Modelling nutrient fluxes into the Mediterranean Sea

Area of Science:

• Environmental Science
• Hydrology
• Eutrophication Studies

Background:

• Mediterranean freshwater and marine ecosystems face significant pressure from human activities and pollution.
• Eutrophication is a high-risk phenomenon in the region due to nutrient enrichment.

Purpose of the Study:

• To extend the Geospatial Regression Equation for European Nutrient losses (GREEN) model for Mediterranean river basins.
• To quantify nutrient loads from various sources and assess management options for water and nutrient sustainability.

Main Methods:

• Utilized an extended version of the GREEN model with a 5 arc-minute spatial resolution.
• Incorporated the latest global data for nutrient load estimations, including diffuse and point sources.
• Performed source apportionment analysis for nitrogen and phosphorus compounds.

Main Results:

• Estimated annual discharges into the Mediterranean Sea (2003-2007): 1.87 Tg/y total nitrogen (TN), 1.22 Tg/y nitrates (N-NO3), 0.11 Tg/y total phosphorus (TP), and 0.03 Tg/y orthophosphate (P-PO4).
• Identified agriculture as the primary source of TN and N-NO3 loads, while wastewater and scattered dwellings dominate P-PO4 sources.
• Scenario analysis indicated that a 50% reduction in nitrogen surplus significantly cuts nitrogen emissions in intensive agricultural areas.

Conclusions:

• Agriculture and wastewater management are critical for controlling nutrient pollution in the Mediterranean.
• Upgrading wastewater treatment plants to tertiary level is effective for reducing total phosphorus loads.
• Sustainable water and nutrient management strategies are essential for mitigating eutrophication risks in the region.