<b>Enhanced Regulation of Carbon Emissions and DOM Transport by Cascade Reservoirs in the Upper Yellow River</b>
<p dir="ltr">Under the influence of global climate change and human activities, the carbon emission characteristics and driving mechanisms of inland waters, especially river reservoir systems, have attracted widespread attention in recent years. However, studies on the biogeochemical...
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2025
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| Summary: | <p dir="ltr">Under the influence of global climate change and human activities, the carbon emission characteristics and driving mechanisms of inland waters, especially river reservoir systems, have attracted widespread attention in recent years. However, studies on the biogeochemical processes, transport mechanisms, and emission dynamics of carbon emissions from inland waters in the Qinghai–Tibet Plateau—the region most sensitive to global climate change remain scarce. The focus of this study is typical cascade reservoirs in the upper Yellow River. During spring thawing periods, surface water samples were collected from Longyangxia(LYX), Lijiaxia(LJX), and Liujiaxia(UJX) reservoirs along with stratified water from reservoir areas and natural rivers upstream/downstream. The greenhouse gas(GHG) emission characteristics of the upper Yellow River cascade reservoir–river system under the interaction between human activities and natural processes were clarified. This study comparatively analyzed the carbon source components and their origins in the upper Yellow River, including natural river sections, cascade reservoirs, individual reservoirs, different reservoir zones, and varying depths. It also investigated their correlation with GHG emission characteristics. Overall, the diffusion flux of CO2(FCO2) and CH4(FCH4) at the water–air interface in each reservoir area exceeded those in natural channels. FCO2 showed a decreasing trend along the flow direction, whereas FCH4 exhibited the opposite pattern. The FCH4 in the study area was significantly lower than that of CO2. The vertical distribution of dissolved organic matter (DOM) is depth-dependent: the shallow waters of reservoirs with shallow water depths (≤40 m) had high DOM and humic acid content, humification levels and hydrophobic organic components, whereas the deep waters of reservoirs with deeper water depths (≥70 m) had high DOM and humic acid content, humification levels and hydrophobic organic components. The carbon emissions of the LYX reservoir are mainly endogenous and more affected by climate change, whereas the carbon emissions of UJX are the result of the combined effects of endogenous and exogenous sources and are more affected by human activities. The construction of cascade reservoir systems has intensified the control over aquatic carbon emissions and DOM transport.</p> |
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