Unusual Roles of Discharge, Slope and SOC in DOC Transport in Small Mountainous Rivers, Taiwan

Lee, Li Chin; Hsu, Ting; Lee, Tsung-Yu; Shih, Yu-Ting; Lin, Chuan-Yao; Jien, Shih‐Hao; Hein, Thomas; Zehetner, Franz; Shiah, Fuh Kwo; Huang, Jing

doi:10.1038/s41598-018-38276-x

Cited by 17 publications

(10 citation statements)

References 41 publications

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“…Our results showed that DOC concentration and river discharge had a significant positive correlation ( n = 12; p < 0.01) in the lower Changjiang River (Figure 5a), indicating a general hydrological control on DOC abundance. Similar positive correlations between DOC and discharge have been observed in other rivers, such as the arctic rivers (Guo et al., 2012; Raymond et al., 2007), the Mississippi River (Cai et al., 2015), and some small rivers (Lee et al., 2019; Warnken & Santschi, 2004). In summer, the flooding would have flushed more organic‐rich soils from deep flow paths, likely through soil erosion and DOM leaching in the river.…”

Section: Discussionsupporting

confidence: 67%

Seasonal Variations in Molecular Size of Chromophoric Dissolved Organic Matter From the Lower Changjiang (Yangtze) River

2021

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Biogeochemistry of dissolved organic matter (DOM) in estuarine and coastal areas is an important topic of carbon cycling studies on both global and local scales (Cai et al., 2012;Barrera et al., 2017;Seidel et al., 2014). The bulk DOM in aquatic environments has been shown to be heterogeneous in size, composition, and biological/chemical reactivity (Benner & Amon, 2015;Xu & Guo, 2017). Construction of dams and reservoirs along the main river channel and tributaries may also change the fluxes and composition of terrestrial materials transported by the large rivers Yu et al., 2011;. Thus, further knowledge is needed to better understand processes and mechanisms that control the composition, seasonal variations, and cycling pathways of DOM in large river dominated ocean margins on various spatial and temporal scales (Cao et al., 2016).In large river dominated estuarine areas, the concentrations and inventories of biogeochemical constituents, such as DOM and nutrients, are largely controlled by the export fluxes from rivers (Gao et al., 2015;Song et al., 2017). The biogeochemical cycling of many chemical species in coastal and marine environments is also closely connected with the physical and chemical properties of those terrestrial compounds (Cai

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Section: Discussionsupporting

confidence: 67%

Seasonal Variations in Molecular Size of Chromophoric Dissolved Organic Matter From the Lower Changjiang (Yangtze) River

2021

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“…Riverine DOC (i.e., baseflow and storm events) is rarely documented in small headwater catchments across the tropics, whereby heavy rainfall, dynamic riparian areas, steep slopes, soil characteristics, low stream water pH, and high solar radiation exposure (Figure ) are key features controlling SOC mobilization (Lee et al, ; Shih et al, ; Wymore et al, ). This study demonstrated that large daily rainfall up to 250 mm (a typical rainfall amount during tropical storm passages; Zhang et al, ) and sustained saturation within riparian areas (Figures a and ) led to rapid allochthonous DOC transport to the stream network (Figure b).…”

Section: Discussionmentioning

confidence: 99%

“…Global DOC export usually ranges from 1 to 15 g C · m 2 · year ‐1 (Neff & Asner, ), with a mean annual value of 1.08 g C · m 2 · year ‐1 (Li et al, ; Table ). While large tropical river systems (e.g., Amazon, Mekong, Orinoco, Parana; Table ) exhibited DOC export values between ~2‐5 g C · m 2 · year ‐1 , pristine and dynamic tropical forested catchments, such as Quebrada Grande, revealed a significant potential to export greater DOC amounts, in most cases, than temperate and arctic streams or large river systems (Lee et al, ). Baseflow and storm events contributed 37.8% and 62.2%, respectively, to the total discharge‐weighted DOC export from Quebrada Grande (6.7±0.1 g C · m ‐2 · year ‐1 ).…”

