About half of the global CO₂ sequestration due to chemical weathering occurs in warm and high-runoff regions. To evaluate the temporary and net sinks of atmospheric CO₂ due to chemical weathering, we selected a typical subtropical catchment as our study area and did fieldwork to sample surface water along the main channel and major tributaries in 1 hydrological year. The result of mass balance calculation showed that human activities dramatically decreased the CO₂ net sink.

Ocean acidification is the process by which the oceans are changing due to carbon dioxide emissions from human activities. Studying this process in the Arctic Ocean is essential as this ocean and its ecosystems are more vulnerable to the effects of acidification. Water chemistry measurements made in recent years show that waters in and around the Canadian Arctic Archipelago are considerably affected by this process and show dynamic conditions that might have an impact on local marine organisms.

Environmental exposure histories can affect organismal sensitivity to climate change and ocean deoxygenation. The natural variability of environmental conditions for nearshore deep-sea habitats is poorly known due to technological challenges. We develop and test a novel, autonomous, hand-deployable lander outfitted with environmental sensors and a camera system and use it to characterize high-frequency oxygen, temperature, and pH variability at 100–400 m as well as seafloor community responses.

We measured the effect of photosynthesis, the largest flux in the carbon cycle, on the triple oxygen isotope composition of atmospheric CO₂ at the leaf level during gas exchange using three plant species. The main factors that limit the impact of land vegetation on the triple oxygen isotope composition of atmospheric CO₂ are identified, characterized and discussed. The effect of photosynthesis on the isotopic composition of CO₂ is commonly quantified as discrimination (ΔA).

Fungi have recently been identified to produce the greenhouse gas methane. Here, we investigated the stable carbon isotope values of methane produced by saprotrophic fungi. Our results show that stable isotope values of methane from fungi are dependent on the fungal species and the metabolized substrate. They cover a broad range and overlap with stable carbon isotope values of methane reported for methanogenic archaea, the thermogenic degradation of organic matter, and other eukaryotes.

In this study, we provide a holistic view of soil responses to precipitation changes. A total of 16 meta-analyses focusing on the effects of precipitation changes on 42 soil response variables were compared. A strong agreement was found that the belowground carbon and nitrogen cycling accelerate under increased precipitation and slow under decreased precipitation, while bacterial and fungal communities are relatively resistant to decreased precipitation. Knowledge gaps were also identified.

The coastal ecosystem of the Gulf of Alaska (GOA) is especially vulnerable to the effects of ocean acidification and climate change. To improve our conceptual understanding of the system, we developed a new regional biogeochemical model setup for the GOA. Model output suggests that bottom water is seasonally high in CO₂ between June and January. Such extensive periods of reoccurring high CO₂ may be harmful to ocean acidification-sensitive organisms.