Recent  

Mercury is a problematic metal in the environment. It is crucial to understand the Hg circulation in ecosystems. We explored the mercury concentration in foliage from a diverse set of plants, locations and sampling periods to study the accumulation of Hg in leaves/needles over time. Mercury was always higher in older tissue: in broadleaved trees, conifers and wheat. Specific leaf area, the leaf area per unit leaf mass, turned out to be critical for Hg accumulation in leaves/needles.

A glacial-interglacial methane-fuelled redistribution of reactive phosphorus between the oceanic and sedimentary phosphorus reservoirs can occur in the ocean when falling sea level lowers the pressure on the seafloor, destabilizes methane hydrates, and triggers the dissolution of P-bearing iron oxides. The mass of phosphate potentially mobilizable from the sediment is similar to the size of the current oceanic reservoir. Hence, this process may play a major role in the marine phosphorus cycle.

Biological activity in the shallow Weddell Sea affects the biogeochemistry of recently-formed deep waters. To investigate the drivers of carbon and nutrient export, we measured rates of primary production and nitrogen uptake, characterised the phytoplankton community, and estimated nutrient depletion ratios across the under-sampled western Weddell Sea in mid-summer. Carbon export was highest at the ice shelves, and was determined by a combination of physical, chemical, and biological factors.

This investigation of microbial biogeography in terrestrial mud volcanoes expands the studying sites with a geographic distance up to 10,000 km. It compares microbial community compositions coupling with geochemical data across a 3D space in the Eurasian continent. We demonstrate stochastic processes operating at continental scales and environmental filtering at local scales drive the formation of patchy habitats and the pattern of diversification for microbes in terrestrial MVs.

Wildfire-derived molecules are ubiquitous in the aquatic environment, but their biotic fate remains understudied. We have evaluated the compositional changes that occur to wildfire-derived molecules after incubation with soil microbes. We observe a significant degradation, but also a production of numerous new labile molecules. Our results indicate that wildfire-derived molecules can be reworked and consumed by microbes leading to their incorporation into food webs and the global carbon cycle.

Peatlands are a significant global carbon store, which can be compromised by drainage and afforestation. We measured the peat decomposition under a 30 year old drained forest plantation; 115 ± 16 g C m⁻² y⁻¹, c. 40 % of total soil respiration. Considering also input of litter from trees, our results indicate that the soils in these 30 year-old drained and afforested peatlands are a net sink for C, since substantially more C enters the soil as organic matter, than is decomposed heterotrophically.

The Peruvian system supports 10 % of the world's fishing yield. In the Peruvian system, wind and earth’s rotation bring cold, nutrient-rich water to the surface and allow phytoplankton to grow. But observations show that it grows worse at high upwelling. Using a model, we find that high upwelling happens when air mixes the water the most. Then phytoplankton is diluted and grows slowly due to low light and cool upwelled water. This study helps to estimate how it might change in a warming climate.

Understanding how vegetation might respond to climate change is especially important in arctic-alpine ecosystems, where major shifts in shrub growth have been observed. We studied how such changes come to pass and how future changes might look like by measuring hourly variations in stem diameter of dwarf shrubs from one common species. From this data, we are able to discern information about growth mechanisms and can thus show the complexity of shrub growth/microenvironment relations.

This study shows that the introduction of a multi-layer snow scheme in the LPJ-GUESS DGVM improved simulations of high latitude soil temperature dynamics and permafrost extent compared to observations. In addition, these improvements led to shifts in carbon fluxes and vegetation distribution that contrasted within and outside of the permafrost region. Our results show that a realistic snow scheme is essential to accurately simulate snow-soil-vegetation relationships and carbon-climate feedbacks.

Europe was affected by an extreme drought in 2018. We show that this drought has increased forest disturbances across Europe, especially Central and Eastern Europe. Disturbance levels observed 2018–2020 were the highest on record for 30 years. Increased forest disturbances were correlated with low moisture and high atmospheric water demand. The unprecedented impacts of the 2018 drought on forest disturbances calls for urgent need to adapt Europe's forests to a hotter and drier future.

