Sediment and nutrient retention in ponds on an agricultural stream: evaluating effectiveness for diffuse pollution mitigation
Robotham, John; Old, Gareth ORCID: https://orcid.org/0000-0002-4713-1070; Rameshwaran, Ponnambalam; Sear, David; Gasca-Tucker, David; Bishop, James; Old, Joanne; McKnight, David.
2021
Sediment and nutrient retention in ponds on an agricultural stream: evaluating effectiveness for diffuse pollution mitigation [in special issue: Mitigating the impacts of agricultural water pollution on river ecology]
Water, 13 (12), 1640.
27, pp.
https://doi.org/10.3390/w13121640
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Abstract/Summary
The creation of ponds and wetlands has the potential to alleviate stream water quality impairment in catchments affected by diffuse agricultural pollution. Understanding the hydrological and biogeochemical functioning of these features is important in determining their effectiveness at mitigating pollution. This study investigated sediment and nutrient retention in three connected (on-line) ponds on a lowland headwater stream by sampling inflowing and outflowing concentrations during base and storm flows. Sediment trapping devices were used to quantify sediment and phosphorus accumulations within ponds over approximately monthly periods. The organic matter content and particle size composition of accumulated sediment were also measured. The ponds retained dissolved nitrate, soluble reactive phosphorus and suspended solids during baseflows. During small to moderate storm events, some ponds were able to reduce peak concentrations and loads of suspended solids and phosphorus; however, during large magnitude events, resuspension of deposited sediment resulted in net loss. Ponds filtered out larger particles most effectively. Between August 2019 and March 2020, the ponds accumulated 0.306 t ha−1 sediment from the 30 ha contributing area. During this period, total sediment accumulations in ponds were estimated to equal 7.6% of the suspended flux leaving the 340 ha catchment downstream. This study demonstrates the complexity of pollutant retention dynamics in on-line ponds and highlights how their effectiveness can be influenced by the timing and magnitude of events.
Item Type: | Publication - Article |
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Digital Object Identifier (DOI): | https://doi.org/10.3390/w13121640 |
UKCEH and CEH Sections/Science Areas: | Hydro-climate Risks (Science Area 2017-) |
ISSN: | 2073-4441 |
Additional Information. Not used in RCUK Gateway to Research.: | Open Access paper - full text available via Official URL link. |
Additional Keywords: | water quality, natural flood management, suspended sediment, phosphorus, nitrate, organic matter, on-line ponds, constructed wetlands, particle size |
NORA Subject Terms: | Ecology and Environment |
Date made live: | 09 Jul 2021 13:46 +0 (UTC) |
URI: | https://nora.nerc.ac.uk/id/eprint/530666 |
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