Small Streams Make Big Contribution to Carbon Cycle

Marx, Anne; Geldern, Robert van; Barth, Johannes A. C.

doi:10.1029/2018eo078009

Cited by 2 publications

(2 citation statements)

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“…Other catchments of disturbed tropical basins under mixed land use (Tana River basin, Kenya, and Ayeyarwady and Thanlwin rivers, Myanmar) had lower TC concentrations (Bird et al, 2008;Tamooh et al, 2012) than the concentrations of all three catchments of this study. The TN concentrations of the natural forest catchment were in the same range as those of subcatchments under mixed land use of the Yangtze River, Jialing River and Wujian River, China, during the wet season but exceeded the concentrations of intensified agricultural catchments in the USA, New Zealand and Spain by up to 12-fold (López-Tarazón et al, 2016;McDaniel et al, 2009;McDowell, 2015). The TN concentrations of the agricultural catchments of this study were within the ranges of concentrations in intensified temperate agricultural catchments (Pavanelli and Selli, 2013;Walling et al, 2001) (Table 6).…”

Section: Land Use Affects Sediment-associated Carbon and Nutrient Concentrationssupporting

confidence: 59%

Particulate macronutrient exports from tropical African montane catchments point to the impoverishment of agricultural soils

Kroese

Quinton

Jacobs

et al. 2021

SOIL

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Abstract. Agricultural catchments in the tropics often generate high concentrations of suspended sediments following the conversion of natural ecosystems. The eroded fine particles are generally enriched with carbon (TC) and nutrients (TN and TP) originating from the topsoil of agricultural land. Sediment-associated TC, TN and TP are an important loss to the terrestrial ecosystem and tightly connected to an increase in riverine particulate TC and nutrient export. Soil nutrient depletion can limit crop growth and yields, whereas an excess of nutrients in streams can cause eutrophication in freshwater systems. Streams in East Africa, with widespread land conversion from forests to agriculture, are expected to receive high loads of sediment-associated TC, TN and TP. In this study, we assess the effect of land use on particulate TC, TN and TP concentrations. Suspended sediments (time-integrated, manual-event-based and automatic-event-based sediment samples) were analysed for TC, TN and TP concentrations collected at the outlet of a natural montane forest (35.9), a tea-tree plantation (33.3) and a smallholder agriculture (27.2 km2) catchment in western Kenya during a wet sampling period in 2018 and a drier sampling period in 2019. Particulate TC, TN and TP concentrations were up to 3-fold higher (p<0.05) in the natural forest catchment compared to fertilized agricultural catchments. However, because of higher sediment loads from the smallholder agriculture catchment, the total sediment-associated loads of TC, TN and TP were higher compared to the natural forest and tea-tree plantation catchment. The higher C:N ratios in the natural forest suggest that the particulate nutrients are of organic origin due to tighter nutrient cycles, whereas lower ratios in both agricultural catchments suggest a mixture of mineral and organic sediment sources. The findings of this study imply that with the loss of natural forest, the inherent soil fertility is progressively lost under the current low fertilization rates and soil management strategies.

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Section: Land Use Affects Sediment-associated Carbon and Nutrient Concentrationssupporting

confidence: 59%

Particulate macronutrient exports from tropical African montane catchments point to the impoverishment of agricultural soils

Kroese

Quinton

Jacobs

et al. 2021

SOIL

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“…water hyacinth) (Lung'ayia et al, 2001). When C enters the watercourse, it can be mineralised and emitted as a greenhouse gas (Marx et al, 2017b(Marx et al, , 2017a.…”

Section: Introductionmentioning

confidence: 99%

Particulate macronutrient exports from tropical African montane catchments point to the impoverishment of agricultural soils

Kroese¹,

Quinton²,

Jacobs³

et al. 2020

Preprint

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Abstract. Catchments in the tropics often generate high concentrations of suspended sediments following the conversion of forests to agriculture. The eroded fine particles are generally enriched with carbon and nutrients originating from the topsoil. Sediment associated carbon and nutrients are an important loss to the terrestrial ecosystem and tightly connected to processes controlling riverine particulate carbon and nutrient export. Soil nutrient depletion can limit crop growth and yields, whereas an excess of nutrients in streams can cause eutrophication in freshwater systems. Streams in East Africa, with widespread land conversion are expected to receive high loads of sediment associated carbon, nitrogen and phosphorus. In this study, we build the knowledge base for particulate carbon, nitrogen and phosphorus for contrasting land uses. Suspended sediments (time integrated, manual event based and automatic event based sediment samples) were analysed for total carbon, nitrogen and phosphorus concentrations collected at the outlet of a natural montane forest, a tea tree plantation and a smallholder agriculture catchment in western Kenya during two sampling campaigns in 2018 and 2019. Particulate carbon and nutrient concentrations were up to three fold higher (p

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Small Streams Make Big Contribution to Carbon Cycle

Abstract: A recent paper in Reviews of Geophysics discussed the carbon dynamics of headwater streams.

Cited by 2 publications

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Particulate macronutrient exports from tropical African montane catchments point to the impoverishment of agricultural soils

Particulate macronutrient exports from tropical African montane catchments point to the impoverishment of agricultural soils

Particulate macronutrient exports from tropical African montane catchments point to the impoverishment of agricultural soils

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