Abstract

Profile assessment of the behavior of total polycyclic aromatic hydrocarbons (TPAH – sum of 16 US EPA priority PAHs) in water and suspended particulate matter (SPM) from Cross River estuary, SE Nigeria in response to hydrological cycles and human-induced activities as well as their sources were undertaken using gas chromatography-flame ionization detector (GC-FID). TPAH concentrations in water were in the range 0.23–3.98 ng/L, with a minimum and maximum values found in April and December, respectively (mean = 0.97 ± 0.65 ng/L) having higher concentrations in the dry season. The low PAHs levels recorded in water for the wet season were linked to dilution effect. On the other hand, TPAH concentrations in SPM (suspended particulate matter) ranged between 5.16 ng/g in February and 40.52 ng/g in June (mean = 17.77 ± 8.48 ng/g). Higher PAHs levels found in the wet season were associated with greater wash-in of terrigenous materials occasioned by intense rainfall events via river discharges/wet precipitation coupled with the high adsorption capacity of PAHs toward solid matrix as well as proximity to fish settlement. Seasonal changes in salinity, temperature and suspended sediment concentration (SSC or SPMC) somewhat influenced the PAH phase association. Higher SSC in the wet season accounted for the higher PAHs levels in SPM (r = 0.9295), whereas lower salinity aided desorption from SPM in the wet season, temperature did not show regular trend with PAHs levels in both seasons. Application of principal component analysis (PCA) and multiple linear regression (MLR) to both water and SPM data indicated a scenario predominated by petroleum and wood combustion PAHs with a moderate vehicular exhaust emission and coal tar inputs (11%).

摘要

对来自尼日利亚东南部克罗斯河河口的水和悬浮颗粒物 (SPM) 中总多环芳烃（TPAH - 16 种美国 EPA 优先 PAH 的总和）的行为进行剖面评估，以响应水文循环和人为活动以及它们的来源是使用气相色谱-火焰离子化检测器 (GC-FID) 进行的。水中 TPAH 浓度在 0.23-3.98 ng/L 范围内，最小值和最大值分别出现在 4 月和 12 月（平均值 = 0.97 ± 0.65 ng/L），在旱季浓度较高。雨季水中记录的低 PAHs 水平与稀释效应有关。另一方面，SPM（悬浮颗粒物）中的 TPAH 浓度介于 2 月的 5.16 ng/g 和 6 月的 40.52 ng/g 之间（平均值 = 17.77 ± 8.48 ng/g）。在雨季发现的较高 PAHs 水平与通过河流排放/湿降水的强降雨事件以及 PAHs 对固体基质的高吸附能力以及靠近鱼类栖息地的高强度降雨事件引起的陆源物质的更大冲刷有关。盐度、温度和悬浮泥沙浓度（SSC 或 SPMC）的季节性变化在一定程度上影响了 PAH 相关联。雨季较高的 SSC 说明了 SPM 中较高的 PAHs 水平（r = 0.9295），而较低的盐度有助于在雨季从 SPM 解吸，温度在两个季节都没有显示出 PAHs 水平的规律趋势。