Effect Of Rare Earth Mining On Red Soil Ecosystem And Revegetation Mechanism In Its Wasteland

Changting was one of the most serious part in red soil region ofsouthern China and the most accumulation of rare earth resources in Fujian.With the rising of prices,rare earth ore mining was developed in more and more area of Chancing.Rare earth minging in Chancing was carried out by heap-leaching process which was simple and conducted ecological deterioration problems such as vegetation destruction,soil structure damage,soil codification,heavy metal pollution and soil and water loss.Especially during the heavy rain season,the heavy metal pollution and soil codification caused by mining would take that to the farmland and rivers by a large number of flood.In the role of the geochemical circulation migration,the vegetation and soil in the abandoned mine area woud cause serious harm and the ecological environment deterioration get more serious,and the vegetation restoration get very hardlyTherefore,the important subject in the current environment science need to be research was:1)how to reveal the influence of soil ecological system by the ionic rare earth mining on red soil erosion area.2)How to select the optimal mode of vegetation restoration on the abandoned land.3)What is the plant recovery mechanism of rare earth wasteland.Although many domestic and abroad scholars carried the research on the environmental impact of rare mining and got some achievements.But their reserch were mainly concentrated in the soil physical and chemical properties and less impact on soil microorganisms.The research on revelation were focued on the slop due to the rare earth mining by in-situ leaching and pond-leaching.By the review of past research results,we found that selected plants could grow in the cultivation conditions of artificial fertilization but some plant growth recessed obviously.We also foud some plants died gradually till to disappear.Now the mechanism of plant recession after vegetation restoration in wasteland of rare erarth mine is not very clear.The main limiting factor of Revelation is also unknow.The synergy mechanism of plant root and soil is a lack of understanding when the vegetation is under the environment of adversity.All of that was the key poin of vegetation restoration in the abandoned land of rare earth mining,which had severely restricted the vegetation restoration of rare earth wasteland in the southern of China.In view of this,this paper was carried out based on the research of my tutor’s study group and subsidized by the public welfare forestry industry special project of state forestry administration(201304303),scientific research special project of National science and technology support programme(2014BAD15B02)and co-operative major science and technology project of Fijian province(2013 N5002).First,we conduct a full investigation of the soil of rare earth mine wasteland for the research on the influence of mining,especially using 16S rDNA sequencing technology to investigate the ionic rare earth mining soil bacterial community composition and diversity of red soil erosion area,revealing the changes of soil physical and chemical properties,soil enzymes,heavy metal pollution,soil microbial groups,bacterial community composition and diversity on red soil erosion area.Then we found the main limiting factors of Revelation of ionic type rare-earth ore mining wasteland.Secondly,in view of the main limiting factors,we researched different plants’ mechanism of the response to environmental stress by setting the nutrients,heavy metals stress experiment.Based on the different response,the suitable plants were selected.Finally,different vegetation configuration mode was designed for ecological restoration.The screen in models was carried out by the comprehensive evaluation of plant species diversity,soil physical and chemical properties,soil microbial community composition and diversity.At the same time,vegetation degradation mechanism after the Revelation was revealed by canonical correlation and path analysis for the vegetation restoration of ionic rare-earth ore wasteland in the south of our country.The main conclusions were as follows:(1)Compared to unmine areas,the soil property of post-mine area changed variously as below:a)Soil density increased significantly,and the capacity of soil water conservation was reduced.b)Soil nutrients except hydrolysis nitrogen in heap leaching pool increased,the rest of the various indexes were significantly decreased,and soil pH value raised in heap leaching pool while decreased in rented earth pits.c)Urey,dehydrogenase activity decreased significantly after mining,sucrase,cellphone,amylase,cattail,phenol oxidant,peroxidase and acid phosphorescent,miscellaneous changed complexly.