山东省巨野县土壤B和Mo地球化学特征及有效态的周期变化

Geochemical Characteristics and Periodic Bioavailability Change of B and Mo in Soil of Juye County in Shandong Province

植物对土壤微量元素的需求和大量元素不同,有相当大的比重仍然依靠土壤本身提供,通常不经其他途径补给,土壤微量元素受成土母质控制,同时受表生作用影响,在各地分布往往具有显著的差异。通过对巨野县表层土壤地球化学调查,可以发现微量元素的分布规律,研究元素总量的控制机理,进而了解表生作用对该地区乃至整个黄河下游冲积平原区土壤地球化学环境的影响。研究发现,区内土壤B略缺乏,Mo和黄河下游流域背景一致,均远低于山东和全国水平。巨野组和鱼台组的分布与Mo元素异常分布相吻合。土壤粒度和质地对元素含量有一定影响,区内砂质土壤Mo含量较低,粘质土壤较高,B在各类土壤中含量水平基本一致,与土壤质地关系不明显。与数年前土壤调查数据对比发现短期内表生作用对Mo的影响较显著,土壤B的流失十分显著,B和Mo在局部地区的年变化率可达1%以上。土壤有效态B和Mo的变化具有显著的周期性,夏季有效态含量较秋季增加明显,有效Mo增长显著。

Different from the major elements,the microelements for plants are mainly provided by soil itself rather than any other ways,the content levels of microelements in the soil are defined by its parent material,in the meantime,the distribution of them in different areas often have significant differences because of the hypergenesis effect.Through geochemical survey of the surface soil in Juye county,distribution pattern and the controlling factors of the microelements can be found,which can help us to understand the influence of hypergenesis on the geochemistry environment in this region and even the whole plain of lower reaches of the Yellow River. It is showed that the content of B in soil in this region is slightly lacking,like the background value of the plain,the content of Mo in the soil in this region is far lower than average level in Shandong province and the nation. The anomaly distribution area of Mo matches the distributions of Juye and Yutai formations,soil particle size and texture have a certain effect on the elements contents,the content of Mo in sandy soil is lower than in the clay soil,the contents of B in all types of soils are basically equal,no obvious relationship with soil texture was found. Comparing with soil survey data several years ago,it is showed that the hypergenesis has a great impact on the distribution of Mo in short term,the loss of B in soil is very significant,the annual change rates of B and Mo in some areas can be up to 1%. The bioavailability of B and Mo in soil changes periodically,the bioavailable contents are relatively higher in summer than in autumn,the increase of Mo is especially significant.