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Deciphering the Incipient Phases of Ice–Mineral Interactions as a Precursor of Physical Weathering
ACS Earth and Space Chemistry ( IF 2.9 ) Pub Date : 2021-04-19 , DOI: 10.1021/acsearthspacechem.0c00345
Rebecca A. Lybrand 1, 2 , Daniel P. Veghte 3 , Swarup China 3 , Dragos G. Zaharescu 4 , Christopher R. Anderton 3 , Ruben Aleman 1 , Paul A. Schroeder 5 , Odeta Qafoku 3
Affiliation  

The formation of ice on particles in the atmosphere influences Earth’s global hydrological cycle and is widely studied given the impacts of ice nucleation on precipitation and climate. Yet, the intricacies of freeze–thaw processes in natural soils, such as how ice nucleation on mineral surfaces is influenced by soil organic matter and biological activity, needs additional insight. We assessed in situ ice nucleation on unreacted mineral particles and particles containing fungal–mineral interfaces and coatings following exposure to natural soil and laboratory weathering conditions. Our experiments were performed with an ice nucleation chamber interfaced with an environmental scanning electron microscope, where in situ ice formation was examined via rapid imaging of individual mineral particles at submicron resolutions. Our results indicate that mineral coatings, presumably from soil microbes, influence where and how ice forms whereas fungal–mineral contacts did not impact ice nucleation activity in this study. We observed that mineral grains exposed to biological activity in natural soil conditions showed enhanced ice formation at significantly lower relative humidity with respect to ice formation when compared to unreacted grains. This work contributes to a growing body of evidence suggesting the importance of soil organic matter for promoting ice nucleation activity on particles suspended in the atmosphere and those in soil. Furthermore, identifying the intricacies of ice formation on mineral grains and the organic coatings that originate from soil represents an important area of emerging research that will advance understanding of how Earth’s surface erodes and how well rock-derived nutrients can be delivered to plants.

中文翻译:

解释冰矿相互作用的初始阶段作为物理风化的前兆

大气中颗粒上冰的形成会影响地球的全球水文循环,鉴于冰成核对降水和气候的影响,人们对此进行了广泛的研究。然而,天然土壤中冻融过程的复杂性,例如矿物表面上的冰成核如何受到土壤有机质和生物活性的影响,还需要更多的见识。暴露于天然土壤和实验室风化条件后,我们评估未反应的矿物颗粒以及含有真菌-矿物界面和涂层的颗粒的原位冰成核作用。我们的实验是用与环境扫描电子显微镜相连接的冰成核腔室,在那里进行原位通过以亚微米分辨率对单个矿物颗粒进行快速成像,检查了冰的形成。我们的结果表明,可能来自土壤微生物的矿物涂层影响冰的形成位置和方式,而真菌-矿物质的接触并不影响冰的成核活性。我们观察到,与未反应的谷物相比,在天然土壤条件下暴露于生物活性的矿物质谷物在相对较低的相对湿度下相对于冰形成具有增强的冰形成。这项工作为越来越多的证据做出了贡献,这些证据表明土壤有机物对于促进悬浮在大气中的颗粒和土壤中的颗粒上的冰成核活性至关重要。此外,
更新日期:2021-05-20
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