Appraisal of lead (Pb) contamination and potential exposure risk associated with agricultural soils and some cultivated plants in gold mines

Environmental Systems Research

Table 4 Pb concentration (mg/kg), and single pollution index (SPI) and Nemerow composite pollution index (NCPI) of the farmland across the study sites

Soil depth (cm)	Pb concentrations in soil (mg/kg) samples			SPI
Soil depth (cm)	Abare	Bagega	Dareta	Abare	Bagega	Dareta
0–20	364.995 ± 24.43a	70.44 ± 5.19a	25.38 ± 10.27a	0.91	0.18	0.06
21–40	179.1625 ± 56.24b	58.7 ± 4.32b	21.15 ± 8.56b	0.45	0.15	0.05
41–60	134.371875 ± 42.18c	44.025 ± 3.24c	15.8625 ± 6.42c	0.34	0.11	0.04
p-value	0.025	0.045	0.035
NCPI				0.52	0.36	0.27

Pb (Lead), SPI (Single pollution index), NCPI (Nemerow composite pollution index); DPR 2002 for soil: 85 mg/kg, USEPA 2001for soil: 400 mg/kg; SPI and NCPI < 1 = Safe, SPI and NCPI > 1 = Pollution critical limit thus, unsafe; values are means ± standard errors (n = 3);means with the same superscript letter within each column are not significantly different at p < 0.05