Assimilative Capacity-Based Evaluation of Nitrogen and Phosphorus Pollution in a Semi-Arid Sub-Basin Using Grey Water Footprint Approach

Summary

This study applies a Tier-1 grey water footprint methodology to evaluate nitrogen and phosphorus pollution pressures in the Ankara River Sub-basin, integrating data from agricultural diffuse sources and municipal wastewater treatment plants. The analysis reveals phosphorus as the limiting pollutant and demonstrates that regulatory compliance on concentration thresholds alone does not protect river assimilative capacity, highlighting the need for basin-scale cumulative impact management frameworks.

Regional applicability

This study was conducted in Turkey and addresses semi-arid basin conditions specific to the Ankara River system. The methodology and findings on assimilative capacity-based management frameworks may be transferable to United Kingdom river basins facing similar agricultural and municipal nutrient loading pressures, though local hydrology, geology, and regulatory contexts would require adaptation of thresholds and leaching assumptions.

Key measures

Grey water footprint (million m³ yr⁻¹), nitrogen and phosphorus concentrations, leaching–runoff fractions, water quality thresholds, assimilative capacity of river

Outcomes reported

The study quantified grey water footprint (GWF) for nitrogen and phosphorus pollution in the Ankara River Sub-basin, identifying phosphorus as the primary limiting pollutant and estimating total GWF at 8294 million m³ yr⁻¹. It assessed sectoral contributions from agricultural diffuse sources (10%) and municipal wastewater treatment plants (31%) to basin-wide pollution.

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