Large rivers transport a significant amount of terrestrially derived dissolved organic matter (DOM) to coastal oceans, consisting of a critical component of the global biogeochemical cycle. Although high flow events usually introduce more terrestrial DOM than baseflow, the underlying molecular complexity and lability of DOM during high discharge are not well constrained, especially in large river ecosystems. By combining ultraviolet and fluorescent spectroscopy, and ultrahigh-resolution mass spectrometry, we found that stronger terrestrial DOM signal was detected during high discharge than normal discharge in the Yangtze River mainstream. The averaged DOC concentration was higher during high discharge than normal discharge. Optical properties confirmed higher aromaticity and relatively higher humic-like fluorescent components in DOM during high discharge. The molecular composition showed significantly higher molecular complexity, averaged molecular weight, aromaticity, relative abundances of polyphenols and highly unsaturated compounds of DOM during high discharge than normal discharge. A large set of unique molecular formulae (up to 4927) was only detected during high discharge. These unique molecular formulae were mostly lignin degradation products, likely due to more intensive soil leaching during high discharge. By comparing with incubation experiments and the Yangtze River mouth and East China Sea DOM molecular composition, some of these unique molecular formulae during high discharge are resistant to both bio- and photo-degradation, and persist during their transport to the East China Sea. Therefore, we suggest that high discharge will additionally introduce a relatively recalcitrant pool of DOM into the Yangtze River mainstream and persist during its journey to the ocean. Considering the projected increase of flood frequency, this study provides a preliminary foundation for further studies to better assess the underlying mechanisms how hydrology affect the biogeochemical cycling of DOM in large rivers.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142803 | DOI Listing |
Arch Microbiol
January 2025
Jiangsu Key Laboratory for the Research and Utilization of Plant Resources, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, China.
Throughout the life cycle of mushrooms, countless spores are released from the fruiting bodies. The spores have significant implications in the food and medicine industries due to pharmacological effects attributed to their bioactive ingredients. Moreover, high concentration of mushroom spores can induce extrinsic allergic reactions in mushroom cultivation workers.
View Article and Find Full Text PDFNano Lett
January 2025
College of Chemistry and Materials Science, Hebei University, Baoding 071002, Hebei, P. R. China.
Ultrahigh nickel cathode materials are widely utilized due to their outstanding energy and power densities. However, the presence of cobalt can cause significant lattice distortion during charge and discharge cycles, leading to the loss of active lithium, the formation of lattice cracks, and the emergence of a rock salt phase that hinders lithium-ion transport. Herein, we developed a novel cobalt-free, aluminum-doped cathode material, LiNiMnAlO (NMA), which effectively delays the harmful H2-H3 phase transition, reduces lattice distortion, alleviates stress release, and significantly enhances structural stability.
View Article and Find Full Text PDFRev Sci Instrum
January 2025
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
We describe a simple gas expansion ion source based on static discharge voltages and a commercially available pulsed valve. The discharge is initiated by the gas pulse itself between two high voltage electrodes, without the need for fast voltage switches or complex timing schemes. The ion source very reliably produces intense bursts of molecular ions (with currents exceeding 100 μA during the pulse-on phase) with only minor pulse-to-pulse variations in intensity and pulse shape.
View Article and Find Full Text PDFAnal Chem
January 2025
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-41061, United States.
Glow discharge optical emission spectrometry (GDOES) allows fast and simultaneous multielemental analysis directly from solids and depth profiling down to the nanometer scale, which is critical for thin-film (TF) characterization. Nevertheless, operating conditions for the best limits of detection (LODs) are compromised in lieu of the best sputtering crater shapes for depth resolution. In addition, the fast transient signals from ultra-TFs do not permit the optimal sampling statistics of bulk analysis such that LODs are further compromised.
View Article and Find Full Text PDFAims: Risk prediction indices used in worsening heart failure (HF) vary in complexity, performance, and the type of datasets in which they were validated. We compared the performance of seven risk prediction indices in a contemporary cohort of patients hospitalized for HF.
Methods And Results: We assessed the performance of the Length of stay and number of Emergency department visits in the prior 6 months (LE), Length of stay, number of Emergency department visits in the prior 6 months, and admission N-Terminal prohormone of brain natriuretic peptide (NT-proBNP (LENT), Length of stay, Acuity, Charlson co-morbidity index, and number of Emergency department visits in the prior 6 months (LACE), Get With The Guidelines Heart Failure (GWTG), Readmission Risk Score (RRS), Enhanced Feedback for Effective Cardiac Treatment model (EFFECT), and Acute Decompensated Heart Failure National Registry (ADHERE) risk indices among consecutive patients hospitalized for HF and discharged alive from January 2017 to December 2019 in a network of hospitals in England.
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