The Interactions among the Heavy Metals in Soils and in Weeds and Their Antioxidant Capacity under the Mining Activities in Thai Nguyen Province, Vietnam

Figure 4

The significant pair to pair correlation of nine variables including As, Pb, Zn concentration in tissue, Zn concentration on soil, DPPH scavenging activity at 100 μg/mL and 500 μg/mL, SRSA scavenging activity at 100 μg/mL and 500 μg/mL. The distribution of each variable is shown on the diagonal. On the bottom of the diagonal, the bivariate scatter plots with a fitted line are displayed. On the top of the diagonal, the value of the correlation plus the significance level is denoted as stars. Each significance level is associated with a symbol: value < 0.001, value < 0.01, and value <0.05. The Pearson method was used to compute the correlation coefficient.