Continental–scale distribution and source identification of boron in soils of China

Abstract

Boron is an essential trace element in the growth and development of plants, animals, and humans. Based on the China Geochemical Baseline Project (CGB), this study is the first to systematically sample and analyze boron in topsoil throughout China and presents baseline values and spatial distribution trends. The high–boron zones are distributed over a large area in Southwest, Central and South China. The low–boron zones are mainly located in Northeast China and the southeastern coastal regions. The anomalous features and spatial distribution of boron are primarily influenced by parent material, boron deposits, industrial emissions, soil composition and climate. The parent material plays a decisive role in the spatial distribution of boron in the soil, with soils in the carbonaceous shale, mirabilite and slate regions having higher boron concentrations. The formation and mining of boron deposits can lead to substantial boron accumulation in localized areas. Higher contents of clay minerals, iron and aluminum oxides or hydroxides, and organic matter in soil components are conducive to the adsorption and enrichment of boron in soils. 42 % of the arable land in China is deficient in boron, with the largest proportion of deficiencies found in the Dongbei Plain. Boron–rich arable land is mainly concentrated in the middle–lower Yangtze Plain and the Zhujiang Delta Plain. The findings provide geochemical information for protecting food security and human health and identifying key mineral resources.