Section: Discussionmentioning

confidence: 99%

DOC Transport and Export in a Dynamic Tropical Catchment

et al. 2019

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Dissolved organic carbon (DOC) transport and export from headwater forests into freshwaters in highly dynamic tropical catchments are still understudied. Here we present a DOC analysis (2017) in a pristine and small (~2.6 km2) tropical catchment of Costa Rica. Storm flows governed a rapid surface and lateral allochthonous DOC transport (62.2% of the annual DOC export). Cross‐correlation analysis of rainfall and stream discharge indicated that DOC transport occurred on average ~1.25 hr after the rainfall maxima, with large contributions of event water, ranging from 42.4±0.3% up to 98.2±0.3% of the total discharge. Carbon export flux (annual mean=6.7±0.1 g C · m‐2 · year‐1) was greater than values reported in subtropical and temperate catchments. Specific ultraviolet absorbance indicated a mixture of hydrophobic humic and hydrophilic nonhumic matter during both baseflow and storm events. Our results highlight the rapid storm‐driven DOC transport and export as well as low biogeochemical attenuation during baseflow episodes in a climate sensitive hot spot. By understanding the key factors controlling the amount of organic carbon transported to streams in dynamic tropical landscapes, better global‐ and catchment‐scale model assessments, conservation practices, and water treatment innovations can be identified.

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“…This also indicates that low relief regions with stronger hydrologic connectivity to streams and rivers are likely a major source of riverine DOC (Connolly et al, 2018;Mzobe et al, 2020). The shallow soil depth in steeper regions may also be an influencing factor in constraining DOC generation (Lee et al, 2019). The correlation of SUVA254 with mean drainage slope suggests that steeper catchments tend to export DOC with less aromaticity (Fig.…”

Section: Geomorphologic Controls On Doc Exportmentioning

confidence: 92%

Geographical controls and anthropogenic impacts on dissolved organic carbon from mountainous rivers: Insights from optical properties and carbon isotopes

Chen

Zhong

Ran

et al. 2022

Preprint

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Abstract. Mountainous rivers (MRs) are one of the critical systems in transporting dissolved organic carbon (DOC) from terrestrial environments to downstream ecosystems. However, how geographical factors and anthropogenic impacts control the composition and export of DOC in mountainous rivers remains largely unclear. Here, we explore DOC dynamics in three subtropical mountainous catchments (i.e., the Yinjiang, Shiqian, and Yuqing catchments) in southwest China which are highly influenced by anthropogenic activities. Water chemistry, stable and radioactive carbon isotopes of DOC (δ13CDOC and Δ14CDOC) and optical properties (UV absorbance and fluorescence spectra) for river water were employed to assess the biogeochemical processes and controlling factors of DOC. The radiocarbon ages of the DOC in the Yinjiang River varied widely, ranging from 928 years before present to modern. Both allochthonous and autochthonous sources had an important effect on riverine DOC export. Results from carbon isotopes suggested that in-stream processing of POC is also an important source of DOC. DOC in catchments with higher slope gradients and lower annual air temperature was characterized by lower concentration and more aromatic, which was distinct from those with gentle slopes and higher temperature. Variabilities in DOC concentrations and δ13CDOC were also explained by land use, showing that higher DOC concentrations with 13C-depleted characters were observed in urban and agricultural land use areas. Moreover, DOM was less aromatic, less recently produced and had a higher degree of humification in catchments with a higher proportion of urban and agricultural land use area. This research highlights the significance of incorporating geographical controls and anthropogenic impacts into the MRs to better understand their DOC dynamics and quality of dissolved organic matter (DOM).

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Unusual Roles of Discharge, Slope and SOC in DOC Transport in Small Mountainous Rivers, Taiwan

Cited by 17 publications

References 41 publications

Seasonal Variations in Molecular Size of Chromophoric Dissolved Organic Matter From the Lower Changjiang (Yangtze) River

Seasonal Variations in Molecular Size of Chromophoric Dissolved Organic Matter From the Lower Changjiang (Yangtze) River

DOC Transport and Export in a Dynamic Tropical Catchment

Geographical controls and anthropogenic impacts on dissolved organic carbon from mountainous rivers: Insights from optical properties and carbon isotopes

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