Table T4. Budgets for Norg below 1.45 mcd horizon based on pore water ammonium.

Table T4. Budgets for N_org below 1.45 mcd horizon based on pore water ammonium.


Parameters used in calculations	Site 1234	Site 1235

Average porosity,	0.65	0.65
Diffusivity, D_s, (m²/day)*	5.0 x 10^–5	5.0 x 10^–5
Sediment accumulation rate, w_s, m/day	2.15 x 10^–6	1.9 x 10^–6
Pore fluid burial rate, w_pw, m/day	1.33 x 10^–6	1.9 x 10^–6
Peclet number = D_s x /[(1 + K) x w]^{†, ‡}	0.42	0.23
(found by fitting the profiles)	0.065	0.02
Calculated fluxes
J_A2 – J_A1	0.019	0.015
J_D2 – J_D1	0.006	0.003
Total ammonium production flux, P_N	0.025	0.018
Total N_org flux at 1.45 mcd**	0.131	0.097
Fraction buried below zone of active diagenesis^††	81% ± 10%	82% ± 10%

Notes: Fluxes are in mmol/m² x d. * = D_s = D_m/[1 – ln(²)] (Boudreau, 1997; Li and Gregory, 1974); D_m = molecular diffusivity. † = K = 1.3, ammonium partition coefficient (Berner, 1980), dimensionless. ‡ = = 1/e-folding distance for ammonium profiles. ** = TN_org flux = P_N + TN_org at the bottom of active diagenesis zone; TN_org = TN x 0.8, since adsorbed ammonium is 20% of TN. †† = The uncertainty is based on assumed porosity uncertainty of 5%.