Ancient aquatic environments in Yellowknife Bay, Gale crater, Mars, could create favorable conditions for adsorption of chlorine compounds (perchlorate and chloride) on Fe (III) (hydr)oxides present in the Sheepbed mudstone, such as akaganeite and ferrihydrite. In this work, 5.2 mM ClO₄⁻ and 1.7 to 12 mM Cl⁻ were adsorbed onto ferrihydrite and 5.2 mM ClO₄⁻ was adsorbed onto akaganeite at ultraacidic (pH 2–2.5), acidic (pH 3.8–4.5), and near‐neutral (pH 6.2–7.7) pH. Samples were characterized by evolved gas analysis and compared to the data collected for the Cumberland sample from the Sheepbed mudstone. Evolved gas analysis showed that ferrihydrite with 0.5–1 wt.% ClO₄⁻ adsorbed under ultraacidic and acidic conditions had a well‐resolved O₂ peak at 306 °C due to the thermal decomposition of adsorbed ClO₄⁻. All akaganeite samples with 0.5 wt.% adsorbed ClO₄⁻ had a weak peak at 312 °C tentatively assigned to decomposing perchlorate. Evolved gas analysis demonstrated that 0.5–2 wt.% Cl⁻ adsorbed on ferrihydrite at ultraacidic and acidic pH was the main contributor to HCl evolved at >470 °C. Comparison with martian observations indicated that the temperature of the O₂ peak originating from ClO₄⁻ adsorbed on ferrihydrite matched well with the thermal evolution of O₂ from the Cumberland. Evolved HCl originating from Cl⁻ adsorbed on ferrihydrite was within the temperature range of the high‐temperature HCl release from Cumberland (~770 °C). These observations suggest that ferrihydrite containing adsorbed ClO₄⁻ and Cl⁻ could exist in the mudstone. Experimental results are consistent with adsorption at acidic pH < 4 environments through postdepositional water‐rock interactions of ferrihydrite with acid‐sulfate groundwater containing dissolved chloride and perchlorate.

中文翻译：

---

在火星上大风火山口的羊床泥岩中，氯离子被三价铁吸附的证据。

火星大风火山口的耶洛奈夫湾的古代水生环境可以为吸附在床层泥岩中的铁（III）（氢）氧化物（如赤铁矿和水铁矿）上的氯化合物（高氯酸盐和氯化物）创造有利条件。在这项工作中，5.2毫CLO ₄ ^-和1.7至12mM的氯^-被吸附到水铁矿和5.2毫CLO ₄ ^-在ultraacidic（pH为2-2.5），酸性的（pH值3.8-4.5）吸附到akaganeite，和近中性（pH 6.2–7.7）pH。通过析出气体分析对样品进行表征，并将其与从羊床泥岩中采集的坎伯兰郡样品的数据进行比较。逸出气体分析表明，水铁矿与0.5-1重量％的CLO。₄ ^-吸附ultraacidic和在酸性条件下有良好分辨ö ₂在306℃下的峰由于吸附CLO的热分解₄ ^- 。所有akaganeite样品用0.5％（重量）被吸附CLO。₄ ^-在312有一个弱峰℃下暂时分配给分解高氯酸盐。逸出气体分析表明，0.5-2重量％的Cl。^-在ultraacidic和酸性pH吸附在水铁矿是主要贡献者的HCl演进在> 470℃。与火星观察比较表明，将O的温度₂从CLO峰始发₄ ^-吸附在水铁矿与的O-热演化匹配良好₂来自坎伯兰郡。选自Cl演进盐酸始发^-吸附在水铁矿是温度范围从坎伯兰（〜770℃）的高温的HCl释放的范围内。这些观测结果表明含有吸附CLO那铁矿₄ ^-和Cl ^-可在泥岩存在。实验结果与亚铁酸盐与含有溶解的氯化物和高氯酸盐的酸性硫酸盐地下水的沉积后水-岩相互作用在酸性pH <4环境下的吸附相一致。