Unyimadu John P, Osibanjo Oladele, Babayemi Joshua O
Nigerian Institute for Oceanography and Marine Research, Victoria Island, Lagos, Nigeria.
Department of Chemistry, University of Ibadan, Ibadan, Nigeria.
J Health Pollut. 2019 May 22;9(22):190606. doi: 10.5696/2156-9614-9.22.190606. eCollection 2019 Jun.
Pollution in aquatic ecosystems is a serious environmental concern. There is a great need for constant assessment and monitoring of hazardous substances, particularly in aquatic environments in developing countries, as rivers are media with easy trans-boundary transport of chemical substances.
The present study assessed the occurrence and distribution of organochlorine pesticides (OCPs) in the sediments of the Niger River, Nigeria.
A total of 120 samples of sediment were collected from 15 locations along the river using Van Veen grab. The Environmental Protection Agency (USEPA) 3570 method with slight modification was used for sample preparation. Organochlorine pesticides were analyzed using Hewlett Packard 5890 series II gas chromatography with electron capture detector. Confirmation of OCPs was performed using a gas chromatograph/mass spectrometer (Shimadzu QP2010) and capillary column type HP1MS (30 m × 0.25 um × 0.25 mm id).
The highest concentration of ∑OCPs in the sediment samples of the River Niger (5023±1596 μg/kg, 4672-7009 μg/kg) was detected in a location at Onitsha, while the lowest concentration (1570±204.5, 1214-1820 μg/kg) was detected in a location at the Nicolas River.
High values of ∑OCPs (>2000 μg/kg) were detected in all of the locations except in three locations where lower levels were detected. The ∑OCPs were higher during the dry season compared to the rainy season. This may be because the resident time of the sediment transported was higher during the dry season compared to the rainy season, which is characterized by storms, high current, and bottom scour. The chlordane concentration ranged between 24.4 and 134.1 μg/kg dry weight (dw) in locations Nicolas 14 and Lokoja 5; and the Probable Effect Concentration guidelines were exceeded. Dieldrin was detected at very low levels in most of the locations and ranged from 5.67 to 70.3 μg/kg dw in locations Onitsha 9 and 8; and the Probable Effect Concentration guideline was only exceeded in location Onitsha 8; however, the Toxic Effect Concentration guideline was exceeded at all of the locations. Dichlorodiphenyldichloroethane (DDD) was not detected in location Lokoja 6 or 7, and Onitsha 8 and 9, although the concentration in all other locations exceeded the guidelines. Dichlorodiphenyldichloroethylene (DDE) concentrations exceeded the guidelines except in location Nicolas 13.
Due to the environmental/human risk and potential danger of the elevated levels of OCPs, there is a need for continuous monitoring of the Niger River.
The authors declare no competing financial interests.
水生生态系统中的污染是一个严重的环境问题。迫切需要持续评估和监测有害物质，特别是在发展中国家的水生环境中，因为河流是化学物质易于跨界运输的媒介。
本研究评估了尼日利亚尼日尔河沉积物中有机氯农药（OCPs）的存在情况和分布。
使用Van Veen抓斗从该河沿岸15个地点共采集了120个沉积物样本。采用经轻微修改的美国环境保护局（USEPA）3570方法进行样本制备。使用配有电子捕获检测器的惠普5890系列II气相色谱仪分析有机氯农药。使用气相色谱/质谱仪（岛津QP2010）和HP1MS型毛细管柱（30 m×0.25 um×0.25 mm内径）对OCPs进行确证。
在尼日尔河沉积物样本中，∑OCPs的最高浓度（5023±1596 μg/kg，4672 - 7009 μg/kg）在奥尼查的一个地点检测到，而最低浓度（1570±204.5，1214 - 1820 μg/kg）在尼古拉斯河的一个地点检测到。
除三个检测到较低水平的地点外，所有地点的∑OCPs值均较高（>2000 μg/kg）。与雨季相比，旱季的∑OCPs更高。这可能是因为与以风暴、高水流和底部冲刷为特征的雨季相比，旱季沉积物的停留时间更长。在尼古拉斯14和洛科贾5地点，氯丹浓度在24.4至134.1 μg/kg干重（dw）之间，超过了可能效应浓度指南。在大多数地点检测到的狄氏剂水平非常低，在奥尼查9和8地点，其浓度范围为5.67至70.3 μg/kg dw；仅在奥尼查8地点超过了可能效应浓度指南；然而，在所有地点均超过了毒性效应浓度指南。在洛科贾6或7地点以及奥尼查8和9地点未检测到二氯二苯二氯乙烷（DDD），尽管所有其他地点的浓度均超过了指南。除尼古拉斯13地点外，二氯二苯二氯乙烯（DDE）浓度均超过了指南。
由于OCPs水平升高带来的环境/人类风险和潜在危险，有必要对尼日尔河进行持续监测。
作者声明不存在相互竞争的财务利益。
