Cryoconite holes are ponds on the glacier surface that play an important role in glacier nutrient pathways. This paper presents the first description of the carbon and nitrogen isotopic composition of cryoconite consumers (tardigrades and rotifers) and their potential food. We showed that consumers differ in nitrogen isotopes and carbon isotopes vary between taxa and between glaciers. The study contributes to improving knowledge about cryoconite hole functioning and cryoconite trophic networks.

In Southeast Asia, oil palm plantations have largely replaced tropical forests. The impact of this shift in land use on greenhouse gas fluxes and soil microbial communities remains uncertain. We have found emission rates of the potent greenhouse gas nitrous oxide on mineral soil to be higher from oil palm plantations than logged forest over a 2-year study and concluded that emissions have increased over the last 42 years in Sabah, with the proportion of emissions from plantations increasing.

In the literature, it is generally assumed that alpine lichen heaths keep their direct environment cool due to their relatively high albedo. However, we reveal that the soil temperature and soil heat flux are higher below lichens than below shrubs during the growing season, despite a lower net radiation for lichens. We also show that the differences in microclimatic conditions between these two vegetation types are more pronounced during warm and sunny days than during cold and cloudy days.

Winter atmospheric nitrogen (N) and phosphorus (P) depositions were measured for the first time in the Western Sayan Mountains (Siberia). The low and very low atmospheric N and P depositions could be responsible for the observed lake phytoplankton N–P colimitation. We hypothesize that slight imbalances in the nutrient deposition, as expected in the context of global change (climate, forest fires and anthropogenic nitrogen emissions), could have important effects on the ecology of these lakes.

The concentration of carbon dioxide (CO₂) in water samples is often measured using a gas chromatograph. Depending on the chemical composition of the water, this method can produce wrong results. We quantified the possible error and how it depends on water composition and the analytical procedure. We propose a method to correct wrong results by additionally analysing alkalinity in the samples. We provide an easily usable computer code to perform the correction calculations.

Water-soluble salt and nutrient concentrations of soils collected along the Shackleton Glacier, Antarctica, show distinct geochemical gradients related to latitude, longitude, elevation, soil moisture, and distance from coast and glacier. Machine learning algorithms were used to estimate geochemical gradients for the region given the relationship with geography. Geography and surface exposure age drive salt and nutrient abundances, influencing invertebrate habitat suitability and biogeography.

The South Atlantic near 40° S is one of the high-productivity and most dynamic nutrient regions in the oceans, but the sources and fluxes of trace elements (TEs) to this region remain unclear. This study investigates seawater Ra-228 and provides important constraints on ocean mixing and dissolved TE fluxes to this region. Vertical mixing is a more important source than aeolian or shelf inputs in this region, but particulate or winter deep-mixing inputs may be required to balance the TE budgets.

We describe the carbon system dynamics of a new CO₂ seep system located off the coast of La Palma. We explored for over a year, finding points with lower levels of pH and alkalinity; high levels of carbon; and poorer levels of aragonite and calcite, both essential for calcifying species. The seeps are a key feature for robust experimental designs, aimed at comprehending how life has persisted through past eras or at predicting the consequences of ocean acidification in the marine realm.

The Atlantic north of 50° N is an intense ocean sink area for atmospheric CO₂. Observations in the vicinity of Iceland reveal a previously unrecognized Arctic contribution to the North Atlantic CO₂ sink. Sustained CO₂ influx to waters flowing from the Arctic Ocean is linked to their excess alkalinity derived from sources in the changing Arctic. The results relate to the following question: will the North Atlantic continue to absorb CO₂ in the future as it has in the past?

Evolution of organic carbon content in soils could be a major driver of atmospheric greenhouse gas concentrations over the next century. Understanding factors controlling carbon persistence in soil is a challenge. Our study of unique long-term bare-fallow samples, depleted in labile organic carbon, helps improve the separation, evaluation and characterization of carbon pools with distinct residence time in soils and gives insight into the mechanisms explaining soil organic carbon persistence.

