阿曼苏丹卡布斯大学Ali, Arshad课题组成员通过海水中增强岩石风化封存二氧化碳的实验研究，揭示了对沿海和开阔海洋环境中气候变化减缓策略的见解。这一研究成果发表在2024年9月18日出版的国际学术期刊《地球化学学报》上。

据研究人员介绍，本团队对来自巴基斯坦Mthemlim Bagh蛇绿岩中的超镁铁质岩的增强风化(EW)进行了实验研究，以探索碳封存作为沿海和开放海洋环境的气候变化缓解策略。本研究是一项成本效益高的非原位实验，以研究岩粉、海水和CO₂之间相互作用产生的EW反应路径的影响。

实验显示，随着比表面积的增大，来自不同研磨程度的橄榄岩样品的实验滤液显示出Mg/Ca比的降低，加快了反应速率。这表明原岩中浸出的镁元素可能在EW沉积过程中水镁石、蛇纹石和碳酸盐的形成过程中被消耗掉了。

尽管程度不同，类似的反应途径也是在角闪岩中观察到的化学变化的原因。另一方面，与原岩相比，实验残留物的燃烧损失量有所增加，表明EW通过多种反应途径促进H₂O和CO₂进入次生矿物结构，形成水辉石、蛇纹石和碳酸盐。实验残留物的热重分析根据它们的分解温度证实了这些矿物的存在。

此外，XRD分析在橄榄岩和角闪岩样品的残留物中发现了一系列碳酸盐，证实了碳化反应的发生。扫描电镜图像揭示了两种样品的结构变化，支持通过EW形成次生矿物，与未经处理样品的岩相研究观察结果一致。对海水中CO₂吸收的对照实验显示，pH值下降，突出了CO₂排放增加导致的海洋酸化。

然而，当岩石粉末被添加到海水—CO₂混合物中时，pH值增加了。这说明超镁铁质岩粉的EW可以通过形成次生矿物来封存CO₂，同时提高海水pH值。考虑到世界范围内具有丰度的超镁质岩石以及沿海和开阔海洋环境的可用性，该研究可以作为电子战应用的模拟。然而，在应用CO₂封存策略之前，还需要进一步研究其他元素在EW过程中的行为及其对海洋化学的影响。

附：英文原文

Title: Experimental studies on CO₂ sequestration via enhanced rock weathering in seawater: Insights for climate change mitigation strategies in coastal and open ocean environments

Author: Ali, Arshad, Kakar, Muhammad I., El-Ghali, Mohamed A. K., Rehman, Hafiz Ur, Abbasi, Iftikhar A., Moustafa, Mohamed

Issue&Volume: 2024-09-18

Abstract: Enhanced weathering (EW) of ultramafic rocks from the Muslim Bagh Ophiolite, Pakistan, has been studied in laboratory experiments to explore carbon sequestration as a climate change mitigation strategy for coastal and open sea environments. The research focused on a cost-effective ex situ experiment to examine the effects of EW reaction pathways arising from the interactions among rock powder, seawater and CO₂. The experimental filtrates from different milled peridotite samples exhibit a decrease in the Mg/Ca ratio as the specific surface area increases, which accelerates reaction rates. This suggests that the leached Mg from the original rock may have been consumed in the formation of brucite, serpentine and carbonates during EW. Similar reaction pathways are also responsible for the chemical alterations observed in amphibolite, albeit to varying degrees. On the other hand, the experimental residues showed an increase in loss on ignition compared to the original rock, indicating that EW has facilitated the incorporation of H₂O and CO₂ into secondary mineral structures through various reaction pathways, leading to the formation of brucite, serpentine and carbonates. Thermal gravimetric analysis of the experimental residues confirms the presence of these minerals based on their decomposition temperatures. Additionally, XRD analysis identified a range of carbonates in the residues of both peridotite and amphibolite samples, validating the occurrence of carbonation reactions. SEM images reveal textural changes in both samples, supporting the formation of secondary minerals through EW, consistent with observations from the petrographic study of untreated samples. Control experiments on CO₂ absorption in seawater showed a decrease in pH, highlighting ocean acidification from increased CO₂ emissions. However, when rock powder was added to the seawater-CO₂ mixture, the pH increased. This suggests that the EW of ultramafic rock powders can sequester CO₂ while raising seawater pH through the formation of secondary minerals. This research could serve as an analog for EW applications, considering the worldwide abundance of ultramafic rocks and the availability of coastal and open ocean environments. However, further research is required to understand the behavior of other elements and their impacts on ocean chemistry in EW processes before applying CO₂ sequestration strategies.

DOI: 10.1007/s11631-024-00735-w

Source: https://link.springer.com/article/10.1007/s11631-024-00735-w