AUTHORS: Fangkai Zhao*, Lei Yang, Shoujuan Li, Long Sun, Liding Chen – Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences
ABSTRACT: Soils in peri-urban area are facing with increasing socio-economic and eco-environmental pressures under rapid urbanization. Especially, the extensive use of manures in peri-urban inevitably aggravates the ecological risks posed by antibiotics and metals in agricultural soils. Quantifying the effects of land use intensity on soil contamination and identifying the dominant contamination sources are essential for soil security and ecosystem services in peri-urban areas. In this study, the distribution of antibiotics and metal elements in soils of a typical peri-urban catchment of east China were investigated. The landscape development intensity (LDI) index was used to characterize the potential influence of landscape variance on soil antibiotic and metal pollution. Results showed the total antibiotic concentrations in farmland reached 395.6 µg/kg, and there were relatively lower concentrations of total antibiotics in soils from orchard and forest with maximum concentrations of 26.4 µg/kg and 3.7 µg/kg, respectively. Redundancy analysis showed that land use pattern in buffer zone of 300 m had an appropriate explanation on the variation of soil contamination by antibiotics and metals. Meanwhile, the LDI in 300 m buffers had a close correlation with concentrations of total antibiotics. This indicated soil contamination in peri-urban area was mainly determined by land use pattern and was correlated with intensive agricultural activities. Results of structural equation modeling showed that Al, Cu, Zn can aggravate the concentrations of tetracyclines in soils, while there were only significantly direct paths from Cu to ciprofloxacin and norfloxacin. According to the results of variation partitioning analysis, a total of 6.7% variance of tetracyclines and 8.7% variance of fluoroquinolones in soils could be explained by metal elements. In conclusion, the co-contamination of antibiotics and metals in peri-urban areas were influenced by complex land uses and intense human activities. Optimization the landscape pattern of peri-urban areas can improve the soil security.