Behaviour of the soil residues of the bipyridylium herbicide, [$^{14}C$]paraquat in the micro-ecosystem

Micro-ecosystem중 bipyridylium 제초제 paraquat 토양잔류물의 행적

In order to elucidate the fate of the residues of the bipyridylium herbicide paraquat in soil, maize plants were grown for 4 weeks on the specially-made pots filled with two different types of soils containing fresh and 6-week-aged residues of [$^{14}C$]paraquat, respectively. The mineralization of [$^{14}C$]paraquat to $^{14}CO_{2}$ during the aging period and the cultivation period of maize plants amounted to $0.13{\sim}0.18%$ and $0.02{\sim}0.17%$, respectively, of the original $^{14}C$ activities. At harvest the roots and shoots contained less than 0.1% and 0.01% of the originally applied $^{14}C$ activities, respectively, whereas the $^{14}C$ activities remaining in soil were more than 97% in both soils. The water extractability of the soil where maize plants were grown for 4 weeks was less than 1.2% of the original $^{14}C$ activities. Most of the non-extractable soil-bound residues of [$^{14}C$]paraquat were incorporated into the humin fraction. Soil pHs during the aging of soil B and after cultivation in all treatments increased. The distribution of the $^{14}C$ activities in subcellular particles of the maize plant roots was the highest in the residue fraction(incompletely homogenized tissue). Dehydrogenase activities increased after vegetation, regardless of soil aging.

Bipyridylium계 제초제 paraquat 잔류물의 토양중 행적을 구명하기 위하여 [$^{14}C$]paraquat의 신생 및 6주간의 숙성잔류물을 함유한 2종의 토양을 가지고 특수하게 제작한 pot에서 옥수수를 4주간 재배하였다. 숙성기간과 옥수수 재배기간 동안 $^{14}CO_{2}$로 무기화된 양은 총처리 방사능의 각각 $0.13{\sim}0.18%$와 $0.02{\sim}0.17%$이었다. 옥수수 재배기간중 뿌리와 줄기에 흡수 이행된 $^{14}C$은 두 토양 모두에서 각각 0.1%와 0.01% 미만이었으나 토양중에 남아 있는 $^{14}C$은 두 토양 모두에서 총처리 방사능의 97% 이상이었다. 4주간 옥수수를 재배한 후 토양중 paraquat의 물에 의한 추출율은 1.2% 이하로 매우 낮았고 [$^{14}C$]paraquat 추출불가 토양잔류물의 대부분은 humin에 혼입되어 있었다. 토양을 숙성하는 동안 토양 B의 pH가 증가하였고 옥수수 재배후에는 모든 처리구에서 토양의 pH가 증가하였다. 옥수수뿌리의 각 subcellular particle중에서 residue 분획(incompletely homogenized tissue)에 가장 많은 $^{14}C$이 분포해 있었다. 토양의 dehydrogenase 활성은 숙성에 관계없이 옥수수 재배후에 증가하였다.