Temporal And Spatial Distribution And Risk Assessment Of Phenolic Pollutants In Nansi Lake Basin

With the widespread use of phenolic compounds in industry and long-term retention in the environment,they are also easily harmful to the environment and organisms.Therefore,the occurrence of phenolic compounds in the environment has become a global concern.At present,research on the occurrence of phenolic compounds is mainly concentrated in the coastal industrially areas,and relatively little research on inland areas.Nansi Lake Basin is the largest freshwater lake in North China,and it is also an important water channel and storage lake for the East Route of the South-to-North Water Diversion Project.It’s meaningful to select the Nansi Lake Basin as the research area for phenolic compounds pollution research.This study collected surface water/sediment/soil samples from 27 main rivers in the Nansi Lake Basin in summer and winter;detected and analyzed the phenolic compounds,conventional water quality indicators and microbial community composition in surface water,the phenolic compounds,particle size,TOC in sediment/soil,and further studied the temporal and spatial differentiation characteristics of phenolic pollutants in the Nansi Lake Basin and their correlation with the main conventional water/sediment/soil indicators.Discussed the composition and structure of the microbial community in surface water and its correlation with phenolic compound pollution,and the risk quotient of phenolic compounds to the environment and human body was estimated.The source contribution frequency of Jining,Heze,Zaozhuang and Jiangsu four prefecture-level cities to Nansi Lake Basin phenolic compounds was calculated.The main results of the paper are as follows:（1）The detection frequency of the five phenolic compounds in the surface water and sediment/soil of the 27 main rivers in the Nansi Lake Basin were 100%,and the detection levels were ng/L andμg/kg respectively.The overall detection concentrations of phenolic compounds in surface water,sediments,and soil range from 0.45-1825.1 ng/L,0.21-837.36μg/kg,0.01-297.18μg/kg,respectively.The content of phenolic compounds in surface water,sediment/soil,from high to low,respectively,were NP>OP>BPF>BPA>BPS,BPS>OP>NP>BPF>BPA.In general,the concentration of phenolic compounds in the three environmental media from high to low was sediment>soil>surface water.（2）In terms of time,the occurrence law of phenolic compounds in the three environmental media is that the wet period is higher than the dry period.The overall concentration of phenolic compounds in the surface water during the wet period ranges from 1.48-1825.1 ng/L,and during the dry period was 0.44-236.58 ng/L;NP and OP were the main phenolic pollutants in the two water periods,and their contribution frequency are as high as 60-80%.The overall range of phenolic compounds concentrations in sediments and soil during wet periods were 0.35-837.36μg/kg and 0.33-297.18μg/kg,respectively;the overall range of phenolic compound concentrations in sediments and soil during dry periods were 0.42-477.41μg/kg and 0.01-263.22μg/kg,BPS only has a higher contribution frequency in the wet periods.In terms of space,the occurrence law of phenolic compounds in water/sediment/soil is that the concentration of upper lake（S12-S27）is higher than that of lower lake（S1-S11）;the concentration of phenolic compounds in surface water is higher.The first five points are S15（2332.56 ng/L）,S17（661.81ng/L）,S3（521.44 ng/L）in Jining,S25（461.51 ng/L）in Heze and S13（470.66 ng/L）in Zaozhuang;the higher concentrations of phenolic compounds in the sediment/soil include Jining’s S1（1628.178μg/kg）,Hezedong’s S23（1571.10μg/kg）,S20（1501.25μg/kg）and Zaozhuang’s S10（1284.80）.μg/kg),S4（1090.19μg/kg）in Xuzhou.（3）The results of T-test analysis show that the concentration changes of BPA,BPF and NP in surface water are correlated with seasonal changes,and the concentration changes of BPS and OP have no correlation with seasonal changes.The concentration of phenolic pollutants in sediment/soil except NP changes are all related to seasonal changes.RDA analysis results show that phenolic compounds and conventional water quality indicators COD,NH₃-N,NO₃-N,TN and TP concentration were correlated.The correlation analysis results show that in sediments,OP was significantly positively correlated with very coarse sand,BPA and fine sand（p<0.01）;in soil,BPA was significantly positively correlated with sand（p<0.01）,OP and BPS are positively correlated with gravel（p<0.05）,and the rest of phenols there was no correlation between the concentration distribution of the compound in the sediment/soil and the particle size.The content of five phenolic compounds in soil has no correlation with TOC;BPA,BPF and TOC in sediments are positively correlated,and the concentration of BPS,NP and OP has no correlation with TOC.Through high-throughput sequencing analysis of the microbial community composition in the surface water of major rivers,it was found that three species of bacteria related to the degradation of phenolic compounds were Pseudomonas,Flavobacterium,and Novosphingobium.Among them,the proportions of Pseudomonas and Flavobacterium in all samples were relatively high,which indirectly indicates that the study area is contaminated by phenolic compounds.（4）The risk entropy method was used to evaluate the environmental risk of phenolic compounds in three environmental media in two water periods.The results showed that the five phenolic compounds showed low risk to the water environment during the two water periods（<0.053）,but presents a high risk to sediment/soil（0.009-21.400）.The five phenolic compounds in the three environmental media have a higher risk value in the wet period than in the dry period;the 27 main rivers in the Nansi Lake basin and the five phenolic compounds Hormone toxicity equivalent（EEQ）is less than 1 ng/L,indicating that the pollutants in this watershed are less risky to human health;principal component analysis combined with multiple linear regression（PCA-MLR）model is used to analyze the four prefecture levels in the Nansi Lake basin during the dry season.Analyzed the contribution rate of phenolic compounds in the city,and calculated that there are two main factors.Among them,the contribution rate of factor 1（A,B,C,and D are common source）is 66.435%,and the contribution rate of factor 2（A,B,C,and D is common source）is 66.435%.Source)contribution rate is 33.564%.