Practical Application Of Suaeda Salsa On Enrichment Of Heavy Metals And Restoration Ability To Pollutants In Wetland Soils

Wetland,as an ecosystem with multiple functions and rich resources,is one of the important living environments for human beings and also the main habitat for wildlife.Due to the acceleration of industrialization and the rapid development of cities,wastes generated from human production and living activities continuously enter into the wetland,causing damage to the ecological environment of the wetland.Heavy metals,as non-degradable pollutants,can enter into the wetlands through the transportation of water and atmosphere and accumulate continuously.Their toxicity and amplification through the food chain are potential threats to the ecological environment and human health.Therefore,it is no time to delay to control heavy metal pollution.At present,the main remediation methods for heavy metal pollution include physical leaching,chemical precipitation and phytoremediation.Due to the advantages such as low implementation cost and environmental friendly,phytoremediation has attracted extensive attention from scholars at home and abroad.In this paper,Qinhuangdao wetland was selected as the research area.By measuring the content of heavy metals in Suaeda salsa and the changes of heavy metal concentrations in surface soils and columnar soils in different months after the planting of Suaeda salsa.The enrichment ability of different heavy metals from soils,and the distribution and migration of heavy metals in Suaeda salsa were analyzed.The changes of heavy metal concentrations in surface soils and columnar soils after Suaeda salsa plantation were discussed in order to provide theoretical basis for wetland restoration by utilization of salt-tolerant plants.The main research results are as follows:Fe(0.4².1 g?kg^-1),Zn(11.69²3.32 mg?kg^-1)and Cu(5.08⁹.21 mg?kg^-1)were found to be higher in Suaeda salsa.All these are essential elements for the growth and development of plants;The highest bioconcentration factor of all heavy metals?except Cr?in Suaeda salsa appears in September,explain that from July to September,the roots and soil interact intensely,enhanced the uptake of metals by root,at the same time,The Bioconcentration factor of Cd,Mo,Cu,Zn and As>1,Translocation factor of Mo,Zn,Cd>1,means that Suaeda salsa mainly absorbed Cd,Mo,Cu,Zn and As from soils,and transferred Cd,Mo and Zn into leaves for storage.The study of Enrichment factor shows that Suaeda salsa has a certain ability to remove Cd,Mo,Zn and Cu from soilsOn the background of the study area according to the survey,the sequence of average heavy metal concentration in the study area soils was Fe>Zn>Cr>Pb>Ni>Cu>As>Mo>Cd,The concentrations of all heavy metals are relatively low and at a relatively clean level.Stations with high concentrations of heavy metals are located near the land and rivers,which may be affected by water and land pollution.After planting Suaeda salsa,the concentration of Cu,Zn,As,Mo and Cd in the planting area surface soil,from February to September,was reduced by 13.11%,11.63%,15.32%,49.40%and 30.59%respectively,at the same time columnar soil of Cu,As,Cd and Zn concentration in?0⁵ cm?layer is less than or similar to the layer of?5¹0 cm?,showed that the Suaeda salsa has the enrichment ability of these elements.The?0⁵cm?layer concentration of Cr,Ni and Mo was higher than that of?5¹0 cm?layer,indicating that Suaeda salsa had a stabilization effect on these elements and could prevent them from migrating to deep soil.Belt of Cu,Zn,Mo,and As,Extractable fraction content between May and July are reduced,Cu Extractable fraction was reduced by 64.45%between May and July,it may due to the high concentration of Exchangeable fraction and Carbonate-bond fraction of Cu.,the elevate of Organio-bond fraction content and decrease of Exchangeable fraction content of Mo,Cr reflects the roots has ability to stabilize these heavy metals.the Extractable fraction content of the Cd rise is likely to be influenced by external pollution,and the decrease of the Extractable fraction of Fe may be the transformation to Residual fraction,but the proportion and the content of Extractable fraction of Ni and Pb do not changes much.