氮添加对马尾松和木荷幼苗根系土壤挥发性有机化合物的影响

为了解土壤挥发性有机化合物(VOCs)对氮沉降的响应,本研究以马尾松和木荷幼苗为研究对象,设置3个氮水平(5.6、15.6和20.6 g·m^-2·a^-1)和两种氮添加方式(土壤施氮和叶面施氮),通过质子转移反应飞行时间质谱仪分析植物土壤VOCs对不同氮水平和氮添加方式的响应。结果表明,马尾松和木荷幼苗根系土壤释放的总VOCs通量为19.50~70.94 pmol·g^-1·h^-1,以含氧VOCs(乙醛、甲醇和乙烯酮)和含氮VOCs(甲酰胺和丙胺)为主,分别占总VOCs的22.04%~47.71%和3.31%~38.68%。两种氮添加方式均显著地促进马尾松和木荷幼苗根系土壤含氮VOCs释放,这与土壤铵态氮和硝态氮含量显著相关。叶面施氮处理下马尾松根系土壤总VOCs释放显著增加,不同幼苗根系土壤释放的不同种类VOCs对氮水平和氮添加方式的响应不一致。研究结果可为评估土壤VOCs对大气氮沉降增加的响应提供基础数据。

Effects of nitrogen addition on soil volatile organic compounds of Pinus massoniana and Schima superba seeding root zone soils

In order to understand the responses of fluxes of soil volatile organic compounds(VOCs)to elevated nitrogen deposition,this study employed proton transfer reaction-time of flight-mass spectrometry(PTR-TOF-MS)to study the responses of soil VOCs to three nitrogen application levels(5.6,15.6,and 20.6 g·m^-2·a^-1)and two application methods(soil application of N and foliage application of N)for the root zone soils of two tree species(Pinus massoniana and Schima superba).Results showed that the total VOC emission rates of P.massoniana and S.superba seeding root zone soils ranged from 19.50 to 70.94 pmol·g^-1·h^-1,with oxygenated VOCs(mainly acetaldehyde,methanol and ethenone),and nitrogenous VOCs(mainly formamide and propylamine)being the species with the largest proportion,which accounted for 22.04%~47.71%and 3.31%~38.68%,respectively.The emission rates for soil nitrogenous VOCs increased significantly with N enrichment for both N application methods and tree species,and the emission rates showed significantly positive correlation with soil NH4+and NO3-contents.Total VOC emission rates increased significantly with N addition for P.massoniana root zone soil in the FAN treatment,and VOCs from both tree species showed various responses to nitrogen levels and application methods.The results can provide basic data for future evaluation of the potential contribution of soil VOCs to elevated nitrogen deposition.