PURPOSE Association of element concentrations for the escarpment soils of northeastern North Dakota formed from different geologic parent materials was determined based on geochemical data. These soils overlie the Cretaceous Pierre Formation, and parent materials consist of shale rich glacial till, residual shale, and colluvial materials. MATERIALS AND METHODS Samples were analyzed for cadmium and other trace elements using nitric acid digestion followed by optical emission spectroscopy. Morphologic and laboratory analysis of soil cores indicate high clay content, indicative of the influence of shale residuum on the parent materials of the escarpment soils. RESULTS AND DISCUSSION An average, cadmium concentration of 0.24±0.22 mg/kg was determined for 136 samples from eight (approx. 2.4 m deep) cores. The concentration of molybdenum had a range between 0.00 and 7.99 mg/kg. Zinc levels determined in the samples had a wide range between 18.76 and 128.02 mg/kg. Principal component analysis revealed that elevated trace element concentrations for the shale-rich portion of the soils in northeastern North Dakota are linked to a variety of factors including organic matter content, pH, elevation, and electrical conductivity. CONCLUSIONS Results of this study suggest that erosion and transport of Cretaceous shales downslope on the escarpment have resulted in enriched trace element concentrations in the soils.

中文翻译：

---

美国北达科他州东北部土壤中金属含量自然升高，重点是镉。

目的 根据地球化学数据确定由不同地质母质形成的北达科他州东北部陡坡土壤的元素浓度关联。这些土壤覆盖白垩纪皮埃尔地层，母质由富含页岩的冰川土、残余页岩和崩积物组成。材料和方法 使用硝酸消解和光学发射光谱分析样品中的镉和其他微量元素。土壤芯的形态和实验室分析表明粘土含量高，表明页岩渣对陡坡土壤的母质有影响。结果与讨论 来自八个（约 2.4 m 深）岩心的 136 个样品的平均镉浓度为 0.24±0.22 mg/kg。钼的浓度范围在 0.00 和 7.99 mg/kg 之间。样品中测定的锌水平在 18.76 至 128.02 mg/kg 之间很宽。主成分分析表明，北达科他州东北部富含页岩的土壤中微量元素浓度升高与多种因素有关，包括有机质含量、pH、海拔和电导率。结论 这项研究的结果表明，白垩纪页岩在悬崖上下坡的侵蚀和运输导致土壤中微量元素的富集。主成分分析表明，北达科他州东北部富含页岩的土壤中微量元素浓度升高与多种因素有关，包括有机质含量、pH、海拔和电导率。结论 这项研究的结果表明，白垩纪页岩在悬崖上下坡的侵蚀和运输导致土壤中微量元素的富集。主成分分析表明，北达科他州东北部富含页岩的土壤中微量元素浓度升高与多种因素有关，包括有机质含量、pH、海拔和电导率。结论 这项研究的结果表明，白垩纪页岩在悬崖上下坡的侵蚀和运输导致土壤中微量元素的富集。