Publication Date:
2024-03-15
Description:
Ocean acidification may alter the cycling of nitrogen in coastal sediment and so the sediment-seawater nitrogen flux, an important driver of pelagic productivity. To investigate how this perturbation affects the fluxes of NOX- (nitrite/nitrate), NH4+ and O2, we incubated estuarine sand and subtidal silt in recirculating seawater with a CO2-adjusted pH of 8.1 and 7.9. During a 41-day incubation, the seawater kept at pH 8.1 lost 97% of its NOX- content but the seawater kept at pH 7.9 lost only 18%. Excess CO2 increased benthic photosynthesis. In the silt, this was accompanied by a reversal of the initial NOX- efflux into influx. The estuarine sand sustained its initial NOX- influx but, by the end of the incubation, released more NH4+ at pH 7.9 than at pH 8.1. We hypothesise that these effects share a common cause; excess CO2 increased the growth of benthic microalgae and so nutrient competition with ammonia oxidising bacteria (AOB). In the silt, diatoms likely outcompeted AOB for NH4+ and photosynthesis increased the dark/light fluctuations in the pore water oxygenation inhibiting nitrification and coupled nitrification/denitrification. If this is correct, then excess CO2 may lead to retention of inorganic nitrogen adding to the pressures of increasing coastal eutrophication.
Keywords:
Alkalinity, total; Alkalinity, total, standard deviation; Ammonium; Ammonium, flux; Ammonium, standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; Calcite saturation state; Calculated using CO2calc; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Containers and aquaria (20-1000 L or 〈 1 m**2); Difference; Entire community; Event label; EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Hauraki_Gulf; Identification; Laboratory experiment; Light mode; Nitrate and Nitrite; Nitrate and Nitrite, standard deviation; Nitrite and nitrate, flux; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Oxygen uptake, total; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Potentiometric; Salinity; Salinity, standard deviation; Sediment type; Soft-bottom community; South Pacific; Tauranga_Harbour; Temperate; Temperature, water; Temperature, water, standard deviation; Time point, descriptive; Treatment; Type
Type:
Dataset
Format:
text/tab-separated-values, 2627 data points
