Table 3.

Summary of 12 environmental variables by their effects on sediment biogeochemical reaction rates.

Variable	Marginal effects	Conditional effects
	Lambda 11	Lambda A2	p	F
pH	0.24	0.24	0.02	3.85
As	0.21	0.04	0.328	1.33
Grain size	0.17	0.06	0.158	1.57
%N	0.13	0.12	0.04	2.63
$\left[S{O}_4^{2-}\right]$	0.12	0.09	0.09	2.12
Salinity	0.12	0.18	0.006	3.34
%C	0.11	0.02	0.788	0.29
%S	0.09	0.03	0.35	1.23
$\left[N{O}_3^{-}\right]$	0.07	0.04	0.304	1.23
Fe	0.06	0.04	0.4	1.04
Porosity	0.04	0.04	0.336	1.14
Corg:N	0.04	0.06	0.172	1.72

¹Lambda 1 indicates the percentage of the variability in the sediment biogeochemical reaction rates explained by a single variable.

²Lambda A indicates the percentage of the variability explained by a variable after the forward selection starting from the best variable (marginal effects).

Each subsequent variable is ranked on the basis of the fit that the variable gives in conjunction with the variables already selected (conditional effects). p and F values indicate the level of significance of each variable obtained by Monte Carlo permutations under the null model with 499 random permutations. The significant environmental variables were marked in italic bold.