Study On The Distribution Characteristics And Correlation Of Dissolved Rare Earth Elements And Antibiotics In Surface Water Of Guiyang City

In this paper,surface water samples from 42 sampling points were collected at Lake Aha Catchment and Nanming River Catchment,for the qualitative and quantitative analysis of rare earth elements and antibiotics.The positive abnormal of gadolinium(Gd)in the study area was determined,and the migration of anthropogenic Gd and its influencing factors were also mentioned.Moreover,the relationship between anthropogenic Gd and antibiotics is analyzed,revealing that the anthropogenic Gd is a potential tracer for urban wastewater.The main research results are as follows:(1)At Lake Aha Catchment and Nanming River Catchment,rare earth element concentrations normalized to Post-Archean Australia Shale(PAAS)for the study area showed the heavy rare earth element enrichment of all water samples.The average concentration of dissolved rare earth elements in the Lake Aha Catchment(55.3 ng/L)was lower than that in the Nanming River Catchment(64.20 ng/L).The positive Gd anomaly was found in the study areas.Anthropogenic Gd ranged from 0.56 to 29.51ng/L in the Lake Aha Catchment and from 0.28 to 64.29 ng/L in the Nanming River Catchment,respectively.Higher concentrations of anthropogenic Gd could be also observed at wastewater treatment plant water and downstream sampling points.It seemed that the positive Gd anomaly only was found in well-developed medical care and densely populated areas,which could be attributed to the gadolinium-based contrast agents used in magnetic resonance imaging at the hospital.And results from correlation analysis showed that there were significant positive correlations between rare earth elements and physical parameters(temperature and conductivity).(2)A total of 8 antibiotics were detected in the study area,with 3.45%?100%detection rates of antibiotics.The total concentration of antibiotics in the study areas was 82.80?253.60 ng/L(Lake Aha Catchment)and 57.60?1406.20 ng/L(Nanming River Catchment).The concentration and distribution of antibiotics had a relationship with human activities.The average antibiotic concentrations in the Nanming River decreased in the following order: midstream>upstream>downstream.However,the Youyu River and the Baiyan River have the lowest antibiotic concentration for the single source of pollution.Moreover,high concentrations of quinolone antibiotics were detected in the study areas due to the low cost,high efficiency,and wide applications.(3)The correlations among anthropogenic gadolinium and antibiotics were analyzed,showing a significant positive correlation between the anthropogenic gadolinium elements and ofloxacin.In addition,there was no significant difference in the anthropogenic Gd at the downstream sampling point of the sewage treatment plant,indicating the possibility of tracing ofloxacin from the sewage treatment plant.As a medical source,the anthropogenic Gd has a good indication effect on ofloxacin and even antibiotics,which can be further used as a tracer of municipal wastewater.