黄河源区湿地、草地土壤理化性质和碳氮组成及其稳定同位素特征分析

Analysis of Nitrogen and Carbon Composition and Stable Isotope Characteristics and Physicochemical Properties of Wetland and Grassland Soil in Source Region of the Yellow River

为探究黄河源区湿地和相邻草地土壤的有机碳和全氮状况,采用野外调查与室内分析相结合,对其理化性质和碳氮组成及其稳定同位素特征进行测定和分析。结果表明,湿地土壤含水量为21.08%~48.95%,容重为0.57~1.46g/cm3,pH为6.4~9.0,全磷含量为34.6~123.44mg/kg,有效磷含量为7.8~71.48mg/kg,有机碳含量为0.53%~16.57%,全氮含量为0.05%~1.47%,δ13 C丰富度介于(-26.65‰)^(-22.10‰)之间,δ15 N丰富度介于1.15‰~5.49‰之间,Corg/N在8.20~11.53之间变化。与湿地邻近的草地土壤含水量变化为13.97%~48.47%,容重变化为0.68~1.42g/cm3,pH为6.1~8.9之间,全磷含量为57.84~143.62mg/kg,有效磷含量为9.74~60.19mg/kg,有机碳含量为0.88%~9.79%,全氮含量为0.09%~0.88%,δ13 C丰富度介于(-25.80‰)^(-21.42‰),δ15 N丰富度介于2.64‰~6.81‰之间,Corg/N在8.60~12.00之间变化。无论是湿地还是草地土壤含水量均<50%,但草地土壤的含水量变异范围大于湿地;源区土壤绝大多数呈弱碱性,少部分近中性或呈弱酸性;有机碳和全氮随湿地类型和采样点的不同也存在很大的差异。总体上,湿地土壤的容重、全磷、有效磷、δ13 C、δ15 N、Corg/N低于草地土壤。土壤有机碳氮及其稳定同位素相互间有显著的相关性,土壤有机质的δ13 C表明源区没有C4植物。

The wetland and grassland soils in source region of the Yellow River were collected and lab analysis were carried out.The physicochemical properties and carbon and nitrogen stable isotope composition were investigated.The ranges of the wetland soil indicators were water content from 21.08% to 48.95%,bulk density from 0.57 to 1.46g/cm^3,pH from 6.4to 9.0,total phosphorus content from 34.6to 123.44mg/kg,available phosphorus content from 7.8to 71.48 mg/kg;organic carbon content from 0.53% to16.57%,total nitrogen content from 0.05% to 1.47%,δ13 C from-26.65‰ to-22.10‰,δ15 N from1.15‰to 5.49‰ and Corg/N from 8.20 to 11.53.The values of the adjacent meadow soil indicators were：water content from 13.97%to 48.47%,bulk density from 0.68 to 1.42g/cm^3,pH from 6.1to 8.9,total phosphorus content from 57.84 to 143.62mg/kg,available phosphorus content from 9.74 to 60.19mg/kg,organic carbon content from 0.88% to 9.79%,total nitrogen content from 0.09% to 0.88%,δ13 C from-25.80‰to-21.42‰,δ15 N from 2.64‰to 6.81‰ and Corg/N from 8.60 to 12.00.The soil moisture in both wetland and grassland was less than 50%,but the variation of moisture in grassland soil was greater than that in wetlands.The majority soil in the source region exhibited weak alkaline,but a few presented near-neutral or slight acidic.The organic carbon and total nitrogen showed big difference as results of different wetland type and sampling location.On the whole,the soil bulk density,total phosphorus,available phosphorus,δ13 C,δ15 N andCorg/N of wetland soil were lower that of grassland soil.There were significant relationship between soil organic carbon and nitrogen with their stable isotopes.Theδ13C of soil organic carbon indicated no C4 plants in this region.