Fluvial discharge and coastal erosion of the permafrost-dominated East Siberian Arctic delivers large quantities of terrigenous organic carbon (Terr-OC) to marine waters. We assessed its fate and composition in different marine pools with a suite of biomarkers. The dissolved organic carbon is transporting off-shelf “young” and fresh vascular plant material, while sedimentary and near-bottom particulate organic carbon preferentially carries old organic carbon released from thawing permafrost.

Our results show that Finnish eelgrass meadows are minor carbon sinks compared to the Danish meadows, and that majority of the Corg produced in the Finnish meadows is exported. Similarly, the estimates for Corg accumulation in Finnish meadows were over 1 magnitude lower compared to Denmark. Our results further showed that > 40 % of the variation in the Corg stocks was explained by sediment characteristics. To clarify the role of seagrasses in global carbon budget, more studies are in urgent need.

Seasonal variation of Ω in bottom water in Hope Valley, a biological hotspot in the southern Chukchi Sea, was reconstructed from 2-year-round mooring data of temperature, salinity and oxygen, with empirical equations derived from ship-based observations.

Ocean acidification is challenging phenotypic plasticity of individuals and populations. We studied phenotypic plasticity of the calanoid copepod Acartia bifilosa in the course of a pelagic, large-volume mesocosm study in the Baltic Sea. We found significant negative effects of ocean acidification on adult female copepod size and egg hatching success. Overall, these results indicate that A. bifilosa could be affected by projected near-future CO₂ levels.

Tropical rain forest are likely to grow more, and produce more litterfall, as a result of increasing temperature and carbon dioxide. We experimentally doubled litterfall in large plots in forest in Panama; there were also removal plots. After 6 years of continuously adding litter, we found that soil organic matter and many plant-available nutrients were increased down to as far as 30 cm into the soil. This increase in organic carbon in the soil reduces the carbon dioxide in the atmosphere.

The objective of this study was to determine whether natural variation in environmental exposure changes the sensitivity of thecosome pteropods to high CO₂ and low O₂ by comparing individuals from the Atlantic and Pacific oceans. Of the species studied, no thecosome showed a change in oxygen consumption in response to high CO₂ alone. Only one species, Limacina retroversa from the Atlantic, showed a reduced metabolic rate in response to the combined treatment.

The results of this paper report the analysis of the fate and transport of wastewater and anthropogenic nitrogen along the Potomac River estuary, from Washington D.C. to the Chesapeake Bay. In conjunction with a mass balance approach, nitrate isotopes were used to estimate fluxes and trace the sources and transformations of N along the estuary. This study shows that estuaries have a large capacity to transform N inputs, but with large seasonal variability due to hydrological extremes.

Changes in tundra vegetation structure may amplify Arctic climate warming. Our simulations with a new tundra vegetation model suggest that precipitation increases favour grass abundance, whereas warming favours shrub dominance. However, abrupt permafrost thaw initiating wetland formation leads to grass dominance. Our simulations show that a wetter tundra, due to increased precipitation or abrupt permafrost thaw, could result in local shrub decline instead of the widely expected shrub expansion.

Ongoing ocean acidification is being superimposed on the natural carbonate buffer system to influence the physiology of phytoplankton. Here, we show that coastal and oceanic diatoms respond differentially to diurnal fluctuating carbonate chemistry in current and ocean acidification scenarios. We propose that the ability to acclimate to dynamic carbonate chemistry may act as one determinant of the spatial distribution of diatom species.

Our primary finding of increased plankton biomass in the deep sea suggests that energy transfer efficiency from phytoplankton to intermediate and higher trophic levels has been underestimated, and that global carbon models need to account for the large portion of oceanic primary production that zooplankton is likely respiring in the deep-pelagic realm.

Plateau pika is common on the Qinghai-Tibet Plateau (QTP). Since pika dig burrows and graze on grassland to compete with yaks and sheep, they are believed to be a pest. They have been killed by humans since the 1950s. However, there are no serious studies that quantitatively evaluate the grazing and excavating effects of pika on grassland. With the advancement of UAV technology, we did a pilot study to evaluate the grazing and burying effects of pika.

Northern Australian savanna landscapes are a region earmarked for potential agricultural expansion. Greenhouse gas emissions from savanna land use change were quantified to determine the relative impact of increased rates of deforestation on Australia's national greenhouse gas accounts. Emissions from historic rates of deforestation were similar to savanna burning, but expanded clearing across northern Australia could add 3 % to Australia’s national greenhouse gas emissions.

We used a model to quantify the carbon stock and its changes in terrestrial ecosystems of Alaska during the last 15 000 years. We found that the changes in vegetation distribution due to climate were the key factors in the spatial variations of carbon in different time periods. The warming during 11–9 k years ago characterized by the increased summer temperature and seasonality of radiation, along with the high precipitation, might play an important role in causing the high carbon accumulation.

We introduce a new method of quantifying time since disturbance and carbon flux across forested landscapes in the Pacific Northwest at a 30m scale by combining remote-sensing-based disturbance year, type, and above-ground biomass with forest inventory data in a carbon modeling framework. Our approach will be applied to forestlands in other regions of the conterminous US to advance a comprehensive monitoring, mapping, and reporting of the carbon consequences of forest change across the US.

Fjord and continental shelf environments in the polar regions are host to some of the planet's most productive ecosystems and support economically important fisheries. A key limiting nutrient for many of these marine phytoplankton is nitrogen. Here we evaluate the potential for a melting Greenland Ice Sheet to supply nitrogen to Arctic coastal ecosystems. We show nitrogen fluxes of a similar order of magnitude to one large Arctic river but yields that are double those typical of Arctic rivers.

Soil CO₂ emissions are a major determinant of the carbon (C) cycle and its interactions with climate. Here, we show that soil CO₂ emissions have two origins: (1) the well-known microbial cell respiration and (2) an extracellular oxidative metabolism (EXOMET) carried out by soil-stabilized enzymes and mineral catalysts. These two metabolisms have distinct C isotope signatures, allowing their detection in soil CO₂ emissions.