Anna Wieland

Universität Heidelberg · Department of Geosciences

Aquatic ecosystems play an important role in global methane cycling and many field studies have reported methane supersaturation in the oxic surface mixed layer (SML) of the ocean and in the epilimnion of lakes. The origin of methane formed under oxic condition is hotly debated and several pathways have recently been offered to explain the “methane...

Aquatic ecosystems play an important role in global methane cycling and many field studies have reported methane supersaturation in the oxic surface mixed layer (SML) of the ocean and in the epilimnion of lakes. The origin of methane formed under oxic condition is hotly debated and several pathways have recently been offered to explain the ‘methane...

The Qinling Mountains (Qinling Mts.) are characterized as a distinct transition of bioclimatic zones along the north-south geographic boundary in China. Although ongoing global warming may affect the growth of most tree species across elevation gradients, the effect of modern warming on the stable hydrogen isotopes of tree-ring wood is still unknow...

Stable hydrogen isotope ratios of wood lignin methoxy groups (δ²HLM values) of mid-latitude forests are increasingly applied to reconstruct δ²H patterns in precipitation of regional to sub-continental scales. To date, the knowledge about the effect of topographic factors on δ²HLM values is still scare, especially in the biogeographic boundary. We m...

Stable hydrogen and carbon isotope ratios of wood lignin methoxy groups (δ13C and δ2H values) have been shown to be reliable proxies of past temperature variations. Previous studies showed that δ2H values even work in temperate environments where classical tree-ring width and maximum latewood density measurements are less successful for climate rec...

Stable hydrogen and carbon isotope ratios of wood lignin methoxy groups (δ13CLM and δ2HLM values) have been shown to be reliable proxies of past temperature variations. Previous studies showed that δ2HLM values even work in temperate environments where classical tree-ring width and maximum latewood density measurements are less skilful. Here, we an...

Stable hydrogen isotope values of wood lignin methoxy groups (δ²HLM) are increasingly applied to reconstruct the stable hydrogen isotope composition of precipitation (δ²Hprecip) and mean annual temperatures (MAT) of mid latitudes regions. Recently, the analytical procedure for measuring δ²HLM values was considerably improved by the availability of...

Methane (CH4) production in the ocean surface mixed layer is a widespread but still largely unexplained phenomenon. In this context marine algae have recently been described as a possible source of CH4 in surface waters. In the present study we investigated the effects of temperature and light intensity (including daylength) on CH4 formation from t...

Methane (CH4) production within the oceanic mixed layer is a widespread phenomenon, but the underlying mechanisms are still under debate. Marine algae might contribute to the observed CH4 oversaturation in oxic waters, but so far direct evidence for CH4 production by marine algae has only been provided for the coccolithophore Emiliania huxleyi. In...

The world’s oceans are considered to be a minor source of methane (CH4) to the atmosphere although the magnitude of total net emissions is highly uncertain. In recent years the origin of the frequently observed in situ CH4 production in the ocean mixed layer has received much attention. Marine algae might contribute to the observed CH4 oversaturati...