The mineral content in archaeological wood pile dwellings and in the surrounding sediments in a volcanic lake was investigated. Calcium was the most abundant element; the second most abundant element was arsenic in sapwood. Sulfur, iron and potassium were also present. The mineral compounds are linked to the volcanic origin of the lake, to bioaccumulation processes induced by bacteria (i.e. sulfate-reducing bacteria) and to biochemical processes.

Soils store more carbon (C) than any other terrestrial C reservoir, but the processes that control how much C stays in soil, and for how long, are very complex. Here, we used a recent method that involves heating soil in the lab to measure the range of C ages in soil. We found that most C in soil is decades to centuries old, while some stays for much shorter times (days to months), and some is thousands of years old. Such detail helps us to estimate how soil C may react to changing climate.

Cyanobacterial blooms are associated with whiting events – natural occurrences of fine-grained carbonate precipitation in the water column. The role of organic matter (OM) produced by cyanobacteria in these events has been overlooked in previous research. Our laboratory experiments showed that OM affects the size and quantity of CaCO₃ minerals. We propose a model of OM-associated CaCO₃ precipitation during picoplankton blooms, which may have been neglected in modern and ancient events.

The taiga ecosystem in northeastern Siberia changed during the extreme wet event in 2007. Before the wet event, the NDVI in a typical larch forest showed a positive correlation with soil moisture, and after the event it showed a negative correlation. For both periods, NDVI correlated negatively with foliar C/N. These results indicate that high soil moisture availability after the event decreased needle production, which may have resulted from lower N availability.

The Rhodes Gyre, eastern Mediterranean Sea, is the main Levantine Intermediate Water formation site. In this study, we use a 3D physical–biogeochemical model to investigate the seasonal and interannual variability of organic carbon dynamics in the gyre. Our results show its autotrophic nature and its high interannual variability, with enhanced primary production, downward exports, and onward exports to the surrounding regions during years marked by intense heat losses and deep mixed layers.

Nitrous oxide (N₂O) is an important greenhouse gas. However, N₂O emissions from estuaries underlie significant uncertainties due to limited data availability and high spatiotemporal variability. We found the Elbe Estuary (Germany) to be a year-round source of N₂O, with the highest emissions in winter along with high nitrogen loads. However, in spring and summer, N₂O emissions did not decrease alongside lower nitrogen loads because organic matter fueled in situ N₂O production along the estuary.

Cave stalagmites contain substances that can be used to reconstruct past changes in local and regional environmental conditions. We used two classes of biomarkers (polycyclic aromatic hydrocarbons and monosaccharide anhydrides) to detect the presence of fire and to also explore changes in fire regime (e.g. fire frequency, intensity, and fuel source). We tested our new method on a stalagmite from Mayapan, a large Maya city on the Yucatán Peninsula.

Small cascades greatly enhance mountain stream gas emissions through the turbulent energy dissipation rate and air bubbles entrained into the water. We numerically studied the local contribution of these mechanisms driving gas transfer velocity used to quantify the outgassing. The gas evasion is primarily due to bubbles concentrated in irregular spots of limited area. Consequently, the gas exchange velocity is scale-dependent and unpredictable, posing concerns about its use in similar scenarios.

Ocean fronts are ecological hotspots, associated with higher diversity and biomass for many marine organisms, from bacteria to whales. Using in situ data from the California Current Ecosystem, we show that far from being limited to the production of diatom blooms, fronts are the scene of complex biophysical couplings between biotic interactions (growth, competition, and predation) and transport by currents that generate planktonic communities with an original taxonomic and spatial structure.

Model–data fusion (MDF) allows us to combine ecosystem models with Earth observation data. Fragmented landscapes, with a mosaic of contrasting ecosystems, pose a challenge for MDF. We develop a novel MDF framework to estimate the carbon balance of fragmented landscapes and show the importance of accounting for ecosystem heterogeneity to prevent scale-dependent bias in estimated carbon fluxes, disturbance fluxes in particular, and to improve ecological fidelity of the calibrated models.

Coastal seas experience sediment discharges whose intensity and frequency can strongly be affected by human activities and climate change. We analysed the response of benthic species in an experimental set-up. After the burial under a single thick layer of sediment or multiple thin layers at different times, the analysed species migrate rapidly towards the surface. A stronger effect of a single thick deposit on standing stocks and biodiversity is visible compared to frequent low-sediment inputs.

We quantified how microbial respiration is controlled by discharge and the supply of C, N, and P in a stream. We ran two rounds of experiments adding a conservative tracer, an indicator of aerobic respiration, and nutrient treatments: a) N, b) N+C, c) N+P, and d) C+N+P. Microbial respiration remained similar between rounds and across nutrient treatments. This suggests that complex interactions between hydrology, resource supply, and biological community drive in-stream respiration.

In our study, we included bioturbation into a soil erosion model and ran the model for several years under two conditions: with and without bioturbation. We validated the model using several sediment fences in the field. We estimated the modeled sediment redistribution and surface runoff and the impact of bioturbation on these along a climate gradient. Lastly, we identified environmental parameters determining the positive or negative impact of bioturbation on sediment redistribution.