DOI: 10.5194/hess-18-1009-2014
Scopus记录号: 2-s2.0-84900583695
论文题名: Phosphorus transport and retention in a channel draining an urban, tropical catchment with informal settlements
作者: Nyenje P ; M ; , Meijer L ; M ; G ; , Foppen J ; W ; , Kulabako R ; , Uhlenbrook S
刊名: Hydrology and Earth System Sciences
ISSN: 10275606
出版年: 2014
卷: 18, 期: 3 起始页码: 1009
结束页码: 1025
语种: 英语
Scopus关键词: Fate and transport
; Informal settlements
; Kampala , Uganda
; Orders of magnitude
; Phosphorus transport
; Sorption characteristics
; Sub-saharan africa
; Untreated wastewater
; Adsorption
; Calcite
; Calcium
; Housing
; Phosphorus
; Runoff
; Suspended sediments
; Urban transportation
; Catchments
; adsorption
; biogeochemistry
; catchment
; channel flow
; informal settlement
; iron
; phosphate
; phosphorus
; retention
; runoff
; sorption
; urban area
; urban drainage
; Kampala
; Uganda
英文摘要: Urban catchments in sub-Saharan Africa (SSA) are increasingly becoming a major source of phosphorus (P) to downstream ecosystems. This is primarily due to large inputs of untreated wastewater to urban drainage channels, especially in informal settlements (or slums). However, the processes governing the fate of P in these catchments are largely unknown. In this study, these processes are investigated. During high runoff events and a period of base flow, we collected hourly water samples (over 24 h) from a primary channel draining a 28 km2 slum-dominated catchment in Kampala, Uganda, and from a tertiary channel draining one of the contributing slum areas (0.54 km2). The samples were analysed for orthophosphate (PO4-P), particulate P (PP), total P (TP), suspended solids (SS) and hydrochemistry. We also collected channel bed and suspended sediments to determine their geo-available metals, sorption characteristics and the dominant phosphorus forms. Our results showed that the catchment exported high fluxes of P (0.3 kg km2 d-1 for PO4-P and 0.95 for TP), which were several orders of magnitude higher than values normally reported in literature. A large proportion of P exported was particulate (56% of TP) and we inferred that most of it was retained along the channel bed. The retained sediment P was predominantly inorganic (> 63% of total sediment P) and consisted of mostly Ca and Fe-bound P, which were present in almost equal proportions. Ca-bound sediment P was attributed to the adsorption of P to calcite because surface water was near saturation with respect to calcite in all the events sampled. Fe-bound sediment P was attributed to the adsorption of P to iron oxides in suspended sediment during runoff events given that surface water was undersaturated with respect to iron phosphates. We also found that the bed sediments were P-saturated and showed a tendency to release P by mineralisation and desorption. During rain events, there was a flushing of PP which we attributed to the resuspension of P-rich bed sediment that accumulated in the channel during low flows. However, first-flush effects were not observed. Our findings provide useful insights into the processes governing the fate and transport of P in urban slum catchments in SSA. © 2014 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/78300
Appears in Collections: 气候变化事实与影响
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作者单位: UNESCO, IHE Institute for Water Education, Department of Water Science and Engineering, P.O. Box 3015, Delft, Netherlands; Department of Civil and Environmental Engineering, Makerere University, P.O. Box 7062, Kampala, Uganda; Delft University of Technology, Section of Water Resources, P.O. Box 5048, 2600 GA Delft, Netherlands; VU University Amsterdam, Faculty of Earth and Life Sciences, De Boelelaan 1085, 1081 HV Amsterdam, Netherlands
Recommended Citation:
Nyenje P,M,, Meijer L,et al. Phosphorus transport and retention in a channel draining an urban, tropical catchment with informal settlements[J]. Hydrology and Earth System Sciences,2014-01-01,18(3)