5 research outputs found

    Data_Sheet_1_Moderate increase of precipitation stimulates CO2 production by regulating soil organic carbon in a saltmarsh.docx

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    Saltmarsh is widely recognized as a blue carbon ecosystem with great carbon storage potential. Yet soil respiration with a major contributor of atmospheric CO2 can offset its carbon sink function. Up to date, mechanisms ruling CO2 emissions from saltmarsh soil remain unclear. In particular, the effect of precipitation on soil CO2 emissions is unclear in coastal wetlands, due the lack of outdoor data in real situations. We conducted a 7-year field manipulation experiment in a saltmarsh in the Yellow River Delta, China. Soil respiration in five treatments (−60%, −40%, +0%, +40%, and + 60% of precipitation) was measured in the field. Topsoils from the last 3 years (2019–2021) were analyzed for CO2 production potential by microcosm experiments. Furthermore, quality and quantity of soil organic carbon and microbial function were tested. Results show that only the moderate precipitation rise of +40% induced a 66.2% increase of CO2 production potential for the microcosm experiments, whereas other data showed a weak impact. Consistently, soil respiration was also found to be strongest at +40%. The CO2 production potential is positively correlated with soil organic carbon, including carbon quantity and quality. But microbial diversity did not show any positive response to precipitation sizes. r-/K-strategy seemed to be a plausible explanation for biological factors. Overall, our finding reveal that a moderate precipitation increase, not decrease or a robust increase, in a saltmarsh is likely to improve soil organic carbon quality and quantity, and bacterial oligotroph:copiotroph ratio, ultimately leading to an enhanced CO2 production.</p

    β‑Cyclodextrin Polymer Network Sequesters Perfluorooctanoic Acid at Environmentally Relevant Concentrations

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    Per- and poly fluorinated alkyl substances (PFASs), notably perfluorooctanoic acid (PFOA), contaminate many ground and surface waters and are environmentally persistent. The performance limitations of existing remediation methods motivate efforts to develop effective adsorbents. Here we report a β-cyclodextrin (β-CD)-based polymer network with higher affinity for PFOA compared to powdered activated carbon, along with comparable capacity and kinetics. The β-CD polymer reduces PFOA concentrations from 1 μg L<sup>–1</sup> to <10 ng L<sup>–1</sup>, at least 7 times lower than the 2016 U.S. EPA advisory level (70 ng L<sup>–1</sup>), and was regenerated and reused multiple times by washing with MeOH. The performance of the polymer is unaffected by humic acid, a component of natural organic matter that fouls activated carbons. These results are promising for treating PFOA-contaminated water and demonstrate the versatility of β-CD-based adsorbents

    Benchmarking Micropollutant Removal by Activated Carbon and Porous β‑Cyclodextrin Polymers under Environmentally Relevant Scenarios

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    The cost-effective and energy-efficient removal of organic micropollutants (MPs) from water and wastewater is challenging. The objective of this research was to evaluate the performance of porous β-cyclodextrin polymers (P-CDP) as adsorbents of MPs in aquatic matrixes. Adsorption kinetics and MP removal were measured in batch and flow-through experiments for a mixture of 83 MPs at environmentally relevant concentrations (1 μg L<sup>–1</sup>) and across gradients of pH, ionic strength, and natural organic matter (NOM) concentrations. Performance was benchmarked against a coconut-shell activated carbon (CCAC). Data reveal pseudo-second-order rate constants for most MPs ranging between 1.5 and 40 g mg<sup>–1</sup> min<sup>–1</sup> for CCAC and 30 and 40000 g mg<sup>–1</sup> min<sup>–1</sup> for P-CDP. The extent of MP removal demonstrates slower but more uniform uptake on CCAC and faster but more selective uptake on P-CDP. Increasing ionic strength and the presence of NOM had a negative effect on the adsorption of MPs to CCAC but had almost no effect on adsorption of MPs to P-CDP. P-CDP performed particularly well for positively charged MPs and neutral or negatively charged MPs with McGowan volumes greater than 1.7 (cm<sup>3</sup> mol<sup>–1</sup>)/100. These data highlight advantages of P-CDP adsorbents relevant to MP removal during water and wastewater treatment

    The Up-regulation of Carbonic Anhydrase Genes of <i>Bacillus mucilaginosus</i> under Soluble Ca<sup>2+</sup> Deficiency and the Heterologously Expressed Enzyme Promotes Calcite Dissolution

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    <div><p>Molecular mechanisms and gene regulation are of interest in the area of geomicrobiology in which the interaction between microbes and minerals is studied. This paper focuses on the regulation of the expression of carbonic anhydrase (CA) genes in <i>Bacillus mucilaginosus</i> and the effects of the expression product of the <i>B. mucilaginosus</i> CA gene in <i>Escherichia coli</i> on calcite weathering. Real-time fluorescent quantitative PCR (RT-qPCR) was used to explore the relationship between CA gene expression in <i>B. mucilaginosus</i> and promotion of calcite dissolution under condition of Ca<sup>2+</sup> deficiency. The results showed that adding calcite to the medium, which lacks Ca<sup>2+</sup>, can up-regulate the expression of the bacterial CA genes to accelerate calcite dissolution for bacterial growth. CA genes from <i>B. mucilaginosus</i> were transferred into <i>E. coli</i> by cloning. We then employed crude enzyme extract from the resultant <i>E. coli</i> strain in calcite dissolution experiments. The enzyme extract promoted calcite dissolution. These findings provide direct evidence for the role of microbial CA on mineral weathering and mineral nutrition release.</p></div

    Thermodynamic Evaluation of Aromatic CH/π Interactions and Rotational Entropy in a Molecular Rotor

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    A molecular rotor built with a stator formed by two rigid 9β-mestranol units having a 90° bent angle linked to a central phenylene rotator has an ideal structure to examine aromatic CH/π interactions. Energies and populations of the multiple solution conformations from quantum-mechanical calculations and molecular dynamics simulations were combined with variable-temperature (VT) <sup>1</sup>H NMR data to establish the enthalpy of this interaction and the entropy associated with rotation about a single bond. Rotational dynamics in the solid state were determined via VT cross-polarization magic-angle spinning <sup>13</sup>C NMR spectroscopy