Bound residual (BR) fraction typically represents the “endpoint” of soil pollution risk assessment and remediation. However, it remains unclear whether the BR fraction of sulfamethoxazole (SMX) still presents a release risk after immobilized by biochar. Therefore, the SMX migration rate in different fractions were quantified. Results revealed that there are three extractable fractions of SMX in biochar-soil systems, allowing the migration of SMX among these various fractions. 1.0 % biochar could increase 8.5 %∼14.1 % BR fraction and 17.9 %∼36.9 % non-extractable fraction, respectively. Model simulations and Sobol Global Sensitivity Analysis results revealed that migration of SMX from BR fraction to labile fraction or stably-adsorbed fraction significantly affects overall fraction migration, suggesting BR fraction still poses a potential release risk. When considering the BR fraction, the half-life of SMX extended to 93.8 ∼ 132.0 days. Thus, the potential release risk of SMX in the BR fraction should not be overlooked when applying biochar for soil remediation.

中文翻译：

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是否应该忽视生物炭土壤系统的结合残留部分中磺胺甲噁唑的释放风险？


结合残差 （BR） 分数通常代表土壤污染风险评估和修复的“终点”。然而，目前尚不清楚磺胺甲噁唑 （SMX） 的 BR 组分在被生物炭固定后是否仍然存在释放风险。因此，对不同组分的 SMX 迁移率进行了量化。结果显示，生物炭土壤系统中有三种可提取的 SMX 组分，允许 SMX 在这些不同的组分之间迁移。1.0 % 生物炭可分别增加 8.5 %∼14.1 % BR 组分和 17.9 %∼36.9 % 的不可萃取组分。模型模拟和 Sobol 全局敏感性分析结果表明，SMX 从 BR 馏分迁移到不稳定馏分或稳定吸附馏分会显著影响整体馏分迁移，表明 BR 馏分仍存在潜在的释放风险。当考虑 BR 分数时，SMX 的半衰期延长至 93.8 ∼ 132.0 天。因此，在应用生物炭进行土壤修复时，不应忽视 SMX 在 BR 组分中的潜在释放风险。