Table 3. The relationships between the functional genes detected and the environmental factors selecteda by RDA.

Functional process	The first canonical axis			The sum of all canonical axes
	Eigenvalue	F-value	P-value	Eigenvalue	F-value	P-value
All	0.451	2.249	0.001	0.553	2.231	0.001
C cycling	0.230	2.688	0.029	0.589	2.579	0.001
N cycling	0.212	2.415	0.059	0.588	2.565	0.001
P utilization	0.244	2.898	0.013	0.608	2.791	0.001
S cycling	0.232	2.713	0.025	0.598	2.673	0.001

Abbreviation: RDA, redundancy analysis.

^aThe five environmental factors selected include four interstitial water factors (the concentrations of ammonium, total nitrogen, total phosphorus and sulfate) and one sediment factor (nitrate concentration).