An irreversible shift in the chemical make-up of the Arctic Ocean driven by climate change is disrupting the region’s food chain, a study suggests.

Reservoirs are widely recognized as important sites for carbon burial, but their true potential as climate regulators has remained partially understood. A new study from Guizhou University published in Carbon Research provides a mechanistic explanation for why reservoirs in karst landscapes—regions formed from soluble rocks like limestone—are exceptionally effective carbon sinks. By tracing the journey of carbon from water to sediment, the research demonstrates that these unique ecosystems not only capture vast amounts of carbon but also lock it away in a highly stable, long-lasting form.

The investigation centered on the Songbaishan Reservoir in China, a typical system within a karst basin. These regions are characterized by water rich in dissolved inorganic carbon from rock weathering, which provides a key ingredient for aquatic photosynthesis. The research team, led by corresponding author Wanfa Wang, employed a sophisticated suite of analytical techniques, including stable isotope tracing, organic carbon fractionation, and high-resolution mass spectrometry, to build a complete picture of the reservoir's carbon cycle. This allowed them to quantify how much carbon was produced internally versus washed in from land and to determine its ultimate fate in the sediment.

The Karst Advantage

A central finding is the powerful role of the biological carbon pump (BCP), a process where phytoplankton convert dissolved carbon into organic matter. During the warm season, the reservoir's water column becomes thermally stratified, creating ideal conditions for algal blooms in the sunlit upper layer. This supercharged BCP consumes enormous amounts of dissolved inorganic carbon, generating a massive pool of autochthonous organic carbon (AOC)—carbon produced within the reservoir itself. This internal production supports a remarkably high organic carbon burial rate of 89.5 g C m⁻² a⁻¹, significantly higher than rates in many non-karst reservoirs.

In the Triassic, the modern animals we know were just beginning to diversify into a menagerie of forms and body plans that rhyme with the lifestyles of extinct and living animals better known to the public, but nested in groups that ended up taking wildly divergent paths. Case in point: Labrujasuchus expectatus. 

Described in the journal Journal of Vertebrate Paleontology, Labrujasuchus looked very much like ornithomimosaurs, a group of bipedal dinosaurs from the Cretaceous with body plans similar to those of modern ostriches. But Labrujasuchus comes from the branch of archosaurs that led to crocodiles, famously four-legged and full of teeth. The newly-described Labrujasuchus navigated the world on two legs with tiny arms and a toothless mouth tipped in a beak—about as far away from a crocodile as possible. 

Most people think of ice as frozen and lifeless, but research at Umeå University shows the opposite. A new study published in PNAS demonstrates that ice actively speeds up the breakdown of iron minerals and may release more iron than current environmental models account for. This is crucial for predicting how nutrient cycles, carbon storage, and water quality will change in polar and mountain regions as the planet warms.