Diatoms are crucial for Arctic coastal spring blooms, and their growth is controlled by nutrients and light. At the end of the bloom, inorganic nitrogen or silicon can be limiting, but nitrogen can be regenerated by bacteria, extending the algal growth phase. Modeling these multi-nutrient dynamics and the role of bacteria is challenging yet crucial for accurate modeling. We recreated spring bloom dynamics in a cultivation experiment and developed a representative dynamic model.

The concentration of chlorophyll is commonly used as an indicator of the abundance of photosynthetic plankton (phytoplankton) in lakes and oceans. Our study investigates why a deep chlorophyll maximum, located near the bottom of the upper, illuminated layer develops in the Mediterranean Sea. We find that the acclimation of cells to low light is the main mechanism involved and that this deep maximum represents also a maximum in the biomass and carbon fixation activity of phytoplankton.

Humid tropical soils are important sources and sinks of methane. We used model simulation to understand how different kinds of microbes and observed soil moisture and oxygen dynamics contribute to production and consumption of methane along a wet tropical hillslope during normal and drought conditions. Drought alters the diffusion of oxygen and microbial substrates into and out of soil microsites, resulting in enhanced methane release from the entire hillslope during drought recovery.

The reliability of ocean acidification research was challenged in early 2020 when a high-profile paper failed to corroborate previously observed impacts of high CO₂ on the behaviour of coral reef fish. We now know the reason why: the replicated studies differed in many ways. Open-minded and collaborative assessment of all research results, both negative and positive, remains the best way to develop process-based understanding of the impacts of ocean acidification on marine organisms.

The main source of excess DOC occurring in coastal seawater off an artificial lake, which is enclosed by a dike along the western coast of South Korea, was determined using a combination of various biogeochemical tools including DOC and nutrient concentrations, stable carbon isotope, and optical properties (absorbance and fluorescence) of dissolved organic matter in two different seasons (March 2017 and September 2018).

CMIP5 and CMIP6 models, and a high-resolution regional model, were evaluated by comparing historical simulations with observations in the northwest North Atlantic, a climate-sensitive and biologically productive ocean margin region. Many of the CMIP models performed poorly for biological properties. There is no clear link between model resolution and skill in the global models, but there is an overall improvement in performance in CMIP6 from CMIP5. The regional model performed best.

Estuaries are responsible for a large contribution of dissolved organic carbon (DOC) to the global C cycle, but it is unknown how this will change in the future. DOC fluxes from unvegetated sediments were investigated ex situ subject to conditions of warming and ocean acidification. The future climate shifted sediment fluxes from a slight DOC source to a significant sink, with global coastal DOC export decreasing by 80 %. This has global implications for C cycling and long-term C storage.

Anoxia in lakes is a major growing concern. In this study we applied a multiproxy approach combining high-resolution hyperspectral imaging (HSI) pigment data with specific HPLC data to examine the Holocene evolution and main drivers of lake anoxia and trophic state changes. We find that when human impact was low, these changes were driven by climate and natural lake-catchment evolution. In the last 500 years, increasing human impact has promoted lake eutrophication and permanent anoxia.

In fresh and brackish waters, algal blooms are often dominated by cyanobacteria, which have the ability to utilize atmospheric nitrogen. Cyanobacteria are also unusual in that they float to the surface and are dispersed by wind-driven currents. Their patchy and dynamic distribution makes it difficult to track their abundance and quantify their effects on nutrient cycling. We used remote sensing to map the distribution of cyanobacteria in a large Baltic lagoon and quantify their contributions.

Upwelling intensity along NW Africa varies on the interannual to decadal timescale. Understanding its changes is key for the prediction of future changes of CO₂ sequestration in the northeastern Atlantic. Based on a multiyear (1988–2009) sediment trap experiment at the site CBmeso, fluxes and the species composition of the diatom assemblage are presented. Our data help in establishing the scientific basis for forecasting and modeling future states of this ecosystem and its decadal changes.

Turbidity flows – underwater avalanches – are large-scale physical disturbances believed to have profound impacts on productivity and diversity of benthic communities in the deep sea. We reviewed published studies and found that current evidence for changes in productivity is ambiguous at best, but the influence on regional and local diversity is clearer. We suggest study design criteria that may lead to a better understanding of large-scale disturbance effects on deep-sea benthos.