Sources of nitrogen and phosphorus emissions to Irish rivers and coastal waters: Estimates from a nutrient load apportionment framework

Abstract

More than half of surface water bodies in Europe are at less than good ecological status according to Water Framework Directive assessments, and diffuse pollution from agriculture remains a major, but not the only, cause of this poor performance. Agri-environmental policy and land management practices have, in many areas, reduced nutrient emissions to water. However, additional measures may be required in Ireland to further decouple the relationship between agricultural productivity and emissions to water, which is of vital importance given on-going agricultural intensification. The Source Load Apportionment Model (SLAM) framework characterises sources of phosphorus (P) and nitrogen (N) emissions to water at a range of scales from sub-catchment to national. The SLAM synthesises land use and physical characteristics to predict emissions from point (wastewater, industry discharges and septic tank systems) and diffuse sources (agriculture, forestry, etc.). The predicted annual nutrient emissions were assessed against monitoring data for 16 major river catchments covering 50% of the area of Ireland. At national scale, results indicate that total average annual emissions to surface water in Ireland are over 2700tyr of P and 82,000tyr of N. The proportional contributions from individual sources show that the main sources of P are from municipal wastewater treatment plants and agriculture, with wide variations across the country related to local anthropogenic pressures and the hydrogeological setting. Agriculture is the main source of N emissions to water across all regions of Ireland. These policy-relevant results synthesised large amounts of information in order to identify the dominant sources of nutrients at regional and local scales, contributing to the national nutrient risk assessment of Irish water bodies.

Which factors influence farmers' intentions to adopt nutrient management planning?

“…Agriculture is important to the Irish economy and in terms of environmental impacts, especially on water quality, associated with agricultural nutrients (Mockler et al, 2017). Production is concentrated on milk and beef export, benefiting from low-input costs by using grass based feeding systems (Hyland et al, 2018).…”

Catchment characteristics predicting nitrogen and phosphorus losses in Finland

“…In response to population growth and associated activities, riverine nutrient loads have increased, leading to a deterioration in the ecological state of rivers, lakes, reservoirs, and marine areas in many regions of the world (Alexander et al, ; Carstensen, Andersen, Gustafsson, & Conley, ; Mockler et al, ; Morales‐Marín, Wheater, & Lindenschmidt, ). The cumulative effects of global change will likely further intensify such a trend (Rabalais, Turner, Díaz, & Justic, ).…”

Assessment of Nutrient Loads and Self-Remediation: A Case Study of the South Rangsit Canal in Thailand’s Pathum Thani Province

“…Specifically, the pollutants loads during the rainy season are linked to the point and nonpoint sources [16]. In addition, land use could contribute to nitrogen enrichment in the river [17], while phosphorus emission from wastewater is prevalent in highly populated areas [18].…”