氰在土壤中的吸附与转化

氰(C2N2)是一种具有替代溴甲烷潜力的新熏蒸剂,明确C2N2在土壤中的吸附与转化行为对C2N2的安全应用具有重要的意义.利用静态法研究了C2N2在土壤中的吸附与转化过程,土壤对C2N2的吸附速率与土壤的理化性质有关,受环境温度、土壤含水量和土壤生物的影响较少,与熏蒸浓度无关.采用气相色谱(GC)和流动注射分析仪(FIA)测定了土壤对C2N2的吸附率和C2N2在土壤中的可能转化产物.结果表明,土壤对C2N2的吸附能力很强,熏蒸2h吸附率在75％以上,熏蒸24 h吸附率在98％以上,并可快速转化为HCN、NH4+和NO3-.其中,大约20％的C2N2转化为NH4+和NO3-,13％的C2N2转化为HCN.熏蒸48 h未检测到NO2-.HCN在土壤中不稳定,可进一步转化为其他含氮化合物.

Adsorption and transformaton of cyanogen in soil

Cyanogen (C₂N₂) is a new type of fumigant that has the potential to replace methyl bromide. So it is of important significance to ascertain the behaviour of C₂N₂ in adsorption and transformation in soil for its safety application. Adsorption and transformation of C₂N₂ in soil was investigated using the static method under controlled conditions. C₂N₂ adsorption rates in soil was related with physicochemical properties of the soil, and slightly related with the ambient temperature, the soil water content and soil organisms, but not related with the application rate of the fumigant. C₂N₂ adsorption rate and its possible transformation products (HCN, NH₄⁺, NO₃^-and NO₂^-) were determined using the gas chromatography (GC) coupled with a nitrogen-phosphorus detector (NPD) and the flow injection analyzer (FIA) with a Photometric detector. Results show that the soil had a very high C₂N₂ adsorption capacity with a rate being over 75% within 2 h of fumigation and over 98% within 24 h. The absorbed C2N2 could be quickly transformed, about 13% into HCN, and 20% into NH₄⁺ and NO₃^-. No NO₂^-was detected within 48 h. HCN in soil was not stable and could be further transformed into other nitrogenous compounds.