TABLE 1.

Comparison of metal concentrations used for stress response experiments with concentrations found in uncontaminated and contaminated groundwater^a

Metal	Concentration from:		Stress used (μM)
	US EPA (μM)b	NABIR FRC (μM)c
Cadmium	0.04	39.59	6
Chromium	1.92	96.15	40-54d
Selenium	0.63	632.91	300
Uranium	0.13	289.92	200-1000e

^aUncontaminated data was determined as per U.S. EPA Maximum Contaminant Level Goals, contaminated data was determined at NABIR Field Research Center (FRC).

^bData are from the U.S. EPA website, http://www.epa.gov/safewater/hfacts.html.

^cData are from the NABIR FRC website, http://www.esd.ornl.gov/nabirfrc/. The highest value of recently sampled wells is reported.

^dTwenty seven micromolars of potassium dichromate contains 54 μM chromium.

^eA concentration of 200 μM uranyl nitrate was used for transcriptional analysis, as significant precipitation was observed in the 1,000 μM treatment.