We estimated monthly air–sea CO₂ fluxes in the Arctic Ocean and its adjacent seas north of 60° N from 1997 to 2014, after mapping pCO₂ in the surface water using a self-organizing map technique. The addition of Chl a as a parameter enabled us to improve the estimate of pCO₂ via better representation of its decline in spring. The uncertainty in the CO₂ flux estimate was reduced, and a net annual Arctic Ocean CO₂ uptake of 180 ± 130 Tg C y⁻¹ was determined to be significant.

Large amounts of soil organic carbon are stored in the circumpolar permafrost region. This article aims to improve how we map this carbon. Typically the amount of soil organic carbon is estimated using soil or land cover maps. Here the amount of carbon is modeled using machine learning. This is done at a very fine spatial resolution of 1 × 1 m. This reveals a lot of small-scale landscape variability and underlines the importance of permafrost-related landforms vulnerable to a warming climate.

A 2-year biogeochemical record provides annual sediment and element flux estimates for the non-dammed Sabaki River, Kenya, establishing a baseline for future research in light of impending construction of the first major upstream reservoir. Over 80 % of material fluxes occur across the wet season, with annual yields comparable to the adjacent, and dammed, Tana River. Observations at low-flow periods suggest large mammalian herbivores may be vectors of terrestrial subsidies to the water column.

We show climate–carbon feedbacks accelerate and enhance ocean acidification. Such an acceleration of ocean acidification may further undermine the ability of marine biota to adapt to the changing environment. Our study also identifies the need to use Earth system models to make future ocean acidification projections (relevance to AR6) and the need to reduce the uncertainty in the climate–carbon feedbacks.

Organic carbon in aquifer recharge waters and sediments can fuel microbial reactions that affect groundwater quality. We used high-resolution mass spectrometry to molecularly characterize organic carbon mobilized off sediment collected from a Bangladeshi aquifer, to reference its composition against dissolved organic carbon in aquifer recharge water, to track compositional changes during incubation, and to advance understanding of microbial processing of organic carbon in anaerobic environments.

We measured methane fluxes of a boreal bog from six different plant community types in 2012–2014. We found only little variation in methane fluxes among plant community types. Peat temperature as well as both leaf area of plant species with air channels and of all vegetation are important factors controlling the fluxes. We also detected negative net fluxes indicating methane consumption each year. Our results can be used to improve the models of peatland methane dynamics under climate change.

Our results highlight the importance of soil physicochemical properties (mainly SOC, C : N, and pH) rather than elevation (i.e., canopy cover and environmental factors, especially temperature) in determining base cation and micronutrient availabilities in soils and subsequently their concentrations in plant tissues.

Based on an intense monitoring of CO₂ concentrations and organic and inorganic carbon in the reservoir, in the rivers upstream and downstream, and of CO₂ emissions from the drawdown area, we confirmed the importance of the flooded stock of organic matter as a source of C fueling emissions and we show that the drawdown area contributes, depending on the year, from 50 to 75 % of total annual gross emissions in the flat and shallow Nam Theun 2 Reservoir.

Rising temperature affect the wood production of forests. However, in some cases, we observe positive and in others negative changes. In this study, we used a new simulation approach to generate ~ 400 000 forest stands, which cover various types of temperate forests (low to high divers; young to old; even aged to uneven aged). We treated each forest with different temperature scenarios and analysed, which forest characteristics triggered the different reaction of forest to temperature change.

The n-alkane in litterfall and the microbial community in litter layer in different habitats of lowland subtropical rainforest were studied. We revealed that the plant vegetation of forest not only dominated the n-alkane input of habitats but also governed the diversity of microbial community of litter layer. In this study, we found that the habitat which had high n-alkane input induced a shift of relative abundance toward phylum of Actinobacteria and the growth of alkB gene contained bacteria.

The latitudinal dependency of POC / PON in ocean and inland water is significant, regulated by trophic state and climate, etc. factors. POC / PON significantly increased from coastal water (6.89 ± 2.38) to open ocean (7.59 ± 4.22) with the increasing rate of 0.0024 / km. The re-examination of the global relationship between, and variations in, POC and PON could be important for the global and regional coupling between the carbon and nitrogen cycles in the ocean and freshwater.

Long-term and annual field observations on key organisms are a critical basis for predicting changes in Southern Ocean ecosystems. Coccolithophores are the most abundant calcium-carbonate-producing phytoplankton and play an important role in Southern Ocean biogeochemical cycles. In this study we document the composition, degree of calcification and annual cycle of coccolithophore communities in one of the largest unexplored regions of the world oceans: the Antarctic zone.

This study examined the effect of adding carbon to a sediment-based effluent treatment system to treat nitrogen-rich aquaculture waste. The research was conducted in incubation chambers to measure the exchange of gases and nutrients across the sediment–water interface and examine changes in the sediment microbial community. Adding carbon increased the amount of nitrogen retained in the treatment system, thereby reducing the levels of nitrogen needing to be discharged to the environment.

The soil microbial properties were investigated along altitudinal gradients in the Arctic. Systematic altitudinal shift in MCS resulting in high F / B ratios at the most elevated sites was observed. The changes in composition, size and activity of microbial communities were mainly controlled through the effect of vegetation on edaphic properties and by bedrock chemistry. The upward migration of vegetation due to global warming will likely diminish the spatial variability in microbial properties.