In:
Geoscientific Model Development, Copernicus GmbH, Vol. 14, No. 1 ( 2021-01-19), p. 295-321
Abstract:
Abstract. A carbonate chemistry balance module was implemented into a biogeochemical model of the planktonic food web. The model, named Eco3M-CarbOx, includes
22 state variables that are dispatched into 5 compartments: phytoplankton, heterotrophic bacteria, detrital particulate organic matter, labile
dissolved organic, and inorganic matter. This model is applied to and evaluated in the Bay of Marseille (BoM, France), which is a coastal zone impacted
by the urbanized and industrialized Aix–Marseille Metropolis, and subject to significant increases in anthropogenic emissions of CO2. The model was evaluated over the year 2017, for which in situ data of the carbonate system are available in the study site. The biogeochemical state
variables of the model only change with time, to represent the time evolution of a sea surface water cell in response to the implemented realistic
forcing conditions. The model correctly simulates the value ranges and seasonal dynamics of most of the variables of the carbonate system except for the
total alkalinity. Several numerical experiments were conducted to test the response of carbonate system to (i) a seawater temperature increase,
(ii) wind events, (iii) Rhône River plume intrusions, and (iv) different levels of atmospheric CO2 contents. This set of numerical experiments
shows that the Eco3M-CarbOx model provides expected responses in the alteration of the marine carbonate balance regarding each of the considered
perturbation. When the seawater temperature changes quickly, the behavior of the BoM waters alters within a few days from a source of CO2
to the atmosphere to a sink into the ocean. Moreover, the higher the wind speed is, the higher the air–sea CO2 gas exchange fluxes
are. The river intrusions with nitrate supplies lead to a decrease in the pCO2 value, favoring the conditions of a sink for atmospheric
CO2 into the BoM. A scenario of high atmospheric concentrations of CO2 also favors the conditions of a sink for atmospheric
CO2 into the waters of the BoM. Thus the model results suggest that external forcings have an important impact on the carbonate
equilibrium in this coastal area.
Type of Medium:
Online Resource
ISSN:
1991-9603
DOI:
10.5194/gmd-14-295-2021
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2456725-5
Permalink