An official website of the United States government
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
LockA locked padlock
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Image Number K8452-2
To determine nutrients in shallow ground water, chemist James Hill places water in an autosampler of the flow-through colorimetric autoanalyzer.
Photo by Scott Bauer.
640 pixels wide: (k8452-2.jpg)