Overlooked Vital Role of Persistent Algae-Bacteria Interaction in Ocean Recalcitrant Carbon Sequestration and Its Response to Ocean Warming.

Long-term carbon sequestration by the ocean's recalcitrant dissolved organic carbon (RDOC) pool regulates global climate. Algae and bacteria interactively underpin RDOC formation. However, on the long-term scales, the influence of their persistent interactions close to in situ state on ocean RDOC dynamics and accumulation remains unclear, limiting our understanding of the oceanic RDOC pool formation and future trends under global change.

Methane fueled lake pelagic food webs in a Cretaceous greenhouse world.

Methane (CH) is a potent greenhouse gas but also an important carbon and energy substrate for some lake food webs. Understanding how CH incorporates into food webs is, therefore, crucial for unraveling CH cycling and its impacts on climate and ecosystems. However, CH-fueled lake food webs from pre-Holocene intervals, particularly during greenhouse climates in Earth history, have received relatively little attention.

Millennial changes and cooling trends in land surface warm-season temperatures during the Holocene.

The scarcity of proxies and calibration models for quantitatively reconstructing millennial timescale seasonal temperature tremendously constraints our understanding of the Holocene thermal variation and its driven mechanisms. Here, we established two global warm-season temperature models by applying deep learning neural network analysis to the branched tetraether membrane lipids originating from surface soil and lacustrine sediment bacteria. We utilized these optimal models in global well-dated lacustrine, peatland, and loess profiles covering the Holocene.

Testate amoebae (Protozoa) in lakes of the Qinghai-Tibet Plateau: Biodiversity, community structures, and protozoic biosilicification in relation to environmental properties and climate warming.

The Qinghai-Tibet Plateau (QTP) is characterized by a vast number of frozen and unfrozen freshwater reservoirs, which is why it is also called "the third pole" of the Earth or "Asian Water Tower". We analyzed testate amoeba (TA) biodiversity and corresponding protozoic biosilicification in lake sediments of the QTP in relation to environmental properties (freshwater conditions, elevation, and climate). As TA are known as excellent bio-indicators, our results allowed us to derive conclusions about the influence of climate warming on TA communities and microbial biogeochemical silicon (Si) cycling.

Mass extinctions, their causes and consequences: an interview with Douglas H. Erwin and Shuzhong Shen.

'Mass extinctions' have been a hot topic for several decades. What triggers a mass extinction? How does a mass extinction impact the evolution of life? How does our ecosystem recover after a mass extinction? These questions attracted the interest of both scientists and the public alike. NSR spoke to two renowned researchers in the field of mass extinctions: Prof.

Eco-engineering approaches for ocean negative carbon emission.

The goal of achieving carbon neutrality in the next 30-40 years is approaching worldwide consensus and requires coordinated efforts to combat the increasing threat of climate change. Two main sets of actions have been proposed to address this grand goal. One is to reduce anthropogenic CO emissions to the atmosphere, and the other is to increase carbon sinks or negative emissions, i.

Intensified continental chemical weathering and carbon-cycle perturbations linked to volcanism during the Triassic-Jurassic transition.

Direct evidence of intense chemical weathering induced by volcanism is rare in sedimentary successions. Here, we undertake a multiproxy analysis (including organic carbon isotopes, mercury (Hg) concentrations and isotopes, chemical index of alteration (CIA), and clay minerals) of two well-dated Triassic-Jurassic (T-J) boundary sections representing high- and low/middle-paleolatitude sites. Both sections show increasing CIA in association with Hg peaks near the T-J boundary.

How Does Sphagnum Growing Affect Testate Amoeba Communities and Corresponding Protozoic Si Pools? Results from Field Analyses in SW China.

The policy and practice of ecological restoration and conservation in China obtained some remarkable results. For example, Sphagnum moss growing on abandoned farmland, which was peatland before agricultural use, has rapidly expanded the wetland area in SW China. Microorganisms such as testate amoebae are sensitive to environmental change and thus have been widely used as ecological indicators in various habitats.

The elemental enrichments at Dajiuhu Peatland in the Middle Yangtze Valley in response to changes in East Asian monsoon and human activity since 20,000 cal yr BP.

Here we present multiproxy inorganic geochemical records from a peat core (ZK5) from the Dajiuhu Basin in central China to investigate peatland deposition processes and atmospheric metal pollution and to explore their relationships with East Asian monsoon change and human activities in the Middle Yangtze Valley since 20,000 cal yr BP. The peat physicochemical data including total organic carbon (TOC), trace elements, and grain-size show that the site has changed from a lake during the cold-wet Last Glacial Maximum (LGM; 20,000-18,000 cal yr BP), to a marshy wetland during the mild last deglaciation (18,000-11,500 cal yr BP) and a peatland during the mostly warm and dry Holocene (11,500 cal yr BP-present). This general sequence corresponds with changes in East Asian monsoon indicated by stalagmites δO records and boreal summer insolation.