(2)Soil microorganisms varied after mining in the rare earth ore of Chancing.Soil bacteria,fungi and interactions were significantly declined after mining in rented earth pits while got down in heap leaching mine area.Ammonia bacteria and bacterial were dominant physiological groups.Cellulose decomposing bacteria,Ammonia bacteria,nitrogen-fixing bacteria,nitrogen acid bacteria,citric acid bacteria,electrifying bacteria in the soil bacterium were on the decline,the physiological microorganism except the electrifying bacteria microbial raised in different levels.Soil bacteria,fungi and interactions were significantly decreased in the rented earth pits of Chancing rare earth mine area,while the heap-leaching pool were significantly increased;The soil Ammonia bacteria and bacterial in rare earth mining are dominant physiological groups both in pr-mining and post-mining wasteland;cellular microbe bacteria,Ammonia bacteria,nitrogen-fixing bacteria,nitrogen acid bacteria,citric acid bacteria,electrifying bacteria in the soil was averaging a downward trend;Apart from the electrifying bacteria in heap leaching pool,physiological groups are on the rise.The soil samples of rented earth pits and abandon heap-leaching pools,which were derived from Chancing ionic type rare-earth ore mining.Abundance and diversity of soil bacteria were changed significantly after mining.But the advantage of soil bacteria species were still Firestorm which composed the domain bacteria with Protectorate,Bacterial,Bactericidal,Antimicrobial,Bacteria,Introspect,Sycophancy and Hermit.(3)There was significant difference among the heavy metal pollution of different wasteland areas.The heavy metal contents of rare earth mines were higher than the background values of non-mined areas in Fijian Province.The Cd pollution was the most serious compare with other heavy metals.The Cd concentration in borrowed earth pits and waste ponds of heap leaching mine areas was 97 times and 69 times of background value in Fijian Province respectively.The evaluations result by the Geo-accumulation index and the Homeowner pollution index show that there were uncontaminated by Cr and Cu,heavy polluted by Cd in four areas sampled.(4)By the study of the soil ecosystem influence of rare earth mining on the red soil region in Chancing,we found that the limiting factors of Revelation on rented pits of rare earth mine in Changing were soil poor nutrient and cadmium pollution,whiles the abandoned heap-leaching pool were soil poor nutrients,soil codification and cadmium pollution.(5)The stress experiment of nutrition,heavy mental and acid was carried out based on the limiting factors of Revelation on rare earth mine wasteland.Comprehend evaluation of variety indexes of plant physiology,the suitable vegetation was selected.Suitable vegetation for rented pits were Pabulum Wittgenstein,Liquidator Formosa,Schema Superbowl,Salespeople bicolor,Corpuscles restrictive,Calcareous restrictive,Aleichem McClure.While the suitable plant for abandoned heap-leaching pool were Pabulum Wittgenstein,Liquidator Formosa,Schema Superbowl,Salespeople bicolor,Corpuscles restrictive,Aleichem McClure,Camellia proliferate.(6)According to the selected plants and practice experience,different vegetation respiration models were applied in the wasteland of rare earth mine in Chancing.The result showed that vegetation diversity increased as well as the new species in the communities,and preliminary ecological respiration had been forward to good succession.But some plants appeared varied degree of degradation.Soil physical-chemical properties varied in both rented earth pits and heap-leaching mine area.Soil pH and bulk density in rented earth pits and soil bulk density and hydrolyze N in heap-leaching mine area decreased,and the rest of soil index increased after vegetation recovery.Soil enzyme activity changed significantly in abandon mine area of Chancing.Soil inverse,amylase,cellulose enzyme,Urey,phosphorescent,cattail activity increased significantly both in rented earth pits and heap-leaching mine area.The soil phenol oxidant activity increased in all Revelation models of rented earth pits while decreased in some model of heap-leaching mine area.