Study On The Effect Of Heavy Metal (Hg) Stress On The Biological Crusts Of Syntrichia Caninervis

Soil heavy metal pollution has become a hot issue in environmental and soil science.With the development of society,the industrial and agricultural production and urban life emissions of various pollutants and caused serious damage to the soil environment in economic belt on the northern slope of Tianshan Mountain in Xinjiang,the sustainable development of Xinjiang oasis has caused some obstacles.Therefore,it is necessary to study the plant growth of the enrichment of heavy metals in soil to provide a theoretical basis for thedevelopment of arid area repair and excellent plant resources,also has importantpractical significance on soil improvement and improve the ecologicalenvironment.In this paper,the southern Gurbantunggut Desert growth?Syntrichia caninervis?as the research object,through the different concentration of HgCl₂ solution and the number of days under the condition of Syntrichia caninerviscell ultrastructure,photosynthetic pigment concentration,osmotic adjustment,antioxidant substances and other changes,based on analysis of tooth the rib erythritol tolerance mechanism of heavy metal stress,play its role in the ecological restoration in the environment,to provide a good basis for the prevention and control of desertification in Xinjiang and ecological restoration,plant remediation of heavy metal etc.The results are as follows:?1?Under the condition of a series of concentrations of heavy metal mercury stress,the minimum lethal concentration was 30mmol/l,which was lower than 30mmol/l,but the activity was not inhibited.When the concentration is higher than 30mmol/l,with the change of time,the phenomenon of death,along with the increased concentration of mortality,increased after 7 days of continuous culture 75mmol/l,Syntrichia caninervis were all dead.?2?The HgCl₂ concentration is 10mmol/L,the ultrastructure of Syntrichia caninervis cells did not change,normal,intact cell wall,cell membrane clear,complete chloroplast structure,the nucleus and nuclear membrane were clea;the concentration of 20mmol/L and 30mmol/L,Syntrichia caninervis cell wall began to plasmolysis,cell the walls began to blur,chloroplast swelling;at the concentration of 40mmol/L and 50mmol/L,Syntrichia caninervis plasmolysis phenomenon is serious,serious and even disintegration vacuolization of chloroplat,cytoplasm damage,nuclear disintegration.?3?With the increase of the concentration and the number of days,the chlorophyll content of the tooth moss decreased gradually.Under the highest stress concentration,the chlorophyll content was the lowest,which was below 0.15mg/g.?4?Osmotic adjustment substances?soluble sugar,soluble protein and proline?showed different trends under different concentrations and days.With the increase of Hg concentration and the number of days,the soluble sugar content of Syntrichia caninervis appear downward trend,with a first increased and then decreased to some degree,in a concentration of about 20mmol/l appeared peak;with the increase in number of days.the total content of Syntrichia caninvis soluble protein showed a slow downward trend,with a certain degree of volatility,the soluble protein content reached the maximum value at 20mmol/L;with the increase of days the content of proline was significantly increased,the highest concentration?75mmol/l?treatment,the contentof proline peak is about 45mg/g.?5?The effects of mercury stress on superoxide dismutase?superoxide dismutase,peroxidase and malondialdehyde?content in different layers and days were also different.The content of Syntrichia caninervis MDA increased up to0.6?mol/l;Syntrichia caninervis leaf POD activity showed first increased and then decreased,the stress concentration is 20mmol/l POD activity peak is about 20U/g;the tooth rib cell SOD erythritol leaves showed low trend after the first increase in the fall,when the concentration of 20mmol/l SOD and thehighest activity can reach about 60U/g.?6?The results show that there is a close relationship between Syntrichia caninervis ultrastructure and physiological and biochemical indexes and HgCl₂ concentration and stress time,and with a clear threshold response,i.e.at low concentrations?<20mmol/L?,a few days ago when the stress of Syntrichia caninervis strong ability to adapt,then obviously change.The results indicated that the strain had potential adaptability to adversity.At the same time,it also explains the reasons for the changes of some physiological and biochemical indexes.