川中丘陵区紫色土抗生素残留特征及其生态风险

Antibiotics Residue and Ecological Risks in Purple Soils of the Central Sichuan Basin,China

抗生素在表层土壤中富集,将干扰植物、土壤动物以及微生物的生长发育,威胁生态系统安全。紫色土作为长江中上游重要的农业土壤资源,其抗蚀性弱和优先流发育的特点为环境残留抗生素迁移提供了动力条件。目前相关研究多针对目标抗生素的环境迁移行为,土壤残留抗生素的自然丰度、自然污染特征以及环境风险尚不明晰。本研究选择川中丘陵区6种典型土地利用类型(旱地、林地、果园、水田、化肥菜园和粪肥菜园)的紫色土土壤及灌溉水为研究对象,对5类11种抗生素进行残留量的测定,并利用风险商值法进行抗生素生态风险评估。结果表明:(1)土壤中检出金霉素、诺氟沙星、环丙沙星和恩诺沙星。其中,诺氟沙星、环丙沙星和恩诺沙星仅在粪肥菜园土壤中有检出,其残留量分别为5.95、3.36和6.52μg·kg^(-1);金霉素在粪肥菜园土壤中残留量最高,为43.00μg·kg^(-1)。(2)灌溉水中各类抗生素含量均低于仪器检出限。(3)研究区内土壤抗生素风险商值范围为0.08~0.43,处于中低生态风险水平,但抗生素残留量均小于国际土壤生物毒性触发值(100μg·kg^(-1)),处于相对安全的生态风险水平。(4)研究区内土壤抗生素来源可能与有机肥施用有关,通过调整施肥结构可能在一定程度上降低抗生素的环境生态风险。本研究可为川中丘陵紫色土区生态安全建设提供依据。

The enrichment of antibiotics in topsoil will interfere with the growth and development of plants,soil fauna,and microorganisms,threatening ecosystem security.As an important agricultural soil resource in the middle and upper reaches of the Yangtze River,China,purple soils are characterized by weak erosion resistance and preferential flow development,which provide dynamic conditions for the migration of environmental residual antibiotics.Formerly,most of the related studies in antibiotics migration in purple soil focused on the mechanism of environmental migration of target antibiotics;unfortunately,the natural abundance,natural contamination characteristics,and environmental risks of soil residual antibiotics are not yet addressed.In this study,purple soil in 6 land use types(dryland,woodland,orchard,paddy field,fertilizing vegetable garden and manuring vegetable garden)and irrigation water in the hilly area of central Sichuan basin,China were targeted for determination of residue levels of 11 antibiotics in five categories,followed by an ecological risk assessment of antibiotics using the risk quotient method.(1)Chlortetracycline(CTC),norfloxacin(NFX),ciprofloxacin(CFX)and enrofloxacin(EFX)were detected in purple soils.NFX,CFX and EFX were only detected in manuring vegetable garden,with soil residues values of 5.95,3.36 and 6.52μg?kg^(-1),respectively.CTC had the highest residue of 43.00μg?kg^(-1) in manuring vegetable garden among six typical land uses.(2)No antibiotics were detected in irrigation water in the study area,suggesting that the levels of all types of antibiotics residues in irrigation water were below the detection limit of instrument to be used in the study.(3)The risk quotient values(RQ)of antibiotics in purple soils in the study area ranged from 0.08 to 0.43,which were at a low or middle ecological risk level;the antibiotics residues were all lower than the international soil biological toxicity trigger value(100μg?kg^(-1)),at a relatively safe ecological risk level.(4)The source of antibiotics in the study area might contribute to the application of organic fertilizer;therefore,environmental and ecological risks of antibiotics in soil might be reduced to a certain extent by adjusting the fertilizer application structure.This study provides a basis for ecological security construction in the purple soil area of the central Sichuan basin.