(7)Bacteria,fungi,interactions and carbon physiological groups in all models showed variously increase after vegetation restoration on abandon rare earth mine.Among nitrogen physiological groups,Ammonia bacteria,citric acid bacteria,nitrogen acid bacteria,bacteriologic,also showed a trend of increase,but electrifying bacteria f showed decline.Soil bacterial sequencing results showed that:Five vegetation recovery models in rented earth pits evolution into 4 kinds of soil bacteria community.Four vegetation recovery models in heap-leaching pool evolved into three kinds of soil bacteria community.Soil microbial abundance and diversity were significant different during various vegetation restoration pattern both in rented earth pits and heap-leaching pool.Soil bacterial diversity index on the site of "Pabulum Wittgenstein+Salespeople bicolor+ Schema Superbowl +Liquidator Formosa+ Aleichem McClure" was higher than other models in rented earth pits.Soil bacterial diversity index on the site of "Pabulum Wittgenstein+Salespeople bicolor+ Schema Superbowl +Liquidator Formosa "was higher than other patterns in heap-leaching mine area.Result of RDA analysis showed that soil microbial phyla correlated to the soil physical and chemical properties by organic matter,total nitrogen,available phosphorus,available potassium.(8)43 indexes composed of soil physical-chemical properties,soil enzyme activity and soil microbial diversity,plant community diversity was clustered in the various models of Revelation in both rented earth pits and abandon heap-leaching pool.The result showed "Schema Superbowl+Liquidator Formosa+ Staphylococcal divisors+Salespeople bicolor+Pabulum Wittgenstein" and "Schema Superbowl +Liquidator Formosa+Salespeople bicolor+Pabulum Wittgenstein" was suitable for rented earth pits."Schema Superbowl +Liquidator Formosa+ Camellia proliferate+Salespeople bicolor+Pabulum Wittgenstein" and "Schema Superbowl +Liquidator Formosa+Eucalyptus grandis+Salespeople bicolor+Pabulum Wittgenstein" were the best patterns for heap-leaching pool.However,due to the degradation of Schema Superbowl after vegetation restoration,the Revelation model of rented earth pits could be optimized as "Liquidator Formosa+ Staphylococcal divisors+Salespeople bicolor+Pabulum Wittgenstein" and "Liquidator Formosa+Salespeople bicolor+Pabulum Wittgenstein".And "Liquidator Formosa+ Camellia proliferate+Salespeople bicolor+Pabulum Wittgenstein" and "Liquidator Formosa+Eucalyptus grandis+Salespeople bicolor+Pabulum Wittgenstein" were optimized for heap-leaching pool.(9)The main reason of vegetation growth degradation after restoration by model"Liquidator Formosa+Schema Superbowl+Eucalyptus grandis + Salespeople bicolor+Pabulum Wittgenstein" in abandoned land of rare earth mine was the great consumption of soil nutrition during the late recovery of vegetation.Especially,the decreased organic matter content caused the soil enzyme activity and microorganism quantity and plant community diversity declined.So,synergy mechanism research of plant roots and soil in the process of vegetation restoration need to strengthen for improving the quality of the abandoned land of rare earth mine in the south of China.(10)Canonical variable coefficient between soil nutrients and enzyme,soil nutrient and bacteria,soil bacteria and enzyme were significant in wasteland of rare earth mine after vegetation restoration in Changeability.So soil nutrition,enzyme and bacteria proceeded collectively during the process of regeneration.The preseason of good ecological result of "Schema Superbowl +Liquidator Formosa+ Aleichem McClure +Salespeople bicolor+Pabulum Wittgenstein" was that soil total potassium and available phosphorus content enhanced by plant roots and litter to improve the soil enzyme activity and plant species diversity,and then improve the effect of the ecological recovery."Schema Superbowl+Liquidator Formosa+ Corpuscles restrictive +Salespeople bicolor+Pabulum Wittgenstein" reached the goal of the good ecological restoration mainly by increasing soil organic matter content in soil microbial diversity,especially the abundance Chloroform branch bacteria,and by improving the cellphone activity to promote the decomposition of litter,and final make the soil nutrient accumulation form a virtuous cycle."Schema Superbowl + Liquidator Formosa+ Camellia proliferate+Salespeople bicolor+Pabulum Wittgenstein" got good ecological Restoration mainly by improving the soil enzyme activity and plant species diversity,and then the rare earth soil fertility,to enhance the restoration of community ecological stability.The ecological restoration mechanism of "Schema Superbowl +Liquidator Formosa +Salespeople bicolor+Pabulum Wittgenstein" was that the raising the content of available P in soil increased the abundance of Testimonials,TM6,so as to increase the soil nutrient and enzyme activity.