Fig. 2From: Heavy metal gradients from rural to urban lakes in central ChinaConcentrations (mean ± SD) of a Cd, b Co, c Pb, d Cr, e As, f Ni, g Cu, h Zn, i Mn, j Fe, and k Al in water samples of lakes along a rural to urban gradient in central China. Note: different letters above bars indicate significant group difference (P < 0.05)Back to article page