Fig. 1.
Sample sites (S1, Huagong Bridge; S2, Longwan Bridge; S3, Wastewater Treatment Plant; S4, Daochi Village; P1, Chlor-alkali Plant; P2, Privately owned Zinc Smeltery; P3, State-owned Zinc Smeltery)
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.