添加外源硫对农田土壤挥发性含硫气体释放的影响

摘要

In this paper,the influences of different exogenous sulfur and environmental conditions on the emissions of volatile sulfur gases from soil were investigated by gas chromatography for the representative farmland soil samples in arid area of Xinjiang.The results showed that sources of exogenous sulfur had different influences on the kind and the amount of volatile sulfur gases emitting from incubation soils.Volatile sulfur gases released from the soil with cystine,cysteine,methionine,sodium sulfate and sodium thiosulfate addition contributed fewer to total sulfur emission,being 1.71％,0.52％,11.5％,0.0016％ and 0.0014％,respectively.The conversion rate was the highest for methionine but lowest for inorganic sulfate.Organic sulfur acted as a major contributor to volatile sulfur gases emission from soil.As the main product,H2S accounted for 97.9％ and 90.8％ of the total emissions from cystine and cysteine by microbial decomposition.CH3SH was the main product detected from methionine decomposition and accounted for 88.3 ％ of the total emissions.The amounts of volatile sulfur gases were positively proportional to the amounts of added cysteine (1 ～ 10 ag· g-1).The influence of added carbon and nitrogen fertilization was related to the kind of evolved volatile sulfur gases.Incubation conditions such as the soil types and irrigation water had substantial effect on sulfur gases emissions,with the moisture in incubation soil having the larger influence.%选择新疆地区代表性农田土壤为样品,采用气相色谱法进行测定,通过室内培养的方式考察了各种添加外源硫和环境条件对土壤挥发性含硫气体释放的影响.结果表明:不同添加源对挥发性含硫气体种类及数量的影响各不相同.添加胱氨酸、半胱氨酸、甲硫氨酸、硫酸钠和硫代硫酸钠后,释出的挥发性含硫气体在总硫中所占的比例依次为1.71％、0.52％、11.5％、0.0016％和0.0014％,表明转化率均较低,其中无机硫的转化率最低,甲硫氨酸的转化率最高,有机硫是主要来源.在土壤微生物分解作用下,胱氨酸、半胱氨酸的主要分解产物是H2S,分别占总释放量的97.9％、90.8％;甲硫氨酸能够释放较多的CH3SH气体,占总释放量的88.3％.在一定范围内(1～10mg·g-1),含硫气体的释放量随半胱氨酸添加量的增加而增加.碳、氮源加入的影响与挥发性含硫气体的种类有关.环境条件对挥发性含硫气体的释放也有影响,培养用水的影响远高于土壤类型,是相对重要的因素.