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Biological particles, as a fraction of organic particles, potentially play a crucial role in ice nucleation processes. However, the contributions and relationships of biological components and organic matter (OM) to atmospheric ice nucleation remain largely unexplored. Here, total ice nucleating particles (INPs), heat‐resistant INPs, lysozyme‐resistant INPs, nanoscale INPs (<0.22 μm), and heat‐resistant nanoscale INPs in precipitation collected at the summit of Mt. Lu, China, were determined using droplet freezing assays coupled with corresponding pretreatments. Heat‐sensitive INPs and lysozyme‐sensitive INPs were considered as biological INPs and bacterial INPs, respectively. Microorganisms and OM molecules in precipitation were identified by high‐throughput sequencing technology and ultrahigh‐resolution mass spectrometry, respectively. Results revealed a predominant biological (heat‐sensitive) composition (78.8% and 93.2%) of total and nanoscale INPs at temperatures above −15°C. Specifically, bacterial (lysozyme‐sensitive) INPs accounted for 36.1% of the biological INPs at temperatures above −15°C. A notable correlation between sulfur‐containing organic compounds, mainly proteinaceous and lignin‐like substances, and INPs was uncovered, with a co‐occurrence network linking these compounds to Gram‐positive bacteria and Agaricomycetes. This study underscored the possible significance of sulfur‐containing organic compounds in the ice nucleation capacity of biological INPs, further shedding light on the ice nucleation mechanisms and potential sources of biological INPs. Plain Language Summary: Ice nucleating particles (INPs) are particles that facilitate the freezing of water at temperatures above the homogenous freezing point, impacting cloud formation and precipitation processes in the atmosphere. This study identified different types of INPs, microbes, and organic matter in precipitation sampled from Mt. Lu in southeastern China and investigated the connections among them. The findings suggested that a significant portion of INPs were of biological origin. Sulfur‐containing organic compounds likely played an important role in ice nucleation, which may originate from certain microbial taxa. This study helps us understand the role of microbes and organic molecules in ice formation, which has broader implications in areas such as preserving biological materials at low temperatures or facilitating artificial snow production. Key Points: Biological materials predominated among the ice nucleating particles (INPs) identified in precipitationSulfur‐containing organic compounds, associated with specific microbial taxa, likely acted as efficient INPs in precipitationThis study provides a preliminary understanding of the connections among INPs, organic matter, and microorganisms [ABSTRACT FROM AUTHOR]

Dissolved organic sulfur (DOS) is an important component of dissolved organic matter (DOM) and widely exists at the land‐atmosphere interface. However, the characterization of DOS at the molecular level among different environmental samples in coastal regions has not been sufficiently focused. Here, we investigated DOS in aerosol, rainwater, and river water samples in Shanghai using an improved method–online liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (LC‐FT‐ICR MS). This system is utilized to separate DOS from complicated environmental matrices. The results showed that the average relative abundance of DOS in three different environmental media (aerosol, rainwater, and river water samples) accounted for 16.8%, 21.9% and 13.1%, respectively. The common molecules of the three mediums in coastal Shanghai contain an abundance of aromatic and aliphatic DOS of anthropogenic origin in addition to the natural sources of sea spray. Notably, results from a new structural classification scheme for DOS demonstrate that anthropogenic sulfonates and their derivatives are widely spread, although their molecular diversity in different medium was recorded due to complex environmental conditions and diverse sources. Plain Language Summary: Ion suppression of abundant non‐sulfur containing species hinders the detection of dissolved organic sulfur species by direct infusion electrospray ionization mass spectrometry. A newly developed method is proposed to evaluate organic sulfur‐containing compounds at the molecular level using an online liquid chromatography coupled to ultrahigh resolution mass spectrometry, which was applied to aerosol, rainwater, and river water samples in Shanghai. Our study suggests that the novel method allows a detailed investigation of organic sulfur‐containing compounds and provides molecular evidence of the ubiquitous presence of anthropogenic DOS in the ambient environment. Key Points: The ubiquity of natural and anthropogenic dissolved organic sulfur was observed at the water‐atmosphere interfaceNatural dissolved organic sulfur at the coastal water‐atmosphere interface is mainly from sea spray‐based biological sourcesOnline liquid chromatography coupled to FT‐ICR Mass Spectrometry is an ideal system to separate dissolved organic sulfur [ABSTRACT FROM AUTHOR]

