Rare earth elements and yttrium in the soil forming materials and ploughing horizons of north-west Russia

Abstract

This study presents the rare earth elements (REE) and Y concentrations in the main soil forming materials and ploughing horizons of North-West Russia agricultural soils. The study area covers Leningrad region, west part of Novgorod and Pskov regions and southern Karelia. Investigated area (200,000 km2) was subdivided into a net of square cells 50 km on 50 km in size. Eighty-one samples of topsoil (0–25 cm, ploughing layer) and subsoil (C-horizon) were collected. REE and Y concentrations were measured using ICP-MS (Perkin Elmer Sciex Elan 5000). The median concentrations of the investigated elements in the soil forming materials were as follows (mg/kg): Y—15.3, La—21.7, Ce—45.0, Pr—5.5, Nd—20.9, Sm—3.9, Eu—0.8, Gd—3.5, Tb—0.5, Dy—2.7, Ho—0.5, Er—1.5, Tm—0.2, Yb—1.5, Lu—0.2. It was found that the content of REE in northwestern Russia soil forming materials is less than in Earth crust. Varve clays and carbonate moraines are enriched in REE content relatively another soil forming materials of northwestern Russia (non-carbonate moraines, lacustrine-glacial loams, sandy loams and sands, fluvioglacial sands and alluvial sands). Content of REE in soils depends on their concentrations in soil forming materials, therefore, spatial distribution of REE in ploughing horizons of agricultural soils reflects regional abundance of different soil forming materials.