Evaluation of hydrocarbon accumulation and some chemical properties of soil sediment from crude oil polluted mangrove ecosystem in Okrika
Department of Crop and Soil Science, University of Port Harcourt, Choba, Nigeria.
Research Article
Open Access Research Journal of Science and Technology, 2023, 07(01), 036–043.
Article DOI: 10.53022/oarjst.2023.7.1.0072
Publication history:
Received on 03 November 2022; revised on 01 February 2023; accepted on 03 February 2023
Abstract:
Composite soil sediments samples collected from three polluted sites in Okrika local Government Area of Rivers State. Old Isakka (01), Imonitanbie (1M) and Agiahi Ama (AA) were investigated to examine the effects of crude oil pollution on chemical properties of soil sediments from mangrove ecosystems. The soil sediments were collected at a distance of 0, 20, 40 meters and a control sample taken from distance of 140 meters away from the polluted sites near the river with a spade from each of the locations. A total of twelve soil sediments samples were collected from the three locations. The samples were analyzed for: Total hydrocarbon contents (THC), Total Nitrogen (TN), Available Phosphorus (P), soluble potassium (K), Total organic carbon (TOC) and soil pH. Results of the study showed significant (P<0.05) difference in % TOC in polluted soil sediments in all the distances and locations over the control samples. Percentage TOC increases in a decreasing order in the studied locations as: AA>1M>01. Available P in polluted soil sediments were significantly (P<0.05) lower than the control soil sediments. Available P in soil sediments increases with distance away from the polluted site with control samples having the highest values in all the locations. The value of P were below the critical limits of 8.15mg/kg. Total nitrogen was significantly higher in polluted sediments over control. There were significant variations in the content of soluble K in both the distance and locations in the studied area. The values of K were not consistent with crude oil pollution but above the critical limit. The order of significant of soluble K were 01>1M>AA. Significant (P<0.05) difference was observed in THC between the crude oil polluted sediment and the control samples in all the distances and locations. Pollution of the soil sediment with crude oil impacted negatively on some soil sediments properties as there was a decrease in available P content, reduction of the soil sediment pH to strongly acidic (4.00±10c to 4.30±0.1a) in all the locations and an increase in TOC , TN and THC of the mangrove sediments. THC of the soil sediments in the three locations decreases in the order of 01>1M>AA. The THC of the studied sites exceeded the alert and intervention limit of 200 and 20000mg/kg for less sensitive soils and 100 and 1000mg/kg for sensitive soils.
Keywords:
Mangrove soil sediments; Crude oil; THC; Soil chemical properties; Okrika
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