Massive formation of early diagenetic dolomite in the Ediacaran ocean: Constraints on the "dolomite problem".

Paleozoic and Precambrian sedimentary successions frequently contain massive dolomicrite [CaMg(CO)] units despite kinetic inhibitions to nucleation and precipitation of dolomite at Earth surface temperatures (<60 °C). This paradoxical observation is known as the "dolomite problem." Accordingly, the genesis of these dolostones is usually attributed to burial-hydrothermal dolomitization of primary limestones (CaCO) at temperatures of >100 °C, thus raising doubt about the validity of these deposits as archives of Earth surface environments.

East Asian hydroclimate modulated by the position of the westerlies during Termination I.

Speleothem oxygen isotope records have revolutionized our understanding of the paleo East Asian monsoon, yet there is fundamental disagreement on what they represent in terms of the hydroclimate changes. We report a multiproxy speleothem record of monsoon evolution during the last deglaciation from the middle Yangtze region, which indicates a wetter central eastern China during North Atlantic cooling episodes, despite the oxygen isotopic record suggesting a weaker monsoon. We show that this apparent contradiction can be resolved if the changes are interpreted as a lengthening of the Meiyu rains and shortened post-Meiyu stage, in accordance with a recent hypothesis.

Response of carbon cycle to drier conditions in the mid-Holocene in central China.

The nature and extent to which hydrological changes induced by the Asian summer monsoon affected key biogeochemical processes remain poorly defined. This study explores the relationship between peatland drying and carbon cycling on centennial timescales in central China using lipid biomarkers. The difference between peat n-alkane δH and a nearby stalagmite δO record reveals that intervals of prominent peatland drying occurred during the mid-Holocene.

Nitrogen fixation sustained productivity in the wake of the Palaeoproterozoic Great Oxygenation Event.

The marine nitrogen cycle is dominated by redox-controlled biogeochemical processes and, therefore, is likely to have been revolutionised in response to Earth-surface oxygenation. The details, timing, and trajectory of nitrogen cycle evolution, however, remain elusive. Here we couple nitrogen and carbon isotope records from multiple drillcores through the Rooihoogte-Timeball Hill Formations from across the Carletonville area of the Kaapvaal Craton where the Great Oxygenation Event (GOE) and its aftermath are recorded.

Holocene ENSO-related cyclic storms recorded by magnetic minerals in speleothems of central China.

Extreme hydrologic events such as storms and floods have the potential to severely impact modern human society. However, the frequency of storms and their underlying mechanisms are limited by a paucity of suitable proxies, especially in inland areas. Here we present a record of speleothem magnetic minerals to reconstruct paleoprecipitation, including storms, in the eastern Asian monsoon area over the last 8.

Rapid oxygenation of Earth's atmosphere 2.33 billion years ago.

Molecular oxygen (O2) is, and has been, a primary driver of biological evolution and shapes the contemporary landscape of Earth's biogeochemical cycles. Although "whiffs" of oxygen have been documented in the Archean atmosphere, substantial O2 did not accumulate irreversibly until the Early Paleoproterozoic, during what has been termed the Great Oxygenation Event (GOE). The timing of the GOE and the rate at which this oxygenation took place have been poorly constrained until now.

Ediacaran Marine Redox Heterogeneity and Early Animal Ecosystems.

Oxygenation has widely been viewed as a major factor driving the emergence and diversification of animals. However, links between early animal evolution and shifts in surface oxygen levels have largely been limited to extrapolation of paleoredox conditions reconstructed from unfossiliferous strata to settings in which contemporaneous fossils were preserved. Herein, we present a multi-proxy paleoredox study of late Ediacaran (ca.

Diversity, distribution and biogeography of testate amoebae in China: implications for ecological studies in Asia.

Testate amoebae are a group of shelled protozoa that occur in high density populations in wet environments. More than 1900 testate amoebae species or subspecies have been reported in published literature over the last 200 years, from many regions of the world. Testate amoebae are classified as Lobosea or Filosea respectively, according to the presence of lobose or filiform pseudopodia.

Pentagonia zhangduensis nov. spec. (Lobosea, Arcellinida), a new freshwater species from China.

The morphology of a new testate amoeba Pentagonia zhangduensis nov. spec. was investigated using light and scanning electron microscopy.

Two episodes of microbial change coupled with Permo/Triassic faunal mass extinction.

Microbial expansion following faunal mass extinctions in Earth history can be studied by petrographic examination of microbialites (microbial crusts) or well-preserved organic-walled microbes. However, where preservation is poor, quantification of microbial communities can be problematic. We have circumvented this problem by adopting a lipid biomarker-based approach to evaluate microbial community changes across the Permo/Triassic (P/Tr) boundary at Meishan in South China.