Seagrass meadows store carbon in their biomass and sediments, but they have also been shown to be sources of carbon dioxide (CO₂) and methane (CH₄). We experimentally investigated the effect of warming and prolonged darkness on CO₂ and CH₄ fluxes in Red Sea seagrass (Halophila stipulacea) communities. Our results indicated that sublethal warming may lead to increased emissions of greenhouse gases from seagrass meadows which may contribute to further enhance global warming.

Paleoenvironment reconstructions, retrieved from δ¹⁸O and Δ₄₇ values measured in carbonate, are compromised when crystallization occurs in isotopic disequilibrium. We show that some paleoenvironmental information can still be retrieved from these paired disequilibrium Δ₄₇ and δ¹⁸O values. The possibility of retrieving information on paleowaters, sediments' interstitial waters, or organisms' body water at the carbonate precipitation loci will help understand past Earth and life evolution.

Marine silicate weathering is a key process of the marine silica cycle; however, its controlling processes are not well understood. In the Guaymas Basin, silicate weathering has been studied under markedly differing ambient conditions. Environmental settings like redox conditions or terrigenous input of reactive silicates appear to be major factors controlling marine silicate weathering. These factors need to be taken into account in future oceanic mass balances of Si and in modeling studies.

Marine micro-algae bind carbon dioxide, CO₂. During their decay, snowflake-like aggregates form that sink, remineralize and transport organically bound CO₂ to depth; this is referred to as the biological carbon pump. In our model study, we elucidate how variable aggregate composition impacts the global pattern of vertical carbon fluxes. Our mechanistic model approach advances the representation of the global biological carbon pump and promotes a more realistic projection under climate change.

This study offered detailed information on dFe concentrations, distribution and the magnitude of yield in the Rajang River, the largest river in Malaysia. Three blackwater rivers, draining from peatlands, were also included in our study. Compared with the Rajang River, the dFe concentrations and yield from three blackwater rivers were much higher. The precipitation and agricultural activities, such as palm oil plantations, may markedly increase the concentration dFe in these tropical rivers.

Analysing the impact of environmental changes due to climate change, e.g. geographical spread of climate-sensitive infections (CSIs) and agriculture crop modelling, may require land surface modelling (LSM) to predict future land surface conditions. There are multiple LSMs to choose from. The paper proposes a multivariate spatio-temporal data science method to understand the inherent uncertainties in four LSMs and the variations between them in Nordic areas for the net primary production.

Unexpectedly high diversity was revealed in areas licenced for polymetallic nodule mining exploration in the Pacific Ocean. For the first time, a comprehensive reference library including 287 novel ophiuroid sequences allocated to 43 species was produced. Differences in food availability along the nodule province of CCZ were reflected in the biodiversity patterns observed. The APEI3's dissimilarity with the exploration contract areas questions its ability to serve as a biodiversity reservoir.

Ocean deoxygenation and warming are observed and projected to intensify under continued greenhouse gas emissions. Whereas temperature is considered the main climate change indicator, we show that in certain regions, thermocline doxygenation may be detectable before warming.

Worldwide, peatlands are important sources of dissolved organic matter (DOM) and trace metals (TMs) to surface waters, and these fluxes may increase with peatland degradation. In Southeast Asia, tropical peatlands are being rapidly deforested and drained. This work aims to address the fate of organic carbon and its role as a trace metal carrier in drained peatlands of Indonesia.

Lakes are important emitters of the greenhouse gas methane. We use field observations and a model to evaluate the importance of known drivers of methane production and release. Fast and slow changes of the diffusive flux were governed by wind speed and sediment temperature, respectively. Increased turbulence enhanced release, but storms depleted the lakes of gas and limited emissions. Our findings may inform model studies on the effects of weather and climate change on lake methane emissions.

This study focuses on benthic foraminiferal distribution in an Arctic fjord characterised by continuous sea ice production during winter and the consequent cascading of salty and corrosive waters (brine) to the seabed. The inner fjord is dominated by calcareous species (C). In the central deep basins, where brines are persistent, calcareous foraminifera are dissolved and agglutinated (A) dominate. The high A/C ratio is suggested as a proxy for brine persistence and sea ice production.

