Soil Quality And Environmental Risk Assessment Of Harmful Elements In The Volcanic Soil Of Changbai Mountain

Changbai Mountain is the highest mountain system on the eastern edge of Eurasia.It is located in the southeast of Jilin province,near the border of China and North Korea.Tianchi volcano in Changbai Mountain is one of the most potentially dangerous volcanoes in the world,and it is also a large-scale modern active volcano with the most potentially catastrophic eruption in China.Once the volcano erupts,it will pose a great threat to the human safety,ecological environment,property safety and economic development of the region.In addition,the material generated by the volcanic eruption will have a profound impact on the atmosphere,water,soil and ecological environment of the region.The main objective of this research is to explore the impact of volcanic eruptions on the soil environment.Volcanic soil and volcanic ash samples were collected around the volcano and the concentrations of 21 metals?Al,Fe,K,Ca,Na,Mg,Mn,Ti,Cu,Pb,Zn,Cr,Ni,Ba,Ga,Li,Co,Cd,As,Sn and Sr?were determined.According to physical and chemical properties,entropy method and weighted comprehensive evaluation method were used to evaluate soil quality in the study area.Inverse distance weighting?IDW?interpolation was used to obtain the spatial distribution of metal elements,and Pearson correlation analysis,cluster analysis and principal component analysis were integrated to identify the source of metal.The geo-accumulation index(I_geo),enrichment factor?EF?,contamination factor?CF?and potential ecological risk index?RI?were used to evaluate the potential ecological risk of metals,and the human health risk assessment model was used to evaluate the carcinogenic and non-carcinogenic risks of metals.The main results were as follows:?1?The coefficient of variation of physical properties except water content was relatively small?3.03%-16.93%?,which was relatively stable;the coefficient of variation of chemical properties other than pH was large?13.61%-64.59%?;for the characteristics of volcanic soil,the coefficient of variation of volcanic glass was small?2.92%-6.68%?,the coefficient of variation of phosphate retention was large?32.03%-63.85%?.For physical and chemical properties,there were basically two kinds of laws: top volcanic soil > substratum volcanic soil > volcanic ash or substratum volcanic soil > top volcanic soil > volcanic ash.The reason for the large coefficient of variation may be the interaction between physical and chemical properties of soil,topography,soil parent material,local precipitation and evaporation and other natural factors,as well as the influence of different land use patterns and the uneven distribution of sampling sites and other human factors.?2?The overall soil fertility quality was at a medium level,and it was less affected by human factors.The soil fertility quality in areas where vegetation naturally grows is high.The secondary standard was commonly used as the quality standard for soil environmental quality assessment,which showed that there was slight pollution.The soil quality in the study area was in the middle-very high grade.Soil quality was mainly affected by natural factors such as elevation,rainfall and vegetation cover,as well as human factors such as population and development of scenic spots.?3?The average concentrations of most metals in Tianchi volcano were either lower or similar to those of other volcanoes.The concentrations of only a few metals?such as Zn?were very high at Tianchi volcano.The concentrations of Fe,K,Na,Mn,Pb,Zn,As and Sn were higher near Tianchi.The concentrations of Ca,Mg,Ti,Cu,Cr,Ni,Ba,Co and Sr were higher in the north to the west of the study area,and there were some low concentration areas,while there were some high concentration areas in the south slope.?4?Among the physical and chemical properties and the characteristics of volcanic soil,only the soil bulk density,soil porosity,available phosphorus,altitude and phosphate retention have certain effects on the accumulation of most metals.Fe,Mn and As were mainly of anthropogenic.Other elements?Al,K,Ca,Na,Mg,Ti,Cu,Pb,Zn,Cr,Ni,Ba,Ga,Li,Co,Cd,Sn and Sr?were mainly of natural derived,but Li,Pb and Zn may be of anthropogenic.The Changbai Mountain is mainly woodland and tourist attraction,and the anthropogenic in the study area are mainly vehicle traffic.?5?There was no potential ecological risk and non-carcinogenic risk because of the low concentrations of the metals;however,it is necessary to pay attention to the carcinogenic risk of Cr and As in children.According to the results of the study,five risk management measures were proposed,including strengthening the government's leading role,formulating corresponding standards,increasing the monitoring types of polluting metal elements,paying attention to traffic source pollution,and enhancing public environmental awareness.The study of the impact of volcanic eruption on soil quality in the region can provide theoretical basis for the study of the effect of volcanic eruption on soil environment;the environmental risk assessment of harmful elements,from the perspective of environmental risk provides a new idea for the study of volcanoes in China,which can guarantee the food security,groundwater drinking and soil environment in Changbai Mountain.