Localized alteration of ferrihydrite natural organic matter coprecipitates following reaction with Fe(II)
Localized alteration of ferrihydrite natural organic matter coprecipitates following reaction with Fe(II)
复制标题
水铁矿天然有机物与 Fe(II) 反应后共沉淀的局部变化
DOI：
10.1002/saj2.20366
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发表时间：
2022
影响因子：
2.9
通讯作者：
Thompson, Aaron
中科院分区：
文献类型：
--
作者：
Noor, Nadia;Thompson, Aaron
天然有机物（NOM）与水铁矿（Fh）的共沉淀可以改变Fe（II）催化转化的轨迹。高C/Fe摩尔比的Fh-NOM共沉淀物预期完全抵抗转化并保留有机物质（OM）。为了探索异质NOM如何影响这一过程，我们将低（0.8）和高（1.8）C/Fe摩尔比的Fh-NOM共沉淀物（用a13 C标记的植物凋落物提取物合成）与2 mM Fe（II）在缺氧条件下反应1和14 d，并用穆斯堡尔谱（MBS）和扫描透射电子显微镜的二次电子图像检查固相的变化。穆斯堡尔谱学数据表明，Fe（II）与共沉淀物的相互作用增加了Fe矿物的结晶度，降低了C/Fe摩尔比和延长了老化时间。然而，从头结晶相的发展仅在Fe（II）反应的共沉淀物中观察到（通过二次电子图像），并且仅当有机碳（OC）负载低时。例如，低C/Fe共沉淀物在与Fe（II）反应1 d后形成局部板条状晶体相，而板条状相仅在高C/Fe共沉淀物中在失去一些NOM（C/Fe比从1.8降低至0.7）并与Fe（II）反应14 d后形成。此外，在所有处理中，共沉淀物13 C-NOM与培养基（可能是有机PIPES缓冲液）中的C发生部分交换，但与Fe（II）反应加剧，表明共沉淀物OM组成可能随时间推移而演变，特别是当暴露于Fe（II）时。我们的研究结果表明，Fe（II）介导的Fh-NOM转化是高度动态的，并有可能影响Fh中NOM的稳定性。
Coprecipitation of natural organic matter (NOM) with ferrihydrite (Fh) can alter the trajectory of Fe(II)‐catalyzed transformation. High C/Fe molar ratio Fh‐NOM coprecipitates are expected to resist transformation completely and preserve organic matter (OM). To explore how heterogeneous NOM would influence this process, we reacted low (0.8) and high (1.8) C/Fe molar ratio Fh‐NOM coprecipitates (synthesized with a13C‐labeled plant litter extract) with 2 mM Fe(II) for 1 and 14 d under anoxic conditions and examined changes in the solid phase with Mössbauer spectroscopy (MBS) and secondary electron images using scanning transmission electron microscope. Mössbauer spectroscopy data suggests Fe(II) interaction with coprecipitates increases Fe mineral crystallinity, as did lower molar C/Fe ratios and longer aging times. However, de novo crystal phase development was only observed (via secondary electron images) in the Fe(II)‐reacted coprecipitates and only when the organic carbon (OC) loading was low. For example, the low C/Fe coprecipitate developed localized lath‐like crystal phases after 1 d of reaction with Fe(II), while the lath‐like phases only developed in the high C/Fe coprecipitates after they lost some NOM (C/Fe ratio decreased from 1.8 to 0.7) and reacted with Fe(II) for 14 d. In addition, partial exchange of coprecipitate13C‐NOM for C in the media (likely the organic PIPES buffer) occurred in all treatments but was accentuated by reaction with Fe(II), suggesting coprecipitate OM composition likely evolves over time, especially when exposed to Fe(II). Our findings suggest that Fe(II) mediated Fh‐NOM transformation is highly dynamic and has the potential to influence the stability of NOM in Fh.