Effect of pH on metal bioavailability and phytotoxicity in agricultural soils spiked with acidic copper-rich mine wastes

摘要

Soil pollution with Cu-rich mine wastes may result in soil acidification, thus leading to confounding effects on Cu phytotoxicity. A laboratory assay was developed to evaluate the effect of pH on Cu solubility and phytotoxicity in two agricultural soils and a commercial sand spiked with a fixed amount of smelter dust (SD) or oxidized tailing sand (TS) known to be phytotoxic. The pH of experimental mixtures was adjusted to 4, 6, and 7 using non metal complexing buffers. The short-term barley root elongation toxicity test was used to assess the effect of total dissolved Cu, pH, and DOC in pore water in the different substrates. The results showed that substrate acidification resulting from addition of acidic Cu-rich mine wastes (TS and SD) are more toxic to plants than non-acidic mine wastes, primarily due to higher metal solubility in soil pore water.