Nitrilotriacetic acid in sludge-amended soil: mobility and effects on metal solubility

Abstract

Soil column studies were undertaken to determine the mobility of nitrilotriacetic acid (NTA) in agricultural topsoil and its effect on the solubility of Cd, Cu, Mn, Ni, Pb and Zn following land application of sludge containing NTA. The total weight of NTA retained on the columns was >99% of that applied, with the levels of leached NTA becoming undetectable after 56 days. The presence of NTA increased the solubility of all six metals studied, although the degree of solubilisation varied with the individual metal, NTA dose and sludge application rate. Such an effect may result in greater metal mobility in sludge-amended soils, with possible changes in availability to plants and/or groundwater contamination.