Sources and Mechanisms of Low-Flow River Phosphorus Elevations: A Repeated Synoptic Survey Approach
| Autor: | Noeleen McDonald, Sophie C. Sherriff, Simon Leach, Per-Erik Mellander, Sara E. Vero, Karen Daly |
|---|---|
| Přispěvatelé: | Department of Agriculture, Food and the Marine |
| Rok vydání: | 2019 |
| Předmět: |
lcsh:Hydraulic engineering
010504 meteorology & atmospheric sciences Geography Planning and Development Drainage basin chemistry.chemical_element 010501 environmental sciences Aquatic Science 01 natural sciences Biochemistry lcsh:Water supply for domestic and industrial purposes lcsh:TC1-978 phosphorus mobilization 0105 earth and related environmental sciences Water Science and Technology Hydrology lcsh:TD201-500 geography geography.geographical_feature_category synoptic survey Phosphorus Sediment low-flow point source Macrophyte sediment chemistry Water Framework Directive Environmental science Water quality Arable land Groundwater |
| Zdroj: | Water, Vol 11, Iss 7, p 1497 (2019) Water Volume 11 Issue 7 |
| ISSN: | 2073-4441 |
| DOI: | 10.3390/w11071497 |
| Popis: | High-resolution water quality monitoring indicates recurring elevation of stream phosphorus concentrations during low-flow periods. These increased concentrations may exceed Water Framework Directive (WFD) environmental quality standards during ecologically sensitive periods. The objective of this research was to identify source, mobilization, and pathway factors controlling in-stream total reactive phosphorus (TRP) concentrations during low-flow periods. Synoptic surveys were conducted in three agricultural catchments during spring, summer, and autumn. Up to 50 water samples were obtained across each watercourse per sampling round. Samples were analysed for TRP and total phosphorus (TP), along with supplementary parameters (temperature, conductivity, dissolved oxygen, and oxidation reduction potential). Bed sediment was analysed at a subset of locations for Mehlich P, Al, Ca, and Fe. The greatest percentages of water sampling points exceeding WFD threshold of 0.035 mg L&minus 1 TRP occurred during summer (57%, 11%, and 71% for well-drained, well-drained arable, and poorly drained grassland catchments, respectively). These percentages declined during autumn but did not return to spring concentrations, as winter flushing had not yet occurred. Different controls were elucidated for each catchment: diffuse transport through groundwater and lack of dilution in the well-drained grassland, in-stream mobilization in the well-drained arable, and a combination of point sources and cumulative loading in the poorly drained grassland. Diversity in controlling factors necessitates investigative protocols beyond low-spatial and temporal resolution water sampling and must incorporate both repeated survey and complementary understanding of sediment chemistry and anthropogenic phosphorus sources. Despite similarities in elevation of P at low-flow, catchments will require custom solutions depending on their typology, and both legislative deadlines and target baselines standards must acknowledge these inherent differences. |
| Databáze: | OpenAIRE |
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