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.
(A) Loading plot in the plane of the two lowest-order PCs. Original variables of chemical pollutants are shown. (B) Score plot in the plane of the two lowest-order PCs. Samples are identified with different colours on the basis of the monitoring station of origin. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)
