Environmental effects of crude oil spill on the physicochemical and hydrobiological characteristics of the Nun River, Niger Delta

Abstract

Oil spill pollution has remained a source of several international litigations in the Niger Delta region of Nigeria. In this paper, we examined the impacts of small recurrent crude oil spills on the physicochemical, microbial and hydrobiological properties of the Nun River, a primary source of drinking water, food and recreational activities for communities in the region. Samples were collected from six sampling points along the stretch of the lower Nun River over a 3-week period. Temperature, pH salinity, turbidity, total suspended solids, total dissolved solids, dissolved oxygen, phosphate, nitrate, heavy metals, BTEX, PAHs and microbial and plankton contents were assessed to ascertain the quality and level of deterioration of the river. The results obtained were compared with the baseline data from studies, national and international standards. The results of the physicochemical parameters indicated a significant deterioration of the river quality due to oil production activities. Turbidity, TDS, TSS, DO, conductivity and heavy metals (Cd, Cr, Cu, Pb, Ni and Zn) were in breach of the national and international limits for drinking water aquatic health. They were also significantly higher than the initial baseline conditions of the river. Also, there were noticeable changes in the phytoplankton, zooplankton and microbial diversities due to oil pollution across the sampling zones.

Distribution of oil products in bottom sediments of the Irtysh River in the urban area

“…The pollution of the bottom sediments of the Irtysh river with specific toxic substances: oil products and heavy metals is associated with the operation of the river fleet, the transportation of oil products, the removal of pollutants from floodplain areas where various enterprises operate, as well as the discharge of polluted sewage into the catchment area of the Irtysh river. The main sources of pollution are [2,3,9] industrial companies, the river fleet, agricultural and domestic wastewater, in connection with which the water and bottom sediments of rivers are polluted with oil products.…”

“…organismic -decrease in growth rate and survival, morphological malformations, developmental abnormalities, behavior changes, worsening chemotaxis [6,9,[24][25][26][27][28][29][30][31][32][33][34][35][36][37];…”

“…biocenotic -a change in the species, size and trophic structure, type of dominance, violation of interspecific relationships and interpopulation relations [5,8,9,11,25,38,[40][41][42][43][44][45][47][48][49][50][51];…”

“…ecosystem -disruption of the material-energy cycle, imbalance of the biotic cycle, distortion of the information field, change in the direction of production-destruction processes, trophic status of water bodies, self-cleaning processes, unsuitability of the bottom substrate for recolonization [9,10,27,38,[52][53][54];…”

“…In the south of the Tyumen region in the Irtysh basin, a number of large oil fields have been discovered, which are start operating. It is worth noting that oil companies consider [3][4][5][6][7][8][9] the main polluting source of oil and its derivatives in the environment, including transportation [10][11][12][13]. Almost 11 million people live in the Irtysh River basin within the Russian Federation, including 75% in cities and urban settlements, 25% in rural areas [14].…”