TABLE 3.

Correlation matrix (coefficients and significance levels) for parameters investigated during the field study (July 1997 to September 1999)^a

Treatment	Parameter	Correlation coefficientb
		pH	Dry wt	NH4-N	NO3-N	P	Heterotrophs	Oil degraders	Respiration	Catalase activity	Lipase activity
Natural attenuation	Hydrocarbon concn	0.8234∗∗∗	0.4242∗	−0.8030∗∗∗	0.1276 NS	−0.5760∗∗	0.7920∗∗∗	0.2394 NS	0.1049 NS	−0.1869 NS	0.2434 NS
	pH		0.4742∗∗	−0.6825∗∗∗	−0.1242 NS	−0.4198∗	0.6232∗∗∗	−0.0040 NS	−0.1240 NS	−0.3677∗	0.5152∗∗
	Dry wt			−0.2287 NS	−0.0473 NS	0.0628 NS	0.1381 NS	0.1689 NS	−0.0359 NS	−0.1651 NS	0.3539∗
	NH4-N				0.0945 NS	0.6672∗∗∗	−0.7345∗∗∗	−0.2332 NS	−0.2028 NS	0.1797 NS	−0.0236 NS
	NO3-N					−0.1159 NS	0.2895 NS	0.4856∗∗	0.2709 NS	0.2126 NS	−0.2808 NS
	P						−0.7735∗∗∗	−0.1921 NS	−0.1333 NS	−0.0126 NS	0.1417 NS
	Heterotrophs							0.3303	0.0972 NS	−0.1420 NS	0.1346 NS
	Oil degraders								0.0418 NS	0.0624 NS	−0.1715 NS
	Respiration									0.1820 NS	−0.4393∗
	Catalase activity										−0.2616 NS
Biostimulation	Hydrocarbon concn	0.6860∗∗∗	0.0867 NS	0.4709∗∗	0.3101 NS	0.4685∗∗	0.7776∗∗∗	0.7663∗∗∗	0.8506∗∗∗	0.4421∗∗	0.8368∗∗∗
	pH		0.1774 NS	0.3860∗	0.1849 NS	0.3991∗	0.5357∗∗	0.5372∗∗	0.4391∗	0.0283 NS	0.6489∗∗∗
	Dry wt			−0.1870 NS	−0.2377 NS	−0.1347 NS	−0.1973 NS	−0.2771 NS	−0.0375 NS	0.1896 NS	0.1962 NS
	NH4-N				−0.7785∗∗∗	0.8375∗∗∗	0.6469∗∗∗	0.6113∗∗∗	0.3464∗	0.3727∗	0.5510∗∗∗
	NO3-N					0.8497∗∗∗	0.4793∗∗	0.4405∗∗	0.3709∗	0.3936∗	0.4333∗
	P						0.6455∗∗∗	0.6416∗∗∗	0.3966∗	0.4729∗∗	0.5172∗∗
	Heterotrophs							0.9087∗∗∗	0.5105∗∗	0.4473∗	0.7305∗∗∗
	Oil degraders								0.5909∗∗∗	0.4754∗∗	0.5876∗∗∗
	Respiration									0.5582∗∗∗	0.5409∗
	Catalase activity										0.4020∗

^aA total of 33 samples were used in the analysis (three replicate lysimeters were used for each treatment and sampling date). 

^bNS, not significant; ∗, P > 0.05; ∗∗, P > 0.01; ∗∗∗, P < 0.001.