Abstract：
Pen shells (PS), a type of shellfish, are abundantly consumed, and their inedible shell residues are often discarded near the coast without consideration of reutilization. This study sought to investigate the use of natural pen shells (NPS) and calcined pen shells (CPS) to stabilize Pb and As-contaminated soil. During the investigation, NPS and CPS were applied to the contaminated soil in amounts ranging from 1 to 10 wt% and cured for 28 days. After the curing process, the mineral phase was examined through X-ray powder diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analysis. The XRD and SEM-EDX results revealed the presence of riversideite and ettringite, which contribute to Pb and As stabilization in the CPS-treated soil. The leachability of Pb and As in the treated soil was further examined with three types of chemical extraction methods. Extraction results using 0.1 M HCl displayed a notable pH fluctuation in the extractant due to the residual amendments (NPS and CPS). The fluctuation resulted in a strong correlation of leached Pb and As with the pH of the extractant, which might hinder an accurate assessment of stabilization. In order to minimize the effect of pH, an EDTA-NH4OAc extraction was employed, suggesting its potential as a suitable assessment method. EDTA-NH4OAc extraction showed a higher effectiveness of CPS than NPS at 10 wt% of input amounts. In the SBET extraction, that uses a strongly acidic solution, a higher As leachability was observed by increasing the addition of CPS, which implied a CPS-related chemical fixation mechanism. The comparison of various extraction methods showed a higher CPS effectiveness as compared to NPS. However, it was recommended that CPS-treated soil required caution in strongly acidic conditions, especially for arsenic. This study explores the applicability of PS, which has not been investigated as an amendment for Pb and As-contaminated soil previously. Furthermore, this study revealed that utilization of various extraction methods is beneficial for gaining a comprehensive understanding of the role of CaCO3-based amendment in Pb and As-contaminated soil.
摘要：
笔壳（PS），一种贝类,大量消费，它们不可食用的贝壳残留物经常被丢弃在海岸附近，而不考虑再利用。这项研究旨在研究使用天然笔壳（NPS）和煅烧笔壳（CPS）来稳定Pb和As污染的土壤。在调查过程中,将NPS和CPS以1至10wt％的量施用于受污染的土壤，并固化28天。在固化过程之后,通过X射线粉末衍射（XRD）和扫描电子显微镜以及能量色散X射线光谱（SEM-EDX）分析检查了矿物相。XRD和SEM-EDX结果表明，钙矾石和钙矾石的存在，这有助于CPS处理土壤中Pb和As的稳定。用三种化学提取方法进一步检查了处理后土壤中Pb和As的可浸出性。使用0.1MHCl的萃取结果显示，由于残留的改良剂（NPS和CPS），萃取剂中的pH值出现明显波动。波动导致浸出的Pb和As与萃取剂的pH值有很强的相关性，这可能会阻碍对稳定的准确评估。为了最小化pH的影响，采用EDTA-NH4OAc萃取，提出了它作为一种合适的评估方法的潜力。EDTA-NH4OAc萃取在10wt%的输入量下显示CPS比NPS更高的效力。在SBET提取中，使用强酸性溶液，通过增加CPS的添加观察到更高的As浸出性，这暗示了与CPS相关的化学固定机制。各种提取方法的比较显示与NPS相比更高的CPS有效性。然而,建议CPS处理的土壤在强酸性条件下需要谨慎，尤其是砷。本研究探讨了PS的适用性，以前没有对铅和砷污染土壤的改良进行过研究。此外，这项研究表明，利用各种提取方法有助于全面了解CaCO3基改良剂在Pb和As污染土壤中的作用。
