Fig. 3From: Heavy metal gradients from rural to urban lakes in central ChinaConcentrations (mean ± SD) of a Cd, b As, c Co, d Ni, e Pb, f Cu, g Zn, h Cr, i Mn, j Fe, and k Al in sediment 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