| 1. |
- Berggren, Martin, et al.
(författare)
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Unified understanding of intrinsic and extrinsic controls of dissolved organic carbon reactivity in aquatic ecosystems
- 2022
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 103:9
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Tidskriftsartikel (refereegranskat)abstract
- Despite our growing understanding of the global carbon cycle, scientific consensus on the drivers and mechanisms that control dissolved organic carbon (DOC) turnover in aquatic systems is lacking, hampered by the mismatch between research that approaches DOC reactivity from either intrinsic (inherent chemical properties) or extrinsic (environmental context) perspectives. Here we propose a conceptual view of DOC reactivity in which the combination of intrinsic and extrinsic factors controls turnover rates and determines which reactions will occur. We review three major types of reactions (biological, photochemical, and flocculation) from an intrinsic chemical perspective and further define the environmental features that modulate the expression of chemically inherent reactivity potential. Finally, we propose hypotheses of how extrinsic and intrinsic factors together shape patterns in DOC turnover across the land-to-ocean continuum, underscoring that there is no intrinsic DOC reactivity without environmental context. By acknowledging the intrinsic–extrinsic control duality, our framework intends to foster improved modeling of DOC reactivity and its impact on ecosystem services.
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| 2. |
- Garnier, Aurélie, et al.
(författare)
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Coastal darkening exacerbates eutrophication symptoms through bottom-up and top-down control modification
- 2023
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Ingår i: Limnology and Oceanography. - : Wiley. - 1939-5590 .- 0024-3590. ; 68:3, s. 678-691
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Tidskriftsartikel (refereegranskat)abstract
- Coastal eutrophication due to excessive anthropogenic nutrient loading is a major threat worldwide, and especially in estuaries and semi-enclosed waterbodies, like the brackish Baltic Sea. In addition, coastal waters may become darker (coastal darkening) due to increased input of colored compounds from terrestrial run-off and sediment resuspension. Still, the effects of darkening on coastal food web responses to eutrophication are unknown. In a mesocosm experiment with benthic and pelagic habitats, we manipulated nutrient loading, presence of fish and light availability to disentangle bottom-up and top-down control of eutrophication symptoms in ambient and darkened waters. Overall, we found higher pelagic Chlorophyll a concentrations (a proxy of algal biomass) with darkening and with nutrient enrichment in both clear and dark waters. Albeit fish had a strong impact on zooplankton and zoobenthos, they had no cascading effect on algae. We conclude that coastal darkening due to changes in land use and climate change can pose an additional challenge concerning the recovery of coastal waters from eutrophication.
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| 3. |
- Younes, Hani, et al.
(författare)
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The first continuous δ13C record across the Late Silurian Lau Event on Gotland, Sweden
- 2017
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Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 139:1, s. 63-69
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Tidskriftsartikel (refereegranskat)abstract
- The positive δ13C excursion associated with the Late Silurian Lau Event is recognized globally and is the most prominent carbon isotope excursion of the Phanerozoic. We present new δ13C data (195 samples) and the first continuous carbon isotope stratigraphy across the stratigraphic range of this bioevent based on two drill cores from Gotland, the informal type area for the Lau Event. The positive δ13C anomaly reaches a peak value of 9.01‰ in an interval correlated to the Icriodontid conodont Zone in the upper Eke Formation, an interval with generally impoverished fauna and strongly dominated by one single conodont species, Panderodus equicostatus, and a mass-occurrence of oncoids. The distinct morphology of this Late Ludfordian Carbon Isotope Excursion, including a well-defined rising limb, a plateau and a falling limb can be used for intercontinental correlation of the strata.
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