Contents Of Heavy Metals In The Soil Of Two Coal Mines And The Effect Of Coal Dust On The Photosynthesis And Growth Of Hedysarum Laeve

Coal mineral resources are the important material base of globaleconomic and social development, coal resources are very abundant in Ordos, InnerMongolia, and the proven reserves is150billion tons, accounting for1/6of thecountry’s. In recent years, with the intensification of local development, unreasonableexploitation of coal resources had damaging effects on the local ecologicalenvironment, and led to a series of problems. In this paper, we chose the two coalmines with two different coal mining methods, underground and open-csatrespectively, as our study objects. The two coal mines, Cementer and Telabula, areboth around Ordos Sandland Ecological Researh Station (OSES), in the northeasternOrdos plateau of Mu Us Sandy Land. We collected soil samples near the two coalmines, and analysed the heavy metal content by field investigation and indoorinstrument analysis. In addition, we investigated the coal dust settling of main roadsaround the two mines, and determined the effect of coal dust settling onphotosynthetic physiology and growth of local dominant plant, Hedysarum leave, by apot experiment. The main results are as follows:(1) We analysed the the soil sample around the two mining area, and determinedconcentration of Cr、Cu、Zn、Ni、Cd. We found that activities about coal resource,including exploitation and transportation, had resulted in the different level ofaccumulation of these heavy metal elements in the soil. Concentration of Cr and Znwas relatively higher than other elements,from98.56to115.72and42.02to64.66mg·kg-1. The concentration of Ni and Cd was lower than that of Cr and Zn. Theconcentration of heavy metal elements in the soil around the two mining was higherthan that of control, but not Cu. In addition, pH of the soil around coal mining washigher than that of control, which showed that coal mining might increase the salinityof the soil. (2) The concentration of Cd in the underground mining is higher than theopen-cast mining, the pH ing the underground mining is higher than the open-castmining, too.(2) We determined the photosynthetic physiological (net photosynthetic rate, etc.)and growth (biomass, etc.) traits of seedlings of Hedysarum laeve under differentgradient of coal dust settling (0-3.5mg·cm-2), and structural equation modeling(SEM)analysis showed that, the different levels of coal dust settling changed the stomatalconductance (Gs), intercellular CO2concentration (Ci) and vapor pressure deficit(Vpdl) of the leaf of Hedysarum leave, which caused the decrease of netphotosynthetic rate (Pn) and transpiration rate (Tr), and then reduced the seedlingheight, leaf number and ground and underground biomass. Coal dust settling affectedthe leaf photosynthesis physiological processes by influencing the water vapor of theleaf stomata and the light intensity, which affected the seedling growth traits ofHedysarum leave finally.