Risk Assessment of Heavy Metals Contamination in Paddy Soil, Plants, and Grains (Oryza sativa L.) at the East Coast of India

Table 2

Mean values of heavy metals (Pb, Cd, Cu, Cr, Mn, and Zn) for uncontaminated paddy soils, mean values for worldwide normal surface soils, critical concentrations for contaminated soils, Indian standards, and European Union standards, compared with the values of present study.

Elements (𝜇g g^−1)	Mean values for paddy soils^a	Mean values for worldwide normal surface soils ^b	Critical soil concentration^c	Indian standards^d	European Union standards^e; (EU 2002) [69]	Present study
Pb	23.3	22–44	100–400	250–500	300	5.3–19.8
Cd	0.34	0.37–0.78	3–8	3–6	3	0.2–0.6
Cu	20.7	13–24	60–125	135–270	140	1.10–2.9
Cr	64	12–83	75–100	—	—	1.3–7.8
Mn	0.39	0.27–0.53	1.5–3	—	—	12.5–33.9
Zn	61	45–100	70–400	300–600	300	3.8–33.8

aMean of total concentrations of elements in uncontaminated paddy soils. Data are from Wong et al. (2002) [4]; Wang et al. (2003) [66];    Chandrajith et al. (2005) [67].
^bMean of total concentrations of elements in the surface horizon of worldwide normal soil, and normal means that the data do not include contaminated or mineralized soils. Data are from Kabata-Pendias (2001) [46]; Essington (2004) [68].
^cHigher concentrations may be toxic to plants depending on speciation (Alloway, 1995) [48].
^dIndian standards (Awashthi, 2000) [47] for agricultural soils.
^eEuropean standards (EU 2002) [69] for agricultural soils.