Using biochar to remediate metal-contaminated agricultural soil has attracted increasing attention due to it is relatively low cost and high efficiency. In this study chemical speciation, greenhouse experiments, and column leaching study were conducted to understand the mechanisms of copper (Cu) immobilization by pine needle biochar (PNB) and sweet potato residue biochar (SPRB) to evaluate the effect of biochar amendment rate for remediation Cu contaminated soils. The results showed that both PNB and SPRB amendment effectively raised soil pH and converted Cu into more stable chemical forms. 1% (W/W) SPRB was adequate for reducing exchangeable Cu fractions from 43.3 to 9.9 mg kg−1 in the contaminated soils. 1% (W/W) SPRB and 5% (W/W) PNB treatments show the best result to promote sweet potato growth. Over liming caused by 5% (W/W) SPRB resulted in inhibition of plant growth. 5% (W/W) PNB treatment also shows the best result for reducing Cu mobility: the cumulative amount of Cu in the leachate after 9 leaching events was reduced from 7.0 to 1.0 mg kg−1. However, 5% (W/W) SPRB amendment is a little effective for reducing Cu mobility. Although the biochar amendment can provide additional sorption sites for metal pollution remediation, soil pH after an amendment is also a critical factor to estimate optimal biochar application dosage for promoting plant growth and reduce metal leachability. Biochar can effectively reduce exchangeable Cu concentration in soil matrix with sweet potato residue biochar is more effective than pine needle biochar. High dose Sweepboat biochar (5%) reduce plant growth and promote Cu mobility. High dose Pine needle biochar reduce Cu phytotoxicity and reduce Cu mobility Biochar can effectively reduce exchangeable Cu concentration in soil matrix with sweet potato residue biochar is more effective than pine needle biochar. High dose Sweepboat biochar (5%) reduce plant growth and promote Cu mobility. High dose Pine needle biochar reduce Cu phytotoxicity and reduce Cu mobility

中文翻译：

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生物炭作为土壤改良剂对降低铜植物毒性和迁移率的剂量依赖性影响

使用生物炭修复受金属污染的农业土壤因其成本相对较低且效率高而受到越来越多的关注。在本研究中，通过化学形态、温室实验和柱浸研究，了解松针生物炭 (PNB) 和甘薯渣生物炭 (SPRB) 固定铜 (Cu) 的机制，以评估生物炭修正率对修复的影响铜污染土壤。结果表明，PNB 和 SPRB 改良剂均有效提高了土壤 pH 值，并将 Cu 转化为更稳定的化学形式。1% (W/W) SPRB 足以将受污染土壤中的可交换 Cu 组分从 43.3 减少到 9.9 mg kg-1。1% (W/W) SPRB 和 5% (W/W) PNB 处理显示出促进甘薯生长的最佳效果。由 5% (W/W) 的 SPRB 引起的过度石灰导致植物生长受到抑制。5% (W/W) PNB 处理也显示出降低 Cu 迁移率的最佳结果：9 次浸出事件后浸出液中 Cu 的累积量从 7.0 mg kg-1 减少到 1.0 mg kg-1。然而，5% (W/W) SPRB 修正对降低 Cu 迁移率有点有效。虽然生物炭改良剂可以为金属污染修复提供额外的吸附位点，但改良剂后的土壤 pH 值也是估算促进植物生长和降低金属浸出性的最佳生物炭施用剂量的关键因素。生物炭能有效降低土壤基质中的交换性铜浓度，甘薯渣生物炭比松针生物炭更有效。高剂量 Sweepboat biochar (5%) 减少植物生长并促进 Cu 迁移。高剂量松针生物炭降低Cu药害，降低Cu迁移率 生物炭能有效降低土壤基质中可交换Cu的浓度，甘薯渣生物炭比松针生物炭更有效。高剂量 Sweepboat biochar (5%) 减少植物生长并促进 Cu 迁移。高剂量松针生物炭降低铜植物毒性并降低铜迁移率