Fe-Modified Common Reed Biochar Reduced Cadmium (Cd) Mobility and Enhanced Microbial Activity in a Contaminated Calcareous Soil

Abstract

The immobilization of soil cadmium (Cd) by biochar and modified biochar is an eco-friendly and cost-effective strategy. In the current study, the effect of raw biochar (BC) and iron-modified biochar (Fe-BC) derived from common reed on the fractionation and mobility of Cd was evaluated, as was its effect on soil microbial activity in contaminated calcareous soil. Treatments involved a combination of two factors: type of biochar (CK: Control, BC, and Fe-BC) and soil Cd concentration (0, 15, and 30 mg kg −1). Treatments were applied to the soil and incubated for 90 days. The application of both biochars increased soil pH and soil organic carbon content (16.6-48.0%), microbial biomass carbon (40.5-75.1%), basal respiration (16.6-48.0%), substrate-induced respiration (12.4-41.9), and dehydrogenase activity (25.5-102.1%), while it reduced diethylene-triamine pentaacetic acid (DTPA)extractable Cd (22.1-39.5%). The addition biochars, particularly Fe-BC, prominently decreased the concentration of exchangeable and carbonate fractions and increased the concentration of Fe-MnOx, as well as the organic and residual fractions of Cd in the soil. Moreover, relative to the control treatment, the incorporation of raw and Fe-modified biochar into 30 mg kg −1 Cd-spiked soil significantly decreased the Cd mobility factor (MF) value by 14.5 and 21.8%, respectively. Fe-modified biochar had a more significant impact than raw biochar on the immobilization of Cd in the soil, and its improved soil microbial activity to a greater extent. Overall, the findings indicate that Fe-modified biochar derived from common reed can immobilize Cd and improve soil microbial attributes in contaminated calcareous soil. Therefore, it can be used as an eco-friendly amendment for restoring Cdcontaminated calcareous soil.

Biochar for the Management of Nutrient Impoverished and Metal Contaminated Soils: Preparation, Applications, and Prospects

“…1 The surface structure of biochar prepared from rice straw biochar showing the presence of macro-and micro-pores (red circles), which not only increase the porosity but also a hiding place for beneficial microbes against various pathogens (Ahmed et al 2021) Carbonized biological materials can fundamentally have altered physicochemical characteristics, depending upon the production method used, pyrolysis conditions, and type of feedstock used (Ahmad et al 2014;Abdelaal et al 2020). Various methods such as torrefaction (pyrolytic process mainly at a low temperature), sluggish pyrolysis, transitional pyrolysis, firm pyrolysis, gasification, heat carbonization, and hydrothermal carbonization (HTC) have been used for the production of biochar (Zwieten et al 2010;Liu et al 2013;Moradi and Karimi 2021). Biochar can be manufactured both in the customary stone charcoal kilns in which the process of pyrolysis, combustion, and gasification takes place and in the modern biochar retorts in which the process of combustion and pyrolysis is substantially parted by the metal barricade (Crombie et al 2013).…”

“…Many studies have recommended that conversion techniques play an important role in controlling the properties of the biochar (Yao et al 2011). To enhance the adsorption capacity of biochar, modifications through different activation procedures have been made (Ahmed et al 2016;Moradi and Karimi 2021). A summary of different strategies for biochar modification is presented in Table 3.…”

“…Due to anthropogenic practices such as mining, urban waste, industrial effluents, and their use for irrigation purposes especially in the technologically industrialized world, the soil has been contaminated via metals (Quartacci et al 2017;Liu et al 2020a, b, c;Moradi and Karimi 2021;Rizwan et al 2021). Heavy metal pollution in the soil is a global environmental problem, which has captivated substantial public.…”

“…According to Koltowski et al (2017), the initial intended price of remediation through biochar is very low compared to the traditional techniques like physical treatment process, electro-kinetic remediation, organic remediation, and phytoremediation. The use of biochar in remediation is ascribed to its physicochemical characteristics like permeable structure, functional groups, large surface area, CEC, and abundant carbon contents (Ijaz et al 2020;Sabir et al 2020;Moradi and Karimi 2021). The impact of biochar application on heavy metals' contaminated soils is summarized in Table 5.…”

“…It offers a cost-effective and eco-friendly way to use organic waste (Ding et al 2016;Mandal et al 2016;Lahori et al 2017). The activated carbon in biochar is effective for the remediation of soil and sediments because it can bind pollutants and reduce their bioavailability (Ahmad et al 2016;Moradi and Karimi 2021). Biochar also offers carbon storage for a longer period than the original organic waste due to its more stable structure.…”