贵州茂兰国家自然保护区砂页岩黄壤剖面镉的分布特征

Distribution Characteristics of Cadmium in Yellow Soil Profile of Sandstone and Shale in Guizhou Mao Lan Karst Forest

【目的】探究茂兰国家自然保护区镉在砂页岩黄壤剖面的分布特征,为国家保护区土地安全利用提供科学依据。【方法】选择在自然保护区内采集5个砂页岩黄壤剖面土样以及15个表土样品,分析所采集土壤发生层土样及表土样品镉赋存形态,检测土壤pH、土壤速效磷(AP)、土壤碱解氮(AN)和土壤有机质(SOM)的含量。【结果】潜在迁移指数法显示,土层越往下,则镉迁移性越弱;Person相关系数法表明,在腐殖质层土壤镉易迁移而在淋溶层和淀积层中富集,主要受pH影响较大。另外,降雨及镉高地球化学背景值特征对黄壤剖面镉含量分布特征有极大影响。地质积累指数法表明,表层土壤主要是轻度污染和偏中度污染;单因子指数法表明,表层土壤以轻微污染和轻度污染及中度污染为主。【结论】黄壤剖面镉含量整体呈现中间高、两端低的分布特征,这主要与其地方性气候特征、高地质化学背景值和植物生长过程影响有关。

【Objectives】To explore the distribution characteristics of cadmium in the yellow soil section of sandstone and shale in Mao Lan Karst Forest,and provide a scientific basis for the safe use of land in the national natural protected areas.【Methods】5 soil samples of yellow soil section of sandstone and shale and 15 topsoil samples in the natural protected areas were collected,and the collected soil samples of the soil generation layer and the topsoil samples of cadmium occurrence were analyzed.Soil pH value,soil available phosphorus(AP),soil alkalihydrolyzed nitrogen(AN),and soil organic matter(SOM)were measured.【Results】The potential migration index showed that the lower the soil layer,the weaker the cadmium migration.The Pearson correlation coefficient showed that cadmium migrated easily in the humus layer and accumulated in the eluvial layer and illuvial layer,which was mainly affected by pH value.In addition,the characteristics of rainfall and the high geochemical background value of cadmium showed great influence on the distribution characteristics of cadmium content in yellow soil profile.The geological accumulation index showed that the surface soil was mainly lightly and moderately polluted.The single factor index showed that the surface soil was mainly slightly,lightly,and moderately polluted.【Conclusions】Cadmium content in the yellow soil profile was high in the middle and low at both ends,which was mainly related to the local climate characteristics,high geochemical background value,and plant growth process.