Response of CaCl2-extractable heavy metals, polychlorinated biphenyls, and microbial communities to biochar amendment in naturally contaminated soils

Abstract

Purpose Biochar can be used to reduce the bioavailability and leachability of heavy metals, as well as organic pollutants in soils through adsorption and other physicochemical reactions. The objective of the study was to determine the response of microbial communities to biochar amendment and its influence on heavy metal mobility and PCBs (PCB52, 44, 101, 149, 118, 153, 138, 180, 170, and 194) concentration in application of biochar as soil amendment. Materials and methods A pot (macrocosm) incubation experiment was carried out with different biochar amendment (0, 3, and 6 % w/w) for 112 days. The CaCl 2 -extractable concentration of metals, microbial activities, and bacterial community were evaluated during the incubation period. Results and discussion The concentrations of 0.01 M CaCl 2 -extractable metals decreased (p>0.05) by 12.7 and 20.5 % for Cu, 5.0 and 15.6 % for Zn, 0.2 and 0.5 % for Pb, and 1.1 and 8.9 % for Cd, in the presence of 3 and 6 % of biochar, respectively, following 1 day of incubation. Meanwhile, the total PCB concentrations decreased from 1.23 mg kg −1 at 1 day to 0.24 mg kg −1 at 112 days after 6 % biochar addition, representing a more than 60 % decrease relative to untreated soil. It was also found out that biochar addition increased the biological activities of catalase, phosphatase, and urease activity as compared with the controls at the same time point. Importantly, the Shannon diversity index of bacteria in control soils was 3.41, whereas it was 3.69 and 3.88 in soils treated with 3 and 6 % biochar soil. In particular, an increase in the number of populations with the putative ability to absorb PCB was noted in the biochar-amended soils. Conclusions The application of biochar to contaminated soils decreased the concentrations of heavy metals and PCBs. Application of biochar stimulated Proteobacteria and Bacteroides, which may function to absorb soil PCB and alleviate their toxicity.

Effect of coapplication of poultry litter biochar and mineral fertilisers on soil quality and crop yield

“…Additionally, the reduction of available forms of Cd and Pb reported in our study was beneficial for dehydrogenases activity. The results presented by Liu et al (2016) showed that these elements may be among the main inhibitors of dehydrogenases activity, and the decrease in soil pH changes the degree of oxidation of these metals and reduces their adverse effects on the enzymatic activity of soil. Studies of Zheng et al (2015) have found that only biochar produced from rice straw reduced the availability of Pb, but it was not reflected in the rice biomass.…”

Synthesis of Novel Core-Shell Magnetic Fe₃O₄@C Nanoparticles with Carboxyl Function for Use as an Immobilisation Agent to Remediate Lead-Contaminated Soils

“…In summary, it can be seen from results of the six immobilisation remediation experiments that the suitable conditions for immobilisation by Fe 3 O 4 @C-COOH in lead-contaminated soil are: AA of 3.3%, pH of 7.33, WC of 50%, conductivity of 142.6 μS•cm -1 , OM of 63.04 g•kg -1 , and an exposure time of no less than 10 days. However, Pb state could be transferred reciprocally and the transformation impacts the toxicity of heavy metal ions in soil [15,[43][44]. Therefore, a leaching toxicity test (TCLP) is an appropriate method to evaluate the stabilization treatment of heavy metal-contaminated soil [8].…”

Biochar remediation of soil: linking biochar production with function in heavy metal contaminated soils

“…Amending HM contaminated soils with biochar has shown increased microbial abundance which suggests increased HMs tolerance (Liu et al 2016, Chen et al 2017, with changes in microbial population size, composition and activity (Liu et al 2016, Yang et al 2016, Chen et al 2017, Xu et al 2018. A number of studies have shown biochar dosage influences soil microbial population and activity, at low concentrations of biochar (1%) increased the relative abundance of bacterial and fungal species, while at higher application rates (5%) abundance declined (Huang et al 2017).…”