In order to quantify riverine carbon (C) exchange with the atmosphere in permafrost regions, we report a first assessment of CO₂ and CH₄ concentration and fluxes of the largest permafrost-affected river, the Lena River, during the peak of spring flow. The results allowed identifying environmental factors controlling GHG concentrations and emission in the Lena River watershed; this new knowledge can be used for foreseeing future changes in C balance in permafrost-affected Arctic rivers.

Animal burrowing is important because it impacts the physical and chemical evolution of Earth’s surface. However, most studies are species specific and compilations of animal community effects are missing. We present an inventory of the currently known 390 burrowing species for all Chile along its climate gradient from the Atacama desert to Patagonia. We observed increasing amounts of excavated material from an area with dry conditions along a gradient towards more humid conditions.

We present images of foraminiferal pseudopodia stained with two different actin-labelling fluorescent probes (SiR-actin and Phalloidin Atto 488) showing very similar staining patterns. The highest intensity of fluorescence in both channels is observed in micrometre-sized granules. These observations allow for rejection the staining artefacts hypotheses and support the possibility that these granules contain physiologically functional form of actin cytoskeleton in foraminifera.

Peatlands have been subject to a range of land management regimes over the past century. This has affected the amount of carbon that drains into surrounding streams and rivers. In our study, we measured carbon concentrations in streams draining from drained, non-drained and restored areas of the Flow Country blanket bog in N Scotland. We found that drained peatland had higher concentrations and fluxes of carbon relative to non-drained areas. Restored peatland areas were highly variable.

Oxygen minimum zones in the ocean are characterized by enhanced carbon dioxide (CO₂) levels and are being further acidified by increasing anthropogenic atmospheric CO₂. Here we report CO₂ system measurements in a mesocosm study offshore Peru during a rare coastal El Niño event, to investigate how CO₂ dynamics may respond to on-going ocean deoxygenation. Our observations show that nitrogen limitation, productivity and plankton community shift play an important role in driving the CO₂ dynamics.

Volcanic islands consist mainly of basaltic rocks. Additionally, there are often occurrences of small phonolite rocks differing in color and surface. On the Canary Island of La Palma, phonolites appear to be more suitable for plants than the omnipresent basalts. Therefore, we expected phonolites to be species-rich with larger plant individuals compared to the surrounding basaltic areas. Indeed, as expected, we found more species on phonolites and larger plant individuals in general.

Nitrogen is one of the most important elements for life in the ocean. A major source is the riverine discharge of dissolved nitrogen. While most global models omit rivers as nutrient source, we included nitrogen from rivers in our Earth System model and found that additional nitrogen affected marine biology locally but also in regions far off the coast. Depending on regional conditions, primary production was enhanced or even decreased, due to internal feedbacks in the nitrogen cycle.

We reconstruct Holocene landscape P yield and lake water TP concentration for 24 sites across the Northern Hemisphere by applying a process model to published lake sediment geochemical records. We find sites with the same landscape development history show similar geochemical profiles depending on climate, human impact and other local factors. Our reconstructions can be used to understand present day terrestrial P cycling, lake water nutrient status, and export of terrestrial P to the oceans.

Based on current experimental evidence, climate change will affect up to 90 % of coral reefs worldwide. The originality of this study arises from our recent discovery of an exceptional study site, where environmental conditions (temperature, pH and oxygen) are even worse than those forecasted for the future. While these conditions are generally recognized as unfavorable for marine life, we found a rich and abundant coral reef thriving well under such extreme environmental conditions.

Oxygen not only penetrates sediments from the ocean bottom waters but also from the basement. The impact of the latter is poorly understood. We show that this basement oxygen has a clear impact on the nitrogen cycle, the redox state and the distribution of manganese, nickel cobalt and organic matter in the sediments. This is important for (1) global biogeochemical cycles (2) understanding sedimentary life (3) the interpretation of the sediment record to reconstruct the past.

High sensitive phosphate measurements in the Mediterranean Sea allowed detecting vertical gradients of phosphate concentration above the phosphacline. Estimated phosphate fluxes from below were comparable to atmospheric deposition except under the influence of rain and Saharan dust. Taken together, external sources of phosphate contributed little to total phosphate requirements which were mainly sustained by enzymatic hydrolysis of the organic phosphorus pool.

