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Distribution and cycling of terrigenous dissolved organic carbon in peatland-draining rivers and coastal waters of Sarawak, Borneo

The carbon cycle is a key control for the Earth’s climate. Every year rivers deliver a lot of organic carbon to coastal seas, but we do not know what happens to this carbon, particularly in the tropics. We show that rivers in Borneo deliver carbon from peat swamps to the sea with at most minimal biological or chemical alteration in estuaries, but sunlight can rapidly oxidise this carbon to CO₂. This means that south-east Asian seas are likely hotspots of terrestrial carbon decomposition.

Predominance of methanogens over methanotrophs in rewetted fens characterized by high methane emissions

Rewetting drained peatlands may lead to prolonged emission of the greenhouse gas methane, but the underlying factors are not well described. In this study, we found two rewetted fens with known high methane fluxes had a high ratio of microbial methane producers to methane consumers and a low abundance of methane consumers compared to pristine wetlands. We therefore suggest abundances of methane-cycling microbes as potential indicators for prolonged high methane emissions in rewetted peatlands.

Contrasting biosphere responses to hydrometeorological extremes: revisiting the 2010 western Russian heatwave

Northern forests enhanced their productivity during and before the 2010 Russian mega heatwave. We scrutinize this issue with a novel type of multivariate extreme event detection approach. Forests compensate for 54 % of the carbon losses in agricultural ecosystems due to vulnerable conditions in spring and better water management in summer. The findings highlight the importance of forests in mitigating climate change, while not alleviating the consequences of extreme events for food security.

Reviews and syntheses: Carbon use efficiency from organisms to ecosystems – definitions, theories, and empirical evidence

Carbon fixed by plants and phytoplankton through photosynthesis is ultimately stored in soils and sediments or released to the atmosphere during decomposition of dead biomass. Carbon-use efficiency is a useful metric to quantify the fate of carbon – higher efficiency means higher storage and lower release to the atmosphere. Here we summarize many definitions of carbon-use efficiency and study how this metric changes from organisms to ecosystems and from terrestrial to aquatic environments.

Potential for phenol biodegradation in cloud waters

Biogeosciences
DOI 10.5194/bg-15-5733-2018
28 September 2018

The main objective of this work was to evaluate the potential degradation of phenol, a highly toxic pollutant, by cloud microorganisms. Phenol concentrations measured on five cloud samples collected at the PUY station in France were from 0.15 to 0.74 µg L⁻¹. Metatranscriptomic analysis suggested that phenol could be biodegraded directly in clouds, likely by Gammaproteobacteria. A large screening showed that 93 % of 145 bacterial strains isolated from clouds were able to degrade phenol.

Tracing water masses with ¹²⁹I and ²³⁶U in the subpolar North Atlantic along the GEOTRACES GA01 section

Biogeosciences
DOI 10.5194/bg-15-5545-2018
18 September 2018

The investigation of water mass transport pathways and timescales is important to understand the global ocean circulation. Following earlier studies, we use artificial radionuclides introduced to the oceans in the 1950s to investigate the water transport in the subpolar North Atlantic (SPNA). For the first time, we combine measurements of the long-lived iodine-129 and uranium-236 to confirm earlier findings/hypotheses and to better understand shallow and deep ventilation processes in the SPNA.

GEOTRACES GA01 section">Read more

Integrated management of a Swiss cropland is not sufficient to preserve its soil carbon pool in the long term

It is of great interest to know whether croplands act as a net source or sink of atmospheric CO₂and if soil carbon © stocks are preserved over long timescales due to the role of C in soil fertility. For a cropland in Switzerland it was found that managing the field under the Swiss framework of the Proof of Ecological Performance (PEP) resulted in soil C losses of 18.0 %. Additional efforts are needed to bring Swiss management practices closer to the goal of preserving soil C in the long term.

Dissolved Pb and Pb isotopes in the North Atlantic from the GEOVIDE transect (GEOTRACES GA-01) and their decadal evolution

During a French cruise in the northern North Atlantic Ocean in 2014, seawater samples were collected for dissolved Pb and Pb isotope analysis. Lead concentrations were highest in subsurface water flowing out of the Mediterranean Sea. The recently formed Labrador Sea Water (LSW) is much lower in Pb concentration than older LSW found in the West European Basin. Comparison of North Atlantic data from 1981 to 2014 shows decreasing Pb concentrations down to ~ 2500 m depth.

GEOVIDE transect (GEOTRACES GA-01) and their decadal evolution">Read more

Ideas and perspectives: Strengthening the biogeosciences in environmental research networks

As knowledge in biology and geology explodes, science becomes increasingly specialised. Given the overlap of the environmental sciences, however, the explosion in knowledge inevitably creates opportunities for interconnecting the biogeosciences. Here, 30 scientists emphasise the opportunities for biogeoscience collaborations across the world’s remarkable long-term environmental research networks that can advance science and engage larger scientific and public audiences.

In-depth characterization of diazotroph activity across the western tropical South Pacific hotspot of N₂ fixation (OUTPACE cruise)

Here we report N₂ fixation rates from a ∼ 4000 km transect in the western and central tropical South Pacific, a particularly undersampled region in the world ocean.

OUTPACE cruise)">Read more

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