TABLE 4.

Chemical indicators of microbial activity measured in the FC microcosms^a

Indicator	Microbial activity for microcosm with indicated amendment (μmol)
	None	Toluene	NO3−	Toluene + NO3−
CO2	27.18 ± 3.36	41.16 ± 7.97b	27.66 ± 6.18	42.84 ± 4.40b
NO3−	NDc	0.01 ± 0.01	17.52 ± 4.69	15.55 ± 3.16
NO2−	ND	ND	1.14 ± 0.87	0.39 ± 0.07
N2O	ND	ND	11.62 ± 4.14b	0.23 ± 0.34

^aDetermined at the conclusion of the 18-day incubation. Data are means ± standard deviations. 

^bThis value is significantly different (P < 0.05) from that for the nonamended control (CO₂) or those for the nitrate-amended treatments (NO₃⁻, NO₂⁻, and N₂O). 

^cND, not detected.