Ferruginous lakes experience restricted primary production due to phosphorus trapping by ferric iron oxides under oxic conditions. We report the presence of large crystals of vivianite, a ferrous iron phosphate, in sediments from Lake Towuti, Indonesia. We address processes of P retention linked to diagenesis of iron phases. Vivianite crystals had light Fe²⁺ isotope signatures and contained mineral inclusions consistent with antecedent processes of microbial sulfate and iron reduction.

Pteropods are a group of tiny swimming snails whose fragile shells put them at risk from ocean acidification. We investigated the factors influencing the thickness of pteropods shells in the Cariaco Basin, off Venezuela, which is unaffected by ocean acidification. We found that pteropods formed thicker shells when nutrient concentrations, an indicator of food availability, were highest, indicating that food may be an important factor in mitigating the effects of ocean acidification on pteropods.

Acrylic acid (AA) exhibited obvious spatial and temporal variations in the Bohai and Yellow seas. Strong biological production and abundant terrestrial inputs led to high AA in summer. Extremely high AA in sediments might result from the cleavage of intracellular DMSP and reduce bacterial metabolism. Degradation experiments of AA and DMSP proved other sources of AA and microbial consumption to be the key removal source. This study provided insightful information on the sulfur cycle these seas.

The microbial C : N ratio increased with aridity, while the microbial N : P ratio decreased with aridity, which implied that drought-stimulated microbes tend to be more N conservative. Among all examined ecological factors, substrate supply and microbial structure together controlled the microbial stoichiometry. Overall, these results illustrated N and P limitation in microbial biomass at deeper soil depths along the aridity gradient and limited responses to ecological factors in the subsoil.

Nitrification inhibitors (NI) have been shown to reduce emissions of nitrous oxide (N₂0), a potent greenhouse gas, from fertilizer and manure applied to agricultural fields. However difficulties in measuring N₂0 emissions limit our ability to estimate these reductions. Here we propose and test a mathematical model that may allow us to estimate these reductions under diverse site conditions. These estimates will be useful in determining emission factors for NI-amended fertilizer and manure.

Blue carbon ecosystems – tidal marsh, mangrove, and seagrass – serve as important organic carbon sinks, mitigating impacts of climate change. We utilized a robust regional carbon stock dataset to identify ecological, geomorphological, and anthropogenic drivers of carbon stock variability and create high-spatial-resolution predictive carbon stock maps. This work facilitates strategic conservation and restoration of coastal blue carbon ecosystems to contribute to climate change mitigation.

Climate variations can have profound impacts on marine ecosystems. Here we show that on global scales marine ecosystem drivers such as temperature, pH, O₂ and NPP are potentially predictable 3 (at the surface) and more than 10 years (subsurface) in advance. However, there are distinct regional differences in the potential predictability of these drivers. Our study suggests that physical–biogeochemical forecast systems have considerable potential for use in marine resource management.

Dolomite (CaMg(CO₃)₂) is supersaturated in many aquatic settings (e.g., seawater) on modern Earth but does not precipitate directly from the fluid, a fact known as the dolomite problem. The widely acknowledged concept of dolomite precipitation involves microbial extracellular polymeric substances (EPSs) and anoxic conditions as important drivers. In contrast, results from Lake Neusiedl support an alternative concept of Ca–Mg carbonate precipitation under aerobic and alkaline conditions.

Biomass-based terrestrial negative emission technologies (tNETS) have high potential to sequester CO₂. Many CO₂ uptake estimates do not include the effect of nutrient deficiencies in soils on biomass production. We show that nutrients can be partly resupplied by enhanced weathering (EW) rock powder application, increasing the effectiveness of tNETs. Depending on the deployed amounts of rock powder, EW could also improve soil hydrology, adding a new dimension to the coupling of tNETs with EW.

The hadal zone (6–11 km depth) is the least explored habitat on Earth. We studied microbial branched glycerol dialkyl glycerol tetraethers (brGDGTs) in the Challenger Deep, Mariana Trench. One unique feature is the strong predominance of 6-methyl brGDGT, which likely reflects an adaption of brGDGT-producing bacteria to alkaline seawater and low temperature. BrGDGTs, with elemental and isotopic data, suggest an autochthonous product for brGDGT. A new approach is proposed for brGDGT sourcing.