Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils spiked with Cu and aged for 2 months at 35 °C. Cu toxicity was expressed as pEC50(Cu2+), i.e., the negative logarithm of the EC50(Cu2+) activity to plant growth. The determined pEC50(Cu2+) was significantly and positively correlated with both the analytically readily available soil pH and concentration of dissolved organic carbon [DOC] which together could explain 87 % of the pEC50(Cu2+) variation according to the simple equation: pEC50(Cu2+) = 0.98 × pH + 345 × [DOC] − 0.27. Other soil characteristics, including the base cation concentrations (Na+, K+, Ca2+, Mg2+), the cation exchange capacity at soil pH (ECEC), and at pH 7 (CEC7), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC50(Cu2+). Consequently, Cu toxicity, expressed as the negative log of the Cu2+ activity, to plant growth increases at increasing pH and DOC, which needs to be considered in future management of plant growth on Cu-contaminated soils. The developed regression equation allows identification of soil types in which the phytotoxicity potential of Cu is highest.
- Soil contamination
Christiansen, K. S., Borggaard, O. K., Holm, P. E., Vijver, M. G., Hauschild, M. Z., & Peijnenburg, W. J. G. M. (2015). Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils. Environmental Science and Pollution Research, 22(7), 5283-5292. https://doi.org/10.1007/s11356-014-3737-3