School of Environmental Science and Engineering, Yancheng Institute of Technology, No. 211 Jianjun East Road, Yancheng 224051, China.
Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China; Shanghai Clean Land Environmental Technology Co., Ltd, China.
Ecotoxicol Environ Saf. 2023 Jun 1;257:114928. doi: 10.1016/j.ecoenv.2023.114928. Epub 2023 Apr 22.
Pig manure could be an effective fertilizer source for soil, but with high concentrations of xic elements. It has been shown that the pyrolysis method could largely reduce the environmental risk of pig manure. However, the comprehensive analysis of both toxic metals immobilization effect and environmental risk of pig manure biochar applied as a soil amendment is rarely addressed. To address the knowledge gap, this study was carried out with pig manure (PM) and pig manure biochar (PMB). The PM was pyrolyzed at 450 ℃ and 700 ℃, the corresponding biochar was abbreviated as PMB450 and PMB700, respectively. The PM and PMB were applied in a pot experiment growing Chinese cabbage (Brassica rape L. ssp. Pekinensis) with clay-loam paddy soil. The application rates of PM were set at 0.5% (S), 2% (L), 4% (M) and 6% (H). With the equivalent mass principle, PMB450 and PMB700 were applied at 0.23% (S), 0.92% (L), 1.84% (M), 2.76% (H), and 0.192% (S), 0.7% (L), 1.4% (M), 2.1% (H), respectively. Parameters of Chinese cabbage biomass and quality, total and available concentrations of toxic metals in soil, and soil chemical properties were systemically measured. The main results of this study showed that compared with PM, PMB700 was more effective than PMB450, which induced the highest reductions of Cu, Zn, Pb, and Cd contents in cabbage by 62.6%, 73.0%, 43.9%, and 74.3%, respectively. Both PM and PMB increased the total contents of metals (Cu, Zn, Pb, and Cd) in soil, and PMB decreased the mobility of Cu, Zn, Pb, and Cd at high application rates (≥2%). Treatment with H-PMB700 reduced CaCl extractable Cu, Zn, Pb, and Cd by 70.0%, 71.6%, 23.3%, and 15.9%, respectively. For Cu, Zn, Pb, and Cd fractions with BCR extraction, PMB treatments, especially PMB700, were more effective than PM in decreasing the available fractions (F1 +F2 +F3) at high application rates (≥2%). Overall, pyrolysis with high temperature (e.g., 700 ℃) could significantly stabilize the toxic elements in PM and enhance PM's effect on toxic metals immobilization. The marked effects of PMB700 on toxic metal immobilization and cabbage quality improvement might be attributed to high ash contents and liming effect.
猪粪可以成为一种有效的土壤肥料资源，但其中含有高浓度的重金属元素。研究表明，热解方法可以在很大程度上降低猪粪的环境风险。然而，作为土壤改良剂应用的猪粪生物炭的有毒金属固定效果和环境风险的综合分析却很少涉及。为了解决这一知识空白，本研究以猪粪（PM）和猪粪生物炭（PMB）为研究对象。PM 在 450℃和 700℃下进行热解，对应的生物炭分别缩写为 PMB450 和 PMB700。PM 和 PMB 被应用于盆栽实验，种植中国白菜（Brassica rape L. ssp. Pekinensis），所用土壤为粘壤土稻田土。PM 的施用量设为 0.5%（S）、2%（L）、4%（M）和 6%（H）。根据等效质量原则，PMB450 和 PMB700 的施用量分别为 0.23%（S）、0.92%（L）、1.84%（M）、2.76%（H）和 0.192%（S）、0.7%（L）、1.4%（M）、2.1%（H）。系统地测量了中国白菜生物量和品质、土壤中有毒金属的总量和有效浓度以及土壤化学性质等参数。本研究的主要结果表明，与 PM 相比，PMB700 的效果优于 PMB450，对白菜中 Cu、Zn、Pb 和 Cd 的含量分别降低了 62.6%、73.0%、43.9%和 74.3%。PM 和 PMB 均增加了土壤中金属（Cu、Zn、Pb 和 Cd）的总量，且 PMB 在高施用量（≥2%）下降低了 Cu、Zn、Pb 和 Cd 的迁移性。高剂量 PMB700 处理降低了 CaCl2 可提取 Cu、Zn、Pb 和 Cd 的含量，降幅分别为 70.0%、71.6%、23.3%和 15.9%。对于 BCR 提取的 Cu、Zn、Pb 和 Cd 形态，PMB 处理，特别是 PMB700 处理，在高施用量（≥2%）下，比 PM 更有效地降低了有效形态（F1+F2+F3）的含量。总体而言，高温（如 700℃）热解可显著稳定 PM 中的有毒元素，并增强 PM 对有毒金属固定的效果。PMB700 对有毒金属固定和白菜品质改善的显著效果可能归因于高灰分含量和石灰效应。
