地质背景对土壤微量元素的影响——以渝北地区为例

The influence of geological background on trace elements of soil,A case study of Yubei area

研究地质背景对土壤元素的控制特征,可为区域土壤元素地球化学研究、种植施肥和农业布局提供科学依据。本研究利用网格化定位与化学分析的方法,结合GIS技术和相关评价标准,探讨了地质背景对Cl、Mn、B、Zn、Cu和Mo元素含量及分布的影响。结果表明:渝北地区土壤Mn、Cu、Zn元素含量整体处于适中与丰富水平,Mo、B元素丰缺参半;B、Mo元素含量显著高于重庆主城区,Zn元素含量显著高于全国水平。受地质背景影响,B、Cl、Cu、Mn元素呈现高度空间相关性,结构性空间变异起主导作用;Mo、Zn元素表现中等空间相关性,由结构性因素和随机因素双重控制。地层的组对元素含量分布起主控作用,土壤元素含量分布形状在空间上与地层组相对应。成土母岩决定土壤元素含量,是土壤元素含量水平的重要控制因素之一,其影响因素主要为岩石类型,其次为岩石形成的地质时期。土壤类型显著影响元素含量,总体上,Mn、Cu、Zn、Mo、B在石灰岩土中含量最高;除B、Mo元素外,其他元素在黄壤中含量最低。

The study of the control of geological background over soil elements could provide a scientific basis for regional soil ele- ment geochemical research, planting fertilization and agricultural layout. This paper discusses the influence of the geological back- ground on the content and distribution of C1, Mn, B, Zn, Cu and Mo by using the grid location and chemical analysis, combined with the GIS technology and the related evaluation standards. According to the results, the values of Mn, Cu and Zn are generally moderate and at rich level in Yubei area; Mo and B element values are moderately high and are significantly higher than the values of the main urban area of Chongqing; Zn element values are significantly higher than the national level. B, C1, Cu and Mn elements show a high degree of spatial correlation, with structural spatial variation playing a leading role, affected by the geological background. Mo and Zn elements show moderate spatial correlation, influenced jointly by structural factors and stochastic factors. The strata play a dominant role in the distribution of elemental content, and the distribution of soil element content corresponds spatially to the strata. Soil parent rock determines soil elements content level, with the main affecting factor being rock type and the subordinate factor being the geological period of the formation of the rock . These features further explain the impact of strata on soil elements. The influences of soil type on elements are also significant. The content of Mn, Cu, Zn, Mo, B is highest in the limestone soil, and the content of Mo is the lowest in paddy soil. These results indicate that the study of the control of geological background as the dominant factor over soil elements can provide the basis for the study of the planting fertilization and agricultural distribution planning.