Research On The Influence Mechanism Of Spatial Variability Of Heavy Metals Of Critical Zone In The Lower Luanhe River

The study area is located in the middle and lower reaches of Luanhe River.Its geographical location is important,but the mountain is adjacent to sea and plain transition is narrow.And human activity is intense with large pollution risk.In this paper,the large number of test data was used,such as grain-size test data,heavy metal elements,organic carbon and physical parameters of soil of ground water,soil and soil water.The main-control factors of spatial variability of heavy metals were found out,and soil water and vegetation the Earth's critical zone were discussed and the mechanism and risk assessment of heavy metals in plants using the earth's critical zones concept,a variety of methods including water chemistry analysis,multiple regression analysis,random forest algorithm,path analysis,mathematical physics model and so on.The following results were achieved:1.The spatial variability of heavy metals in soil was revealed.The content of heavy metals in soil was affected by the stratum structure obviously.And it fluctuated with grain size.Furthermore the silt content(Silt fraction content)was positively correlated to it and the sand content(Sand fraction content)was negatively correlated to it.The boundary change of lithology is particularly strong.The overall trend of the change was similar to the trend of content change of particle.But the heavy metal elements in water had a significant positive correlation with the percentage of sand.2.Structure parameters and spatial variability model of heavy metal were constructed in 30m of critical zone,and the influence on heavy metal elements of human activities and structure were revealed.It was believed that the migration of the heavy metal element As(metalloid)was mainly affected by human activities in the shallow area of CZO,Luan research area.The structure of CZO had little effect on it,but it played an important role in some local area.Only in a certain structure,the enrichment of heavy metal would migrate caused by the human activities in some local area.3.The main factors of heavy metals in plants were identified.It was concluded that the main controlling factor of heavy metals in corn were mainly structural parameters of CZO,and the next controlling factor was the heavy metals in water and soil.The structural parameters of CZO had a great influence on the content of elements in the soil and water,and the structural parameters had an important influence on the content and distribution of heavy metals in the vegetation.4.Formation mechanism of prominent effect on heavy metals by silt content percentage of CZO was revealed.It was believed that iron ore was the reason of pollution of the river and surrounding soil,high content of susceptibility,and enrichment of heavy metals in silt grain structure.So it leaded the prominent role.5.The different enrichment properties of six heavy metal elements in maize were known.Through the risk assessment of excess elelements in maize,the risk value was recognized,and it was recognized that the larger risk value was mainly due to the Pb element.