Abstract
Marine oil spillage accidents greatly impact major risks to the environment in terms of the acute and chronic adverse effects not only to the offshore, but also the coastal ecosystem. This study assessed single and joint toxicological effect of Dispersit SPC 1000 and Bonny Oil on mudskipper fish (Periophthalmus papilio) from the brackish water research station of African Regional Aquaculture Centre, Buguma, Rivers State, Nigeria. The physicochemical parameters observed throughout the study were the pH, alkalinity and salinity were 6.83 ± 0.1, 40 mg/L± 0.2 and 17,655 mg/L respectively. The temperature and Dissolved oxygen (D.O.) and specific gravity averaged 26.7oC ± 0.1, 5.70 mg/L ± 0.02 and 1.008 ± 0.001, respectively. Dispersit SPC 1000 was found to be toxic to the mudskipper at various % (v/v) concentration, above 60 % (v/v) concentration no fish survived after one hour. The relation between the probit mortality and log concentration showed a strong positive correlation between the dispersant concentration and fish mortality within 3 hours, with r2 = 0.813 p = 0.05;The lethal dose Lc50 was 73.48%. Within 6 hours, the mortality increased as the dispersant exposure concentration was increased (r2 = 0.872, p =0.05). The results of exposure of the mudskippers to the water-oil-dispersant mix (CEWAF) showed lower mortalities. Mortality was observed after 72 hours for dispersant concentration above 54 %. 63% dispersant concentrations, 20% mortalities was observed between 72 and 96 hours. Dispersit SPC 1000 alone was highly toxic, and the toxicity of CEWAF was primarily caused by the presence of dispersant. There was no joint increase in toxicity between bonny oil and the chemical dispersant, as the mixing of the dispersant by the oil resulted in diminished toxicity of CEWAF and lower mortality.Keywords: Joint Toxicity, Dispersit SPC1000, Mudskipper Fish
Highlights
Are in direct contact with water polluted with oil (Feng, 2003; Shirani, 2012).The accumulation of toxic substance is of public health concern
Preparation of Test Stock Solution: Chemically enhanced water accommodated fraction (CEWAF) of crude oil were prepared under laboratory conditions, in closed, low energy mixing systems recently internationally adopted through the "CROSERF" forum (Chemical Response to Oil Spills - Ecological Effects Research Forum).The preparation was done following methods proposed by Sikoki and Lelei (2013); Hemmer et al (2010); Fuller and Rotton et al (1999) and OECD 2014(4) for the preparation of water accommodated fractions (WAF) After 24 h of stirring, 1:10 ratio “high dose” of Dispersit SPC 1000 to crude oil, was added (per standard recommendation for dispersant toxicity for maximum effect, Hemmer et al(2010)
One way ANOVA results showed that there were no significant differences between pH, temperature, Total Dissolved Solids (TDS), salinity, Dissolved Oxygen (DO) and alkalinity for all the media used for the toxicity study, with Electrical conductivity (EC), and hardness indicated that there were some significant differences
Summary
Are in direct contact with water polluted with oil (Feng, 2003; Shirani, 2012).The accumulation of toxic substance is of public health concern. The additions of dispersants to the water accumulated fraction enhance the toxicity of oil toward various aquatic organisms as the total petroleum hydrocarbon concentration (TPH) increases (Sheryll et al, 2015; Dang et al, 2012).
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