Department of Range and Watershed Management, College of Agriculture and Natural Resources of Darab, Shiraz University, Darab 74591, Iran.
Department of Soil Science, Faculty of AgriSciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111626. doi: 10.1016/j.ecoenv.2020.111626. Epub 2020 Nov 10.
Soil application of biochars has been shown to effectively immobilize potentially toxic elements (PTEs). Soil water regime can also affect PTE availability. No previous studies have examined the interactive effect of biochars and soil water regime on Pb availability. Therefore, this study investigated the effect of high and low temperature (300 and 600°C) biochars derived from cow manure (CB), municipal compost (MB) and licorice root pulp (LB) applied at 3 wt%, under two soil moisture regimes (field capacity (FC) and saturation (ST)) on Pb release kinetics and chemical fractions in a Pb-contaminated calcareous soil. Results showed that CB and MB treatments significantly enhanced Pb stabilization compared to LB, attributed to their favorable chemical properties (high P, ash, carbonate, oxidizable C content and high pH) which could promote Pb conversion into stable chemical fractions. Immobilization of Pb was enhanced under saturated conditions compared to FC by the treatments, which is attributed to increased soil pH, reduction of metal oxides and possible formation of sulfides. The most significantly effective treatments were the CB300, CB600 and MB600 treatments under ST, as indicated by significant decrease in soil Pb mobility factor from 29.1% (CL+FC) to 21.2-22.9%, and 11.7-16.3% increase in non-EDTA-extractable Pb. Results of this study demonstrate that combined application of high ash biochars and soil water saturation significantly enhances Pb immobilization in calcareous soil.
土壤施用生物炭已被证明能有效地固定潜在的有毒元素（PTEs）。土壤水分状况也会影响 PTE 的可用性。以前没有研究过生物炭和土壤水分状况对 Pb 可用性的交互影响。因此，本研究调查了在两种土壤水分条件（田间持水量（FC）和饱和（ST））下，以 3wt%的比例施加来自牛粪（CB）、城市堆肥（MB）和甘草根浆（LB）的高温（300°C）和低温（600°C）生物炭对 Pb 释放动力学和化学形态的影响，在 Pb 污染的石灰质土壤中。结果表明，与 LB 相比，CB 和 MB 处理显著增强了 Pb 的稳定性，这归因于它们有利的化学性质（高 P、灰分、碳酸盐、可氧化 C 含量和高 pH），可促进 Pb 转化为稳定的化学形态。与 FC 相比，处理后在饱和条件下 Pb 的固定作用增强，这归因于土壤 pH 的增加、金属氧化物的减少和可能形成的硫化物。在 ST 条件下，最有效的处理是 CB300、CB600 和 MB600 处理，这表明土壤 Pb 迁移因子从 29.1%（CL+FC）显著降低至 21.2-22.9%，非 EDTA 可提取 Pb 增加了 11.7-16.3%。本研究结果表明，高灰分生物炭与土壤水分饱和的联合施用显著增强了石灰质土壤中 Pb 的固定作用。
