How does Three Gorges Dam regulate heavy metal footprints in the largest freshwater lake of China

Herein, a two-dimensional (2-D) vertically-averaged hydrodynamic model was applied to study the heavy metal particle footprints pre-and post-Three Gorges Dam (TGD) in Poyang Lake. Two defined indexes-Reserve Impact Index (sigma(RII)) and Species Impact Index (eta(SII)) were applied to assess the potential impact of the copper footprint on nature reserves and sensitive species quantitatively. The results demonstrated that the movement speed, distribution, and trajectory of copper particle footprints differed enormously pre-and post-TGD. By contrast, the post-TGD footprints were more complex because of the dam-induced variations in hydrology and meteorology. TGD had both pros and cons for the copper footprint on the reserves based on the results of sigma(RII). It had changed the way for the transport of heavy metals and altered the patterns of exposure risk in the reserves. Sustainable management of Poyang Lake could be achieved by optimizing daily monitoring works. The eta(SII) for Finless Porpoises do not differ significantly between scenarios, but the eta(SII) for Siberian White Cranes increased by 0.92 and 0.83 for the two periods pre-and post-TGD, respectively. Heavy metals in food sources and the excreta of Siberian White Cranes could be of great concern in future studies. This study provides a theoretical basis for the in-depth study of the TGD-induced impact on Poyang Lake and provides a reference for the long-term treatment of Poyang Lake and the protection of key species.

Automated summary

The study found significant differences in the movement speed, distribution, and trajectory of copper footprints in Poyang Lake before and after the Three Gorges Dam. The dam had both pros and cons for the copper footprints in the reserves, and the impact on key species like Siberian White Cranes varied significantly.