Content and distribution of arsenic, bismuth, lithium and selenium in mineral and synthetic fertilizers and their contribution to soil

Abstract

Abstract Concentrations of arsenic, bismuth, lithium and selenium were determined by atomic absorption spectrophotometry in 32 samples of commercial fertilizers from various manufacturers and distributors. Arsenic and lithium were detected in all investigated samples, bismuth in 50% of samples and selenium only in two samples. Arsenic content ranged from 2 to 321 ppm; lithium varied from 5 to 0. 1 ppm; bismuth was always lower than 0. 5 ppm; selenium was detectable at the levels of 10 and 13 ppm. Fertilizers made from rock phosphates contained trace elements amounts generally higher than those derived from rock carbonates, synthetic nitrogen fertilizers and potassium sulphate. Additions of trace elements from fertilizers applied at common rates to cultivated soils are tabulated and discussed on the basis of the natural soil reserves and toxicity levels for plants. Whereas applications of bismuth resulted always very low to influence the usual soil content and plant uptakes and selenium was only rarely present in fertilizers, lithium and moreover arsenic additions by fertilizers could influence the trace element status in soil, overcoming occasionally the toxicity levels for more sensitive crops.