Institute for Rural Engineering, National Agricultural and Food Research Organization (NARO), 2-1-6 Kannondai, Tsukuba, Ibaraki, 305-8609, Japan.
Environ Sci Pollut Res Int. 2021 Mar;28(10):12699-12706. doi: 10.1007/s11356-020-11249-2. Epub 2020 Oct 21.
The bioavailability of cadmium (Cd) in agricultural soils is a significant health concern due to the potential risk of human exposure via foods grown in Cd-contaminated fields. Biochar has been known to have a highly porous structure and high pH, as well as containing various functional groups; as such, it can immobilize heavy metals. Although it has found that biochar amendment in Cd-contaminated agricultural soils could be effective in reducing Cd bioavailability in previous studies, differences in plant Cd accumulation from Cd-contaminated soils amended with biochars produced from various types of biomass have not been fully discussed yet; we aimed to address this shortcoming in the present work. The soil investigated was an acid soil (pH 5.1) and had an elevated concentration of Cd (total Cd: 3.3 mg kg-DW). Six kinds of biochar were produced, i.e., from woodchips (Japanese cedar [CE] and Japanese cypress [CY]), moso bamboo (MB), rice husk (RH), poultry manure (PM), and wastewater sludge (WS), at a pyrolysis temperature of 600 °C. Biochars were incorporated into the Cd-contaminated soil at 3% (w/w) and pot experiments using Brassica rapa var. perviridis were conducted for 28 days in a growth chamber. The Cd concentrations in the above-ground portion of the plants were significantly decreased as a result of the incorporation of all biochars compared to the unamended soil, with reduction ratios following the order PM (78%) > > WS (31%) ≈ RH (29%) ≈ MB (28%) ≈ CY (26%) > CE (19%). Among all biochar-amended soils, soil pH and shoot biomass were highest for those amended with PM-derived biochar. These results suggest that in Cd-contaminated soils, PM-derived biochar may offer significant potential in reducing plant Cd accumulation due to the immobilization of soil Cd and an effect of dilution resulting from enhanced plant shoot biomass.
土壤中镉（Cd）的生物可利用性是一个重大的健康问题，因为人类可能通过在 Cd 污染农田中种植的食物接触到 Cd。生物炭具有高度多孔的结构和高 pH 值，并且含有各种官能团；因此，它可以固定重金属。尽管以前的研究表明，在 Cd 污染的农业土壤中添加生物炭可以有效降低 Cd 的生物可利用性，但尚未充分讨论用不同类型生物质制成的生物炭来改良 Cd 污染土壤对植物 Cd 积累的影响；我们旨在解决当前工作中的这一不足。研究的土壤是酸性土壤（pH 5.1），Cd 浓度升高（总 Cd：3.3 mg kg-DW）。制备了 6 种生物炭，即木屑（日本雪松 [CE] 和日本扁柏 [CY]）、毛竹（MB）、稻壳（RH）、家禽粪便（PM）和污水污泥（WS），在 600°C 的热解温度下。将生物炭以 3%（w/w）的比例掺入 Cd 污染土壤中，并在生长室中进行了为期 28 天的 Brassica rapa var. perviridis 盆栽实验。与未添加土壤相比，所有生物炭的添加都显著降低了植物地上部分的 Cd 浓度，降低率按 PM（78%）> > WS（31%）≈ RH（29%）≈ MB（28%）≈ CY（26%）> CE（19%）的顺序排列。在所有添加生物炭的土壤中，添加 PM 衍生生物炭的土壤的 pH 值和地上部生物量最高。这些结果表明，在 Cd 污染土壤中，由于土壤 Cd 的固定和植物地上部生物量增加导致的稀释效应，PM 衍生生物炭可能在降低植物 Cd 积累方面具有显著潜力。