During summer, maxima of phytoplankton chlorophyll concentration (DCM) occur in the subsurface of the Mediterranean Sea, and can play a relevant role in carbon sequestration into the ocean interior. A numerical model based on in situ and satellite observations provides insights on the wide range of DCM conditions across the relatively small Mediterranean Sea, and shows a western DCM that is 25 % shallower and with higher phytoplankton chlorophyll concentration than in the eastern Mediterranean.

Sunlight and microbial activity break down river dissolved organic matter (DOM), releasing greenhouse gases, but are poorly understood in tropical headwaters. We incubated water in light and darkness, using novel methods to quantify changes in DOM concentration and character. Light removed up to 9 % of DOM, but microbial activity had a varied response. Importantly, light affected DOM compounds considered photo-resistant; likewise microbial activity degraded compounds thought to be bio-resistant.

Nitrogen (N₂) fixation is one of the most important nutrient sources to the ocean. Here, we report N₂ fixation in the deep, dark ocean in the South China Sea via a highly sensitive new method and elaborate controls, showing the overlooked importance of N₂ fixation in the deep ocean. By global data compilation, we also provide an easy measured basic parameter to estimate deep N₂ fixation. Our study may help to expand the area limit of N₂ fixation studies and better constrain global N₂ fixation.

We studied the most recent (sub-)fossil remains of one type of algae (coccolithophores) off southernmost Chile and across the Drake Passage, adding to the scarce knowledge that exists in the Southern Ocean, a rapidly changing environment. We found that those can be used to reconstrunct the surface ocean conditions in the north, but not in the south. We also found variations in shape in the dominant species depending on the location, indicating subtle adaptations to environmental conditions.

A previous study documented an intense hydrothermal plume in the south Pacific Ocean, however, the iron release associated with this plume and the impact on microbiology was unclear. We describe metal concentrations associated with multiple hydrothermal plumes in this region and protein signatures of plume-influenced microbes. Our findings demonstrate that resources released from these systems can be transported away from their source and may alter the physiology of surrounding microbes.

While greenhouse gas (GHG) research has adopted highly advanced technology some have adopted appropriate technology and approach (AT&A) such as low-cost instrument, open source software and participatory research and their results were well accepted by scientific communities. In terms of cost, feasibility and performance, integration of low-cost and low-technology, participatory and networking based research approaches can be AT&A for enhancing GHG research in developing countries.

We report the measured biological pumps (BPs) and their controlling mechanisms in the northern South China Sea (NSCS). These BPs were higher than most reports in open oceans, indicating the significance of NSCS to uptake atmospheric CO₂ and store that CO₂ in the ocean’s interior. Winter cooling and extreme events enhanced nutrient availability and elevated BPs conditions. The global warming may have profound impacts on reducing ocean’s uptake and storage of CO₂ in subtropical-tropical oceans.

Surface waters in lowland regions, have a poor surface water quality, mainly due to excess nutrients like phosphate. Therefore, we wanted to know the phosphate levels without humans, also called the pre-industrial background. Phosphate binds strongly to sediment particles, suspended in the river water. In this research we used sediments deposited by a river as an archive for surface water phosphate back to 1800 CE. Pre-industrial phosphate levels were estimated at one third of the modern.

Our study contributed to improving the understanding of temporal variation and climate correlates of canopy disturbances mainly caused by treefalls and branchfalls. We used a unique dataset of five years of approximately monthly drone-acquired RGB imagery for 50 ha of mature tropical forest on Barro Colorado Island, Panama. We found that canopy disturbance rates were highly temporally variable, were higher in the wet season, and were well-predicted by extreme rainfall events.

We used UAS data to measure new vegetation indicators of a tropical forest canopy and found the new, near-infrared-based indicators unveil more heterogeneity of the canopy than traditional indices. Also, the new indicators and one traditional index capture information at smaller scales than the other traditional index and Lidar. The near-infrared radiance of vegetation also tracked daily productivity changes. We show that UAS-based emerging indices can improve tropical forest monitoring.