Source Apportionment and Identification of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment Cores of Selected Creeks in Delta State,Nigeria

Polycyclic aromatic hydrocarbons (PAHs) seasonal variation and sources in Ubeji, Ifie, and Egbokodo Creeks of the Niger Delta, Nigeria, were predicted using diagnostic ratios (DRs) of parent PAHs (Phe/Phe + Ant; Flu/Flu + Pyr; BaA/BaA + Chry, and Ind/Ind + BghiP) and principal component analysis (PCA). A total of 222 sediment core samples were collected during the wet (August 2010) and the dry seasons (January 2011). The samples were dried and Soxhlet extracted; sample extracts were fractionated and analyzed by gas chromatography/flame ionization detection (GC/FID) to identify individual PAHs. The diagnostic PAH ratios revealed that PAHs in the sediment cores at the three creeks, in both seasons, mainly stemmed from the combustion process (pyrogenic sources). Principal component analysis further confirmed that wood-burning, coal combustion, diesel, gasoline-powered vehicular emissions, and petroleum combustion were the dominant contributors of PAHs sources at the sampling location. This study provided information on the origin and sources of PAHs in sediment cores, which may be useful for regulatory actions, environmental quality management, contamination history, and environmental forensic studies.     

Aliphatic Hydrocarbons Distribution in Sediment Cores of Select Creeks in Delta State,Nigeria

The spatial and seasonal changes in the distribution, composition, and concentrations of aliphatic hydrocarbons were investigated in sediment cores of Ubeji, Ifie, and Egbokodo Creeks in the Niger Delta, Nigeria. A total of 222 sediment core samples were collected during the wet season (August 2010) and the dry season (January 2011). The samples were dried, soxhlet extracted, fractionated and analyzed for aliphatic hydrocarbons by using a gas chromatograph with flame ionization detector (GC-FID). The concentrations of aliphatic hydrocarbons ranged from 37 to 286,894 μg/kg (wet season) and from 30 to 11,773 μg/kg (dry season). The concentrations of n-alkanes for a number of stations in this study are comparable to sites with high anthropogenic activities in the Niger Delta. The carbon preference index (CPI) and the pristane/phytane ratios showed that the major source of hydrocarbon pollution in the sediment core was from petrogenic origin.     

7种化合物对新月藻的毒性效应及敏感度差异研究

以新月藻为受试生物,研究了阿特拉津、马拉硫磷、草甘膦、甲苯4种有机化合物和HgCl₂、NaAsO₂、K₂Cr₂O₇ 3种金属化合物对新月藻的毒性效应,探讨了新月藻对这些化合物的敏感度差异与特点及其机理,为这些物质的藻类急性毒性提供基础数据。结果表明,新月藻对阿特拉津、草甘膦、HgCl₂、NaAsO₂、K₂Cr₂O₇敏感度较高,而且响应大小与化合物浓度呈正相关趋势,对马拉硫磷和甲苯有一定响应,但随浓度变化趋势不明显;基于藻类光合作用的急性毒性检测方法,适用于检测可阻碍或抑制藻类光合作用中电子迁移、氧化还原、自由基等反应的毒物。     

Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment Cores of Selected Creeks in Delta State,Nigeria

The spatial and seasonal distribution and concentrations of polycyclic aromatic hydrocarbons (PAHs) were investigated in core sediments of Ubeji, Ifie, and Egbokodo creeks in the Niger Delta, Nigeria. A total of 222 core sediment samples were collected during the wet season (August 2010) and the dry season (January 2011). The samples were dried, Soxhlet extracted, fractionated, and injected into a gas chromatograph with flame ionization detector (GC-FID). The concentrations of PAHs ranged from not detected to 2,654 μg/kg (wet season) and not detected to 3,513 μg/kg (dry season). In general, the concentrations of PAHs for a number of stations in this study are comparable to sites with high anthropogenic activities in the Niger Delta. The toxicity risk assessment based on the total BaP equivalent quotient of the seven carcinogenic PAHs (BaA, Chry, BbF, BkF, BaP, DBA, and Iper) was 97.416 μg/kg and did not exceed the method B cleanup level for benzo(a)pyrene (137 μg/kg), according to toxic equivalency factors, which implied that PAHs in sediments of the present study currently have minimal adverse effects. This study provided information on the concentrations and profiles of PAHs sediment cores, which is useful for source diagnosis, environmental quality management, contamination history, and environmental forensic studies.     

Drinking water quality at Isoko North communities of the Niger Delta Region,Nigeria

Groundwater samples from boreholes and open-hand-dug wells of six communities in the Isoko North Local Government Area of Nigeria were analyzed in respect to physicochemical factors, biological factors, and the metals Na, K, Mg, Ca, Ba, Pb, Cd, Zn, Cu, and Fe for eight consecutive months to give mean values for the wet (July to October 2010) and the dry seasons (November 2010 to February 2011) for each location. The physicochemical parameters complied with World Health Organization (WHO) guidelines, except for the pH being lower and the concentrations of Pb, Cd, and Ba, being higher than the permissible limits of WHO. Total coliform counts indicated bacterial contaminations, especially in one location. The presence of Pb in the drinking water of all communities seemed to be associated with oil exploration and processing activities.