The surface of atmospheric aqueous aerosol is covered with an organic film. However, there have been limited studies about the photochemical process between the organic coating and aqueous samples such as fogwater, which contains light absorbing brown carbon (BrC). Here, the interactional aging process between unsaturated fatty acids and aqueous samples was performed by laboratory studies and field observations. On the one hand, glycine and alanine were selected as organic nitrogen‐containing compounds to form BrC with carbonyl compounds like glyoxal or methylglyoxal. Oleic acid was induced to form organic peroxy radicals through H‐abstraction by the excited triplet BrC or hydroxyl radical (OH). On the other hand, one type of aqueous formation pathway of Criegee intermediates (CIs) was proposed through the oxidation of oleic acid. CIs may be formed by OH addition to C=C bonds and scavenged by interfacial reactions. Results from ultra‐high resolution Fourier transform ion cyclotron resonance mass spectrometry show that the synergistic effect of oleic acid and OH may have a higher oxidative capacity than OH. Furthermore, our study demonstrates that oleic acid can improve the aqueous oxidation ability by producing oxygen‐containing radicals. These findings highlight that the formation of free radicals is greatly influenced by photochemical reactions, which further reveal the complexities of fog organic chemistry. Plain Language Summary: Little is known about how organic coating drives the molecular variance of atmospheric water droplets such as fogwater. Here we report the interactional photochemical process between unsaturated fatty acids and aqueous samples by laboratory studies and field observations. We found that unsaturated fatty acids can enhance the oxidation ability by forming oxygen‐containing radicals to participate in the aging process of aqueous organics. Our results provide unique insight toward a molecular level understanding of the origin, formation, and transformation of reactive intermediates at the air‐water interface, which further reveal the complexities of aqueous atmospheric chemistry. Key Points: Oleic acid is induced to form organic peroxy radicals by the excited triplet brown carbon or OHCriegee intermediates may be formed by OH addition to C=C bonds and scavenged by interfacial reactionsSynergistic effect of oleic acid and OH may have a higher oxidative capacity [ABSTRACT FROM AUTHOR]

Although ether‐based electrolytes have gradually been identified as a vital factor to achieving the excellent electrochemical performance observed in transition metal sulfide (TMS) anodes in sodium‐ion batteries (SIBs), there is still a lack of a fundamental understanding about the origin of the positive effect of ether‐based electrolytes on TMS anodes. Herein, a microspherical CoS2 anode has been taken as a representative of TMS. It has been demonstrated that the sodiation process involves not only a traditional conversion reaction taking place between solid‐state CoS2 and Na2S, but also a solid–liquid phase conversion process between active materials and soluble sodium polysulfide (Na2Sn, 2 < n < 8). More importantly, it is first revealed that the long‐term stability and the reversibility of CoS2 anode are mainly due to the solid–liquid conversion behavior, which makes bulk CoS2 gradually develop into a stable porous structure with fast Na+ transport kinetics and small stress/strain during cycling. Consequently, the CoS2 electrode delivers remarkable long‐cycle life with an ultrahigh capacity retention rate of 94.8% even after 1500 cycles at 2 A g−1 (only 2.13 mAh g−1 fading per 100 cycles) and high volumetric capacity of 949 mAh cm−3 at a high active material loading of 3.3 mg cm−2. [ABSTRACT FROM AUTHOR]

Organic matter in the gas‐phase and particles are important components of the atmosphere. Photochemical degradation is a major transformation pathway of atmospheric organic matter, which changes the atmospherically related life time and the environmental, climatic, and health‐related effects of organic matter, as well as biogeochemical cycles of elements. In addition to field observations and model simulations, laboratory experiments based on smog chambers and flow tubes are important approaches to study the photodegradation mechanisms and influencing factors of atmospheric organics. Isotopic composition is also a useful tracer for photodegradation processes of different organics, for example, carboxylic acids. In this article, research progress on photodegradation of several significant categories of organic pollutants which have aroused widespread concern currently, for example, polycyclic aromatic hydrocarbons, carboxylic acids, brown carbon, organosulfates/organonitrates, microplastics, and bioaerosols, are reviewed. The effects of different degradation mechanisms including photochemical reactions, heterogeneous aqueous reactions, and microbial degradation are also compared. Although the photodegradation of atmospheric organics has been studied to a certain extent, much more effort should be made to fill the large knowledge gap between the actual and simulated photodegradation processes. [ABSTRACT FROM AUTHOR]

