Table 2.

T-tests of silt/clay content (<10%, 10–50%, >50%) vs. OPD, pH sub-surface minima, near-bed pH or pH difference between surface and sub-surface minima value as generated in R

Oxygen penetration depth
	10–50	>50
<10	0.01**	0.008**
10–50	–	0.007**

Depth of pH sub-surface minima
	10–50	>50
<10	0.007**	0.004**
10–50	–	0.024*

Surface pH
	10–50	>50
<10	0.17	0.88
10–50	–	0.58

pH difference between surface and sub-surface minima
	10–50	>50
<10	0.004**	0.014*
10–50	–	0.61

P-values shown represent statistical probability that the null hypothesis is true. A single asterisk denotes significance at 95% confidence and a double asterisk denotes significance at 99% confidence