3. Results
3.1. Concentration and ecological risk of heavy metals in the surface
sediment
The concentrations of heavy metals in the surface sediment at
different sampling points are shown in Fig. 2. Four distinct
patterns were observed based on spatial variation. Pattern 1
(Cd): a dramatic fluctuation in concentration appeared from N1
to N20 with an overall slightly decreasing trend (Fig. 2a); Pattern 2
(Cr and Cu): the concentrations decreased remarkably from N1 to