Thawing of Arctic permafrost soils could trigger the release of vast amounts of carbon to the atmosphere, thus enhancing climate change. Our study investigated how well the current network of eddy covariance sites to monitor greenhouse gas exchange at local scales captures pan-Arctic flux patterns. We identified large coverage gaps, e.g., in Siberia, but also demonstrated that a targeted addition of relatively few sites can significantly improve network performance.

We studied recent (sub-)fossil remains of a 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 reconstruct the surface ocean conditions in the north but not in the south. We also found variations in shape in the dominant species Emiliania huxleyi depending on the location, indicating subtle adaptations to environmental conditions.

The preservation and distribution of alkenones – organic molecules produced by marine algae – in marine sediments allows us to reconstruct past variations in sea surface temperature, primary productivity and CO₂. Here, we explore the impact of remobilization and lateral transport of sedimentary alkenones on their fate in marine sediments. We demonstrate the pervasive influence of these processes on alkenone-derived environmental signals, compromising the reliability of related paleorecords.

The study addresses the potential of marine shell-forming organisms as proxy carriers for heavy metal contamination in the environment. The aim is to investigate if the incorporation of heavy metals is a direct function of their concentration in seawater. Culturing experiments with a metal mixture were carried out over a wide concentration range. Our results show shell-forming organisms to be natural archives that enable the determination of metals in polluted and pristine environments.

In this study, we concluded that the residence times of solutes and the Damköhler number (Da) of the biogeochemical reactions in the domain are governing factors for evaluating the impact of spatial heterogeneity of the domain on chemical (such as carbon and nitrogen compounds) removal. We thus proposed a relationship to scale this impact governed by Da. This relationship may be applied in larger domains, thereby resulting in more accurate modelling outcomes of nutrient removal in groundwater.

Here, we synthesize the results from 62 studies reporting in situ rates of seagrass metabolism to highlight spatial and temporal variability in oxygen fluxes and inform efforts to use seagrass to mitigate ocean acidification. Our analyses suggest seagrass meadows are generally autotrophic and variable in space and time, and the effects on seawater oxygen are relatively small in magnitude.

We present here, for the first time, simultaneously measured dimethylsulfide (DMS) seawater concentrations and DMS atmospheric mole fractions from the Peruvian upwelling region during two cruises in December 2012 and October 2015. Our results indicate low oceanic DMS concentrations and atmospheric DMS molar fractions in surface waters and the atmosphere, respectively. In addition, the Peruvian upwelling region was identified as an insignificant source of DMS emissions during both periods.

Ammonium is a crucial yet poorly understood component of the Southern Ocean nitrogen cycle. We attribute our finding of consistently high ammonium concentrations in the winter mixed layer to limited ammonium consumption and sustained ammonium production, conditions under which the Southern Ocean becomes a source of carbon dioxide to the atmosphere. From similar data collected over an annual cycle, we propose a seasonal cycle for ammonium in shallow polar waters – a first for the Southern Ocean.

Deep-living organisms are a major yet poorly known component of ocean biomass. Here we reconstruct the evolution of deep-living zooplankton and phytoplankton. Deep-dwelling zooplankton and phytoplankton did not occur 15 Myr ago, when the ocean was several degrees warmer than today. Deep-dwelling species first evolve around 7.5 Myr ago, following global climate cooling. Their evolution was driven by colder ocean temperatures allowing more food, oxygen, and light at depth.

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 levels.

Size measurements of the planktonic foraminifer Globorotalia menardii and related forms are used to investigate the shell-size evolution for the last 8 million years in the eastern tropical Atlantic Ocean. Long-term changes in the shell size coincide with major climatic, palaeogeographic and palaeoceanographic changes and suggest the occurrence of a new G. menardii type in the Atlantic Ocean ca. 2 million years ago.

