Diatoms were less inhibited by UV radiation under moderately increased temperature. Benthic diatoms were more resistant to UV radiation than planktonic species under extremely high temperature as found in the intertidal zone. These differential responses were linked to repair and damage processes of photosystem II.

The results of this study highlight the changes of DOM composition in soil solutions and surface runoff, probably controlled by water-table dynamics and pre-event hydrological conditions. These changes should be taken into account for a better understanding of micropollutant mobility. Moreover, this work has implications for modeling DOM export in headwater catchments, as many studies assume that DOM transfer during storm events consists of the flushing of pre-existing soil solution DOM.

We used several observation-based biomass datasets to constrain the historical land-use change carbon emissions simulated by models. Compared to the range of the original modeled emissions (from 94 to 273 Pg C), the observationally constrained global cumulative emission estimate is 155 ± 50 Pg C (1σ Gaussian error) from 1901 to 2012. Our approach can also be applied to evaluate the LULCC impact of land-based climate mitigation policies.

Montane ecosystems in the southern Peruvian Andes were atmospheric sources of the greenhouse gas nitrous oxide, exceeding prior emissions estimates from bottom-up process models. Nitrous oxide flux originated primarily from nitrate reduction. Nitrous oxide fluxes showed an inverse trend with elevation, and only weak evidence of seasonal variability. Nitrous oxide fluxes were influenced by the availability of nitrate and soil moisture content, but were not predicted by inputs of labile carbon.

The balance between organic matter (OM) fixation and decay is a major control on atmospheric CO₂ concentrations. Understanding the environmental, chemical, and physical mechanisms that control the distribution of OM decay rates is therefore critical for constraining the global carbon cycle. In this manuscript, we derive a method to relate OM reactivity to its isotope composition using a kinetic model and provide a novel framework to discern the controls on OM decay rates.

This review represents the outcome from an invigorating workshop discussion that involved tree physiologists, geomorphologists, ecologists, geochemists, and hydrologists and developed nine hypotheses that could be tested. We argue these hypotheses point to the essence of issues we must explore if we are to understand how the natural system of the earth surface evolves, and how humans will affect its evolution. This paper will create discussion and interest both before and after publication.

Earth system models (ESMs) are our main tools for understanding future climate. The Arctic is important for the future carbon cycle, particularly due to the large carbon stocks in permafrost. We evaluated the performance of the land component of three major ESMs at Arctic tundra sites, focusing on the fluxes and stocks of carbon. We show that the next steps for model improvement are to better represent vegetation dynamics, to include mosses and to improve below-ground carbon cycle processes.

In this study we show increasing organic matter (OM) content on ferrihydrite surfaces enhances Fe reduction by the model Fe reducer S. oneidensis and a microbial consortia extracted from peat. Similarities in reduction rates between S. oneidensis and the consortia suggest electron shuttling dominates in OM-rich soils. Community profile analyses showed enrichment of fermenters with pure ferrihydrite, whereas OM–mineral complexes favored enrichment of Fe-reducing Desulfobacteria and Pelosinus sp.

The quantitative importance of northern lakes in terrestrial carbon budgets is uncertain, as year-round observations of carbon fluxes are rare. We measured CH₄ and CO₂ fluxes from a subarctic lake and nearby fen during 2.5 years with one eddy covariance system. We identified drivers of seasonal variability in lake fluxes and show the importance of winter and spring for annual carbon exchange in both ecosystems. The lake as a source of atmospheric carbon partially compensates the fen carbon sink.

The carbon content of the water masses of the Southern Ocean south of Tasmania has increased over the period 1995–2011, leading to a general decrease in pH. An enhancement in the upwelling of DIC-rich deep waters is the main plausible cause of the increase in carbon in surface waters south of the Polar Front. North of the Polar Front, strong winds favor the ventilation of surface to intermediate layers, where the DIC increase is explained by the uptake of atmospheric CO₂.

We quantified different biogenic Si pools in soils of a developing ecosystem and analyzed their influence on short-term changes of the water soluble Si fraction. From our results we concluded small (< 5 µm) and/or fragile phytogenic Si structures to have the biggest impact on short-term changes of water soluble Si. Analyses of these phytogenic Si structures are urgently needed in future as they seem to represent the most important driver of Si cycling in terrestrial biogeosystems in general.

We present a new technique to quantify the chemical conditions under which corals build their skeletons by analysing them with lasers at a very fine resolution, down to 1/100th the width of a human hair. Our first applications to laboratory-cultured and wild corals demonstrates the complex interplay among seawater conditions (temperature and acidity), calcifying fluid chemistry, and bulk skeleton accretion, which will define the sensitivity of coral calcification to 21st century climate change.

Photosynthesis by phytoplankton is a key source of oxygen (O₂) in aquatic systems. We have developed a mathematical technique to calculate the rate of photosynthesis from time series of O₂. Additionally, the approach leads to a better understanding of the influence on O₂ measurements of the tides in coasts and estuaries. The results are important for correctly interpreting the data that are gathered by a growing set of continuous O₂ sensors that are deployed around the world.