Due to recent weir construction on four major rivers in South Korea, sediment has accumulated in the river bottom near the weirs, which has in turn raised concerns over the quality of overlying water. In this study, the seasonal and spatial variations of sediment oxygen demand (SOD) and the influencing factors were explored using pore water chemistry for the weir-impounded rivers. Muddy and sandy sediment samples were taken from 24 different sites along the four major rivers in summer and autumn, 2016. The SOD was measured in a laboratory based on 10-hour incubation at in situ temperature. The measured pore water chemistry included the concentrations of dissolved organic carbon (DOC), total dissolved nitrogen (TDN), inorganic nitrogen (NH-N, NO-N, NO-N), and phosphate phosphorous (PO-P), and the optical properties from UV absorption spectra and fluorescence excitation-emission matrixes coupled with parallel factor analysis (EEM-PARAFAC). Significant differences in SOD values between muddy and sandy sediments were found only in summer (p=0.047). The higher SOD in summer versus autumn (p=0.015) was attributed to seasonal temperature differences. The higher NH-N and the lower NO-N of the pore water samples in summer versus autumn suggested that organic nitrogen decomposition via an ammonification and nitrification process could operate as an important factor for the SOD variations in summer and autumn, respectively. Principal component analysis revealed the mutual contributions of nitrogen-associated processes and the organic composition in pore water to increasing SOD levels. NH-N in sediment pore water alone could be a good predictor for SOD. However, multiple regression analysis using NH-N, fluorescence index and terrestrial humic-like components improved the estimation capability for SOD variations.
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http://dx.doi.org/10.1016/j.scitotenv.2017.10.141 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
State Key Laboratory of Organic-Inorganic Composites, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Hydrogels are popular materials for desalination and can significantly reduce the vaporization enthalpy of water; however, there are few reports on hydrogels with a controllable multilevel structural design for water evaporation. Herein, a calcium alginate and traditional Chinese ink-based evaporator (CIE) are proposed and fabricated using directed freezing technology to construct radial channels, followed by freeze-drying and physical cross-linking. Because of the squeezing of ice crystals and the shaping effect of the PDMS template, the prepared evaporator exhibits a sea-urchin-shaped highly geometrical centrosymmetric structure with numerous multilevel pore channels, which promotes the rapid transport of water under different solar incidence angles as the sun rotates as well as overcomes the structural shrinkage of the hydrogel caused by insufficient water supply.
View Article and Find Full Text PDFNanotechnol Sci Appl
January 2025
Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, Universitas Padjadjaran, Sumedang, 45363, Indonesia.
Purpose: Improving drug solubility is crucial in formulating poorly water-soluble drugs, especially for oral administration. The incorporation of drugs into mesoporous silica nanoparticles (MSN) is widely used in the pharmaceutical industry to improve physical stability and solubility. Therefore, this study aimed to elucidate the mechanism of poorly water-soluble drugs within MSN, as well as evaluate the impact on the dissolution and physical stability.
View Article and Find Full Text PDFTight sandstone gas reservoirs are characterized by high water saturation, significant seepage resistance, low single-well productivity, rapid decline, and low gas recovery. Enhancing the recovery rate of tight sandstone gas reservoirs is a complex engineering challenge that necessitates thorough, refined, and systematic research into its fundamental theories. This study employs a comprehensive approach integrating mercury injection, nuclear magnetic resonance, micro-model visualization, and simulation experiments of displacement and inter-layer seepage flow, alongside foundational seepage theories, to systematically explore the characteristics of tight sandstone gas reservoirs, seepage patterns, and methods for improving gas recovery.
View Article and Find Full Text PDFLangmuir
January 2025
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816, People's Republic of China.
The remarkable flexibility in structural tunability and designability of poly(ionic liquids) (PILs) has garnered significant attention. Integration of PILs with membranes, novel properties, and functionalities is anticipated for applications in the fields of membrane separation. Here, we develop a facile method to prepare PIL-functionalized membranes in a one-step process by combining selective swelling-induced pore generation and ionic liquid functionalization.
View Article and Find Full Text PDFLangmuir
January 2025
Department of Chemistry, The University of Utah, Salt Lake City, Utah 84112, United States.
Slip flow, a fluid flow enhanced in comparison to that calculated using continuum equations, has been reported for many nanopores, mostly those with hydrophobic surfaces. We investigated the flow of water, hexane, and methanol through hydrophilic nanopores in silica colloidal crystals. Three silica sphere sizes were used to prepare the crystals: 150 ± 30, 500 ± 40, and 1500 ± 100 nm.
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