Publications

Publications_Hereon (Photo: J.R. Lippels / Hereon)

Following publications have been announced by our Institute of Carbon Cycles. For further information please contact the marked co-authors of the publications:

Norbisrath, M., van Beusekom, J.E.E., & Thomas, H. (2024): Alkalinity sources in the Dutch Wadden Sea. Ocean Sci., 20, 1423–1440, https://doi.org/10.5194/os-20-1423-2024

Abstract:

Total alkalinity (TA) is an important chemical property that plays a decisive role in the oceanic buffering capacity with respect to CO₂. TA is mainly generated by weathering on land as well as by various anaerobic metabolic processes in the water and sediments. The Wadden Sea, located in the southern North Sea, is hypothesized to be a source of TA for the North Sea, but quantifications are scarce. This study shows observations of TA, dissolved inorganic carbon (DIC), and nutrients in the Dutch Wadden Sea in May 2019. Surface samples were taken along several transects in order to investigate spatial distribution patterns and compare them with data from the late 1980s. A tidal cycle was sampled to further shed light on TA generation and potential TA sources. We identified the Dutch Wadden Sea as a source of TA and estimated an export of 6.6 Mmol TA per tide to the North Sea. TA was generated in the sediments, with deep pore water flow during low tide enriching the surface water. A combination of anaerobic processes and CaCO₃ dissolution were potential TA sources in the sediments. We deduce that seasonality and the associated nitrate availability specifically influence TA generation by denitrification, which is low in spring and summer.

Shi, W., Qin, B., Zhang, Q., Paerl, H.W., Van Dam, B., Jeppesen, E., & Zeng, C. (2024): Global lake phytoplankton proliferation intensifies climate warming. Nat Commun 15, 10572, https://doi.org/10.1038/s41467-024-54926-3

Abstract:

In lakes, phytoplankton sequester atmospheric carbon dioxide (CO₂) and store it in the form of biomass organic carbon (OC); however, only a small fraction of the OC remains buried, while the remaining part is recycled to the atmosphere as CO₂ and methane (CH₄). This has the potential effect of adding CO₂-equivalents (CO₂-eq) to the atmosphere and producing a warming effect due to the higher radiative forcing of CH₄ relative to CO₂. Here we show a 3.1-fold increase in CO₂-eq emissions over a 100-year horizon, with the effect increasing with global warming intensity. Climate warming has stimulated phytoplankton growth in many lakes worldwide, which, in turn, can feed back CO₂-eq and create a positive feedback loop between them. In lakes where phytoplankton is negatively impacted by climate warming, the CO₂-eq feedback capacity may diminish gradually with the ongoing climate warming.