Mineral Neutralizers as a Tool for Improving the Properties of Soil Contaminated with Copper

Abstract

In phytoremediation processes implemented in highly contaminated areas, there is a high risk of contaminant toxicity during the germination of freshly sown plants. In such conditions, it is recommended to support phytoremediation by using neutralizing additives. The present study aimed at assessing the effect of the addition of mineral neutralizers (MNs), i.e., limestone, clay, and zeolite, to soil contaminated with copper (0, 200, 400, 600 mg kg−1). Basic soil indicators were analyzed, such as pH, hydrolytic acidity (HAC), total exchangeable bases (TEB), cation exchange capacity (CEC), base saturation (BS), electrolytical conductivity (EC), total organic carbon (TOC), total nitrogen (Ntot), carbon to nitrogen ratio (C:N),, and interactions of soil micronutrients, such as Cu, Zn, Cd, Cr, Ni, Pb, Mn, and Fe with MNs. Copper contamination significantly decreased the soil pH and increased its HAC. A decrease in the share of TEB was found, which resulted in a decrease in the CEC and in BS of the soil. Among the additives, limestone had the most beneficial effect on reducing soil acidity, contributing to a significant increase in TEB, CEC, and BS. The least favorable effect was shown for clay, which generally caused the deterioration of soil properties. The MNs significantly increased the content of Zn, Cr, and Fe and lowered the content of Ni in the soil compared to the control. The demonstrated interactions indicate the diversified activity of MNs at different levels of soil contamination with copper.

Wood Biomass Ash (WBA) from the Heat Production Process as a Mineral Amendment for Improving Selected Soil Properties

“…The content of available trace metals in the soil depends on various factors, including soil reaction [57,58], carbon content [59], properties of the soil sorption complex [59,60], or salinity [59]. The content of available forms of trace metals in the soil can be modified through the application of mineral substances to the soil [61][62][63]. The content of available forms of metals in the topsoil is closely correlated with the content of total forms of these metals in the soil [57,64].…”

Zeolite Properties, Methods of Synthesis, and Selected Applications

“…The presence of free cations in the zeolite skeleton allows ion exchange with cations present in solution (mainly off-grid sodium participates in the exchange process) [ 125 ]. The effect of zeolites as contaminant sorbents is to bind harmful trace elements into insoluble compounds or organic–mineral complexes [ 126 ], which are less available to plants and immobilized in the soil in a safe form for a long time [ 127 ]. This is confirmed by our study [ 128 ], in which the application of a molecular sieve (crystalline aluminosilicate with a micropore size of 0.3 nm) reduced the concentration of iron (by 5%), nickel (by 8%), cadmium (by 18%), chromium (by 22%), zinc (by 22%), copper (by 13%), and manganese (by 44%) in the aerial parts of sunflowers grown in copper-contaminated soil compared to the control.…”

Effects of Organic Amendments on the Morphology and Chemical Composition of Black Mustard (Sinapis nigra L.) Grown on Soil Contaminated with Copper

“…In order to limit the effects of excess Cu in the soil, attempts are being made to recultivate contaminated areas by, on the one hand, immobilizing mobile forms of copper [12][13][14][23][24][25][26], and, on the other hand, through phytotreatments falling within the scope of the so-called phytoremediation [4,27,28]. Immobilization mainly involves the use of various additives designed to bind copper into forms that are less soluble or even inaccessible to plants and thus trap it in the soil sorption complex [23].…”

“…Immobilization mainly involves the use of various additives designed to bind copper into forms that are less soluble or even inaccessible to plants and thus trap it in the soil sorption complex [23]. These additives include lime [12,25,29], clay minerals [12,13,25], zeolites [12,25,30], and minerals rich in iron (Fe) and phosphorus (P) [24,26,31].…”