Sources and Mechanisms of Low-Flow River Phosphorus Elevations: A Repeated Synoptic Survey Approach

Sara Vero (Lead / Corresponding author), Karen Daly, Noeleen T. McDonald, Simon Leach, Sophie Sherriff, Per-Erik Mellander

Research output: Contribution to journalArticle

1 Citation (Scopus)
36 Downloads (Pure)

Abstract

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−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
Original languageEnglish
Article number1497
Pages (from-to)1-18
Number of pages18
JournalWater
Volume11
Issue number7
Early online date18 Jul 2019
DOIs
Publication statusPublished - 2019

Fingerprint

Rivers
low flow
Phosphorus
river
phosphorus
water
Catchments
rivers
Water
well
grasslands
grassland
catchment
Sampling
mobilization
Sediments
sampling
autumn
sediment chemistry
water quality standards

Keywords

  • phosphorus
  • low-flow
  • synoptic survey
  • mobilization
  • point source
  • sediment
  • Macrophytes
  • Phenology
  • SAV seasonal successions
  • Lake Iseo
  • Bio-optical model
  • Vallisneria spiralis

Cite this

Vero, Sara ; Daly, Karen ; McDonald, Noeleen T. ; Leach, Simon ; Sherriff, Sophie ; Mellander, Per-Erik. / Sources and Mechanisms of Low-Flow River Phosphorus Elevations : A Repeated Synoptic Survey Approach. In: Water. 2019 ; Vol. 11, No. 7. pp. 1-18.
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abstract = "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−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",
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Vero, S, Daly, K, McDonald, NT, Leach, S, Sherriff, S & Mellander, P-E 2019, 'Sources and Mechanisms of Low-Flow River Phosphorus Elevations: A Repeated Synoptic Survey Approach', Water, vol. 11, no. 7, 1497, pp. 1-18. https://doi.org/10.3390/w11071497

Sources and Mechanisms of Low-Flow River Phosphorus Elevations : A Repeated Synoptic Survey Approach. / Vero, Sara (Lead / Corresponding author); Daly, Karen; McDonald, Noeleen T.; Leach, Simon; Sherriff, Sophie; Mellander, Per-Erik.

In: Water, Vol. 11, No. 7, 1497, 2019, p. 1-18.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Sources and Mechanisms of Low-Flow River Phosphorus Elevations

T2 - A Repeated Synoptic Survey Approach

AU - Vero, Sara

AU - Daly, Karen

AU - McDonald, Noeleen T.

AU - Leach, Simon

AU - Sherriff, Sophie

AU - Mellander, Per-Erik

PY - 2019

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AB - 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−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

KW - phosphorus

KW - low-flow

KW - synoptic survey

KW - mobilization

KW - point source

KW - sediment

KW - Macrophytes

KW - Phenology

KW - SAV seasonal successions

KW - Lake Iseo

KW - Bio-optical model

KW - Vallisneria spiralis

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SN - 2073-4441

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