Research On The Plant Toxicity Of Soil Around Coal Gangue Stacking Area

Over the past century,coal has become one of the principal energy sources driving China's economic growth.The mining and washing process of coal will generate a great quantity of coal gangue,which has become the main source of pollution in the mining area.Coal gangue not only takes up a great quantity of land sources,but also releases heavy metals,radioactive elements,PAHs and other hazardous elements through weathering and rain conditions during natural accumulation.These pollutants may be discharged into the surrounding soil or water environment,thus posing a serious threat to the ecological environment and human health.However,few researches have used plat toxicology methods to assess the ecological risk and biotoxicity of coal gangue and its surrounding soil.Therefore,in this research,barley was used as a plant model to explore the soil heavy metal pollution caused by gangue accumulation and its induced phytotoxic effects,so as to supply a theoretical basis for the pollution management of mining areas.In this study,three kinds of coal gangue with different stacking characteristics and soil samples near downstream villages were collected firstly,and barley seeds were exposed to coal gangue and village soil leaching solution at different dilution concentrations.The changes of barley growth indexes(germination rate,shoot length,root length,biomass),chlorophyll content and malondialdehyde(MDA)were detected to explore whether the soil in gangue accumulation area affected the normal growth of plants.The results showed that the coal gangue and village soil extracts of three different accumulation conditions can induce barley germination and growth inhibition,chlorophyll content reduction and MDA content increase.Secondly,this research further discussed the consequences of coal gangue and village soil samples extracts with different stacking characteristics on the genetic toxicity and oxidative stress indicators of barley roots,and explored the toxic effect mechanism of barley growth inhibition.The results showed that the coal gangue and village soil extracts of three different accumulation conditions can all cause the decrease of mitosis index(MI),the increase of chromosome aberration rate(CA)and the incidence of micronucleus(MN)in barley root tip cells,and significant increase in superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)and glutathione(GSH)activities in roots.In addition,the phytotoxicity induced by the Gujiao coal gangue samples accumulated for a period of time is greater than that of the other two coal gangue.Finally,soil samples from different distances downstream of Dongqu coal gangue in Gujiao were collected.The heavy metal content of each soil samples was measured,and the distance-dependent distribution characteristics were explored,and the heavy metal enrichment factors and the ecological risk assessment were carried out.And the soil at different distances is used to cultivate barley seeds in soil to detect the changes in its growth indicators,physiological and biochemical indicators,genetic toxicity indicators and oxidative stress indicators,and the correlation between plant toxicity index and soil heavy metal content index was analyzed.The results show that Cd,Pb and Zn element pollution in the soil at different distances around the gangue accumulation area is more serious,and as the distance from the gangue hill is farther,the soil heavy metal content shows a trend of first increasing and then decreasing.The enrichment factor shows that the Pb,Cd,and Zn element pollution in the soil around the gangue hill accumulation area is relatively heavy,and potential ecological risk index of heavy metal in this area is at a low level.The soils at different distances from the gangue hill cause the growth of barley seedlings to be inhibited,and some soils can induce a significant reduction in the total chlorophyll content of barley leaves,a increase in MDA content,a reduction in MI,and a significant increase in MN.And it induced a increase in SOD,POD and GSH activities in barley leaves,and a significant decrease in CAT activities.Pearson correlation coefficient showed that Cr,As and Zn are positively correlated with barley shoot weight,root weight,and micronucleus rate,respectively.Cu and Pb are negatively correlated with chlorophyll and micronucleus rate,respectively.This study firstly measured the phytotoxic effects induced by coal gangue in different accumulation conditions and the soil of nearby villages,and initially reflected the pollution status and health hazards under the coexistence of multiple pollutants in the actual environment of the mining area.Then collect soils at different distances downstream of the Gujiao gangue hills that have accumulated for a long time to determine the content of heavy metals in each soil sample,distance-dependent distribution characteristics,and ecological risks,and explore the phytotoxic effects induced by them.Finally,the traditional physical and chemical analysis methods of soil heavy metals are combined with the research on the toxicity effects of plant exposure.This provides a theoretical basis for comprehensively assessing the potential ecological risks of coal gangue stacking areas and surrounding soils.