Impact of Biochar on Release Kinetics of Pb (II) and Zn (II) in a Calcareous Soil Polluted with Mining Activities

Abstract

Release kinetics governs the detachment and migration of potentially toxic trace elements (PTEs) over time between the solid phase and soil solutions. The assessment of PTEs' release behavior through time supports more accurate prediction models of toxicity in highly polluted soils. Recently, biochar, a charcoal black carbon ameliorant, was extensively applied for decreasing the release of Zn and Pb to the soil solution. This study was arranged during a short-term (45 days) incubation experiment to estimate the possible effects of walnut leaves (WL) and their biochars produced at three temperatures (200 (B200), 400 (B400), and 600 (B600)°C) on the kinetics of Zn and Pb release in a naturally calcareous and highly polluted soil. Results showed that the biochars could reduce the release of Zn and Pb to the soil solution. The rate of Zn release ("b" in power function) at different biochar levels was 0.35 (2% B600)-0.38 (control) (mg kg −1) −1 , respectively; also, the release of Pb was 0.23 (2% B600)-0.33 (control) (mg kg −1) −1 , respectively. The results illustrated that a lower concentration of these metals was associated with exchangeable and oxides of Fe-Mn, whereas the higher content of residual fractions of Zn and Pb reduced the release of Zn and Pb in soils treated with biochar. Overall, the more the level and temperature of biochar increased, stabilizing PTEs through changing the distribution of metals in the soil, the more biochars succeeded significantly in lessening the release of PTEs, which ultimately could retard the further toxicity in the soil solution.

Study on the physical and chemical properties of lead passivating agent in soil

“…This similar method tried to solve the soil problem by reusing the existing waste materials, but the internal mechanism of the effect has not been explored in depth 33 , 34 . Some scholars attempted to introduce first principles in physics to solve the problem of soil heavy-metal pollution 35 , 36 . Balan et al analyzed the release kinetics of lead from soil, and Zhang et al analyzed the adsorption of kaolinite on Mg, Sb, Cu, As, Al, and other heavy-metal elements 37 , 38 .…”

Combined Effect of Prickly Pear Waste Biochar and Azolla on Soil Fertility, Growth, and Yield of Roselle (Hibiscus sabdariffa L.) Plants

“…−1 ); AZ 0%, AZ 3%, and AZ 6%, Azolla at rates of (0, 3, and 6%). Means denoted by the same letter indicate no significant difference according to Duncan's tests at p < 0.05 However, the conjunction use of BC and AZ resulted in a significant increase in yield and quality via improvement soil properties, increasing soil organic matter which leads to soil carbon-rich that enhances soil microorganisms and nutrient availability resulting higher plant yield and its quality (Eissa 2019;Ghadimi et al 2021;Kabiri et al 2021). Also, combined application of biochar and Azolla improved the growth features of rosemary plants in calcareous soils of arid and semiarid regions (Sadegh Kasmaei et al 2019).…”

Biochar and compost enhance soil quality and growth of roselle (Hibiscus sabdariffa L.) under saline conditions

“…The application of biochar and compost caused remarkable increases in the yield and quality of several field and vegetable crops through increasing the soil organic matter, nutrients availability and plant uptake 30 , 32 , 36 , 37 . The results of the current study revealed that there were increases in the soil microbial biomass carbon and nitrogen associated with the application of biochar and compost.…”