The source of particulate organic matter in headwaters during storm events remains an open question. We use the molecular composition of organic matter sampled during four spring–summer storms and compare it to potential sources. We identify litter, streambed and vicinal soils as the main sources of particulate organic matter. Their proportions depend on (i) the size of the catchment and (ii) the rain event.

Soil contains a large amount of organic carbon and plays a crucial role in regulating Earth's C cycle and climate system. In this study, we collected soil-carbon isotope data within a 1 m depth globally and provided an isotope-based approach for understanding soil carbon decomposition rate. Compared with other methods, utilization of C isotope composition ratios in the soil profile provides an independent approach that does not rely on disruption of plant-soil-microbe interactions.

Time-series observations of nutrients and ²²⁸Ra, a groundwater discharge tracer, were carried out from spring to neap tide in the Luhuitou fringing reef at Sanya Bay in the South China Sea. Nitrate, phosphate, and silicate in the water column showed greater diurnal variation during the spring tide. Biological processes predominantly controlled the composition of nutrients, but there was less of an impact in the spring tide due to groundwater discharge in this reef system.

In the fall of 2014, the upwelling of water from the deep Canada Basin brought water onto the shallower Mackenzie Shelf in the Beaufort Sea. This increased the concentration of CO₂ in water on the shelf, which alters pH and changes the transfer of CO₂ between the ocean and atmosphere. These findings were a combined result of water sampling for CO₂ parameters and the use of a computer model that simulates water movement in the ocean.

We observed that N : P supply ratios had the strongest effect on C : N : P stoichiometry, while temperature and pCO₂ played more influential roles on PIC : POC and polyunsaturated fatty acid proportions in Emiliania huxleyi. Synergistic interactions indicated the enhanced effect of warming under nutrient deficiency and high pCO₂. Simultaneous changes of elements and fatty acids should be considered when predicting future roles of E. huxleyi in biogeochemical cycles and ecological functions.

Cellulose content (CC (%)) series from two high-Alpine species, Larix decidua Mill. (European larch, LADE) and Pinus cembra L. (Swiss stone pine, PICE) are investigated in modern wood samples and Holocene wood remains from the Early and mid-Holocene. Trends in modern and Holocene time series as well as climate–cellulose relationships for modern trees in the Alps show high potential for CC (%) to be established as novel supplementary proxy in dendroclimatology.

For central Europe in addition to rising temperatures, an increasing variability in precipitation is predicted. In a replicated mesocosm experiment we compared evapotranspiration and the biomass productivity of two differently drought-adapted vegetation communities during two irrigation regimes (with and without drought periods). Significant differences between the different communities were found in the response to variations in the water supply and biomass production.

Changes in atmospheric carbon dioxide affect ocean chemistry and the ability of marine organisms to manufacture shells from calcium carbonate. We describe a technique to obtain more reproducible measurements of the thickness of calcium carbonate shells made by microscopic marine algae called coccolithophores, which will allow researchers to compare how the shell thickness responds to variations in ocean chemistry in the past and present.

The Mekong River is among the largest on Earth and is vital for the economy of Vietnam and South East Asia and the livelihood of the local population (70 million across six countries). Numerous dams for hydropower are planned, which will affect the delivery of water and sediments to the Mekong delta, with numerous possible consequences. We report the dynamics of two greenhouse gases (CO₂ and CH₄) in the Mekong delta that can be used as a reference state to evaluate future changes.

The fluorescent dissolved organic matter (FDOM) delivered from riverine discharges significantly affects carbon and biogeochemical cycles in coastal waters. Our results show that the terrestrial concentrations of humic-like FDOM in river water were 60–80 % higher in the summer and fall, while the in situ production of protein-like FDOM was 70–80 % higher in the spring. Our results suggest that there are large seasonal changes in riverine fluxes of FDOM components to the ocean.

Macroalgae farming may provide biofuel. Modelled macroalgae production is given for four sites in UK and Dutch waters. Macroalgae growth depended on nutrient concentrations and light levels. Macroalgae carbohydrate content, important for biofuel use, was lower for high nutrient concentrations. The hypothetical large-scale farm off the UK north Norfolk coast gave high, stable yields of macroalgae from year to year with substantial carbohydrate content.

Arctic, Antarctic and alpine biological soil crusts (BSCs) are formed by adhesion of soil particles to cyanobacteria. BSCs influence ecosystems services like soil erodibility and chemical cycles. In cold environments degradation rates are low and BSCs increase soil organic carbon through photosynthesis, whereby these soils are considered as CO₂ sinks. This work provides a novel method to visualize BSCs with a focus on cyanobacteria and their contribution to soil organic carbon.

Why can biocrust moss survive and flourish in these habitats when stressed simultaneously by drought and sand burial? A field experiment was conducted to assess the combined effects of the two stressors on Bryum argenteum within biocrust. The two stressors did not exacerbate the single negative effects; their mutually antagonistic effect on the physiological vigor of B. argenteum was found, and it provided an opportunity for it to overcome the two co-occurring stressors in arid sandy ecosystems.

Through landscape-scale satellite observations we demonstrate that fire intensity has a dose–response relationship with temperate forest net primary productivity. Increasing fire intensity resulted in persisting step-wise reductions in post-fire net primary productivity. Forests with higher proportions of fire-resistant species generally had lower reductions in post-fire net primary productivity. A conceptual framework for assessing spatiotemporal post-fire effects is presented.

Gross land use change such as shifting cultivation causes carbon emissions because carbon release in cleared forests is larger than absorption in regrowing ones. However, to appropriately account for this process, vegetation models have to represent sub-grid secondary forest dynamics. We found that gross land use emissions can be overestimated if sub-grid secondary forests are neglected in the model. Conversely, rotation lengths of shifting cultivation have a critical role.

We propose a novel modelling approach enabling swift hydrological surveys based on multiple conservative and non-conservative tracers to estimate water retention time, groundwater discharge sites, fractions of water originating from the discharge sites, groundwater recharge sites and sites that are especially important in regard to groundwater recharge. Thus we provide a whole lake hydrological survey while pinpointing sources of pollutants like colored dissolved organic matter and nutrients.

Forest types with specific soil conditions supported the development of distinct soil microbial communities with variable functions. Our results indicate that the main controls on soil microbes and functions vary across forest ecosystems in different climatic zones. This information will add value to the modeling of microbial processes and will contribute to carbon cycling on a large scale.

Associations between diatoms and N-fixing cyanobacteria (diatom–diazotroph associations, DDAs) play an important role in the N cycle of the tropical North Atlantic. Heterocysts are the site of N fixation and contain unique glycolipids. We measured these glycolipids in the water column and surface sediment from the tropical North Atlantic. We found a significant correlation between the concentration of glycolipid and of DDAs, strengthening their application as biomarkers.

Iron is a common dissolved element in river water, recognizable by its orange-brown colour. Here we show that when rivers reach the ocean much of this iron settles to the sediments by a process known as flocculation. The iron is then used by microbes in coastal sediments, which are important hotspots in the global carbon cycle.