Multi-Stage Screening Purification: A New and Effective Method for Cleaning Diatom Samples from Marine Sediments

Diatoms are critical indicators in marine paleoecology and contemporary ecosystem studies, yet the accuracy of diatom analysis depends on effective purification methods. Current screening and purification techniques often yield low accuracy. This study introduces a multi-stage screening purification method that integrates both physical and chemical techniques to enhance the extraction of diatom remains from marine sediments, thereby improving the reliability of subsequent analysis. Using surface sediment samples from the Pacific Ocean, we compared the effectiveness of three purification methods: heavy liquid suspension purification, single-layer screening purification, and the newly developed multi-stage screening purification method. The study aimed to evaluate the impact of each method on diatom abundance, valve size distribution, and the accuracy of taxonomic identification. The results revealed that the multi-stage method significantly improved the accuracy of diatom abundance calculation. With this method, diatom abundance was 21.9 times higher than that obtained using the heavy liquid suspension method and 6.5 times higher than that obtained using the single-stage method. This method also proved to be cost-effective, easy to use, and produced samples with low impurity levels, which enhanced microscopic observation, identification, and the reliability of taxonomic statistics. Key factors influencing diatom abundance included sieve pore size, heavy liquid concentration, and valve size and density, while the type of acid and oxidant had minimal effect. Additionally, the multi-stage screening method facilitated the classification of diatoms into various size categories, providing a comprehensive view of diatom size distribution, including nano-sized diatoms (diameter < 20 μm) that are often overlooked in traditional studies. These findings demonstrate that the multi-stage screening purification method is an effective tool for improving the analysis of diatom remains in sediments, potentially refining the accuracy of diatom-based environmental investigations and paleoceanographic reconstructions.