Figure 1.
Location map of three sampling sites in the Yellow River Delta.
Table 1.
Ecological characteristics of three sampling sites in different sampling seasons.
Table 2.
Summary of physical-chemical properties in the top 20 cm soils at three sampling sites during three sampling seasons.
Figure 2.
Profile distributions of As and heavy metals in marsh soils with P. australis (a), T. chinensis (b) and S. salsa (c) in three sampling seasons.
Table 3.
Mean contents of As and heavy metals in the top 20 cm soils of three sampling sites during the whole sampling period (mg kg−1 dry weight).
Figure 3.
Biological concentration factors of the aboveground parts of plants in each site.
abc Different letters on the error bars represent significant differences (p<0.05).
Figure 4.
Relationships between the contents of aluminum (%) and trace elements (mg/kg) in all soil samples in the Yellow River Delta.
Table 4.
Relationships between soil texture and Al and heavy metals in typical profiles from three sampling sites in three sampling seasons.
Table 5.
Correlation matrix among trace elements and selected soil properties for three sampling sites.
Figure 5.
Box-plots of enrichment factors of trace elements in all soil samples of each site of the three in three seasons (a) Spring; (b) Summer; (c) Fall.
Straight lines represent the EF = 2 or 5; dash line represents EF = 1.5.
Figure 6.
The sum of the toxic units (∑TUs) and toxic contribution of each metal at each soil layer of three sampling sites in three seasons (a) Spring; (b) Summer; (c) Fall.
Figure 7.
Ordination plots of the PCA results for surface soil samples.
The direction of an arrow indicates the steepest increase in the variable, and the length indicates the strength relative to other variables. S, sulfur; BD, bulk density; SOM, soil organic matter; WC, moisture. No. 1, 2, 3 represent three replicates of P. australis wetland in spring; No. 4, 5, 6 represent three replicates of P. australis wetland in summer; No. 7, 8, 9 represent three replicates of P. australis wetland in fall; No. 10, 11, 12, 13, 14 represent five replicates of T. chinensis wetland in spring; No. 15, 16, 17, 18, 19 represent five replicates of T. chinensis wetland in summer; No. 20, 21, 22, 23, 24 represent five replicates of T. chinensis wetland in fall; No. 25, 26, 27, 28 represent four replicates of S. salsa wetland in spring; No. 29, 30, 31, 32 represent four replicates of S. salsa wetland in summer; No. 33, 34, 35, 36 represent four replicates of S. salsa wetland in fall.