Now showing 1 - 2 of 2
  • Publication
    What have we learned from over two decades of monitoring riverine nutrient inputs to Ireland's marine environment?
    Excessive nutrient loading to the marine environment from different sources and pathways, including rivers, has led to nutrient over-enrichment and the phenomenon of eutrophication in estuaries and coastal waters. The systematic monitoring of riverine nutrient inputs to Ireland's marine environment began in 1990. Over this period there has been a large reduction in nutrient inputs with loads of total phosphorus, total ammonia and total nitrogen decreasing by 71.8% (4,716 tonnes), 77.3% (5,505 tonnes) and 39.0% (59,396 tonnes), respectively. The largest reductions, particularly in total phosphorus and total ammonia, were seen in the main rivers discharging to the Celtic and Irish Sea coasts, with smaller or no reductions in rivers discharging along the western and north-western Atlantic coast. The reductions indicate the success of measures to reduce nutrient loss but also the disproportionate reduction in phosphorus over nitrogen. The ratio between nitrogen and phosphorus loads has increased by 2.5% per year and by as much as 4.1% per year for discharges to the Celtic Sea. As a consequence, the stoichiometric N:P ratio of river inputs to the Celtic Sea has more than doubled. The potential for this disparity to create a nutrient imbalance in downstream estuarine and coastal waters is discussed.
      477Scopus© Citations 8
  • Publication
    Linking changes in nutrient load source apportionment to estuarine responses: an Irish perspective
    In the Irish environment, anthropogenic pressures have led to widespread nutrient over-enrichment and eutrophication in surface waters. In the past 25 years European Directives have been implemented resulting in significant measures to improve water quality. Multi-decadal monitoring of nutrient inputs from rivers, and response parameters in estuarine and coastal systems, allows for a comparison of the effectiveness of these measures. In this study, trends in nutrient inputs from eighteen river systems and downstream estuarine parameters between 2000 and 2013 are explored. The results are placed in the context of changes in nutrient source load apportionment modelled through a newly developed GIS tool. Measured phosphorus inputs showed a significant reduction from fifteen catchments, with only four rivers showing a concurrent reduction in nitrogen.Significant Parallel improvements in estuarine water quality were evident in eight downstream systems, highlighting the complexity of response mechanisms. Load apportionment illustrated that the effectiveness of measures largely depended on factors such as land use and the proximity of large urban agglomerations to the estuary. The partitioning of nutrient sources could determine the nutrient landscape of the downstream estuary, with possible implications for the ecological health of the system.The results of the study will inform decision makers on the effectiveness of measures to date and the possible response of systems to future controls in the light of targets set out under the Water Framework Directive.
      406Scopus© Citations 15