Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils

Abstract

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(Cu(2+)), i.e., the negative logarithm of the EC50(Cu(2+)) activity to plant growth. The determined pEC50(Cu(2+)) 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(Cu(2+)) variation according to the simple equation: pEC50(Cu(2+)) = 0.98 × pH + 345 × [DOC] - 0.27. Other soil characteristics, including the base cation concentrations (Na(+), K(+), Ca(2+), Mg(2+)), 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(Cu(2+)). Consequently, Cu toxicity, expressed as the negative log of the Cu(2+) 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.

The Effects of Different Combinations of Cattle Organic Soil Amendments and Copper on Lettuce (cv. Rufus) Plant Growth

“…It is worth noting that the lowest Ti was observed in the lettuces planted in S+Cu, which corresponded to a 3.5-fold increase in the BAF value compared to the S conditions and a decrease in the growth parameters and chlorophyll content. Although the Cu concentration at which toxic effects become evident is plant-species-and soil-type-dependent [62], our findings agree with previous studies where plants with Ti values of <100 experienced stress due to metal contamination along with a net reduction in plant biomass. Conversely, the plant species with a Ti of >100 developed tolerance along with a net biomass increase and improved physiological performance [63,64].…”

A Review of the Distribution Coefficient (&lt;i&gt;K&lt;sub&gt;d&lt;/sub&gt;&lt;/i&gt;) of Some Selected Heavy Metals over the Last Decade (2012-2021)

“…The sorption equilibrium that governs Cu exchange between solid and liquid phases determines its phytotoxicity and the risk of contamination of water resources. The mobility and fate of Cu in the soil environment are directly related to its K d , which indicates the ability of soil to retain a solute as well as the extent of its movement into the liquid phase (Christiansen et al, 2015;Ding et al, 2018;Kumar et al, 2019) to 4317.9 L/kg for arable land (0 -20 cm) and land under permanent grass cover (0 -10 cm).…”

Influence of metal speciation on soil ecotoxicity impacts in life cycle assessment

“…The liquid-phase speciation influences both the BF and the EF as both factors are to be expressed based on the same directly bioavailable metal pool. The effects of speciation on factors underlying the CTP often counteract each other, and whether the resulting CTP increases or decreases depends on the speciation patterns of a metal in the soil and in ecotoxicity test media (Christiansen et al, 2015). In addition, the solid-phase speciation influences both the ACF and FF through its control of the solid-liquid distribution coefficient of a metal in soil (Owsianiak et al, 2013(Owsianiak et al, , 2017.…”