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

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ORIGINAL PAPER

Impact of Biochar on Release Kinetics of Pb (II) and Zn (II) in a Calcareous Soil Polluted with Mining Activities Parvin Kabiri 1 & Hamidreza Motaghian 1

&

Alireza Hosseinpur 1

Received: 23 July 2020 / Accepted: 28 August 2020 # Sociedad Chilena de la Ciencia del Suelo 2020

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. Keywords Pyrolysis temperature . DTPA . Fractions . Modeling release kinetics . Desorption

1 Introduction Soil has drastically become a major reservoir of potentially toxic trace elements (PTEs) due to indiscriminate man-made endeavors, especially when extracting valuable minerals or geological materials from the ground in mining areas (Kabiri et al., 2019; Lahori et al., 2020; Feng et al., 2020). Potentially toxic trace elements can reach the food supply, contaminate microbiota and macrobiota, and ultimately increase hazards to human beings (Lahori et al., 2019). The detrimental effects of PTE exposure and its poisoning of the soil depend on their distribution between various soil ingredients since their total Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42729-020-00336-5) contains supplementary material, which is available to authorized users. * Hamidreza Motaghian [email protected]; [email protected] 1

Department of Soil Science, College of Agriculture, Shahrekord University, Shahrekord, Iran

contents cannot completely predict their migration and noxious effects in the soil (Moore et al., 2015). Th