| Manganese ore mining and smelting often produce large quantities of tailing and tail mud,and the environment was seriously polluted.The abandoned land in Xiangtan manganese mining area was one of the areas seriously polluted by heavy metal in Hunan Province.It is very important to improve the ecological environment and sustainable development of the mining area by selecting the suitable tree species for the restoration of the ecological system.At the same time,the ratio of tailings and tail mud in soil is the key factors to affect the survival rate of plants for vegetation restoration.This research adopts soil of 6 different treatments as growth substrate.They are tailing,tail mud,tailing:tail mud 3:1,tailing:tail mud 2:2,tailing:tail mud 1:3 and control soil.We choosed Koelreuteria paniculata,Schima superba and Pinus massoniana as vegetation restoration tree species for the potted experiment.Manganese content,ground diameter,tree height and biomass of the plants,manganese content and other physical and chemical properties of soil were measured and tested after 340d aiming at studying the effects of different proportions of tailing and tail mud on plant growth and the effect of different tree species on the restoration of waste land.The main results are as follows:(1)Soil physical and chemical properties of different mixed matrix:? the soil bulk density of tail mud,tailing,and control soil were 1.64,1.44 and 1.37 g-cm-3 respectively,and the pH were 5.55,8.01 and 5.00,respectively,the pH increased with the content of tailing in the mixed matrix.?The content of sand and coarse silt in tailing mud,tailing and their mixture were significantly higher than that of control soil(p<0.05),and clay content was significantly lower than that of control soil(p<0.05),However,there was no significant difference between the mixed matrix of different proportions of tailing and tail mud(p>0.05).? There was no significant difference among the total N content of 6 different treatments of soil,but significant for P and available P(p<0.05),and the order of total P content was the tail mud>tailing:tail mud3:1>tailing:tail mud 2:2>tailing:tail mud 1:3>tailings>control soil,the order of available P content was tailing:tail mud 2:2>tailing:tail mud 1:3>tailings>tail mud>control soil>tailing:tail mud3:1.There was significant difference among the content of available P in different soil treatments(p<0.05),and the order was tailing:tail mud 2:2>tailing:tail mud 1:3>tailing>tail mud>control soil>tailing:tail mud 3:1.The content of total Mn and available Mn in tailing,tail mud and their mixture were significantly higher than that of control soil(p<0.05),the order of total Mn was tailing>tailing:tail mud 3:1>tailing:tail mud 2:2>tailing:tail mud 1:3>tail mud>control soil and for available Mn the order was tailing:tail mud 1:3>tailing:tail mud 2:2>tailing:tail mud 3:1>tailing>tail mud.(2)The status of the plant growth in pot experiments under different soil treatment:?The survival rate of Koelreuteria paniculata in the six soil mixed matrix were the highest.And the survival rate of Schima superba were the second.Pinus massoniana had the lowest rate,which meant it was not suitable for the vegetation restoration of manganese ore.?The height increment for Koelreuteria paniculata and the ground diameter increment of Schima superba under different soil treatments were significantly different(p<0.05),the ground diameter increment of Koelreuteria paniculata in the control soil,tailing:tail mud 2:2 and tailing:tail mud 3:1 were significantly higher than that of tail mud and tailing:tail mud 1:3,the ground diameter increment of Schima superba of soil treatments were different significantly(p<0.05),in the tailing:tail mud 2:2 tree high growth is the largest,followed by the other treatments.? The diameter increment and height increment,leaf biomass,root biomass of 4 indicators,through cluster analysis can be divided into 3 clusters:the 1st one was the best,accounted for 20.9%,and the 2nd class,growth medium,accounted for 33.3%,and 3rd was the worst grown plants,accounted for 45.8%.(3)Biomass and productivity of trees in manganese soil pot experiment,the biomass and productivity of Koelreuteria paniculata was the largest,followed by Schima superba,Pinus massoniana was the last.For Koelreuteria paniculata,the trees in tailing:tail mud 2:2 and tailing:tail mud 3:1 had a higher biomass and productivity,and it was close to control soil,but there was no significant difference.For the biomass and productivity of Schima superba,there was no significant difference among the tailing,tail mud and their mixed matrix,but all of them were lower than that of control soil.Pinus massoniana was not suitable for vegetation restoration in manganese mine wasteland because of its low biomass and productivity.The biomass and productivity in tailing:tail mud 1:3 was higher than that of tailing,but both of them were lower than that of control soil,the difference was significant.All above proved that Koelreuteria paniculata and Schima superba are both suitable species for vegetation restoration in mining area,but Pinus massoniana was not suitable.(4)Mn accumulation and transfer in plants in pot experiment:Koelreuteria paniculata and Schima superba had higher Mn uptake in tailing,tail mud and their mixed matrix than in control soil;with the increase of the content of tail mud,uptake of Mn in Schima superba increased,but did not change significantly for Koelreuteria paniculata.The manganese accumulation of Pinus massoniana is small,and it is related to the survival rate.In addition to the control soil,the bioconcentration factor of Koelreuteria paniculata is higher than that of Schima superba and Pinus massoniana.Schima superba had very strong accumulation ability of Mn,and the accumulation ability in tail mud is the strongest.In the mixed matrix,the accumulation ability of Mn of Schima superba increased with the content of tail mud,the accumulation ability of Schima superba did not obviously change.In addition to the control soil and tail mud,the transfer coefficient of Koelreuteria paniculata is the highest in tailings group;for Schima superba,the transfer coefficient was the highest in control soil,and followed by the tail mud.Pinus massoniana had the highest transfer coefficient in control soil,and followed by the tailing group. |
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