长三角典型城郊不同土地利用土壤抗生素组成及分布特征

Composition and Distribution of Antibiotics in Soils with Different Land Use Types in a Typical Peri-urban Area of the Yangtze River Delta

阐明不同土地利用条件下土壤抗生素的组成及其分布特征对于正确客观认识抗生素的空间扩散迁移过程具有重要意义.本研究选取长三角典型城郊地区宁波樟溪流域,在流域内根据土地利用、地形特征等布设样点采集0~40 cm深度土壤样品,利用固相萃取和HPLC-MS/MS测定土壤中抗生素含量,研究不同土地利用类型中土壤抗生素的组成及其含量,以及土壤抗生素在城郊地区的空间分布特征,并对其来源和影响因素进行了初步探讨.研究结果表明,流域内土壤抗生素分布具有较大的空间差异性,抗生素含量范围为0.05~395.55μg·kg^(-1).不同土地利用类型土壤中抗生素含量与组成差异较大,农田土壤抗生素含量范围0.35~395.55μg·kg^(-1),主要成分为四环素类(TCs),约占81.45%;林地土壤抗生素含量显著低于农田,含量范围为0.07~3.65μg·kg^(-1),主要成分为喹诺酮类(QNs),约占70.04%;园地土壤抗生素含量与组成介于两者之间,主要包括TCs(67.63%)和QNs(29.55%),含量范围为0.05~26.43μg·kg^(-1),显著低于农田,但与林地之间没有显著差异.本研究选用距城镇距离、距道路距离、海拔以及土壤C/N来表征人类活动的影响,数据分析表明土壤抗生素含量随4个指标的增加而降低,同时Spearman相关分析表明选取的4个指标均对土壤抗生素总含量具有显著的负影响(P<0.01).研究结果表明典型城郊土壤抗生素污染主要受土地利用的影响,其含量则随人类活动强度的减弱而降低.

Antibiotics have been widely used for agriculture, aquaculture, and livestock, as well as for human disease treatment, in recent decades. However, antibiotics cannot be completely absorbed, and most of them are excreted through urine and feces. A substantial part of the antibiotics enter soils through fertilization and irrigation. Antibiotics persist in the soil environment and threaten human and ecological security. Identifying the composition, distribution, and factors affecting antibiotics in soils with different land use types can help in understanding the spatial distribution and migration processes of antibiotics. In this study, a typical peri-urban catchment located in the Yangtze River delta was selected as the study area, and 82 sampling sites were selected based on land use and topographical features. Soil samples were collected at depths of 0-40 cm at each sampling site. The types and quantity of antibiotics in each soil sample were identified and analyzed by using HPLC-MS/ MS in the laboratory. The composition and concentration of antibiotics in different soil layers and the land use types were compared, and the factors affecting the spatial distribution of soil antibiotics were analyzed. Results from this study showed that the total concentration of antibiotic compounds （∑total） ranged from 0. 05 μg·kg - 1 to 395. 55 μg·kg - 1 in the study area, and a significant spatial distribution of antibiotics was found between different land use types. The ∑total in cropland ranged from 0. 35 μg·kg - 1 to 395. 55 μg·kg - 1 , and tetracyclines （TCs） were the dominant antibiotics （81. 45% ）. The ∑total in forestland ranged from 0. 07 μg·kg - 1 to 3. 65 μg·kg - 1 , with values significantly lower than those in cropland （P 0. 05）. The analysis of the composition and quantity of antibiotics in the soils showed that tetracyclines （TCs） and quinolones （ QNs） were the dominant antibiotic types in orchards （TCs：67. 63% , QNs： 29. 55% ） and forestland （TCs： 13. 25% , QNs： 70. 04% ）. The indices, including distance to town, distance to road, elevation, and C/ N value in soils, were selected to explore the influence of human activity on soil antibiotic concentration. Results of the correlation analysis showed that the concentration of soil antibiotics decreased with increasing values of the four indices. This indicated that the concentrations of soil antibiotics in peri-urban areas were dominantly affected by land use and its spatial distribution, and the concentrations increased with the intensity of human activities. Results of this study can provide scientific guidance for soil management and soil security.