Effects Of Coal Gangue On The Content And Structure Of Heavy Metals In Different Tissues Of Carassius Auratus And Misgurnus Anguillicaudatus

As a kind of important mineral energy,coal plays an essential role in the process of economic development.Coal gangue is a solid waste generated from coal mining,which can cause serious pollution to the surrounding environment,especially when entering the water,the heavy metal elements from coal gangue may affect the survival and development of aquatic organisms.Taking Carassius auratus and Misgurnus anguillicaudatus as the research objects in an one-year pond aquaculture experiment,this study adopts single factor water quality identification index(Pi),ICP-MS and histological paraffin section technique to explore the effects of coal gangue on heavy metal contents in the muscles and gills of Carassius auratus and Misgurnus anguillicaudatus,as well as on their tissue structures under different water/coal gangue mass ratios(300:1-300:7),aiming to provide a scientific reference for the biological protection of wetland and the health of surrounding residents in coal mining subsidence areas.The results show that:(1)Effect of coal gangue on overlying water:in the experimental group,the pH value of overlying water(7.05-7.97)was weakly alkaline,the concentrations of ammonia nitrogen(NH₃-N)and nitrate nitrogen(NO₃-N)were 0.011-0.157mg/L and 0.018-0.389mg/L respectively,the concentrations of total nitrogen(TN)and total phosphorus(TP)were0.192-1.453mg/L and 0.010-0.192mg/L respectively,the conductivity range was 161.8-374.0?s/cm,and the concentration of COD_Mnwas 6.188-9.942mg/L.The results of evaluation on the single factor water quality identification index shows that the quality of the overlying water was generally in line with the Level III surface water quality standard,which was within the standard range of aquaculture water.During the experiment period,the coal gangue did not pollute the overlying water with nutrients,and compared with the control group,the concentrations of the five elements in the overlying water of the experimental group were Zn>Cu>As>Pb>Cd,in which the concentrations of Zn,Cu,As and Pb increased with the water/gangue mass ratio and time.(2)Effects of coal gangue on heavy metal contents in the tissues of Carassius auratus and Misgurnus anguillicaudatus:with the increase of water/coal gangue mass ratio from300:1 to 300:7,the contents of Cu,Cd,Zn and Pb in the muscle tissue of Carassius auratus increased significantly(P<0.05),while the increase of As was not significant.The contents of Cu,Cd,Zn,Pb and As in muscle tissue of Misgurnus anguillicaudatus increased significantly(P<0.05).The change of heavy metal contents in the muscle tissues of two aquatic animals was consistent with that in overlying water,which is Zn>Cu>As>Pb>Cd;the contents of Cu,Zn and Pb in the gill tissue of Carassius auratus increased significantly(P<0.05),and the contents of Cu,Zn,Pb,As and Cd in the gill tissue of Misgurnus anguillicaudatus increased significantly(P<0.05).The condition of heavy metals in the gill tissue of Carassius auratus was consistent with that of Misgurnus anguillicaudatus,which is Zn>Cu>Pb>As>Cd,and the concentrations of Pb and As were different from those in muscle tissues.In the bodies of Carassius auratus and Misgurnus anguillicaudatus,the contents of heavy metals in gill tissues were higher than those in muscle tissues,and the heavy metal concentrating ability of gills was higher than that of muscles.The contents of heavy metals in gills and muscles of both animals increased with the water/coal gangue mass ratio.(3)Effects of coal gangue on different tissue structures of Carassius auratus and Misgurnus anguillicaudatus:in the control group,the muscle tissues and gill tissues of Carassius auratus and Misgurnus anguillicaudatus had no pathological changes,while in the experimental group,the muscle and gill tissue structures of the two animals were affected by coal gangue pollution,with histological pathological changes in different degrees.In the muscle tissue of Carassius auratus,the integrity of muscle cells decreased,the number of nuclei reduced,the dispersion of distribution deepened,and the connective tissue proliferated,while in the gill tissue of Carassius auratus,the distance among gill filaments increased,the cartilage of gill filaments became thinner,the gill lamella at the end of gill filaments detached,and the bending degree of gill lamella increased without regular arrangement.In the muscle tissue of Misgurnus anguillicaudatus,the muscle fibers were partially broken,disorderly arranged,gradually twisted with the gap increased,and the distribution of muscle fiber cells under the muscle intima was uneven,while in the gill tissue of Misgurnus anguillicaudatus,the bending degree of gill filament was more severe,the distance among gill filaments increased gradually,and gill filament expansion and gill lamella detachment also appeared at the end of gill filaments.The degree of pathological changes in muscle and gill tissue structures of Carassius auratus and Misgurnus anguillicaudatus increased with the degree of coal gangue pollution and heavy metal contents in their tissues.Based on the above research results,heavy metal pollution in coal gangue has caused harm to the content and structure of heavy metals in different tissues of crucian carp and loach.In the future,the impact of heavy metal pollution from coal gangue on aquatic organisms and other tissue structures should be further studied in order to deal with the harm to the environment and the human body caused by pathological changes in aquatic animal tissues.