The study looked at how heavy metals like copper, lead, iron, manganese, zinc, chromium, and cadmium accumulate in two types of plants, Phragmites australis and Scirpus mariqueter, in Shanghai's tidal flats. Both plants absorb more iron, manganese, zinc, and copper, but less lead, chromium, and cadmium. Manganese levels in roots are similar to or higher than in stems and leaves, while iron is lower in stems and leaves. Lead and chromium can move from roots to stems and leaves, as can zinc, cadmium, and copper. Heavy metals are absorbed most in summer and spring, released in autumn, and build up again in winter. Scirpus mariqueter generally has higher heavy metal concentrations than Phragmites australis, except for chromium.