Reef islands of the Xisha Islands, South China Sea, were formed during the mid–late Holocene. However, the vertical accretion of ornithogenic sediments of the islands is not well understood owing to a lack of precise dating. Here we present an analysis of seven of the Xisha Islands, and reconstruct their accumulation history based on radiocarbon analysis of seabird subfossils. From Clam‐based age–depth models, a universal development mode of the Xisha Islands is hypothesized. The mean accumulation rate of guano sediments on the Xisha Islands in the late Holocene was 1.02 ± 0.42 mm a−1. The sum of the deposition rate of coral sands and the rate of ornithogenic accumulation is lower than or close to the current rate of sea level rise in the Xisha Islands, implying a potential threat to the islands' safety. This study also provides robust evidence for a sequence of island development associated with seabirds. [ABSTRACT FROM AUTHOR]

Abstract: Compound‐specific 15N analysis of amino acids (AAs) is a powerful tool to determine the trophic position (TP) of organisms. However, it has only been used in a few studies of avian ecology because the AA patterns in the consumer‐diet nitrogen trophic discrimination factor (TDFGlu‐Phe = ∆15NGlu−∆15NPhe) were unknown in birds until recently, and tropical seabirds have never been investigated with this methodology. Here, we explore the application of this method to tropical seabirds. In this study, we recovered the fossilized bones of tropical seabirds from ornithogenic sediments on two coral islands in the Xisha Islands, South China Sea, as well as the bones and muscle of their predominant food source, flying fish (Exocoetus volitans). Compound‐specific 15N and 13C analyses of AAs in both seabird and fish bone collagen were conducted. The TP of flying fish was calculated based on a widely used single TDFGlu‐Phe approach. We then calculated the TP of tropical seabirds in three different ways: (a) according to the composition of their diet; (b) based on the single TDFGlu‐Phe approach; and (c) using a multi‐TDFGlu‐Phe approach. The results of the multi‐TDFGlu‐Phe approach were much closer to the results based on the composition of the seabird diet than the results of the single TDFGlu‐Phe approach, confirming its applicability for tropical seabirds. For seabird bone samples of different ages, TP determined from the multi‐TDFGlu‐Phe approach was most similar to that of bulk δ15N of bird collagen, with seabirds occupying higher TPs during the Little Ice Age, as previously shown. In addition, the 13C Suess effect was reflected in the AAs δ13C in our samples. This study applied a compound‐specific 15N analysis of AAs to determine the TP of tropical seabirds that has potential to extend to all tropical seabirds many of which are widely distributed and play a key role in the evolution of coral island ecosystems. [ABSTRACT FROM AUTHOR]

Organic carbon isotopes in sediments have been frequently used to identify the source of organic matter. Here we present a study of organic δ13C on two sediment profiles influenced by guano from Guangjin and Jinqing islands in the Xisha Archipelago, South China Sea. Organic matter from ornithogenic coral sand sediments has two main sources, guano pellets and plant residues, and their organic δ13C ( δ13COM) are significantly different Organic carbon δ13Cguano is much higher than δ13Cplant, and δ13COM of bulk samples is intermediate. Based on a two-end-member mixing model, the proportions of guano- and plant-derived organic matter in the bulk samples were reconstructed quantitatively. The results showed that seabirds began to inhabit the islands around approximately 1200-1400 AD, and that guano pellets have been an important source of soil organic matter since then. With the accumulation of guano-derived nutrients, plants began to develop prosperously on the islands in the last 200 years, which is reflected by the significant increase of plant-derived organic matter in the upper sediment layer. However, guano-derived organic matter decreased greatly in recent decades, indicating a rapid decrease in seabird population. Our results show that organic δ13C can be effectively used to quantitatively determine different source contributions of OM to bulk ornithogenic coral sand sediments. [ABSTRACT FROM AUTHOR]

Review: 74 refs. [ABSTRACT FROM AUTHOR]