Amino acids were analyzed in a large number of samples of particulate and dissolved organic matter from coastal regions and the open ocean. A statistical analysis produced two new biogeochemical indicators. An indicator of sinking particle and sediment degradation (SDI) traces the degradation of organic matter from the surface waters into the sediments. A second indicator shows the residence time of suspended matter in the ocean (RTI).

This investigation of microbial biogeography in terrestrial mud volcanoes (MVs) covers study sites over a geographic distance of up to 10 000 km across the Eurasian continent. It compares microbial community compositions' coupling with geochemical data across a 3D space. We demonstrate that 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.

A predictor selection algorithm was constructed to decrease the predicting error in the surface ocean partial pressure of CO₂ (pCO₂) mapping by finding better combinations of pCO₂ predictors in different regions. Compared with previous research using the same combination of predictors in all regions, using different predictors selected by the algorithm in different regions can effectively decrease pCO₂ predicting errors.

Although water availability has been linked to the response of ecosystem carbon (C) sink–source to climate warming, the mechanisms by which C uptake responds to soil moisture remain unclear. We explored how soil water and other environmental drivers modulate net C uptake in an alpine swamp meadow. Results reveal that nearly saturated soil conditions during warm seasons can help to maintain lower ecosystem respiration and therefore enhance the C sequestration capacity in this alpine swamp meadow.

We took the water cycle process of soil–plant–atmospheric precipitation as the research objective. In the water cycle of soil–plant–atmospheric precipitation, precipitation plays the main controlling role. The main source of replenishment for alpine meadow plants is precipitation and alpine meltwater; the main source of replenishment for forest plants is soil water; and the plants in the arid foothills mainly use groundwater.

Coral bleaching events continue to drive the degradation of coral reefs worldwide. In this study we measured rates of daytime coral reef community calcification and photosynthesis during a reef-wide bleaching event. Despite a measured decline in coral health across several taxa, there was no change in overall daytime community calcification and photosynthesis. These findings highlight potential limitations of these community-level metrics to reflect actual changes in coral health.

The Arabian Sea is a natural CO₂ source to the atmosphere, but previous work highlights discrepancies between data and models in estimating air–sea CO₂ flux. In this study, we use a regional ocean model, achieve a flux closer to available data, and break down the seasonal cycles that impact it, with one result being the great importance of monsoon winds. As demonstrated in a meta-analysis, differences from data still remain, highlighting the great need for further regional data collection.

Estuaries are key reactive ecosystems along the land–ocean aquatic continuum and are often strongly impacted by anthropogenic activities. We calculated nutrient in and out fluxes by using a 1-D transient model for seven estuaries along the French Atlantic coast. Among these, large estuaries with high residence times showed higher retention rates than medium and small ones. All reveal coastal eutrophication due to the excess of diffused nitrogen from intensive agricultural river basins.

The study assesses impacts of grass cover crop cultivation on cropland during main-crop off-season periods applying the global vegetation model LPJmL (V.5.0-tillage-cc). Compared to simulated bare-soil fallowing practices, cover crops led to increased soil carbon content and reduced nitrogen leaching rates on the majority of global cropland. Yield responses of main crops following cover crops vary with location, duration of altered management, crop type, water regime, and tillage practice.

Ocean acidification, a direct consequence of the CO₂ release by human activities, is a serious threat to marine ecosystems. In this study, we conduct a detailed investigation of the acidification of the Nordic Seas, from 1850 to 2100, by using a large set of samples taken during research cruises together with numerical model simulations. We estimate the effects of changes in different environmental factors on the rate of acidification and its potential effects on cold-water corals.

The origin and evolution of life do not contradict the laws of thermodynamics, but we have no proof that it is an inevitable consequence of these laws. We do not know if the first life arose under illumination or in darkness in the deep ocean or in the Earth's crust. We have no proof that it arose due to a thermodynamic imperative of dissipating the prevailing solar spectrum, as there are other ways for entropy increase in solar radiation. The biosphere may instead delay entropy production.