Abstract:
Abandoned land, paddy fields and dry fields were selected as the research objects, and the change characteristics of the content of As, Cd, Cu and Pb in the soil respectively were determinded, combined with the individual pollution index method and the potential ecological risk index method, conduct ecological risk assessment on the soil in the study area, in order to understand the pollution status and ecological risks of heavy metals in the soil by different agricultural land use pattern and provide a scientific reference for the selection of agricultural land use pattern.The results showed that in the 0-50 cm soil layer, the average value of As content in the soil was as follows dry land(26.96±11.52)mg·kg
-1>paddy field(11.05±3.72)mg·kg
-1>abandoned land(9.04±6.87)mg·kg
-1;the average value of Cd content in the soil was as follows dry land(0.64±0.03)mg·kg
-1>paddy field(0.44±0.18)mg·kg
-1>abandoned land(0.25±0.11)mg·kg
-1;the average value of Cu content in the soil was as follows dry land(34.11±14.83)mg·kg
-1>paddy field(20.44±6.62)mg·kg
-1>abandoned land(13.90±6.64)mg·kg
-1;the average value of Pb content in the soil was as follows paddy field(39.26±9.85)mg·kg
-1>dry field(38.87±7.10)mg·kg
-1>abandoned land(21.94±9.68)mg·kg
-1.The results of individual pollution index analysis showed that the four heavy metals were not polluted in paddy fields and abandoned land, while As and Cd in dry fields were slightly polluted.The results of the potential ecological risk index showed that the four single-factor potential risk indexes of heavy metals were all classified as minor ecological hazards, and the order of Er value was Cd>As>Cu>Pb.The comprehensive potential ecological risk index RI was all less than 150,indicating minor ecological hazards.Among them, dry soil had the largest RI value, and soil heavy metals had the largest contribution rate of Cd.It could be seen that under different agricultural land use pattern, dry land had the strongest ability to accumulate heavy metals, followed by paddy fields, and abandoned land was the weakest.Although agricultural activities played a role in reducing soil pH to a certain extent, but they promoted the accumulation of heavy metals in the soil.