Due to the widespread utilization of antibiotics, antibiotic resistance genes (ARGs) are found to be existing in water environment, and migrate between the water column and sediments. Based on soil column experiments, the vertical transport mechanism of ARGs at water-sediment interface was studied in this paper. It aims to reveal the effects of physicochemical factors (salinity and pH) on the migration of four ARGs: sul(I), tet(A), tet(X), tet(M) and Class I integron (intI1) at water-sediment interface. It was found that salinity and pH both can affect the migration of ARGs between sediment and water. Salinity weakened the vertical migrations of sul(I), and tet(A), and tet(X), while the effect of salinity on tet(M) was opposite. The vertical migrations of sul(I), tet(A), intI1 and 16s were decreased under the acidic conditions (pH=4), while they were enhanced under the alkaline conditions (pH=9.18). For tet(X) and tet(M), both of acidic conditions (pH=4) and alkaline conditions (pH=9.18) weakened the vertical migration.
Antibiotics are widely used in medical and livestock farming. However, large amounts of antibiotics enter the environment, causing a series of problems such as drug-resistant bacteria and ARGs (Pruden, Arabi and Storteboom, 2012). ARGs, as a novel contaminant, can enter the human body through the food chain enrichment. Due to heritability, it has great danger to human health. Since Pruden (2006) identified ARGs as an emerging contaminant, there has been an increasing interest in antibiotics as well as ARGs. In 2000, the World Health Organization defined the problem of antibiotic resistance, i.e., ARGs, as one of the most serious challenges facing humanity in the 21st century.
Studies have shown that aquatic ecosystems are an enriched reservoir of ARGs (Jiang, 2013). Wastewater discharged from sewage treatment plants, farms and hospitals is an important source of ARGs in the environment. The transfer of ARGs at the water-sediment interface plays a crucial role in their transmission. Currently, most of the studies on resistance gene transfer and its patterns have been conducted through bacterial culture tests and soil column simulation tests.
