Nutrient flux and budget in the Ebro estuary

Abstract

ElsevierFalco Giaccaglia, SL.; Niencheski, L.; Rodilla Alamá, M.; Romero Gil, I.; González Del Rio Rams, J.; Sierra, J.; Mösso, C. (2010). Nutrient flux and budget in the Ebro estuary. Estuarine, Coastal and Shelf Science. 87 (1) Abstract: The Ebro river flows to the Mediterranean coast of Spain. During its final stretch, the Ebro behaves in a similar way to a highly stratified estuary. This paper describes the transport of nutrients to the Ebro estuary, evaluates the general movement of nutrients in the estuarine region, using a mass balance approach, and estimates the amounts of nutrients discharged to the coastal environment. Given the strong saline stratification, this study only includes the surface layer that contains the continental freshwater. The annual nutrient budget for the Ebro estuary shows a net excess for nitrogen and phosphorus, while silicate almost attains equilibrium between addition and removal. There are several reasons for gains in nitrogen and phosphorous: a contribution of dissolved and particulate compounds in the freshwater (some of which are mineralized); a lower uptake of phytoplankton indicated by chlorophyll reduction in the estuary; an entrainment of the nutrient-rich upper part of the salt wedge; and, to a lesser extent, the impact of wastewater and agricultural water use. The biggest load discharged into the Mediterranean Sea by the Ebro is nitrogen, followed by silicate with over 10 000 tons of each deposited annually. Phosphorus is discharged at relatively low concentrations and with an annual load of about 200 t yr-1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 ABSTRACTThe Ebro river flows to the Mediterranean coast of Spain. During its final stretch, the Ebro behaves in a similar way to a highly stratified estuary. This paper describes the transport of nutrients to the Ebro estuary, evaluates the general movement of nutrients in the estuarine region, using a mass balance approach, and estimates the amounts of nutrients discharged to the coastal environment. Given the strong saline stratification, this study only includes the surface layer that contains the continental freshwater. The annual nutrient budget for the Ebro estuary shows a net excess for nitrogen and phosphorus, while silicate almost attains equilibrium between addition and removal. There are several reasons for gains in nitrogen and phosphorous: a contribution of dissolved and particulate compounds in the freshwater (some of which are mineralized); a lower uptake of phytoplankton indicated by chlorophyll reduction in the estuary; an entrainment of the nutrient-rich upper part of the salt wedge; and, to a lesser extent, the impact of wastewater and agricultural water use. The biggest load discharged into the Mediterranean Sea by the Ebro is nitrogen, followed by silicate with over 10 000 tons of each deposit...

The “salt wedge pump”: Convection‐driven pore‐water exchange as a source of dissolved organic and inorganic carbon and nitrogen to an estuary

“…During periods of high flows, or during dynamic conditions (spring tides, windy days), salt wedge waters can mix with surface waters. The upward entrainment of enriched salt wedge waters can have a major effect on the distribution of coastal phytoplankton as observed in the Ebro River, Spain (Falco et al 2010), and the Yura River, Japan (Kasai et al 2010). Therefore, any source of dissolved constituents to the salt wedge can have important biological implications to coastal waters.…”

Fluvial contributions of nutrient salts, dissolved trace elements and organic carbon to the sea by pristine temperate rivers (SW Europe)

“…However, no work on small European rivers from non-industrialised and non-human affected areas has been undertaken to determine their natural background state. There is only limited data on metals, DOC, Chl-a and nutrients analysis and river water quality in freshwater systems for dissolved species [8,[11][12][13][14] as well as hydrologic parameters. [15][16][17][18] The characteristics of the dissolved elements transported by the river flow and budgets of this organic and inorganic material draining into the Galician rias are very restricted, [19][20][21][22][23] and this lack of information is one of the reasons of this research.…”

Community structure of benthic macroinvertebrates inhabiting a highly stratified Mediterranean estuary

“…This organic enrichment caused oxygen depletion through microbial consumption (Ibáñez et al, 1995;Casamayor et al, 2001). Recent changes in the nutrient content of the river, especially the reduction of phosphates, have reduced the primary production in the upper layer, whereas in the lower layer it has increased due to higher light penetration (Falco et al, 2010); thus, the hypoxic conditions in the lower layer have decreased (Casamayor et al, 2001;Ibáñez et al, 2008).…”