典型西南岩溶地下水抗生素污染指示因子识别

Identification of indicators of antibiotic pollution in typical karst groundwater in southwestern China

我国南方岩溶地区是全球三大岩溶集中分布区之一,由于岩溶地区独特的含水层结构,其地下水极易受到地表污染。为了探明岩溶地下水中抗生素污染空间分布的主控因素,厘清抗生素浓度与水化学参数的相关关系,进而识别岩溶地区水环境中抗生素污染的指示因子,以西南典型岩溶地下河系统为研究对象,利用超高效液相色谱串联质谱联用仪(UPLC-MS/MS)分析了35种抗生素浓度。结果表明:研究区共检出了30种抗生素,包括3种四环素类(<检出限(MDL)~421 ng/L)、5种大环内酯类(28.3~884 ng/L)、9种磺胺类(2.50~30 ng/L)和13种喹诺酮类(19.5~1807 ng/L)。其中,大环内酯类和喹诺酮类抗生素是研究区检出的主要抗生素,其空间分布特征主要受污染源和稀释作用控制。研究区水化学类型包括HCO_(3)-Ca·Mg型和HCO_(3)-Ca·Na·Mg型,抗生素浓度在不同的水化学类型中存在显著差异,HCO_(3)-Ca·Na·Mg型水样中抗生素浓度显著高于HCO_(3)-Ca·Mg型(2~10倍)(Mann-Whitney检验,p<0.05)。同时,Pearson相关性分析结果表明,三氮(硝氮、亚硝氮与氨氮浓度之和)、总有机碳(TOC)、Na^(+)、Cl^(-)浓度与单一抗生素浓度、不同种类抗生素浓度、抗生素总浓度均呈显著正相关(r=0.81~0.99,p<0.05,N=7~8)。相比三氮、TOC和Na^(+),Cl^(-)在环境中性质更稳定,是岩溶地区地下水系统中更可靠的抗生素污染指示因子。本研究为受县级污水处理厂和农村生活废水排放影响的岩溶地区抗生素污染识别与污染预测提供了理论依据。

[Objective]The karst area in southwestern China is one of the three concentrated karst distribution areas in the world.Karst groundwater is highly susceptible to pollution from the surface due to the unique structure of aquifers.[Methods] To investigate the dominant factors influencing the spatial distribution of antibiotic pollution,clarify the correlation between antibiotics and hydrochemical parameters,and then identify the indicators of antibiotic pollution in karst groundwater systems,a typical karst groundwater system in southwestern China was selected as the research object.Thirty-five antibiotics were analysed using ultra performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS).[Results] The results showed that a total of thirty antibiotics were detected in the study area,including 3 tetracyclines(<MDL-421 ng/L),5 macrolides(28.3-884 ng/L),9 sulfonamides(2.50-30 ng/L) and 13 quinolones(19.5-1 807 ng/L).Among them,macrolides and quinolones were the dominant antibiotics in the study area,whose spatial distribution was dominated by pollution sources and dilution effects.The results of Pearson correlation analysis showed that the concentrations of inorganic nitrogen(the sum of NH^(+)_4-N,NO^(-)_2-N and NO^(-)_3-N),total organic carbon(TOC),Na^(+) and Cl^(-) were significantly positively correlated with the concentration of individual antibiotics,the concentration of various antibiotic species,and the total concentration of antibiotics(r=0.81-0.99,p<0.05,N=7-8).With more stable properties than inorganic nitrogen,TOC and Na^(+),Cl^(-) is a more reliable indicator of antibiotic pollution in groundwater in karst areas.[Conclusion] This study provides a theoretical basis for the identification and prediction of antibiotic pollution in karst areas affected by county-level wastewater treatment plants(WWTPs) and rural domestic wastewater discharges.