We developed century-scale records of wood nitrogen isotopes (δ¹⁵N) from 16 trees across a long-term savanna fire experiment. Results show similar long-term trajectories in three out of four burn treatments. Lack of evidence to support our hypotheses underscores the complexity of nitrogen dynamics inferred from wood δ¹⁵N. This is the first study to our knowledge to investigate multi-decadal effects of fire at different return intervals on wood δ¹⁵N, a potential proxy of nitrogen availability.

We measured reflected sunlight from an evergreen canopy for a year to detect changes in pigments that play an important role in regulating the seasonality of photosynthesis. Results show a strong mechanistic link between spectral reflectance features and pigment content, which is validated using a biophysical model. Our results show spectrally where, why, and when spectral features change over the course of the season and show promise for estimating photosynthesis remotely.

Tussock grasses that grow along coastlines of the Falkland Islands are slow to decay and build up thick peat layers over thousands of years. Grass fragments found in ancient peat can be used to reconstruct past climate because grasses can preserve a record of growing conditions in their leaves. We found that modern living tussock grasses in the Falkland Islands reliably record temperature and humidity in their leaves, and the peat they form can be used to understand past climate change.

Wood stain is challenging the use of the blue intensity technique for dendroclimatic reconstructions. Using stained subfossil trees from eastern Canadian lakes, we compared chemical destaining approaches with the delta blue mathematical correction of blue intensity data. Although no chemical treatment was completely efficient, the delta blue method is unaffected by the staining problem and thus is promising for climate reconstructions based on lake subfossil material.

Here, we quantified the sediment production of methane and carbon dioxide in lake sediments to better characterize the nature of the organic matter at the origin of these two greenhouse gases. We demonstrate that the production of these gases is not adequately represented in models for deep lake sediments. We thus propose to improve the representation of organic matter degradation reactions in current models for improving predictions of greenhouse gas cycling in aquatic sediments.

This study incorporated microbial dormancy into a detailed microbe-based biogeochemistry model to examine the fate of Arctic carbon budgets under changing climate conditions. Compared with the model without microbial dormancy, the new model estimated a much higher carbon accumulation in the region during the last and current century. This study highlights the importance of the representation of microbial dormancy in earth system models to adequately quantify the carbon dynamics in the Arctic.

Potential roles of polythionates as key sulfur cycle intermediates are less appreciated, apparently because, in most of the natural environments, they do not accumulate to easily detectable levels. Our exploration of the eastern Arabian Sea sediment horizons revealed microbe-mediated production and redox transformations of tetrathionate to be important modules of the in situ sulfur cycle, even as high biotic and abiotic reactivity of this polythionate keeps it hidden from geochemical detection.

Ensemble simulations of an Earth system model reveal that ocean acidity extremes have increased in the past few decades and are projected to increase further in terms of frequency, intensity, duration, and volume extent. The increase is not only caused by the long-term ocean acidification due to the uptake of anthropogenic CO₂, but also due to changes in short-term variability. The increase in ocean acidity extremes may enhance the risk of detrimental impacts on marine organisms.

We measured dissolved organic carbon (DOC), nitrogen (DON) and matter (DOM) optical properties in pore waters and near-bottom waters of the eastern tropical South Pacific off Peru. The difference between diffusion-driven and net fluxes of DOC and DON and qualitative changes in DOM optical properties suggested active microbial utilisation of the released DOM at the sediment–water interface. Our results suggest that the sediment release of DOM contributes to microbial processes in the area.

In this paper, we study emissions of volatile organic compounds (VOCs) from three boreal tree species. Individual compounds are quantified with on-line separation analytical techniques, while the total reactivity of the emissions is measured using a custom-built instrument. On some occasions, in particular when the trees suffer from stress, the total reactivity measured is higher than the sum of the reactivity of individual compounds. This indicates that the threes emit VOCs that remain unknown.

In 2015–2016, a massive mangrove dieback event occurred along ~1000 km of coastline in Australia. Multiple lines of evidence from climate data, wood and sediment samples suggest low water availability within the dead mangrove forest. Wood and sediments also reveal a large increase in iron concentrations in mangrove sediments during the dieback. This study supports the hypothesis that the forest dieback was associated with low water availability driven by a climate-change-related ENSO event.

We investigated, for the first time, the spatial distribution of chlorine and fluorine in the shell walls of four benthic foraminifera species: Ammonia tepida, Amphistegina lessonii, Archaias angulatus, and Sorites marginalis. Cross sections of specimens were imaged using nanoSIMS. The distribution of Cl and F was co-located with organics in the rotaliids and rather homogeneously distributed in miliolids. We suggest that the incorporation is governed by the biomineralization pathway.