黄河三角洲盐沼表层土壤有机碳含量、可溶性有机碳含量及其官能团结构特征

Contents of Organic Carbon and Dissolved Organic Carbon and Characteristics of Functional Group Structure in Surface Soils of Salt Marshes in Yellow River Delta

于2018年7月6~8日,在黄河三角洲芦苇(Phragmites anstralis)盐沼、盐地碱蓬(Suaeda salsa)盐沼、柽柳(Tamarix chinensis)盐沼和互花米草(Spartina alterniflora)盐沼中,分别采集了0~20 cm深度土柱,按2 cm一层,将采集的土柱分层,测定了不同深度土层的有机碳和可溶性有机碳含量;利用傅里叶变换红外光谱仪,分析了土样中可溶性有机碳的官能团结构特征。研究结果表明,芦苇盐沼、盐地碱蓬盐沼、柽柳盐沼和互花米草盐沼表层土壤中的有机碳和可溶性有机碳含量都在0~2 cm深度层最大,随着土壤深度的增加,二者都在逐渐减小,其陆源有机碳的贡献率分别为79.81%、42.73%、63.45%和34.91%,海源有机碳的贡献率分别为20.19%、57.27%、36.55%和65.09%;生长着4种植物群落的盐沼表层土壤中的可溶性有机碳的红外光谱特征类似,其官能团结构以醇酚类和芳烃类为主,还包括脂肪族、烯烃、卤代烃和仲酰胺类;在波数为1580~1660 cm-1与2800~3010cm-1处,芦苇盐沼、互花米草盐沼、柽柳盐沼和盐地碱蓬盐沼表层土壤中可溶性有机碳红外光谱的峰面积比分别为0.13、0.61、2.27和5.14,盐地碱蓬盐沼表层土壤可溶性有机碳中惰性碳含量最大。

Soil samples of 0-20 cm depth in Phragmites anstralis salt marsh,Suaeda salsa salt marsh,Tamarix chinensis salt marsh and Spartina alterniflora salt marsh in the Yellow River Delta were collected on July 6-8,2018.The soil samples were cut apart by 2 cm for one layer,and contents of soil organic carbon and dissolved organic carbon were determined.The structural features of functional groups of dissolved organic carbon in surface soils were revealed using the fourier transform infrared spectroscopy.The results showed that contents of organic carbon and dissolved organic carbon in surface soils were the highest at 0-2 cm depth in the Phragmites anstralis salt marsh,Suaeda salsa salt marsh,Tamarix chinensis salt marsh and Spartina alterniflora salt marsh.With the depth of the soil deepened,contents of organic carbon and dissolved organic carbon in surface soils decreased,and the surface soil organic carbon derived from terrestrial sources accounted for about79.81%,42.73%,63.45%and 34.91%,and the corresponding contributions to sea sources were 20.19%,57.27%,36.55%and 65.09%,respectively.The characteristics of dissolved organic carbon in surface soils of the salt marshes with 4 kinds of plants were similar.The functional group structure was dominated by phenolic alcohols and aromatic hydrocarbon,others included aliphatic,olefins,halogenated hydrocarbons,and secondary amides.The ratios of peak area of infrared spectroscopy of dissolved organic carbon in Phragmites anstralis salt marsh,Spartina alterniflora salt marsh,Tamarix chinensis salt marsh and Suaeda salsa salt marsh were 0.13,0.61,2.27 and 5.14 at 1580-1660 cm-1 and 2800-3010 cm-1,which indicated that the content of inert carbon in dissolved organic carbon in Suaeda salsa salt marsh was the highest.