Abstract:
Accumulation of nephrotoxic metals in edible crops and associated soil is a major international
concerns today which results food safety issues and adverse health risks like CKDu. Soils are
considered to be an excellent media to monitor and assess chemical pollution where the application,
deposition and absorption of chemicals are taken place. Therefore, this study attempts to investigate
the bioaccumulation of nephrotoxic metals in soil and rice grains (Oryza sativa) and to interpolate
the spatial distribution of selected chemical elements using Inverse Distance Weighted (IDW)
and Spatial Autocorrelation tools in ArcMap 10.2.2 software in a CKDu hotspot; Girandurukotte
Grama Niladhari Division (GND), Badulla, Sri Lanka via soil analysis. Dambethalawa GND
in Ampara district was selected as the reference site. 30 soil samples were collected according to
random stratified design including 10 paddy cultivated sites and 10 composite rice grain samples
were collected from those paddy fields separately. Microwave digested soil and rice samples were
analyzed by inductively coupled plasma mass spectrophotometry. The average concentrations of
Cd, Pb, As, Cr, Ca and Mg in soil were 0.45±0.02, 0.20±0.02, 0.65±0.25, 0.29±0.04, 4812.00±692.00,
and 15157.00±1275 mg/kg respectively. According to the lower Moran’s indices given by the Spatial
Autocorrelation, the selected metals were evenly distributed throughout the sampling area and Cd,
Pb, Ca and Mg contents in CKDu prevailed area was significantly higher (p<0.05) than the reference.
The higher bioaccumulation factors (from soil to rice grain) (BCF>1) indicated that rice grains tend
to accumulate the nephrotoxic metals including Cd;2.35, Pb;7.48, As;2.60 and Cr;5.80. The calculated
Enrichment factors (EF) which derives the degree of soil contamination by nephrotoxic metals
were Cd;6.49, Pb;6.01, As;1.30 and Cr;1.48 and greater EFs (EF>1) indicates higher availability and
distribution of metals in contaminated soil when compared to the reference. It can be concluded that
the degree of soil contamination by nephrotoxic metals was higher in the selected CKDu hotspot than
the reference. Hence, human renal dysfunctions can be related with consumption of contaminated
rice with those metals.
