This study investigates the impacts of sample preparation procedures on grain-size measurements to determine comparability of data collected using differing methodologies. Grain-size distributions of marine and terrestrial sediments contain important information about the depositional environment. For example, the “sortable-silt index” (⁠or mean grain size between 10 and 63 μm in marine sediments, is used as an indicator of flow speed and has been applied to the reconstruction of ocean current strength before the instrumental period. Similarly, the mean grain size of a sediment is used to classify it (e.g., silt versus sand). Accurate measurements of grain-size distributions often require chemical pre-treatments in order to remove sedimentary components of biogenic origin (e.g., shells), and multiple ways to perform these pre-treatments exist. This study tests whether the choice of pre-treatment introduces variability into grain-size distributions. We simulate multiple commonly used pre-treatments on a well-characterized internal standard (“Sillikers”) and compare the resulting mean size and sortable-silt index in each treatment group to untreated samples using ANOVA. Two instruments, a Coulter Counter Multisizer III and a Coulter LS 230 Laser Diffraction Analyzer are used. Results from the Multisizer III suggest that the choice of pre-treatment method does not significantly impact the final grain-size distributions but underlines the importance of replicates. Results from the laser sizer suggest that oven-drying leads to a small but statistically significant difference of ∼ 0.3 μm in the sortable-silt index, and drying samples via hot plate leads to another small but statistically significant difference of ∼ 0.29 μm. While it is unclear what causes these differences in the laser sizer data, they are smaller than the observed variations in sortable-silt index used to infer changes in current speed in a typical paleoclimate study. In conclusion, grain-size measurements are a robust tool for sediment analysis and are resistant to changes from differing pre-treatment methods tested here.

中文翻译：

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粒度分析中常见的预处理分析（使用粒度标准）

本研究调查样品制备程序对粒度测量的影响，以确定使用不同方法收集的数据的可比性。海洋和陆地沉积物的粒度分布包含有关沉积环境的重要信息。例如，“可分类淤泥指数”（或海洋沉积物中的平均粒度在 10 到 63 微米之间，用作流速的指标，并已应用于仪器时期之前的洋流强度重建。类似地, 沉积物的平均粒度用于对其进行分类（例如，淤泥与沙子）。粒度分布的准确测量通常需要化学预处理以去除生物来源的沉积成分（例如，贝壳），以及存在多种执行这些预处理的方法。本研究测试预处理的选择是否会在粒度分布中引入可变性。我们在充分表征的内标（“Sillikers”）上模拟多种常用的预处理，并使用 ANOVA 将每个处理组中得到的平均大小和可分选淤泥指数与未处理样品进行比较。使用了两种仪器，Coulter Counter Multisizer III 和 Coulter LS 230 激光衍射分析仪。Multisizer III 的结果表明，预处理方法的选择不会显着影响最终的粒度分布，但强调了重复的重要性。激光分级仪的结果表明，烘箱干燥导致可分选淤泥指数出现 ∼ 0.3 μm 的微小但具有统计学意义的差异，通过热板干燥样品会导致另一个小的但具有统计学意义的差异，约为 0.29 μm。虽然尚不清楚是什么原因导致激光粒度仪数据出现这些差异，但它们小于在典型古气候研究中用于推断当前速度变化的可分选淤泥指数中观察到的变化。总之，粒度测量是沉积物分析的强大工具，并且可以抵抗此处测试的不同预处理方法的变化。