Department of Soil and Water Science, University of Florida, Gainesville, FL 32611, USA.
J Contam Hydrol. 2011 Sep 25;126(1-2):29-36. doi: 10.1016/j.jconhyd.2011.06.002. Epub 2011 Jun 24.
Many antibiotics regarded as emerging contaminants have been frequently detected in soils and groundwater; however, their transport behaviors in soils remain largely unknown. This study examined the transport of two antibiotics, sulfamethoxazole (SMZ) and ciprofloxacin (CIP), in saturated porous media. Laboratory columns packed with quartz sand was used to test the effects of solution pH and ionic strength (IS) on their retention and transport. The results showed that these two antibiotics behaved differently in the saturated sand columns. In general, SMZ manifested a much higher mobility than CIP for all experimental conditions tested. Almost all SMZ transported through the columns within one pore volume in deionized water (i.e., pH=5.6, IS=0), but no CIP was detected in the effluents under the same condition after extended column flushing. Perturbations in solution pH (5.6 and 9.5) and IS (0 and 0.1M) showed no effect on SMZ transport in the saturated columns. When pH increased to 9.5, however, ~93% of CIP was eluted from the sand columns. Increase of IS from 0 to 0.1M also slightly changed the distribution of adsorbed CIP within the sand column at pH 5.6, but still no CIP was detected in the effluents. A mathematical model based on advection-dispersion equation coupled with equilibrium and kinetic reactions successfully simulated the transport of the antibiotics in water-saturated porous media with R(2)=0.99.
许多被认为是新兴污染物的抗生素经常在土壤和地下水中被检测到；然而，它们在土壤中的迁移行为在很大程度上仍然未知。本研究考察了两种抗生素磺胺甲恶唑（SMZ）和环丙沙星（CIP）在饱和多孔介质中的迁移行为。使用填充有石英砂的实验室柱来测试溶液 pH 值和离子强度（IS）对它们保留和迁移的影响。结果表明，这两种抗生素在饱和砂柱中的表现不同。一般来说，SMZ 在所有测试条件下的迁移性都比 CIP 高得多。在去离子水中（即 pH=5.6，IS=0），几乎所有的 SMZ 在一个孔隙体积内通过柱体，但在相同条件下延长柱冲洗后，没有 CIP 检测到在流出物中。溶液 pH 值（5.6 和 9.5）和 IS（0 和 0.1M）的干扰对饱和柱中 SMZ 的迁移没有影响。然而，当 pH 值增加到 9.5 时，约 93%的 CIP 从砂柱中洗脱出来。当 IS 从 0 增加到 0.1M 时，在 pH 值为 5.6 时也略微改变了吸附 CIP 在砂柱内的分布，但在流出物中仍未检测到 CIP。基于对流-弥散方程与平衡和动力学反应耦合的数学模型成功地模拟了抗生素在水饱和多孔介质中的迁移，R(2)=0.99。
