Distribution and risk assessment of soil fluorine morphology in the high fluoride zone of Hotan,Xinjiang
To investigate the occurrence and environmental risk of soil fluoride in wheat fields in the high-fluoride area of Hotan,Xinjiang,soil samples were collected from the plow layer and soil profiles.The total fluoride(TF)and fluoride speciation were analyzed to explore influencing factors,compare pollution levels,and assess potential ecological risks associated with TF and fluoride speciation.The results indicated that the TF content in the plow layer soil of the study area ranged from 552 mg·kg-1 to 761 mg·kg-1,with an average of 629 mg·kg-1.The distribution pattern of the various fluoride forms was as follows:residual fluoride(Res-F)≫organic-bound fluoride(Or-F)>water-soluble fluoride(Ws-F)>iron-manganese-bound fluoride(Fe/Mn-F)>exchangeable fluoride(Ex-F).An average Ws-F content of 4.35 mg·kg-1 was observed,indicating significant bioavailability.In soil profiles,the maximum values of TF,Res-F,and Or-F occurred in the surface layer,whereas Ws-F content increased with soil depth.Vertical variations of Ex-F and Fe/Mn-F were not significant.Soil TF showed a highly significant positive correlation with Res-F,and Ex-F had a significant positive correlation with Ws-F and Or-F;there was no significant correlation between Fe/Mn-F and other fluoride forms.Ws-F and Ex-F mutually converted under certain conditions,maintaining a dynamic equilibrium.Overall,the results suggested that aluminum oxide(Al2O3)was the main factor influencing TF and Res-F contents,and boron(B)was the primary factor affecting Ex-F content.Soil organic carbon(SOC)played a key role in influencing Fe/Mn-F contents.Ws-F and Or-F showed no significant correlation with soil physicochemical properties.The soil accumulation index and potential ecological risk index evaluation indicated a generally low pollution level in the study area.The ecological risk assessment based on fluoride speciation was lower than that of a traditional total fluoride-based assessment,providing a more accurate perspective from a biologically available standpoint.
万方数据
维普
