Abstract

The study was conducted to assess the occurrenceand ecological risk of heavy metal concentrations (Cu, Zn, Pb,Cd and As) in the soil of paddy fields in An Giang province in2020. Soil samples were collected at 112 locations in sevenpaddy fields. Cluster analysis (CA) was used to present thespatial distribution of heavy metals. Ecological potential riskindex (RI) was used to determine risk levels caused by heavymetals. The results showed that Cu, Zn, Pb and As in all soilsamples ranging from 1.83-124.04, 4.87-114.18, 7.87-39.22 and4.66-16.32 mg/kg, respectively. Cd was not detected in the soilsamples. All heavy metal values were within the allowable limitsof Vietnamese technical regulation on heavy metals in the soils.However, Cu concentration at the rice area in An Hoa hamlet,Khanh An commune, An Phu district (D10) and Asconcentration at D11 (An Hoa hamlet, Khanh An commune),D33 & D36 (Hoa Ha hamlet, Kien An commune, Cho Moidistrict) and D38 (Phu Thuong 2 hamlet, Kien Thanh commune,Cho Moi district) exceeded the allowable limits. The CA resultsrevealed that soil quality at 112 study sites was classified into 12soil quality groups, possibly reducing the soil monitoring cost by72.32%. As is the most significant contributor to potentialecological risks in soils, although RI values still showed thatheavy metals pose a low risk in rice cultivation areas. However,heavy metals in soils could degrade soil quality, accumulate inagricultural commodities, and eventually humans through thefood chain. Therefore, the frequency of the monitoring can beconsidered to increase to two or three times per year to evaluatethe seasonal variation of the heavy metals.