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.
PCA of selected environmental variables. Component 1 and component 2 explain 56.8±3.8% and 16.9±2.1% variance, respectively. Sites with mining split into group A (heavily mined; symbols outlined) and group B (moderately mined; symbols not outlined).
