对于相同土壤磷水平的土壤，磷素在上层土壤积累量较大，随着土层深度的加深，磷素含量逐渐减小。
In soils with the same phosphorus levels, the contents of various forms of phosphorus were accumulated mainly in the profile of a surface layer and decreased gradually with the depth of the profile.
论文采用数值计算的方法分析了双层土壤结构时土壤反射系数、上层土壤厚度及地网面积大小等因素对地网最优布置的影响规律。
The influences of the reflective coefficient of the double layer soil, the top layer soil thickness and the grounding grid area on the optimum arrangement are analyzed numerically.
研究者们拼凑了包括头骨，手掌，脚掌，上臂，腿和骨盆在内的125块骨骼碎片，并采集挖掘处上层和下层的火山土壤层测定年代。
Researchers have pieced together 125 fragments of bone - including much of her skull, hands, feet, arms, legs and pelvis - which were dated using the volcanic layers of soil above and below the find.
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