Yingru Tao,Weiying Feng,Qiwei Gu,Tengke Wang,Fanhao Song,Tingting Li
Microbial communities serve as crucial mediators of dissolved organic matter (DOM) dynamics in seasonally ice-covered lakes. This comparative study of a saline plateau lake (Lake Daihai) and an eutrophic freshwater lake (Lake Wuliangsuhai) revealed distinct winter microbial patterns, with sediment communities exhibiting 2–3 times higher diversity than ice or water habitats. Fluorescence characterization identified fundamental differences in DOM sources, where saline lake DOM showed mixed terrestrial-autochthonous signatures (fluorescence index: 1.4–1.9), contrasting with the strongly microbial-derived DOM (FI > 1.9) in freshwater systems. Vertical profiling demonstrated progressive humification downward through ice layers, while microbial functional predictions indicated sustained amino acid metabolism despite subzero temperatures. The unique halotolerant community structure of the saline lake contrasted sharply with the psychrophilic Flavobacterium-dominated assemblages in freshwater habitats, reflecting differential adaptation to environmental stressors. Dissolved oxygen and salinity emerged as primary drivers of community composition, while phosphorus availability influenced specific functional groups involved in organic matter processing. These findings highlight the resilience of microbial-mediated carbon cycling under ice cover and provide critical baseline data for predicting ecosystem responses to changing winter conditions in inland waters.
A cement paste with low hydration heat flow is in high demand in hydrate layers cementing at low temperature to inhibit the hydrate decomposition. This paper prepared a heat flow inhibitor (HFI), which was compounded of disodium hydrogen phosphate dodecahydrate (DHPD), sodium silicate (SS) and nano calcium carbonate (NCC). DHPD was employed to reduce the heat flow of cement pastes. Porous ceramic particles were applied to carry DHPD to achieve slow-release. SS and NCC were employed to encapsulate and disperse the particles. The components were released in multi-stage into the cement paste to avoid their being blended into the cement paste at the same time. Setting time, thickening time , compressive strength , isothermal calorimetry , X-ray diffraction, mercury intrusion porosimetry and scanning electron microscopy were used to investigate the effects of HFI on cement hydration . The results showed that HFI reduced the hydration heat flow of cement pastes effectively, while displaying no negative impact on the compressive strength, setting time and thickening time. The maximum temperature of the cement paste dropped by 14.0 °C, and the maximum hydration heat flow was reduced by 28.75% at 8% HFI dosage . HFI is promising to be used in hydrate layers cementing.
危险品化学品经营许可证（带存储）