Bioaccumulation and trophic transfer of PAHs in the Yellow River Estuary
food web: A fugacity-based model for ecological and human health risk assessment
1、Introduction：
Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants (POPs) composed of two or more fused benzene rings and are characterized by their high toxicity, mutagenicity, and carci- nogenicity. These compounds are derived primarily from anthropogenic activities, such as the incomplete combustion of biomass, vehicle exhaust emissions, industrial and agricultural processes, and oil spills (Wang et al., 2007). Once released, PAHs can enter the marine envi- ronment through atmospheric deposition and surface runoff and are commonly found in seawater, sediments, and marine organisms. Aquatic organisms absorb PAHs directly from the water or indirectly through the ingestion of suspended particles and contaminated food, leading to adverse effects such as tumors, tissue lesions, and developmental
malformations (Lourenço et al., 2021; Wang et al., 2025). Humans are primarily exposed via seafood consumption, which can increase the risks of cancer, genetic mutations, immune deficiencies, and developmental delays (Oliva et al., 2017). Certain PAHs biomagnify across trophic levels (TLs), amplifying these risks (Wang et al., 2025). Owing to their persistent and bioaccumulative nature, PAHs have been a focus of environmental research in recent decades (Yang et al., 2020).
Food webs are fundamental components of marine ecosystems and play a critical role in maintaining ecosystem structure and function. However, aquatic food webs are highly complex and consist of numerous interacting species, which makes traditional biological monitoring methods time-consuming, labor-intensive, and costly (Wang et al., 2011). The bioaccumulation of PAHs in these systems is signifi- cantly influenced by the dynamic balance between pollutant uptake and
excretion, which is governed by multiple interrelated factors. Directly analyzing these mechanisms in the field is challenging, but fugacity- based food web models are an efficient and practical approach for pre- dicting the concentrations of hydrophobic organic pollutants, such as PAHs, in organisms (Campfens and Mackay, 1997). Campfens and Mackay already confirmed as early as 1997 that the model’s prediction of organic pollutants in food webs based on fugacity significantly out- performs traditional concentration-based empirical models (Campfens and Mackay, 1997). Subsequent studies have verified its applicability: Wang et al. (2011) developed a fugacity-based food web model to simulate the bioaccumulation of dichloro-diphenyl-trichloroethanes (DDTs) in the aquatic ecosystem of Bohai Bay; Hu et al. (2014) estab- lished a fugacity-based model to simulate the bioaccumulation of butyltins in the food web of the mariculture area of Jincheng Bay. Most of these studies have focused primarily on ecological impacts, with relatively few investigating the potential health risks of organic pollut- ants to humans. Therefore, there is an urgent need to further develop an integrated method combining food web simulation and health risk assessment on the basis of routine monitoring, so as to provide technical support for the scientific prevention and control of PAHs and their ecological and health hazards.
The Yellow River Estuary(YRE), China’s first national park in which land–sea management is integrated, serves as a key habitat for the spawning, feeding, overwintering, and migration of aquatic organisms in the Bohai and Yellow Seas. It also hosts China’s second-largest oil- field—the Shengli Oilfield, and a thriving mariculture industry (Gentry et al., 2017). However, its semienclosed location makes it highly sen- sitive to pollution, and oil exploration has exacerbated PAH contami- nation (Chen et al., 2023; Zhang et al., 2023a). Zhang et al. (2023a) investigated PAH bioaccumulation in YRE organisms and associated human health risks, but the study was limited to a single species—failing to extend to the entire food web or analyze PAH trophic transfer. In contrast, Zhang et al. (2024) constructed a YRE food web via isotope analysis to explore PAH trophic transfer, yet this research only involved a simplified food web and lacked links to environmental media (e.g., seawater, sediments). To fill these gaps and address PAH pollution around YRE oil platforms, we employ a fugacity-based food web model combined with field data to investigate the bioaccumulation and trophic transfer of the 16 USEPA priority PAHs across the YRE’s entire food web.
This approach enables a comprehensive, systematic, and mechanistic understanding of PAH migration. Furthermore, health risk thresholds were also established for key marine functional groups, including fish, crustaceans, and mollusks, thus providing a scientific basis for evalu- ating the ecological impacts of PAHs and developing targeted environ- mental protection strategies.
2、Materials and methods：
2.1. Study area
The Yellow River Estuary is located at the confluence of Bohai Bay and Laizhou Bay, forming a typical coastal estuarine ecosystem. It serves as a critical spawning, feeding, and overwintering ground, as well as a migration corridor, for aquatic organisms in the Bohai Sea and Yellow Sea regions. Consequently, the Yellow River Estuary plays a vital role in biodiversity conservation both in China and globally. The present study focused on the waters surrounding a drilling platform of the Kenli 3–2 Oilfield in the Kenli District within the Yellow River Estuary (Fig. 1).
2.2. Sampling and analysis
Surface seawater, bottom seawater, sediment, and marine organism samples were collected from the coastal waters of the Kenli District, Dongying City, Shandong Province, in October 2022. Each sampling site was collected with one surface seawater sample, one bottom seawater sample, and one sediment sample, resulting in a total of 30 samples. Additionally, 20 species of marine organisms were collected, and the species are listed in Table S3. Detailed procedures for the collection and analysis of the seawater and sediment PAH samples are described in Liu et al. (2024). The samples were sent for testing within 24 h after collection, and the testing department was the Water Environment Remediation Laboratory of the College of Environmental Science and Engineering, Ocean University of China, which has CMA qualifications. Sixteen PAHs were analyzed by gas chromatography–mass spectrometry (GC–MS: Agilent 6890 N-5975B) in marine organism. The concentration procedure for marine organism samples was consistent with that used for sediment samples, as described by Liu et al. (2024). The total organic carbon (TOC) content of each sediment sample was determined in
accordance with the method described by Wang et al. (2011). The organic carbon content (0.4182) was calculated using the van Bemme- len factor according to the formula: organic carbon content = organic matter content/1.724.
Quality assurance and quality control (QA/QC) procedures were used, and the recoveries and blank concentrations were within the acceptable range.
