The Purification Capacity Of Urban Forest Soil Of Different Forest Types For Treating Sewage

In order to ascertain the sewage purification capacity of different forest types in urban forest and research effect of sewage irrigation on nitrogen in soil.Meanwhile,to provide practical reference and theoretical basis for the configuration of waterfront shelter forest This paper selected 3 typical forest types soil in the demonstration base of urban forest in Harbin(Quercus Mongolia plantation,Fraxinus mandshurica plantation,Phellodendron amurense plantation)as the object of this study.Bare ground without vegetative growth was used as contrast.Through the method of field collecting soil column and indoor soil column simulation,the different concentration of ammonium nitrogen solution(100,50,25,0 mg/L)prepared by ammonium sulfate and Majiagou sewage was used for indoor simulation irrigation,determination and analysis soil column leachate and sewage composition as well as the soil column before and after treatment.The results show that:(1)The effects of three forest types soil on the removal of ammonium nitrogen were remarkable(P<0.05),but no significant difference compared with the contrast(P>0.05);Quercus Mongolia plantation soil ammonium nitrogen removal is most significant,followed by Phellodendron amurense plantation soil and Fraxinus mandshurica plantation soil,bare soil is the worst;The total nitrogen and nitrate nitrogen in the three forest type and the control soil column leachate increased significantly;The concentration of total phosphorus in the wastewater was lower in the early stage of irrigation,and the total phosphorus concentration in all the forest type and bare soil column leachate was higher than that of the sewage.The total phosphorus concentration in the sewage was increased to about 1mg/L,and the total phosphorus concentration in the forest type and the bare soil column leachate was lower than that of the sewage.The pH value of the three forest types and contrast soil column leachate were significantly lower than the sewage without filtration of soil column;The dissolved oxygen in the soil column leachate of each forest type was higher than that of the sewage without filtration of soil column,but the difference was not significant and no significant difference compared with the contrast;Except for the Quercus Mongolia plantation,the redox potential,conductivity and total dissolved solids of the other two forest types and contrast soil columns leachate increased significantly compared with the sewage without filtration of soil column.(2)When the influent ammonium nitrogen concentration is 100mg/L,in addition to the control,the content of ammonium nitrogen in the three forest type soil columns increased.At lower than 100mg/L,except for the Quercus Mongolia plantation,the content of ammonium nitrogen in the soil of the other two forest type soil columns was reduced;The content of nitrate nitrogen in soil column of each forest type and control soil increased significantly,but the difference of total nitrogen content was not significant.(3)After watering by the sewage of Majiagou,the nitrogen in the leachate of each forest type soil column is mainly affected by the water influent amount.But the influence of forest type on total nitrogen and nitrate nitrogen has also reached a significant level.The pH value of the soil column leachate was significantly influenced by the forest type.The total phosphorus,solution oxygen,electrical conductivity,redox potential and total dissolved solids in the soil column leachate was not significantly affected by the forest type,water influent amount and the interaction between two sources of variation.After irrigation with different concentrations of ammonium nitrogen,the change of ammonium nitrogen in soil column leachate was not affected by the forest type,water influent amount and their interaction.But the effect on nitrate nitrogen has reached a significant level.The change of nitrogen in the soil column after irrigated significantly influenced by the above three.