Abstract: Bound residue (BR) of ^{14}C-metsulfuron-methyl
(^{14}C-BR) in seven kinds of soil was significantly
negative-related to soil pH and positive-related to the clay content during the
initial 20 d of incubation, but only was significantly negative-related to soil
pH after 30 d incubation. Again, the soil pH was found to be the dominant
factor affecting BR formation from ^{14}C-metsulfuron-methyl
among the basic properties (soil pH, clay, OM and CEC etc.) of soil. The
maximum content of ^{14}C-BR in the 7 soils accounted for
19.3%–52.6% of applied amount. In addition, the composition of the
^{14}C-BR in fluvio marine yellow loamy
(S_7) at the 90 d of incubation was identified using the
coupling technique of LC-MS and isotope tracing method. The results showed that
the ^{14}C-[2-amino-4-hydroxyl-6-methyl-1, 3, 5]-triazine,
^{14}C-[2-amino-4-methoxy-6-methyl-1, 3, 5]-triazine and
^{14}C-metsulfuron-methyl parent compound constituted the
main components of the BR derived from
^{14}C-metsulfuron-methyl in the S_7. The
relative percentage of the three compounds accounted for 41.4%, 35.8% and 19.3%
of total recovery radioactivity, respectively. The results also indicated that
a non-radioactive component, 2-methylformate-benzenesulfonyl-isocyanate, one of
the degraded products of metsulfuron-methyl in soil, was also found to be one
of the components of the BR. The parent compound in BR can well explain the
phytotoxic effect on substitution crops caused by the BR derived from
metsulfuron-methyl in soil.
