Influence Of The Key Water Environmental Factors On The Migration And Transformation Of Heavy Metals In Lean River

In this research, we focus on the problem of heavy metals pollution on LeanRiver and select Lean River as the study area, which is located in the northeast ofJiangxi Province. The area of the Northeast in Jiangxi Province is also the main areaof the mineral resources，which is also the acid mine wastewater drainage area at thesame time, and the population is relatively dense and water is arranged in a crisscrosspattern in the northeast of Jiangxi. A large-scale Copper Mine named Dexing Mineand some Lead and Zinc Mines are located in the upper of Lean River. Heavy metalspollutants can be enriched and increased in organisms along the food chain, and thenreached at the top of the food chain to the human body with high concentrations ofheavy metals. When the amount of heavy metals in the human body focused on acertain amount of time, it will cause great harm to human body, so which isparticularly important on the study of heavy metals pollution on the region. Weselected the upstream, midstream and downstream of Lean River and its tributarynamed Dawu River as the study areas, and selected the most prominent heavy metalpollutants of Copper, Lead and Cadmium as the detected factors, we also conductedwith the comparative method, the mean and deviation methods, the single factor indexmethod and multi-factor index method respectively in the paper. We analyzed thecharacteristics and the influence factors of the migration and transformation of heavymetals in Lean River according to the three different water seasons phase of the threekinds of heavy metals of Copper, Lead and Cadmium in water, sediment and soilbetween the distribution characteristics and migration characteristics. We analyzed themain water environmental factors including water pH values, Total Nitrogen (TN),Total Phosphorus (TP) and the Chemical Oxygen Demand (COD), which influencedon the migration and transformation of heavy metals elements from the water body tothe sediments or soils. We also explored the migration and transformation rules of heavy metals which influenced by the different water environmental factors. We triedto explore to by changing the different water environmental conditions in order toreduce or control heavy metals pollution on the water and sediments of Lean River.The main results are as follows.The results of the pH values, TN values, TP values and COD values in the waterof different sixteen sampling sites in the three different water time included thenormal water period, the abundant water period and the dry season indicated that themeasured values of the above four kinds of water environmental factors in thesampling sites of Haikou Town in Wuyuan County and Taibei Town in Dexing Citywhich located in the source of Lean River in the three different water period wereclosed to the normal values, but the determined values of the above four kinds ofwater environmental factors in the three sampling sites of the tributary named DawuRiver of Lean River were severely exceeded the standard values. And the determinedvalues of the above four kinds of water environmental factors in the sampling site ofGukou were the intermediate among the values of the sampling sites located in thesource of Lean River and in Dawu River. The determined values of the above fourkinds of water environmental factors in other sampling sites which are far away fromthe contaminated areas showed a trend closed to the normal values. The distributioncharacteristics of heavy metals Copper, Lead and Cadmium contents in water andsediments or soils showed significant positive relationship with the discharge amountof the mining area and the adsorption of heavy metals in sediments，which lead to thedistribution characteristics of soil heavy metals in various points showed somecomplexity.The influence of the four kinds of water environmental factors of pH values, TNvalues, TP values and COD values in the water showed that there was a significantpositive correlation between Copper contents in soils and the pH values in water. Theheavy metal of Copper can migrate and transform from the water into the soilenvironment with the increasing of pH values in water, and the heavy metals elementscan be transformed from dissolved morphology into particulate morphology. And the results also indicated that the contents of Lead and Cadmium in the soils andsediments were also showed significant positive correlation with pH values. Theheavy metals of Lead and Cadmium can also migrate and transform from the waterinto the soil or sediments environment with the increasing of pH values in water. TheTN contents in the water also showed significant positive correlation with the contentsof Copper and Lead in the water, but there is no obvious influence on Cadmium inwater. The contents of Copper and Lead in the water can increase with the increasingof TN contents in water, but there is no obvious influence on Cadmium in water,which meant that the eutrophication of water body could help Copper and Lead in thesoils or sediments desorbed into the water. The TP contents in the water also showedsignificant positive correlation with the contents of Copper, Lead and Cadmium in thesoils or sediments. TP can promote Copper, Lead and Cadmium migrate andtransform from water into soil or sediment, which can lead to the dissolved heavymetals in the water transform into particulate and subsided in the bottom sediments.The COD contents in the water also showed significant positive correlation with thecontents of Copper in the soils or sediments, the increasing of the COD contents canhelp the increasing of Copper contents in the soils. The increasing of reducibilityorganic compounds in the water can help promote the increasing of particulate Copper,but there is no obvious influence on Lead and Cadmium in the soils or sediments,which meant that the deterioration of water quality might promote Copper migrate ortransform from water into the soil environment.The migration and transformation of heavy metals in the water, sediments andriparian zone soils of different sampling sites in Lean River showed differentcharacteristics. The results of the contents of three kinds of heavy metals in thesediments of three water periods showed that the contents of heavy metals in theabundant water period are the highest, and those in the dry water period are the lowest.The migration and transformation characteristics of the heavy metals in the sedimentsare similar in the two seasons of normal water season and dry water period. The threekinds of heavy metals contents in the sediments are lower than those of the riparian soils in the both water seasons of normal water period and dry water period. But theheavy metals contents in the sediments in abundant water period were higher thanthose of normal water period and dry water period.Based on the above analysis results, the distribution of heavy metals in differentsampling sites of Lean River showed different characteristics and rules and the reasonis very complex, and the prevention and control of heavy metals pollution in LeanRiver also may be extremely complex, which need further and more related thoroughresearch in the future, and seek some effective ways to reduce or control the heavymetals pollution of river water and river sediment.