Abstract:
This research was aimed to investigate the occurrence of heavy metal contaminations (Ni,
Cd, Cr, Pb and Cu) in five key Sri Lankan green leafy vegetables (GLV) ["Kankun" (Ipomoea
aquatica), “Mukunuwenna (Alternanthera sessilis), “Thampala” (Amaranthus viridis),
“Nivithi” (Basella alba) and “Kohila leaves” (Lasia spinosa)] grown and marketed in and
around Colombo District, Sri Lanka. The study was focused on the heavy metal contents in
soils, fertilizer and irrigated water, distribution patterns, bio-accumulation between
different GLV species and an in vitro gastrointestinal extraction to find the fractions of
heavy metals available for absorption after dietary ingestion of raw and cooked forms of
GLV.
According to results, the average concentrations of Cd, Cu, Ni, Cr and Pb in the tested soils
were 1.45±1.15, 66.5±59.52, 51.5±45.51, 48.4±42.9 and 39.7±32.26 mg kg-1, respectively
in the tested areas. Pb, Cd, Cu and Cr levels in the irrigated water samples collected from
the cultivation areas were complied with the recommended guidelines, except for Ni. The
mean concentrations of heavy metals tested in all GLV exceeded the WHO/FAO safe limits,
except for Cu. Among the GLV analyzed, Kohila leaves showed the highest tendency to
accumulate metals from the environment. Irrespective of the species and the location, all
the collected GLV showed the distribution pattern for the heavy metals as:
roots>stems>leaves. Despite the higher total heavy metal concentrations found in GLV,
the bioaccessible fractions of heavy metals were significantly low (at P<0.05) in raw,
cooked and stir-fried GLV samples.
Keywords: Green leafy vegetables, Heavy metals, In vitro b
