Fang Yihang, Lee Seungyeol, Xu Huifang, Farfan Gabriela A
Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia 20560, United States.
Cryst Growth Des. 2023 May 31;23(7):4872-4882. doi: 10.1021/acs.cgd.3c00102. eCollection 2023 Jul 5.
Calcium carbonate minerals, such as aragonite and calcite, are widespread in biomineral skeletons, shells, exoskeletons, and more. With rapidly increasing CO levels linked to anthropogenic climate change, carbonate minerals face the threat of dissolution, especially in an acidifying ocean. Given the right conditions, Ca-Mg carbonates (especially disordered dolomite and dolomite) are alternative minerals for organisms to utilize, with the added benefit of being harder and more resistant to dissolution. Ca-Mg carbonate also holds greater potential for carbon sequestration due to both Ca and Mg cations being available to bond with the carbonate group (CO). However, Mg-bearing carbonates are relatively rare biominerals because the high kinetic energy barrier for the dehydration of the Mg-water complex severely restricts Mg incorporation in carbonates at Earth surface conditions. This work presents the first overview of the effects of the physiochemical properties of amino acids and chitins on the mineralogy, composition, and morphology of Ca-Mg carbonates in solutions and on solid surfaces. We discovered that acidic, negatively charged, hydrophilic amino acids (aspartic and glutamic) and chitins could induce the precipitation of high-magnesium calcite (HMC) and disordered dolomite in solution and on solid surfaces with these adsorbed biosubstrates via experiments. Thus, we expect that acidic amino acids and chitins are among the controlling factors in biomineralization used in different combinations to control the mineral phases, compositions, and morphologies of Ca-Mg carbonate biomineral crystals.
碳酸钙矿物，如文石和方解石，广泛存在于生物矿化骨骼、贝壳、外骨骼等之中。随着与人为气候变化相关的二氧化碳水平迅速上升，碳酸盐矿物面临溶解威胁，尤其是在海洋酸化的情况下。在合适的条件下，钙镁碳酸盐（特别是无序白云石和白云石）是生物体可利用的替代矿物，其额外好处是更坚硬且更耐溶解。由于钙和镁阳离子都可与碳酸根（CO）结合，钙镁碳酸盐在碳封存方面也具有更大潜力。然而，含镁碳酸盐是相对稀有的生物矿物，因为镁水络合物脱水的高动能障碍在地球表面条件下严重限制了镁在碳酸盐中的掺入。这项工作首次概述了氨基酸和几丁质的物理化学性质对溶液中和固体表面上钙镁碳酸盐的矿物学、组成和形态的影响。通过实验我们发现，酸性、带负电荷的亲水性氨基酸（天冬氨酸和谷氨酸）和几丁质能够在溶液中和带有这些吸附生物底物的固体表面上诱导高镁方解石（HMC）和无序白云石的沉淀。因此，我们预计酸性氨基酸和几丁质是生物矿化中的控制因素之一，它们以不同组合用于控制钙镁碳酸盐生物矿化晶体的矿物相、组成和形态。
