Abstract：
Seasonal water and sediment samples were collected from the Xiaoqing River estuary and the neighboring sea to study the spatial and temporal distributions, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The results showed significant spatial and temporal differences in the concentrations of PAHs and n-alkanes under the influence of precipitation, temperature, and human activities. The concentrations of PAHs in water were lower in the wet season than in the dry season, and those in sediments were higher in the wet season than in the dry season. The concentrations of n-alkanes were higher in the rainy season than in the dry season for both water and sediments. The spatial distributions of PAHs and n-alkanes were estuarine > offshore. The concentration ranges of ∑PAHs in water and sediments were 230.66-599.86 ng/L and 84.51-5548.62 ng/g, respectively, in the wet season and 192.46-8649.55 ng/L and 23.39-1208.92 ng/g, respectively, in the dry season. The proportion of three-ring PAHs in water (57.03% and 78.27% in the wet and dry seasons, respectively) was high, followed by two-ring PAHs (27.31% and 13.59% in the wet and dry seasons, respectively). The proportion of four-ring PAHs was higher in sediments (24.79% and 32.20% in the wet and dry seasons, respectively). The ecological risk of PAHs assessed using the toxicity equivalent quotient and risk quotient was at moderate to moderately high risk levels. The high concentration of n-alkane fraction C16 (611.65-75594.58 ng/L) in the water is indicative of petroleum or other fossil fuel inputs. The main peaks of n-alkanes in river sediments were C27, C29 and C31, indicating higher inputs of plant sources. The sediments in the estuary showed dominance of both short-chain C16 and long-chain C25-C31, indicating a combined input of higher plants and petroleum. The diagnostic ratios of PAHs and n-alkanes indicated that their sources were mainly oil/coal/biomass combustion and petroleum spills attributed to frequent vehicular, vessel and mariculture activities. Given the potential ecological risks of PAHs and n-alkanes in water and sediments, future studies should focus on their bioaccumulation and biotoxicity.
摘要：
采集小清河河口及邻近海域的季节性水沙样本,研究其时空分布,多环芳烃(PAHs)和正构烷烃的来源和生态风险。结果表明，在降水的影响下，PAHs和正构烷烃的浓度存在显著的时空差异，温度,和人类活动。雨季水中PAHs的浓度低于旱季,沉积物中的沉积物在雨季比旱季高。对于水和沉积物，雨季的正构烷烃浓度均高于旱季。多环芳烃和正构烷烃的空间分布为河口>近海。水和沉积物中∑PAHs的浓度范围为230.66-599.86ng/L和84.51-5548.62ng/g，分别,在雨季和192.46-8649.55ng/L和23.39-1208.92ng/g，分别,在干燥的季节。水中三环PAHs的比例(干湿季分别为57.03%和78.27%,分别)很高，其次是双环PAHs（干湿季节分别为27.31％和13.59％，分别)。沉积物中四环PAHs的比例较高（干湿季节分别为24.79％和32.20％，分别)。使用毒性当量商和风险商评估的PAHs生态风险处于中等至中等高风险水平。水中高浓度的正构烷烃馏分C16(611.65-75594.58ng/L)指示石油或其他化石燃料输入。河流沉积物中正构烷烃的主要峰值是C27，C29和C31，表明植物来源的投入较高。河口的沉积物显示出短链C16和长链C25-C31的优势，表明高等植物和石油的联合输入。PAHs和正构烷烃的诊断比率表明，它们的来源主要是石油/煤/生物质燃烧和石油泄漏，归因于频繁的车辆，船只和海水养殖活动。考虑到水和沉积物中PAHs和正构烷烃的潜在生态风险，未来的研究应该集中在它们的生物积累和生物毒性上。
