Pollution Characteristics,Risks And Sedimentary Records Of Heavy Metals And Parabens In The Upper Reaches Of The Huai River

Heavy metals are classified as important persistent pollutants in the environment,due to their toxicity,undegraded and accumulative characteristics.They are mainly discharged into the environment due to human activities such as waste discharge,industrial discharge,and mining development.Parabens are classified as "emerging pollutants" and "pseudo-persistent compounds" because they are found to have potential estrogen activity,and can enter the environment through various ways such as domestic sewage and various types of wastewater.High-production volumes and emissions of these two kinds of substances could pose a threat to the ecological environment and human health.The Huai River is the main source of water in Xinyang,Henan Province and plays a very important role in flood control and irrigation.Thus,this study analyzes the two types of targets in the surface sediment and sediment core samples from the upper reaches of the Huai River.And this study discusses their temporal and spatial distribution characteristics,sedimentary changes,and ecological risks.This will provides a certain theoretical reference for the pollution control of heavy metals and parabens in the study area.The conclusions are as follows:(1)The concentrations of mercury in the surface sediment from the upper reaches of the Huai River for the minimal precipitation season?moderate precipitation season and high precipitation season were 0.010-0.341 mg/kg(mean: 0.073 mg/kg),0.049-3.30 mg/kg(mean: 0.340 mg/kg),0.007-0.486 mg/kg(mean: 0.071 mg/kg),respectively.The detection rate of the three water periods was each 100%.The Hg contents measured in the moderate precipitation season were higher than those in the high precipitation season and the minimal precipitation season.What's more,the contents of Hg measured in the tributaries possessed a larger contribution than the main streams.The Hg contents measured in this study were higher than the background values measured in soils of Henan and water sediments.Compared with the minimal precipitation season and the high precipitation season,the risk assessment results indicated that the moderate precipitation possessed a higher ecological risk.In summary,Hg pollution in the upper surface sediments of the Huai River was moderate level.Correlation analysis showed that TOC and BC had a significant positive correlation with Hg in the minimal precipitation season and the high precipitation season.(2)The order of 14 selected heavy metals was Al> Fe> Mn> V> Cr> Zn> Ni> Cu> Pb> As> Co> Cd> Ag> Hg.Among the 14 heavy metals except Al and Fe,Mn had the highest content in the range of 637-1094 mg/kg with an average value of 903 mg/kg,and Hg possessed the lowest content from 0.002 to 0.100 mg/kg whose average value was 0.048 mg/kg.The concentrations of measured heavy metals were higher than the background concentrations of the Henan soil and water sediments.Cd and Cr displayed higher contents than those of the other six major rivers in China.The concentrations of ?parabens in the sediment core samples were 2.45-22.2 ng/g(mean: 9.47 ng/g;median: 7.92 ng/g),which was lower than those in the upper sediments of the Huai River,indicating that parabens can degrade in a certain rapid.The concentrations of P-HB were 11.3-155 ng/g(mean: 44.1 ng/g;median: 25.4 ng/g).The detection rate of BzP and HeP was lower than the other selected targets.The composition characteristics showed that the proportion of MeP from the bottom layer to the surface layer increased,but the other five parabens showed a decreasing trend.(3)The results of sedimentary analysis showed that the variation of the heavy metals varied in the sediment core samples,and the content level was highest around 1975,and Hg showed a gradual increasing trend.The sedimentary change of ?parabens in the sediment core samples was affected by the local environmental changes.The results of risk assessment indicated that Cd and Ag showed high pollution levels,which was worth noting.Parabens exhibited low ecological risks.Correlation results between heavy metals indicated that Hg had no correlation with other heavy metals,but had a positive correlation with TOC and BC.The effect of particle size on each heavy metal varied.MeP had a positive correlation with P-HB,besides,they both showed a positive correlation with TOC,BC,and particles larger than 63 ?m.