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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. [ABSTRACT FROM AUTHOR]

Bound residue(BR) of 14C-metsulfuron-methyl (14C-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 14C-metsulfuron-methyl among the basic properties(soil pH, clay, OM and CEC etc.) of soil. The maximum content of 14C-BR in the 7 soils accounted for 19.3% - 52.6% of applied amount. In addition, the composition of the 14C-BR in fluvio marine yellow loamy (S7) at the 90 d of incubation was identified using the coupling technique of LC-MS and isotope tracing method. The results showed that the 14C-[2-amino-4-hydroxyl-6-methyl-1, 3, 5]-triazine, 14C-[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 S7. 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.

The expression and root exudation of Cry1Ab toxin protein in cry1Ab transgenic rice (KMD) and its residue in rhizosphere soil were investigated. The results showed that content of Cry1Ab toxin protein in the shoot and root of KMD were 3.23-8.22 and 0.68-0.89 microg/g from early tillering to maturing stage, respectively. The content of the Cry1Ab toxin proteins via root exudation were 1.66-48.02 ng/(individual x d) at that phase. The results also demonstrated that the residue of the Cry1Ab toxin protein in rhizosphere soil was less than detectable level (0.5 ng/g air-dried soil). In addition, insecticidal bioassay indicated that rhizosphere soil and its extraction solution had no significant effect on mortality of first- and third-instar larvae of cotton bollworm (Heliochis armigera). It suggested that the KMD straws returned to the field might have the higher potential environmental risk than the root exudation.

The bioavailability of bound residue (BR) derived from 14C-labeled chlorsulfuron in soil and effect of the main components of the BR on growth of rape (brassica napus) and rice (Oryza sativa L.) were investigated. The results showed that the BR with the concentration of 0.28 and 0.56 nmol/g air-dried soil, which was calculated by special radioactivity of 14C-labeled chlorsulfuron parent compound, resulted in significant depression effect on growth of rape seedling. It was assured that the main components (2-amino-4-methoxyl-6-methyl-1,3,5-triazine, 2-amino-4-hydroxyl-6-methyl-1,3,5-triazine, and 2-chloro-benzenesul-fonamide) of the BR did not inhibit the growth of rape and rice. LC-MS analysis demonstrated that the parent compound previously bound to the soil matrix could be again released and transformed into methanol-extractable residue during the course of rape growth. It was concluded that the molecular leading to the phytotoxicity to rape and rice in the BR is still the parent compound.

A new method for extracting the bound residue(BR) derived from 14C-labeled chlorsulfuron in soils was developed, and the technique of combining LC-MS with isotope tracing method was subsequently applied to identify the composition of the 14C-BR in a loamy Fluvent derived from marine deposit. The results showed that the 14C-[2-amino-4-methoxyl-6-methyl-1,3,5]-triazine, 14C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine and 14C-chlorsulfuron parent compound constituted the main composition of the 14C-BR derived from 14C-labeled chlorsulfuron in the soil. The radioactive ratio of three compounds accounted for 39.8%, 35.4% and 17.9% of total recovered radioactivity, respectively. However, a small amount(3.6% of total recovered radioactivity) of the complex of 14C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine might have existed in the 14C-BR in association with an unknown soil substrate. 2-chlorobenzenesulfonamide was also detected to be one of the components of the BR. The results could well explain the mechanism of phytotoxicity caused by the BR derived from chlorsulfuron in soil. In addition, the mechanism of BR formation in soil was also discussed in details.