Supplementary XRD Material for "Experimental Constraints on Barium Isotope Fractionation during Adsorption-Desorption Reactions: Implications for Weathering and Erosion Tracer Applications"

Repository Overview: Supplementary powder X-ray diffraction (XRD) data for the study "Experimental Constraints on Barium Isotope Fractionation during Adsorption-Desorption Reactions: Implications for Weathering and Erosion Tracer Applications"

Data Provided: Powder X-ray diffractograms of the minerals used in the laboratory batch experiments. Pow

Minerals Analysed:

Clay Minerals:

Kaolinite (KGa-2): purchased from the Clay Minerals Society (CMS).

Montmorillonite (SWy-2): purchased from the Clay Minerals Society (CMS).

Iron Oxyhydroxide Minerals:

Goethite synthesised under alkaline conditions in the laboratories at the Department of Earth Sciences, University of Cambridge, following the method detailed in Schwertmann and Cornell (2008).

2-line ferriydrite synthesised in the laboratories at the Department of Earth Sciences, University of Cambridge, following the method detailed in Schwertmann and Cornell (2008) methods.

XRD Methods:

Instrument and Set Up: Theta-Theta D8 Bruker Advance diffractometer with a Mo anode, Lynxeye XE-T PSD detector and 2 mm divergent slit.

Sample Preparation: Zero-background monocrystalline silicon plate was used to minimize sample mass. The X-ray diffractogram of the silicon plate was measured prior to each sample measurement.

Clay Minerals: 0.02° step size and a 3s step rate.

Iron Oxyhydroxide Minerals: 0.03° increments and a 1s step rate.

Purpose of XRD Analyses:

To verify the correct synthesis of iron oxyhydroxide phases and to detect impurities.

To monitor any mineralogical changes that occurred during adsorption-desorption reactions with water.

Data Format

Column Name
Description
Unit

twotheta
2θ
°

intensity
intensity
counts per second (cps)

ID
mineral ID
unitless

mineral
mineral name
unitless

duration
reaction duration
minutes

Extra Notes

A reaction duration of zero minutes corresponds to an unreacted mineral sample.

数据集仓库概述：本研究《吸附-解吸反应过程中钡同位素分馏的实验约束及其在风化侵蚀示踪应用中的启示》的辅助粉末X射线衍射（XRD）数据集。

提供的数据：实验室批量实验所用矿物的粉末X射线衍射图谱。

分析矿物：

黏土矿物：

高岭石（Kaolinite, KGa-2）：购自黏土矿物学会（Clay Minerals Society, CMS）。

蒙脱石（Montmorillonite, SWy-2）：购自黏土矿物学会（Clay Minerals Society, CMS）。

铁羟基氧化物矿物：

针铁矿（Goethite）：遵循Schwertmann与Cornell（2008）所述方法，于剑桥大学地球科学系实验室碱性条件下合成。

2线水铁矿（2-line ferrihydrite，原文拼写为ferriydrite）：于剑桥大学地球科学系实验室按照Schwertmann与Cornell（2008）所述方法合成。

X射线衍射分析方法：

仪器与设置：采用Theta-Theta型D8 Bruker Advance衍射仪，配置Mo靶、Lynxeye XE-T PSD探测器及2 mm发散狭缝。

样品制备：使用零背景单晶硅片以减少样品用量。每次样品测量前，均预先采集单晶硅片的X射线衍射图谱作为本底。

黏土矿物测试参数：步长0.02°，步速3秒/步。

铁羟基氧化物矿物测试参数：步长0.03°，步速1秒/步。

X射线衍射分析目的：

1. 验证铁羟基氧化物物相的合成正确性，并检测样品中的杂质；
2. 监测矿物在与水发生吸附-解吸反应过程中产生的矿物学变化。

数据格式：

| 列名 | 描述 | 单位 |
| twotheta | 2θ | 度（°） |
| intensity | 强度 | 每秒计数（cps） |
| ID | 矿物标识 | 无单位 |
| mineral | 矿物名称 | 无单位 |
| duration | 反应时长 | 分钟 |

附加说明：反应时长为0分钟对应未经过反应的原始矿物样品。