Organic sorbents alter physicochemical soil properties and mitigate heavy metal (HM) bioavailability. However, some sorbents are labile and, therefore, introduce the risk of HM release into soil after mineralisation. Before field application, new stable organic sorbents such as woodchip biochar (BIO) and brown coal waste (BCW) need to be tested and compared with standard organic amendments like farmyard manure (FYM). An incubated pot experiment was conducted to investigate the efficacy of FYM, BIO and BCW (added to soil in pots at 5 and 10% w/w) to alter soil physicochemical properties and mitigate bioavailability of Cd, Pb and Zn spiked in treatments at different doses (in mg kg⁻¹); 0 (not spiked), 1 (1 Cd, 70 Pb, 100 Zn) and 2 (3 Cd, 500 Pb, 700 Zn), and incubated for 9 weeks. At the end of the experiment, the EDTA-extractable HM fractions, pH, cation exchange capacity (CEC) and specific surface area (SSA, to check trends) were determined in all treated soils. Results showed that FYM, BCW and BIO generally improved all soil properties (except reduced pH from BCW and apparent SSA reduction from FYM) and accounted for respective maximum abatements of Cd (50.2, 69.9 and 25.5%), Pb (34.2, 64.3 and 17.4%) and Zn (14.9, 17.7 and 11.8%) bioavailability in soil. FYM and BCW were more effective at 10% w/w especially in the low contaminated soil, whereas the highest efficacy for BIO was at 5% w/w and in the high contaminated soil. The efficacies of sorption by the organic sorbents varied for different HMs and were in the orders: BCW > FYM > BIO for Cd, FYM > BCW > BIO for Pb and BIO > BCW > FYM for Zn. Soil pH and CEC were strongly correlated with HM bioavailability in all treatments and implied that immobilisation of HMs occurred via complex formation, ion exchange and pH-dependent specific adsorption. All three sorbents were beneficial as soil amendments, and in terms of HM mitigation, BCW had the highest efficacy, followed by FYM and then BIO. Considering the documented high soil stability of BCW and BIO, these results are promising for further trialling at field scale.

有机吸附剂会改变土壤的物理化学性质，并降低重金属（HM）的生物利用度。但是，某些吸附剂不稳定，因此，在矿化后，HM会释放到土壤中。在现场应用之前，需要测试新的稳定有机吸附剂，例如木屑生物炭（BIO）和褐煤废物（BCW），并与标准有机改良剂（例如农家粪肥（FYM））进行比较。进行了一个温育盆实验，研究了FYM，BIO和BCW（分别以5％和10％w / w添加到盆中的土壤）改变土壤理化特性并减轻不同处理条件下加标的Cd，Pb和Zn的生物利用度的功效剂量（以mg kg ^-1为单位）; 0（未加标），1（1 Cd，70 Pb，100 Zn）和2（3 Cd，500 Pb，700 Zn）孵育9周。在实验结束时，在所有处理过的土壤中测定了EDTA可萃取的HM组分，pH，阳离子交换容量（CEC）和比表面积（SSA，以检查趋势）。结果表明，FYM，BCW和BIO总体上改善了所有土壤特性（除了BCW降低了pH值和FYM明显降低了SSA），而且分别减少了Cd（50.2、69.9和25.5％），Pb（34.2、64.3和17.4） ％）和Zn（14.9、17.7和11.8％）在土壤中的生物利用度。FYM和BCW在10％w时更有效/ w，尤其是在低污染土壤中，而BIO的最高功效为5％w / w和在高污染土壤中。对于不同的重金属，有机吸附剂的吸附效率各不相同，依次为：BCW> FYM> CIO对Cd，FYM> BCW> BIO对Pb和BIO> BCW> FYM对Zn。在所有处理中，土壤的pH和CEC与HM的生物利用度均密切相关，这表明HM的固定化是通过复合物的形成，离子交换和pH依赖的特异性吸附实现的。三种吸附剂都可以作为土壤改良剂，在减轻HM方面，BCW的功效最高，其次是FYM，然后是BIO。考虑到已记录的BCW和BIO的高土壤稳定性，这些结果有望在田间规模上进行进一步试验。