Understanding the dynamics of primary productivity requires mechanistic insight into the coupling of light absorption, electron transport and carbon fixation in response to environmental variability. Measuring such rates over diurnal timescales in contrasting regions allowed us to gain information on the regulation of photosynthetic efficiencies, with implications for the interpretation of bio-optical data, and the parameterization of models needed to monitor productivity over large scales.

Soils store large amounts of carbon in soil organic matter, which comes from plant debris and roots. The mechanisms protecting it from biodegradation are not fully understood. Here, we carry out a size-fractionation of soil sampled on different dates in a field experiment. Using carbon and nitrogen content and spectroscopy and microscopy we conclude that organic matter enriched in nitrogen is preferentially protected from biodegradation and that clay minerals have differing protective abilities.

To improve our understanding of the effects of tree species selection and management intensity on dissolved organic matter (DOM), we studied solution samples along the water flow path through forests with spectroscopic methods and biodegradation tests. There are distinct changes in DOM composition and biodegradability following the water path. Aboveground DOM was influenced by tree species selection but not by management intensity. Differences became aligned in mineral soil.

Mineral binding is a major mechanism for soil carbon (C) stabilization. However, soil minerals can also inhibit the growth of bacteria that protect organic C from decay. Here the findings indicate that reduced surface Fe(II) derived from Fe(III)-containing minerals inhibits the growth of bacteria via a free-radical mechanism, which may serve as an ubiquitous mechanism between iron minerals and all of the heterotrophic bacteria in view of bacteria as a vast source of superoxide.

Chlorophyll distribution in the ocean remains to be explored in detail, despite its climatic significance. Here, we document the vertical structure of chlorophyll in the Bay of Bengal using observations and a model. The shape of chlorophyll profiles, characterized by prominent deep chlorophyll maxima, varies in dynamically different regions, controlled by the monsoonal forcings. The present study provides new insights into the vertical distribution of chlorophyll, rarely observed by satellites.

The paper presents a novel study based on the traits of shell size, calcification and feeding behaviour of two planktonic foraminifera life stages using modelling simulations. With the model, we tested the cost and benefit of calcification and explored how the interactions of planktonic foraminifera among other plankton groups influence their biomass under different environmental conditions. Our results provide new insights into environmental controls in planktonic foraminifera ecology.

We used airborne lidar to map the three-dimensional structure and model the biomass of plant canopies across a long-term fire experiment in the Northern Territory of Australia. Our results show that late season fires occurring every 2 years reduce the amount of carbon stored above-ground by 50 % relative to unburnt control plots. We also show how increased fire intensity removes the shrub layer from savannas and discuss the implications for biodiversity conservation.

Although coastal regions only amount to 7 % of the global oceans, their contribution to the global oceanic surface exchange of CO₂ is much greater. In this study, we gain detailed insight into how these coastal marine fluxes compare to CO₂ exchange from coastal land regions. Annually, the coastal marine exchanges are smaller than the total uptake of CO₂ from the land surfaces within the study area but comparable in size to terrestrial fluxes from individual land cover classes of the region.

We used surface water dissolved aluminium concentrations collected in four different GEOTRACES cruises to determine atmospheric deposition fluxes to the ocean. We calculate atmospheric deposition fluxes for largely under-sampled regions of the Atlantic Ocean and thus provide new constraints for models of atmospheric deposition. The use of the MADCOW model is of major importance as dissolved aluminium is analysed within the GEOTRACES project at high spatial resolution.

We quantified the contribution of individual components governing the net ecosystem exchange of CO₂ and how these fluxes respond to environmental changes in a drained and water-saturated site in the polygonal tundra of northeast Siberia. This work finds both sites as a sink for atmospheric CO₂ during the growing season, but sink strengths varied between the sites. Furthermore, it was shown that soil hydrological conditions were one of the key drivers for differing CO₂ fluxes between the sites.

The GEOVIDE cruise (May–June 2014, R/V Pourquoi Pas?) aimed to provide a better understanding of trace metal biogeochemical cycles in the North Atlantic. As particles play a key role in the global biogeochemical cycle of trace elements in the ocean, we discuss the distribution of particulate iron (PFe). Lithogenic sources appear to dominate the PFe cycle through margin and benthic inputs.

Beam attenuation at 660 nm and suspended particle matter (SPM) relationships were determined during the MALINA cruise in August 2009 to the Canadian Beaufort Sea in order to expand our knowledge of particle distributions in Arctic shelf seas. The relationship was then used to determine SPM distributions for four other expeditions to the region. SPM patterns on the shelf were explained by an interplay between wind forcing, river discharge, and melting sea ice that controls the circulation.

Cold-water corals were found at active sites in Pompeia Province (Gulf of Cádiz). Since seeped fluids are harmful for the corals, we approached the environmental conditions that allow corals to colonize carbonates while seepage occurs. As a result, we propose that chemosynthetic microorganisms (i.e. sulfide-oxidizing bacteria and AOM-related microorganisms) play an important role in the colonization of the corals at these sites by feeding on the seeped fluids and avoiding coral damage.

Biomass burning is an important source of trace gases and aerosols in China, with a significant contribution from small-sized crop residue fires. Compared with conventional methods for emission estimation, the approach based on fire radiative energy (FRE) provides a more reasonable estimate for small-fire emissions. By using FRE data derived from satellites, we developed a long-term biomass burning emission inventory for China with a higher resolution (daily, 1 km) than previous studies.