Zhang Y, Spokas K, Wang D
Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, USA.
J Environ Qual. 2005 Aug 9;34(5):1566-72. doi: 10.2134/jeq2004.0374. Print 2005 Sep-Oct.
Recent studies have observed enhanced degradation of methyl isothiocyanate (MITC) from repeated fumigation in agricultural soils. Little is known about fumigant degradation in forest and nursery soils. This study was conducted to determine degradation rates of MITC and chloropicrin (CP) in two forest soils and the impacts of nursery management on degradation of MITC and CP. The half-life values of MITC and CP were evaluated in the laboratory under isothermal conditions (22 +/- 2 degrees C). Three rates representing 0.5x, 1x, and 2x field application rates for each fumigant were used in laboratory incubations. Effect of microbial degradation was determined by conducting incubations with both fresh and sterilized soils. Soil moisture effects were also studied. There was no difference in MITC or CP degradation between fumigated and nonfumigated forest nursery soils. Soil sterilization and high soil moisture content (15% by wt.) reduced MITC and CP degradation. The degradation rates of MITC and CP varied with factors such as nursery history, fumigant application rates, and freshness of tested soils.
近期研究发现，农业土壤中反复熏蒸会增强异硫氰酸甲酯（MITC）的降解。对于森林和苗圃土壤中熏蒸剂的降解情况，人们了解甚少。本研究旨在测定两种森林土壤中MITC和氯化苦（CP）的降解速率，以及苗圃管理对MITC和CP降解的影响。在等温条件（22±2℃）下于实验室评估了MITC和CP的半衰期值。实验室培养中使用了三种代表每种熏蒸剂田间施用量0.5倍、1倍和2倍的施用量。通过对新鲜土壤和灭菌土壤进行培养来确定微生物降解的影响。还研究了土壤湿度的影响。熏蒸过的和未熏蒸过的森林苗圃土壤在MITC或CP降解方面没有差异。土壤灭菌和高土壤含水量（重量比15%）会降低MITC和CP的降解。MITC和CP的降解速率随苗圃历史、熏蒸剂施用量和受试土壤新鲜度等因素而变化。
