Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Spatial representation of in-stream sediment phosphorus release combining channel network approaches and in-situ experiments
AU - Stutter, M.
AU - Richards, S.
AU - Ibiyemi, A.
AU - Watson, H.
PY - 2021/11/15
Y1 - 2021/11/15
N2 - Impairment of rivers by elevated phosphorus (P) concentration is an issue often studied at outlets of mesoscale catchments. Our objective was to evaluate within-catchment spatio-temporal processes along connected reaches to understand processes of internal P loading associated with sediment input, accumulations in channels and sediment-water column P exchange. Our overall hypothesis was that heterogeneous sediment residence within the channel of a 52 km2 mixed land cover catchment resulted in key zones for sediment-water P exchange. We evaluated the channel network through ground-survey, spatial data methods establishing connectivity and energy gradients. This gave a background to understand sampling of sediments and P release/uptake to the water column using 90 s in-situ resuspension isolating a portion of streambed over five sets of three-location transects in May (spring storms, recent active erosion) and September (summer low flow, longer sediment residence). Simple transect position models (top, mid, bottom) predicted increased sediment resuspension yields and P contents in lower settings. Sediment P release following resuspension were mean (and range) 0.5 (−0.8 to 1.8) and 0.5 (−2.5 to 3.6) mg soluble reactive P/m2 bed in May and September, respectively, strengthening generally down the transects but inconsistently. Relationships (log form) showed a steepening rise in fine sediments, P content, background and disturbance-released dissolved P, with specific stream power < 40 W/m2. In-situ methods showed sediments dominantly (12 cases May, 13 cases Sep) as P sources capable of influencing dissolved P concentrations and with potential explanation that heterogeneous locations of internal P loading influence the systems longer-term observed P trends. Combining channel network, stream power assessment and in-situ sorption studies improved the understanding of influential zones of sediment-water P exchange within this mesoscale catchment. Such methods have potential to inform P model development and management.
AB - Impairment of rivers by elevated phosphorus (P) concentration is an issue often studied at outlets of mesoscale catchments. Our objective was to evaluate within-catchment spatio-temporal processes along connected reaches to understand processes of internal P loading associated with sediment input, accumulations in channels and sediment-water column P exchange. Our overall hypothesis was that heterogeneous sediment residence within the channel of a 52 km2 mixed land cover catchment resulted in key zones for sediment-water P exchange. We evaluated the channel network through ground-survey, spatial data methods establishing connectivity and energy gradients. This gave a background to understand sampling of sediments and P release/uptake to the water column using 90 s in-situ resuspension isolating a portion of streambed over five sets of three-location transects in May (spring storms, recent active erosion) and September (summer low flow, longer sediment residence). Simple transect position models (top, mid, bottom) predicted increased sediment resuspension yields and P contents in lower settings. Sediment P release following resuspension were mean (and range) 0.5 (−0.8 to 1.8) and 0.5 (−2.5 to 3.6) mg soluble reactive P/m2 bed in May and September, respectively, strengthening generally down the transects but inconsistently. Relationships (log form) showed a steepening rise in fine sediments, P content, background and disturbance-released dissolved P, with specific stream power < 40 W/m2. In-situ methods showed sediments dominantly (12 cases May, 13 cases Sep) as P sources capable of influencing dissolved P concentrations and with potential explanation that heterogeneous locations of internal P loading influence the systems longer-term observed P trends. Combining channel network, stream power assessment and in-situ sorption studies improved the understanding of influential zones of sediment-water P exchange within this mesoscale catchment. Such methods have potential to inform P model development and management.
KW - Channel network
KW - Phosphorus
KW - Sediment-water exchange
KW - Stream energy
KW - Catchments
KW - Loading
KW - Rivers
KW - Runoff
KW - Mesoscale catchments
KW - P contents
KW - Phosphorus release
KW - Re-suspension
KW - Spatial representations
KW - Stream sediments
KW - Water columns
KW - Sediments
U2 - 10.1016/j.scitotenv.2021.148790
DO - 10.1016/j.scitotenv.2021.148790
M3 - Journal article
VL - 795
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
M1 - 148790
ER -