The annual amount of carbon delivered to the sediment is 42 mol m⁻², of which about 42% becomes buried, the remaining being emitted as methane (7%) or carbon dioxide (50%). Each year about 2.6 mol N m⁻² of particulate nitrogen reaches the sediment; 1.1 mol m⁻² is buried and 1.6 mol m⁻² is mineralized to ammonium. Only 0.42 mol m⁻² yr⁻¹ of the ammonium produced escapes from the sediments, the remaining being first nitrified (1.2 mol m⁻² yr⁻¹) and then denitrified (1.7 mol m⁻² yr⁻¹). Simple calculations indicate that intertidal sediments may account for about 14% and 30% of the total estuarine retention of nitrogen and carbon, respectively.