Impact of anthropogenic activity on antibiotic behaviors in coastal waters

The overuse of antibiotics and the pollution of the ecological environment caused by their emissions had attracted widespread attention. There was little information on the detection and distribution characteristics of antibiotics in coastal environments with complex water-suspended particles interactions and significant salinity changes. In this study, the occurrence, source, and ecological risk of 26 antibiotics, as well as their response mechanisms to anthropogenic activities were studied. Water samples along a typical silty mud coastal area were collected. The total concentration of antibiotics in the coastal water ranged from 8.5 to 132 ng/L. Spatially, the total concentration showed a downward trend along the canal. The results of offshore samples showed that the highest concentrations occurred near the small estuaries and the northwestern sampling sites. This indicated that the small canals provided a large source of pollutants and the antibiotic distribution were also dominated by local hydrodynamic conditions. Based on the results of principal component analysis-multiple linear regression, the domestic sewage and livestock and poultry farming were identified as the predominant sources of antibiotics. The results of the ecological risk assessment showed that 56.8 % sampling sites were in low-risk. The effect of intensity of anthropogenic disturbance on the distribution of antibiotics was represented by the distance between the sampling site and the city center, and the distance value showed a significant negative correlation with the total concentration of antibiotics. However, different kinds of antibiotics showed different patterns: concentrations of tetracyclines and fluoroquinolones had no significant relationship with distance values; sulfonamides, lincosamides, and macrolides decreased with the intensity of anthropogenic disturbance. This study presented a method to quantify the effect of anthropogenic activities, thus provided a new insight of adjust measures to local conditions for the pollution prevention and ecological risk assessment of antibiotics in coastal areas.