生物炭对紫色土中氟苯尼考吸附与迁移的影响

氟苯尼考作为我国常用的兽用抗生素在土壤中被广泛检出，在有机质含量低(约<2%)、吸附性能差的紫色土中具有高迁移性，而具有多孔结构的生物炭对其具有较强的阻控能力. 本文采用批量平衡吸附试验与填装土柱淋溶试验，探究生物炭对氟苯尼考在紫色土中吸附与迁移的影响. 结果表明:Freundlich等温吸附模型可较好地刻画氟苯尼考在供试土壤上的吸附行为，其中，紫色土对氟苯尼考的吸附过程更接近于线性吸附(1/n=0.99±0.07)，而生物炭施用使得紫色土对氟苯尼考的吸附容量常数(K_f)提高了9.69倍，且非线性增强；两点化学非平衡模型可较好地刻画供试土柱中Br?示踪剂与氟苯尼考的穿透曲线(R2≥0.964，RMSE≤0.09)，生物炭施用分别提高了水动力弥散系数、瞬时吸附常数、瞬时吸附交换所占分数及一阶动力学速率系数，但因水土接触时间受限，瞬时吸附常数(K_d-c)远小于分配系数(K_d)和吸附容量常数(K_f)；生物炭的施用使得紫色土中氟苯尼考的残留率增加了38%. 研究显示，紫色土中施用生物炭虽然促进了水分运动，但仍可通过提高吸附能力阻控氟苯尼考的迁移. 

Effects of Biochar on Sorption and Transport of Florfenicol in Purple Soil

Porous biochar can control the transport of florfenicol by enhancing the sorption of purple soil. Florfenicol, a commonly used veterinary antibiotic in China, is widely detected in soils. It has high mobility in purple soil with poor adsorption capacity and low organic matter content (about <2%). This study investigated the effects of biochar on the sorption and transport of florfenicol in purple soil using batch adsorption and packed-column leaching experiments. The results showed that the Freundlich model could better characterize the adsorption behavior of florfenicol in the test soils. The adsorption process of florfenicol in purple soil was closer to linear adsorption (1/n=0.99±0.07), while the biochar application increased the adsorption capacity constant (K_f) by 9.69 times and enhanced nonlinearity. The two-site chemical nonequilibrium models could better fit the breakthrough curve of the tracer Br? and florfenicol in the test soil columns (R2≥0.964, RMSE≤0.09). The application of biochar increased the hydrodynamic dispersion coefficient, adsorption constant, the fraction of equilibrium adsorption sites, and first-order rate coefficients. However, the instantaneous sorption constants were significantly smaller than the partition coefficient and adsorption capacity constant due to the limited contact time between water and soil. As a result, a 38% increase in the residual rate of florfenicol in biochar-amended soils was obtained. The study revealed that the application of biochar could still control the transport of florfenicol by increasing the adsorption capacity although the application promoted water movement.