Effects Of Coal Dust Deposition On The Physiological Properties Of Plants In An Open-Pit Coal Mine

In recent years,the exploitation of open-pit coal mine has provided a lot of lowcost energy to our country,but at the same time it has also caused a lot of ecological environment problems.In Xinjiang East Junggar basin coal mine,the coal dust produced by open-pit mining has a great negative impact on the atmospheric environment,and it will also change the habitat of vegetation near the mining area to some extent.In order to study the physiological and ecological effects of coal dust on the plants near the mining area,the artificial tree plants Ulmus pumila L.,local shrub plants Haloxylon ammodendron(C.A.Mey.)Bunge,and Tamarix chinensis Lour.,and herbaceous Salsola collina Pall.near the East Junggar basin open-pit coal mine were studied.Field control experiments were carried out to study the photosynthetic-light response curves,chlorophyll fluorescence parameters and chlorophyll fluorescence imaging of four kinds of plants under dust and dust-free conditions during the 2018 growing season.The light response curves of photosynthesis were fitted with rectangle hyperbola model(RH),nonrectangle hyperbola model(NRH),modified rectangle hyperbola model(MRH),to calculated the maximum net photosynthetic rate(Pnmax),apparent dark respiration rate(Rd),light saturation point(LSP),light compensation point(LCP)and apparent quantum efficiency(AQE).The influence of coal dust on plants was analyzed by combining electron microscope diagram and stomatal limit value analysis.With the influence of coal dust,the photosynthesis and fluorescence characteristics of this four vegetation types are inhibited to some extent.The deposition of coal dust can limits the photosynthesis of plants.Among them,the Pn of U.pumila was decreased the most,and the Gs and Tr of S.collina was decreased the most.Net photosynthetic rate was decreased from U.pumila(30.7%)> H.ammodendron(28.3%)> S.collina(24.3%)>T.chinensis(18.6%).Stomatal conductance rates was decreased from T.chinensis(42.1%)> U.pumila(33.2%)> T.chinensis(30.9%)> H.ammodendron(24.1%).Transpiration rates was decreased from S.collina(49.1%)> T.chinensis(39.1%)> U.pumila(18%)> H.ammodendron(16.7%).The quantum efficiency of photosystem PSII was decreased from T.chinensis(3.27%)> H.ammodendron(1.25%)> S.collina(1.21%)> U.pumila(1.12%).The main reason for the decrease of photosynthesis of U.pumila was non-stomatal limitation.The main reason for the decrease of photosynthetic rate of H.ammodendron is that coal dust cover hinders the absorption of light.The decrease of photosynthetic rate of T.chinensis was mainly attributed to non-stomatal limitation.The main reason for the decrease of photosynthetic rate of S.collina is stomatal factor.Therefore,the coal dust from open-pit coal will affect the photosynthetic physiological characteristics of U.pumila,H.ammodendron,T.chinensis and S.collina.The deposition of coal dust over time may lead to a decrease in local vegetation cover.