Migration,Transformation And Ecological Effects Of Sediment Heavy Metals In The Hydro-fluctuation Level Of The Large Reservoir

Periodic rise and fall of water level of the large reservoir causes the coastal soil to be periodically exposed to the surface of the water,which made an effect on the transformation of sediment and the ecological effects of heavy metal in the shoreline,so it is necessary to discuss the potential impact on the coastal zone of large reservoirs water and environment safety environment in the reservoir area.In this paper,the migration and transformation of heavy metals---Cr,Cu,Zn,Ba and Pb---in coastal zone were analyzed monthly from Jau to May of 2016.The relationships between sediment respiration and heavy metals’ form were investigated to analyze the ecological effects of heavy metals.Conclusions obtained could be outlined as follows:1)From Jau to May,the concentration of Cr,Cu,Zn and Pb is low,and the concentration of Ba is between 0.032 ~ 0.103 mg/L,and the water quality is consistent with the standard of water protection.2)The contents of Zn,Pb and Ba in sediments are not obvious,while Cr and Cu are mainly in Fe-Mn oxide-bound state,organic matter and sulfide-bound and residual state are present in sediments.The results showed that the ecological availability of Ba and Zn showed a significant decrease with the prolongation of the exposure time,followed by the change of Cu and Cr,The results showed that the contents of Cr,Cu,Zn and Ba in the sediments were in the order of high altitude and low altitude,and the Pb The migration is relatively slow.3)Index of geo-accumulation showed that the pollution level of Cr,Cu,Zn and Pb was 0,the pollution level of Pb was grade 1,and that the pollution degree of five kinds of metals was relatively high,which was between pollution-free and medium pollution.The main heavy metal pollution was Pb>Zn>Cu >Cr,revealing that the main heavy metal risk in the sampling area is from Pb.The potential ecological hazard index of Pb was higher than that of other metals,and that of the nearest sampling layer in the same month was the highest,which was also higher than that of the other in the atmosphere.The hazard diminished with the time of exposure increases.4)There were significant correlations between organic carbon and heavy metal elements in sediments,and organic carbon was an important factor affecting the distribution of heavy metals in sediments.The correlation between heavy metal fraction and ammonia nitrogen was negatively correlated,and the available phosphorus was positively correlated with Cr and Cu.The regression equation was established by stepwise regression analysis,and the influencing factors were determined by single factor,with influencing factors ranking sequentially as water content >total amount of heavy metals> organic matter content>ammonium Nitrogen content >available phosphorus content.Results showed that the contribution of available potassium to heavy metal morphology distribution,migration and transformation is small.5)There was a positive correlation between soil respiration rate and sedimentary temperature,and negatively correlated with sediment moisture content.The respiration rate was negatively correlated with the total amount of Cu,Zn,Ba and Pb,and positively correlated with Cr.