Evaluation of Nitric Acid Extraction of Elements from Soils and Sediments in Two watersheds in East Tennessee

ABSTRACT

Determining the total elemental concentrations of soils requires a total dissolution method, in which hydrofluoric acid (HF) is commonly used. However, this method is tedious and risky due to the dangerous reagent HF. This study compared a single acid extraction technique using a nitric acid (HNO₃) extraction method to total dissolution (HF + microwave assisted aqua regia) for evaluating the total elemental concentrations in soils and sediments. The two methods were used to analyze the elemental content of soils and sediments from the Oostanaula Creek and Pond Creek watersheds in East Tennessee. Twenty-one elements (Al, Ba, Ca, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Nd, P, S, Si, Sr, Ti, V, Zn, and Zr) were subsequently measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The extraction efficiency for HNO₃ relative to the total was compared and discussed. In general, HNO₃ can extract the elements in absorbed phases and those residing in non-silicate minerals. Six elements (Ba, Co, Fe, Ca, Mn, and P) generated significant correlations between total and HNO₃ in both OC and PC watersheds. Finally, the elements were grouped according to the interrelationships of their total elemental concentrations based on the dendrogram plots, suggesting their geochemical association in soils and sediment forming minerals.

KEYWORDS:

• Correlation between nitric-acid extraction and total
• Geochemical association of elements
• Total dissolution method
• Nitric acid extraction

Acknowledgments

This work was sponsored by the U.S. National Institute of Food and Agriculture (NIFA)’s Program (Grant No. 2012-51130-20246). It was also supported by the grant of Society for Applied Microbiology (SfAM). The field sample collection and experimental work were jointly supported by the Department of Biosystems Engineering and Soil Science (BESS) and UT Extension at The University of Tennessee, Knoxville. We give a special thank you to Ms. Lena Beth, the staff of UT Extension, who graciously helped in accessing to the sampling sites. We also give a special acknowledgment of gratitude to Ms. Karina Costa who provided her expertise and labor in the collection of all soil samples and laboratory works utilized in this study.

Supplementary material

Supplemental data for this article can be accessed http://dx.doi.org/10.1080/00103624.2019.1614611.

Additional information

Funding

This work was supported by the Society for Applied Microbiology [Hardship Grant];National Institute of Food and Agriculture [2012-51130-20246].