Extractable fractions of oxytetracycline in soil affect its bioavailability and accumulation in plants. The objective was to assess the bioavailability of different bound fractions of oxytetracycline available in soil to horsebean. After freshly spiking with oxytetracycline for 24 h, soils were treated with water and mild (0.1 mol L⁻¹ CaCl₂) and exhaustive (0.1 mol L⁻¹ Na₂EDTA-McIlvaine) extractants as treatments T₁, T₂, and T₃, respectively, to obtain different extractable oxytetracycline fractions. The control was a nonextracted soil. Horsebean was exposed to the abovementioned soils. The results showed that oxytetracycline was accumulated in shoots and roots at 10 days; however, after 10 days, the amount of oxytetracycline in the roots was below its quantification limits (<0.001 mg kg⁻¹). The remained OTC as resistant bound fraction in T₃ always exhibited the highest shoot concentration factors (SCF) compared with removing fewer extractable fractions during 14–28 days exposure. Moreover, the effect of horsebean upon oxytetracycline extractability during exposure was also studied. Adding horsebean did not affect the change trend of three extractable fractions in the control, T₂, or T₃ during exposure, but changed the trend of CaCl₂- and total-extractable fractions in T₁. Horsebean activity can increase total-extractable concentration in the control, but decrease total-extractable concentration in T₁, T₂ and T₃. The correlation analysis showed that there were close relationships between water-, CaCl₂-, total-extractable fractions in soil and root accumulation for the horsebean at 10 days of exposure. The interesting phenomenon was that resistant bound OTC had a high availability, and its ecological risk in soil had been underestimated in previous investigations.

中文翻译：

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去除土壤中可提取的土霉素成分后，大豆生物利用度和累积的时间变化

土壤中土霉素的可提取部分会影响其生物利用度和在植物中的积累。目的是评估土壤中可利用的土霉素对大豆的不同结合部分的生物利用度。用土霉素新鲜加标24小时后，用水和温和的（0.1 mol L ^-1 CaCl ₂）和详尽的（0.1 mol L ^-1 Na ₂ EDTA-McIlvaine）萃取剂处理土壤，作为处理剂T ₁，T ₂和T ₃分别获得不同的可提取的土霉素级分。对照是未提取的土壤。蚕豆暴露于上述土壤中。结果表明，土霉素在第10天根和茎中积累。但是，10天后，根中土霉素的含量低于其定量限（<0.001 mg kg ^-1）。与在暴露14至28天期间除去较少的可提取馏分相比，保留在T _3中作为抗性结合馏分的OTC始终表现出最高的芽浓度因子（SCF）。此外，还研究了蚕豆对暴露期间土霉素提取能力的影响。添加蚕豆不影响对照中三个可提取馏分T ₂的变化趋势，或T ₃在暴露期间，但是改变了CaCl ₂和T _1中总可提取馏分的趋势。蚕豆的活性可以增加对照中的总提取浓度，但降低T ₁，T ₂和T _3中的总提取浓度。相关分析表明，在暴露10天后，水，CaCl _2-，土壤中总可提取组分与大豆根系积累之间存在密切关系。有趣的现象是抗药性绑定的OTC具有很高的利用率，并且在先前的研究中低估了其在土壤中的生态风险。