[Composition, Characteristics, and Accumulation of Antibiotics in the Soil in Agricultural Land]

Exploring the composition and accumulation of antibiotics in agricultural land soil for soil for quality management of agricultural land and control of antibiotic pollution is of great significance. A total of 95 soil samples were collected from farmland soil in a typical agricultural and sideline production base of northern China. In this study, the concentrations of 10 antibiotics, including tetracycline antibiotics (TCs), macrolide antibiotics (MLs), and sulfonamide antibiotics (SAs), were determined in soil samples from different land use types using HPLC-MS/MS. In addition, the composition and spatial distribution of the antibiotics were compared. The relationships between the concentration distributions and the distance from livestock farms, highways, and rivers were analyzed. Moreover, the composition and accumulation of antibiotics in the soil with different planting patterns and soil properties were preliminarily discussed. The results showed that the concentrations of antibiotics in the soil were low-level, while the detection rate was high; in particular, the detection rate of the total amount of antibiotics was as high as 100%. In the study area, TCs were the dominant antibiotic types, accounting for 94% of the total. The coefficient variation (CV) was high, which reflected a significant difference in the spatial variation of these antibiotics. The spatial distribution and accumulation of antibiotics in the soil in this area were affected by the intensity of human activity. The detection rate and concentrations of the various antibiotics decreased with increasing distance between the soil sample and livestock farms, highways, and rivers. Among these, there was a significant negative correlation between the concentration of antibiotics and the distance between livestock farms and the soil samples (P<0.05). The detection rate of three types of antibiotics in soil samples from within 50 meters of a river reached 100%. The total concentration of the 10 antibiotics was the highest in orchards, followed by vegetable plots, and mixed fruit and vegetable areas. Furthermore, the sources and concentrations of antibiotics in a peach orchard and open-air vegetable field were significantly different from those in a walnut orchard, greenhouse vegetable field, and mixed field. Moreover, the soil pH, soil organic matter (SOM), cation exchange capacity (CEC), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) were selected to characterize soil properties. Redundancy analysis showed that soil properties such as pH, SOM, CEC, AP, AK have a greater impact on the distribution of antibiotics. The distribution of antibiotics was most closely related to AK, and the effect of TN was relatively weak. The results of this study suggested that the composition and accumulation of soil antibiotics in the area were affected by human activities and soil properties.