Clay mineralogy and soil formation in moist acidic tundra and moist nonacidic tundra of northern Sagwon HLS, Alaska

Abstract

Clay mineralogy, physical and chemical characteristics were studied in three sites of moist acidic tundra (MAT) and three sites in moist nonacidic tundra (MNT) in the Northern Sagwon Hills, Alaska. The major similarities found in physical characteristics between MAT and MNT were color, field texture and consistence. Dissimilarities were in the depth, boundary and thickness of the horizons as well as soil structure. The major similarities found in chemical characteristics across MAT and MNT were in % carbon and nitrogen, ammonium phosphorus, iron and aluminum contents. The major dissimilarities were in pH, cation exchange capacity, nitrate and base saturation. Upper horizon pH in MAT was lower than MNT while deeper horizons had similar pH's. The mean average annual soil temperature was around -5°C in both MAT and MNT. The most common clay minerals found were illite, vermiculite and kaolinite. Kaolinite was determined to be detrital, not neoformed. Vermiculite from weathered illite was determined to be the most significant weathering product. The study also determined that the proportion of vermiculite to illite was higher in MAT and the illite to vermiculite proportion was higher in MNT. This finding showed that soil acidity does affect weathering reactions despite the low soil temperature.