外源含硫化合物对土壤挥发性有机硫化合物交换通量的影响

Influence of Exogenous Sulfur-containing Compounds on the Exchange Fluxes of Volatile Organic Sulfur Compounds

通过静态箱采样和Entech7100预浓缩仪-GC-MS分析了半胱氨酸、硫化钠和硫酸钠对土壤吸收或释放羰基硫(COS)、二甲基硫醚(DMS)、二硫化碳(CS2)和二甲二硫醚(DMDS)等4种挥发性有机硫化合物(VOSCs)的影响.结果表明,添加半胱氨酸后,土壤由COS和CS2汇转变为源,DMS和DMDS通量显著增加,且DMS和CS2释放量占总量的89.2%,说明半胱氨酸主要是DMS和CS2的前体物.添加Na2S后土壤DMDS释放量占总量的93.2%,说明Na2S是DMDS的重要前体物.添加Na2SO4后,VOSCs通量与对照土壤无显著差异,说明Na2SO4并非VOSCs的直接前体物质.VOSCs通量最大值发生在添加半胱氨酸6～8 d.添加Na2 S后不同VOSCs通量最大值发生的时间差异较大,且与添加半胱氨酸有较大差异,意味着土壤中Na2 S产生VOSCs的过程较复杂,且有异于半胱氨酸.

The influences of cysteine,sodium sulfide（Na2S） and sodium sulfate（Na2SO4） on the soil-air exchange fluxes of volatile organic sulfur compounds（VOSCs）,including carbonyl sulfide（COS）,dimethyl sulfide（DMS）,carbon disulfide（CS2） and dimethyl disulfide（DMDS）,were studied employing static chamber enclosure followed by laboratory determination using an Entech 7100 preconcentrator coupled with an Agilent 5973 GC-MSD.The results showed that after the addition of cysteine,the soil for the exchange fluxes of COS and CS2 shifted to be the source from sink and the emissions of DMS and DMDS increased significant.The emission amount of DMS and CS2 accounted for 89.2% to the total VOSCs after the addition of cysteine,implying that cysteine is an important precursor for DMS and CS2 in the soil.The amount of DMDS accounted for 93.2% to the total sulfur from the soil after addition of Na2S,indicating that Na2S is a key precursor for DMDS.No significant difference of VOSCs fluxes was found between the controlled soil and the soil with addition of Na2SO4,suggesting Na2SO4 was not the direct precursor for VOSCs in soil.VOSCs exchange rates reached the maximum at 6 to 8 days after addition of cysteine.As for addition of Na2S,the maximal emission rates of different VOSCs appeared at different dates,and the dates differed significantly from those after addition of cysteine,implying that the formation process of VOSCs from the soil with addition of Na2S was more complex and different from the soil with addition of cysteine.