Shen Yating, Lu Dongyu, Zhu Shuai, Pan Meng, Yang Zhipeng, Chen Mei, Fang Xiaochen
National Research Center for Geo-analysis (NRCGA), Beijing, China.
Key Laboratory of Eco-Geochemistry, Ministry of Natural Resources of China, Beijing, China.
Water Environ Res. 2025 May;97(5):e70073. doi: 10.1002/wer.70073.
Polycyclic aromatic hydrocarbons (PAHs) and other aromatic hydrocarbons are persistent environmental contaminants with diverse origins, posing significant risks to marine ecosystems. This study investigates the concentrations, vertical distribution, and sources of these pollutants in the South China Sea near the Xisha Islands, a region with distinct oceanographic conditions and anthropogenic influences. A total of 23 aromatic hydrocarbon compounds were analyzed, including 17 PAHs, 3 phenols, and 3 chlorobenzenes. Of these, 3 PAHs (fluorene, benzo[k]fluoranthene, and dibenz[a,h]anthracene) were below detection limits. Seawater samples collected at four depths (200, 400, 1000, and 1200 m) revealed distinct depth-dependent patterns. Lower-molecular-weight PAHs (2-3 rings) exhibited higher concentrations at shallower depths (200 m and 400 m), likely influenced by atmospheric deposition and surface runoff. High-molecular-weight PAHs (4-6 rings) were found in lower concentrations but persisted at greater depths due to their higher stability and slower degradation rates. Methylated PAHs, such as 2-methylnaphthalene and 1-methylnaphthalene, were concentrated at intermediate depths, suggesting ongoing degradation processes and historical inputs. Phenolic and chlorobenzene compounds displayed relatively consistent concentrations across depths, indicating widespread anthropogenic influence. These results highlight the combined impact of natural and anthropogenic sources, including industrial discharges, shipping activities, and atmospheric transport, on the distribution of aromatic hydrocarbons in the South China Sea. The study provides critical baseline data for understanding pollutant behavior in deep-sea environments and emphasizes the importance of targeted monitoring and effective management strategies to mitigate their ecological impacts. PRACTITIONER POINTS: PAHs and methylated PAHs - Concentrations vary with depth, suggesting diverse sources. Shallow waters -High anilines, phenols, and chlorobenzenes indicate recent inputs. Deeper waters - Complex PAHs persist, highlighting long-term ecological risks. Degradation - Methylated PAHs degrade uniquely, affecting health risk assessments. Management - Findings inform effective monitoring and mitigation of marine pollution.
多环芳烃（PAHs）和其他芳烃是具有多种来源的持久性环境污染物，对海洋生态系统构成重大风险。本研究调查了西沙群岛附近南海这些污染物的浓度、垂直分布和来源，该区域具有独特的海洋学条件和人为影响。共分析了23种芳烃化合物，包括17种多环芳烃、3种酚类和3种氯苯。其中，3种多环芳烃（芴、苯并[k]荧蒽和二苯并[a,h]蒽）低于检测限。在四个深度（200、400、1000和1200米）采集的海水样本显示出明显的深度依赖性模式。低分子量多环芳烃（2 - 3环）在较浅深度（200米和400米）浓度较高，可能受大气沉降和地表径流影响。高分子量多环芳烃（4 - 6环）浓度较低，但由于其较高的稳定性和较慢的降解速率，在更深的深度持续存在。甲基化多环芳烃，如2 - 甲基萘和1 - 甲基萘，集中在中间深度，表明正在进行的降解过程和历史输入。酚类和氯苯化合物在各深度的浓度相对一致，表明广泛的人为影响。这些结果突出了自然和人为来源（包括工业排放、航运活动和大气传输）对南海芳烃分布的综合影响。该研究为理解深海环境中的污染物行为提供了关键的基线数据，并强调了有针对性监测和有效管理策略以减轻其生态影响的重要性。从业者要点：多环芳烃和甲基化多环芳烃——浓度随深度变化，表明来源多样。浅水区——高苯胺、酚类和氯苯表明近期输入。深水区——复杂多环芳烃持续存在，突出长期生态风险。降解——甲基化多环芳烃独特降解，影响健康风险评估。管理——研究结果为有效监测和减轻海洋污染提供依据。
