Environmental Engineering Reference
In-Depth Information
cess is the stepwise dephenylation of the starting TPT as shown in Scheme 2.
Hydroxylated phenyltin derivatives were also formed, but only as minor pho-
toproducts. The process was shown to be efficient with artificial light as well
as with solar light [44].
Onafieldofcrops,thedegradationoforganotincompoundssuchasfungi-
cides mainly proceeds photolytically. TPT is a fungicide used on a variety of
crops throughout the world. In a study of pecan orchards in central Georgia in
the USA, TPT concentrations in foliage and soil immediately after its applica-
tion (0.5 days) were up to 33 and 1.6
gg
-1
dry weight, respectively, and those
after 10 or 15 days were decreased to 11
µ
gg
-1
dry weight (33%, 10 days) and
µ
gg
-1
dry weight (50%, 15 days), respectively. Besides TPT, diphenyltin
(DPT) and monophenyltin (MPT) were present in the leaves and soil, with
MPT generally the predominant compound. The proportion of MPT to TPT
in pecan leaves increased with time after spraying, since MPT is indicative
0.8
µ
Scheme 2
Degradation of TPT by photoredox process taking place in iron(III) aquacom-
plexes [44]
