| As China's largest stock of industrial waste,coal gangue not only occupies a lot of land,but also pollutes the mining area around the ecological environment and destroys of the landscape.Thus,the coal waste pile ‘s ecological treatment is the premise and core to improve ecological environment and implement the mining ecological reconstruction of the mining area.At present,the vegetation reclamation is the main measure of coal gangue treatment in the north of China,but the reconstructed soil after bulldozing of soil may probably cause soil nutrient deficiencies and nutrient profile disorder.Maybe it causes double barrier of heavy metal transport pollution in lower coal gangue.Consequently,soil nutrient and heavy metal pollution are key factors for vegetation restoration of coal gangue which is successful or failed.Therefore,the study of different types of differences between coal gangue's reclamation and reconstruction nutrients and status of heavy metal can provide theoretical guidance for coal gangue vegetation reclamation.In this paper,the reclamation of the orchard(OP),farmland(FL),vegetable land(VL)and grassland(WL)are collected as objects of study from Caocun Coal Mine in Huozhou in Shanxi Province.At the same time,the average condition of four kinds of reclamation species 1m reconstructed soil layer of 1m reclamation land,differences of nutrient profile and heavy metal content and pollution in 0-40 cm soil layer are analyzed,which is in the vicinity of the ordinary agricultural reclamation sample as control(CK).The main findings are as follows:(1)There were some differences in the average nutrient content of 1 m reconstructed soil layer in four kinds of reclamation species.The contents of organic matter and available phosphorus were the highest in reclaimed orchard(OP).The total phosphorus and total nitrogen contents were the highest in reclaimed farmland(FL)and reclaimed grassland(WL).The contents of total potassium,available nitrogen and available potassium are the highest in reclaimed vegetable land(VL).Compared with the control plots(CK),the contents of total nitrogen,total potassium,available phosphorus and available potassium are improved in four kinds of reclaimed plots,but content of the organic matter,total phosphorus and available nitrogen remains to be improved.(2)The differences of nutrient content in the cross-sectional in the use of four display types shows that the content of organic matter and total phosphorus in OP samples is the highest and the total potassium content is the lowest,the contents of total nitrogen and total potassium in VL plots is the highest,the content of organic matter is higher than that of OP,and the total phosphorus content is the lowest,the contents of total P and total potassium in FL samples is similar to those in OP and VL plots respectively and organic matter and total nitrogen content is a little lower,the content of organic matter and total nitrogen in WL samples is the lowest in 0-20 cm soil layers and among the soil organic matter and nutrients in whole amount.The content of available phosphorus in OP is the highest,the content of available potassium in FL samples is the highest and the content of available N is the lowest,the content of available nitrogen in the VL samples is the highest,and the content of available K is higher than that in FL samples,The content of available P and available potassium in WL samples is the lowest in available nutrient.FL samples are higher and low organic matter in total nutrient,and the total nutrient content is the lowest,the nutrient content in the OP plots was slightly higher than that in the WL plots In the 20-60 cm soil layers among soil organic matter and total nutrient content.The content of available N and available phosphorus is the highest,VL samples are the highest available potassium,the available potassium nutrient is the lowest in WL samples in available nutrient.OP samples have the highest organic matter content,the content of total phosphorus and total potassium is the lowest,FL samples are the highest in total nutrient and organic matter content is a bit lower,VL samples have higher potassium content and have little differences with FL samples,The content of organic matter and total nitrogen in WL samples is the lowest in the 60-100 cm soil layer among soil organic matter and nutrients in whole amount.The content of available phosphorus is highest and available potassium is the lowest in the OP,the content of alkali-hydrolyzable nitrogen in VL-sample was the highest and the content of available potassium is similar to that in FL samples and WL samples(3)The content of heavy metals Cd and Hg in 0-40 cm soil layer of four kinds of reclamation sites was similar,and the content of heavy metals Pb in the reclaimed orchard(OP)was similar to that in reclaimed grassland(WL)and the content of Ni and As in the reclaimed vegetable land(VL)is the highest.Compared with the control plots(CK),the content of heavy metals Cd and Pb in 0-20 cm and 20-40 cm soil layers is higher than those in four kinds of reclaimed plots,especially Pb,and Hg,As and Ni in different soil layers are also higher than control plot(CK)in varied degrees.(4)In terms of individual pollution index,Hg is the most polluted which belongs to severe accumulation and Cd reaches moderate accumulation,and As is a slight accumulation in four types of reclamation land in the 0-40 cm soil.Pb in 0-20 cm soil layer is mild accumulation.there are differences in the 20-40 cm soil layer,reclamation of orchards(OP)and reclamation of grassland(WL)reaches moderate accumulation,and reclamation of farmland(FL)is mild accumulation,reclamation vegetable(VL)is the clean state.Ni in 0-20 cm soil layer.In addition to reclamation of orchards(OP)for the clean state,in other reclamation plots have reached a slight accumulation.In the 20-40 cm soil layers,in addition to the reclamation of vegetable land(VL)achieves a slight accumulation,in other reclamation sites are clean state.In terms of the Nemero comprehensive pollution index,Four types of land reclamation have reached severe pollution.In the control soil(CK)0-40 cm soil layers,Hg,Cd and As also reach severe,moderate and mild accumulation,respectively,Pb and Ni in the 0-20 cm soil layers achieves a slight accumulation and in the 20-40 cm soil layer keeps the clean state and Nemero comprehensive pollution has also reached a severe accumulation.(5)From the evaluation results of potential ecological hazard index,Hg and Cd belong to the extremely strong ecological hazard and moderate ecological hazard in the four types of reclaimed land,and Pb,As and Ni are mild ecological hazards,and Hg and Cd are the main ecological risk factors for heavy metal pollution.The average RI of the potential ecological risk index of the four reclamation subsections is:(VL)>Reclamation of orchards(OP)>Reclamation of farmland(FL)>Reclamation of grassland(WL),they belong to a strong ecological risk.The results of the assessment of the potential hazard ecological index of the control plot(CK)are the same as those of the reclaimed plots,and Hg and Cd are extremely strong and moderate ecological hazards respectively,and Pb,As and Ni belong to minor ecological hazards.From the RI value,which is a strong ecological hazards. |
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