Coupling physical and biogeochemical processes in the Río de la Plata plume

TLDR: A coupled three-dimensional physical-biogeochemical model was developed in order to simulate the ecological functioning of the Rio de la Plata estuary and plume as discussed by the authors.

About: This article is published in Continental Shelf Research.The article was published on 2005-03-01 and is currently open access. It has received 71 citations till now. The article focuses on the topics: Nitrogen cycle & Estuary.

Figures

Fig. 4. Paraná and Uruguay discharges for the January 1998 - August 2000 period, interpolated from monthly means.

Fig. 15. Nitrogen fluxes (in mol N×106) between compartments for the area of Fig.11 during the year 1999. Values in boxes are nitrogen quantity change over the year, input from the tidal river and export to the outer estuary, at right, top and down, respectively.

Fig. 9. Monthly mean situations of the Ŕıo de la Plata plume for the year 1999 (From left to right : March, June, September and December). (A) Surface salinity (0.5, 5, 10, 15, 20, 25, 30, 33 isohalines are plotted). (B) Surface chlorophyll a concentration (mgChla/m3) from the model. (C) Surface chlorophyll a concentration (mgChla/m3) from SeaWiFS processed by the OC5 algorithm (Gohin et al., 2002). 7, 3, 5, 6 clear images were available during March, June, September and December, respectively . (D) Integrated primary production (gC/m2/month).

Fig. 10. Surface chlorophyll a concentration (mgChla/m3) on November 12th 1999 from SeaWiFS processed with OC5 (a) and OC4 (b), and from the model (c). November integrated primary production (d).

Fig. 5. Winter (a) and summer (b) mean wind stress (N.m−2) derived from NCEP reanalysis for the period 1990-2000. Only one every three vectors is shown.

Fig. 14. Evolution of the different tracers concentrations in the budgeted area of Fig.11 along the year 1999.

Frequently asked questions

Q1. What are the contributions in "Coupling physical and biogeochemical processes in the río de la plata plume" ?

A coupled three-dimensional physical-biogeochemical model was developed in order to simulate the ecological functioning of the Rio de la Plata estuary and plume this paper. 

Q2. What have the authors stated for future works in "Coupling physical and biogeochemical processes in the río de la plata plume" ?

It also suggests that different processes like denitrification or exchange of organic matter with the sediment would be crucial to consider in future work. Defining eutrophication risks, monitoring of their symptoms on higher trophic levels as it is planned in the emerging IGBP/IMBER core project, are other potential applications for the Ŕıo de la Plata system. 

Q3. What is the main area for biological activity in the o de la Plata?

The frontal zone between the tidal river and the outer estuary, where strong salinity and turbidity gradients occur, is a major area for biological activity. 

Q4. What is the role of the plume in the dynamics of the shelf?

On the inner shelf, the strong salinity plume of the Ŕıo de la Plata plays a major role in the dynamics, modifying the vertical structure of water masses (Piccolo, 1998; Piola et al., 2000). 

Q5. How are the eddy viscosity and diffusivity calculated?

Vertical eddy viscosity and diffusivity are calculated by the resolution of the turbulent kinetic energy equation, with an algebraic formula for the mixing length. 

Q6. What are the main drivers of the water masses characteristics of the shelf?

The coastal part of the shelf is influenced by the Ŕıo de la Plata, but the main drivers of the water masses characteristics are the Brazil and Malvinas currents. 

Q7. What is the main nutrient in the o de la Plata?

in most coastal areas, nitrogen seems to remain the major depleted nutrient, as it is the case for the Ŕıo de la Plata (Nagy et al., 1997). 

Q8. What is the main reason for the influx of DIN to the estuary?

This may suggest that over a year, the DIN supply to the frontal zone is potentially used for primary production, and that the nitrogen supply to the outer estuary and shelf may come from remineralization. 

Q9. What is the way to constrain the nutrient supply to the shelf?

To better constrain the nutrient supply to the shelf in the model, more frequent information on the different nutrient forms along the estuary would be necessary. 

Q10. How is the primary productivity in the estuary compared to the shelf?

At the end of autumn (June), primary productivity is very low over the estuary and shelf, whereas at the beginning of spring (September) primary productivity in the outer estuary is the same or even higher than over the shelf, with values of 45 gC/m2/month. 

Q11. What is the role of modelling in the development of adaptation and mitigation strategies?

Developing adaptation and mitigation strategies to cope with such changes requires modelling as a predictive tool for the system evolution. 

Q12. What is the description of the euphotic zone of the Malvinas?

A variety of physical processes, still not well understood, could lead to enhance supply of nutrient-rich Malvinas current waters into the euphotic zone of this front, among them small-scale eddies or internal waves (Acha et al., 2004).