Release of PAHs from sediments to seawater under wave: Indoor microcosms and level IV fugacity models

• Published in: Journal of hazardous materials 2024-08, Vol.474, p.134799, Article 134799
• Main Authors: Lu, Zhiyang, Tian, Weijun, Chen, Zhuo, Chu, Meile, Zhang, Surong, Liu, Bingkun, Zhao, Jing, Zou, Mengyuan, Huo, Bingjie, Xu, Guohui
• Format: Article
• Language: English
• Subjects: Level IV fugacity model; Polycyclic aromatic hydrocarbons; Release; Seawater-sediment system; Wave
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.134799

Estuaries and coasts are located at the land-sea interface, where sediment liquefaction due to strong wave action results in significant material exchange at the sediment-seawater system. Polycyclic aromatic hydrocarbons (PAHs), as organic pollutants, are distributed across various media. Herein, the impact of wave was studied on the release of PAHs through indoor microcosmic experiments combined with a level IV fugacity model. Comparison revealed that the release amount and rate of PAHs during static consolidation stage were minimal, whereas wave action substantially enhanced the release. Particularly the sediments in a liquefied state, the PAHs release in Stage III was 1.55–1.86 times that in Stage II, reaching 84.73 μg/L. The loss of soil strength and strong hydrodynamic effects resulted in a substantial release of PAHs into seawater along with suspended solids. Due to volatility of 2-ring PAHs and difficult desorption of 6-ring PAHs, 3–5-ring PAHs are the main contributors to releases into seawater. The model results also indicated that the three PAHs had different fates in the sediment-seawater system, with sediment serving as an important "reservoir" for benzo[a]pyrene entering seawater, while functioning as both a "sink" and a "source" for pyrene. [Display omitted] •A novel method combining indoor microcosms with models was proposed to study waves.•The concentration of PAHs in seawater was positively correlated with SS.•3-5-ring PAHs were the main contributors to releases into seawater.•The release of PAHs was increased by 0.55 to 0.86 times by sediment liquefaction.•43.06 % of Pyr was stored in sediments, which were both a "sink" and a "source".