Abstract:
Assessing the level of heavy metal pollution in soil is imperative to evaluate
the potential risks to human health. This study aimed to assess the level of
heavy metal pollution in three land uses of the Madawachchiya, Ranorawa,
Elayapattuwa, Hurathgama and Nawagattegama soil association (all soils
belongs to Alfisols order) using Geo accumulation Index (Igeo) and
Pollution Load Index (PLI). Soil samples (0-30 cm) were collected from
hundred and three geo-referenced locations representing lowland (38),
upland (35) and non- agricultural (30) land uses. Samples were digested with
4M HNO3 and analyzed for total Cu, Pb, Ni, Zn and Cd. Standard reference
material (SRM-2586) was used for data validation and quality control. Geo
accumulation Index (Igeo) and Pollution Load Index (PLI) were calculated
for different land uses. Satisfactory recoveries were obtained with the SRM 2586 for Cd (87%) and Pb (92%) in 4M acid digestion. Microwave digested
SRM sample showed the certified value of 2.7 ± 0.05 mg/kg of Cd and
425.92±39.8mg/kg of Pb ensuring the validity of the data generated.
Concentrations of Cu, Pb, Ni, Zn and Cd were at the range of 1.56-33.51,
2.19-19.22, 1.58-32.17, 6.69-71.32 and 0.13-1.22 mg/Kg respectively.
According to the Igeo classification, all the soils were classified into
uncontaminated class with respect to Cu, Pb, Ni and Zn. Igeo index for Cd
ranged from moderately to strong (Class 1-Class 4) for lowland and upland
while for non-agricultural soils ranging from uncontaminated to moderate
(Class 0-Class 3). The PLI values also confirmed that majority of the soils
were in unpolluted condition in terms of overall heavy metal contamination.
