increase in o/c fraction,aromatic fraction or ash content. these results indicate that the aromatic part of the humic structure plays an important role in the inhibition of 1-naphthol oxidation suggesting they are,at leastpartly,responsibleforthe antioxidant properties of the hs.