River nutrient water and sediment measurements inform on nutrient retention, with implications for eutrophication

Dalu, Tatenda; Wasserman, Ryan J.; Magoro, Mandla L.; Froneman, P. William; Weyl, Olaf L. F.

doi:10.1016/j.scitotenv.2019.05.167

Cited by 66 publications

(17 citation statements)

References 39 publications

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“…Sediment delivery to watercourses in many areas of the world is increasing as catchments are progressively modified through human activities such as agriculture expansion, deforestation, construction, and the urbanization (Duerdoth et al, 2015). This increase of sediment has resulted in modification of the structure and chemical composition of the river bed (Gieswein et al, 2019), aquatic pollution (Dalu et al, 2019), habitat modifications (Ysebaert et al, 2019) and siltation and nutrient enrichment of the reservoirs and dams (Devi et al, 2008;Sutcliffe et al, 2012). Reports show that there is a loss of about 2% of the designed storage volume of reservoirs each year due to sedimentation (Aga et al, 2019).…”

mentioning

confidence: 99%

Land use/land cover change effect on soil erosion and sediment delivery in the Winike watershed, Omo Gibe Basin, Ethiopia

Aneseyee

Elias

Soromessa

et al. 2020

Science of The Total Environment

147

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Background: Information on soil loss and sediment export is essential to identify hotspots of soil erosion for conservation interventions in a given watershed. This study aims at investigating the dynamic of soil loss and sediment export associated with land use/land cover change and identifies soil loss hotspot areas in Winike watershed of Omo-gibe basin of Ethiopia. Spatial data collected from satellite images, topographic maps, meteorological and soil data were analyzed. Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) of sediment delivery ratio (SDR) model was used based on analysis of land use/land cover maps and RUSLE factors. Result:The results showed that total soil loss increased from 774.86 thousand tons in 1988 to 951.21 thousand tons in 2018 while the corresponding sediment export increased by 3.85 thousand tons in the same period. These were subsequently investigated in each land-use type. Cultivated fields generated the highest soil erosion rate, which increased by 10.02 t/ha/year in 1988 to 43.48 t/ha/year in 2018. This corresponds with the expansion of the cultivated area that increased from 44.95 thousand ha in 1988 to 59.79 thousand ha in 2018. This is logical as the correlation between soil loss and sediment delivery and expansion of cultivated area is highly significant (p<0.01).Sub-watershed six (SW-6) generated the highest soil loss (62.77 t/ha/year) and sediment export 16.69 t/ha/year, followed by Sub-watershed ten (SW-10) that are situated in the upland plateau.Conversely, the lower reaches of the watershed are under dense vegetation cover and experiencing less erosion. Conclusion:Overall, the changes in land use/land cover affect significantly the soil erosion and sediment export dynamism. This research is used to identify an area to prioritize the watershed for 2 immediate management practices. Thus, land use policy measures need to be enforced to protect the hydropower generation dams at downstream and the ecosystem at the watershed.

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confidence: 99%

Land use/land cover change effect on soil erosion and sediment delivery in the Winike watershed, Omo Gibe Basin, Ethiopia

Aneseyee

Elias

Soromessa

et al. 2020

Science of The Total Environment

147

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“…These differences could be attributed to sudden increases in water flow from the sewage treatment works which affected metal deposition, occurring further downstream as the channel widened and water flow decreased. More generally, Rajan et al [ 6 ] and Dalu et al [ 39 ] highlighted that during low discharge periods, sediment metals tend to accumulate in freshwater ecosystems and this might have significant effects on the metal bioaccumulation and translocations in flora and fauna.…”

Section: Discussionmentioning

confidence: 99%

Quantifying Metal Contamination and Potential Uptake by Phragmites australis Adans. (Poaceae) Along a Subtropical River System

Netshiongolwe

Cuthbert

Maenetje

et al. 2020

Plants

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: Metal pollution is pervasive across terrestrial and aquatic ecosystems owing to anthropogenic activities. Sediments can accrue high concentrations of metals and act as secondary sources, and thus may be valuable indicators of metal contamination across spatiotemporal scales. In aquatic systems, the extent of metal pollution may be further mediated by transference among sediments and living organisms, with plant metal contaminants potentially predictive of underlying sediment concentrations. The present study thus quantifies the extent of metal pollutants (Na, K, Ca, Mg, Cu, Zn, Mn, B, Fe) across multiple study sites and seasons (cool-dry, hot-wet, hot-dry) in a subtropical river system. Furthermore, uptake by a key macrophyte species, Phragmites australis, was examined and correlated with sediment pollution levels among different plant parts. Overall, sediment pollution load indices differed seasonally, being significantly highest during the cool-dry season irrespective of sampling location, suggesting that periods with reduced water flows can exacerbate metal pollution levels in riverine sediments. Also, metal concentrations were highest in upstream wetland sites, indicating a capacity for metal sink effects in these areas. Overall, macrophytes contained high concentrations of select metals, however composition and concentrations differed across plant parts, with roots containing particularly high concentrations of Fe and B. Correlations between sediment and macrophyte concentrations were mostly non-significant, whilst stem Mn and Fe concentrations correlated significantly negatively and positively to sediment concentrations, respectively. The present study identifies key spatiotemporal differences in multiple metal contaminants in an understudied subtropical aquatic system that align with hydrological regime differences. Whilst macrophytes were not found to be major accumulators, or predictors, of metal contaminants in this study, they may collectively play a central role in concentration regulation in aquatic systems.

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“…The excessive use of fertilizers increases discharge of nutrients from agricultural sectors into the adjacent receiving streams, et al, 2011). The higher amount of sediments and nutrients discharged from agricultural sectors to water bodies have resulted in widespread seasonal hypoxia in many areas around the globe (Dalu et al, 2019).…”

Section: Total Phosphorusmentioning

confidence: 99%

Modelling Wetland Eco-hydrological state in Pressure-State-Response framework validating it using Ecosystem service potentiality approach

Singha

Pal

2021

Preprint

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The present study has tried to model the Eco-hydrological state of wetlands for both pre dam and post dam periods of the Lower Tangon river basin using Pressure-State-Response (PSR) framework with advanced machine learning (ML) algorithms and validated it with Ecosystem service potentiality (ESP) approach along with conventional approaches of validation. All the applied models have explored that 22.48–39.52% wetland under very good EHS zone has converted into 15.52–16.57% relatively lower category of EHS zones indicating the gradual degradation of EHS quality over wider parts of the wetland. The result of model validation has noted the acceptability of all the applied models but performance is found high in the case of REPtree and Bagging models. Expert-based ESP behaves accordingly with the EHS models. Based on the results, the study suggests using ML models for such modelling and used field-based validation approach like ESP.

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River nutrient water and sediment measurements inform on nutrient retention, with implications for eutrophication

Cited by 66 publications

References 39 publications

Land use/land cover change effect on soil erosion and sediment delivery in the Winike watershed, Omo Gibe Basin, Ethiopia

Land use/land cover change effect on soil erosion and sediment delivery in the Winike watershed, Omo Gibe Basin, Ethiopia

Quantifying Metal Contamination and Potential Uptake by Phragmites australis Adans. (Poaceae) Along a Subtropical River System

Modelling Wetland Eco-hydrological state in Pressure-State-Response framework validating it using Ecosystem service potentiality approach

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