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To Study of Risk Assessment Due to Extent of Hydrocarbons Contamination Along Coastline of Karachi

Thesis Info

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Author

Fayyaz Ahmed Ansari

Program

PhD

Institute

University of Karachi

City

Karachi

Province

Sindh

Country

Pakistan

Thesis Completing Year

2015

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/13297/1/Fayyaz_Ahmed_Ansari_Chemistry_2015_Univ_of_Karachi_16.06.2016.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727614574

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Hydrocarbons naturally form in fossil fuels. Automobile exhaust, industrial emission and refused incineration are the major anthropogenic sources. Hydrocarbons enter the marine environment via atmospheric deposition, urban runoff, dumping of untreated industrial waste, petroleum losses from vessels during transportation and accidental oil spills in the sea. On entering the marine environment hydrocarbons distribute in seawater, sediments and biota. Karachi is known as industrial hub of Pakistan, being an industrial city, it produce a great amount of pollutants which ultimately transported to the coastal areas by various means. Therefore, present study was designed to determine the extent, concentration and possible risk level of hydrocarbons to marine fauna as well as on human. Seawater, sediments and marine fauna samples were collected from different sampling stations of Karachi coastal areas include Defense Housing Authorities, Clifton, Oyster Island, entrance of Karachi Harbour, Manora and Sand Spit during 2003-2006. Gas Chromatograph equipped with Flame ionization detector and capillary column was used to analyze the hydrocarbons. Seawater samples were found containing PAHs (Σ16PAHs) 1.280 μg L-1 and 0.366 μg L-1 in 2003 and 2006, respectively. Concentration of Carcinogenic PAHs (Σ7PAHs) was found 2.402 μg L-1 and 0.008 μg L-1 in 2003 and 2006 respectively. Benzo (a) pyrene, the most carcinogenic PAH, was found at 0.641 μg L-1 in 2003 but not detected in 2006. Sediment samples collected from study areas in 2003 contain average PAHs (Σ16PAHs) concentrations of 11641 μg kg-1 while in 2006 it was 37.57μg kg-1. As per sediments Quality Guidelines, Threshold Effect Level/Probable Effect Level and Effect Range Low /Effect Range Median include with mean- Probable Effect Level-quotient and m- Effect Range Median-quotient maximum probability of adverse biological effects was found 85% in 2003 which was gradually reduced to 9% in 2006. In seven fish specie, Apogon cocciveus was found lowest and Escualosa Thoracatta was found highest contaminated specie with 1.51μg/g and 732μg/g of total PAHs, respectively. Among four shellfish specie, Portunus Sanguinolentis was found lowest and Acanthopagrus Latus was found highest contaminated with 9.70 μg/g and 561.2 μg/g of PAHs, respectively. Contrary to PAH, variable levels of aliphatic hydrocarbons were found which could not lead to some meaningful risk effects. Oil spill is found to be the basic root cause for abrupt change of hydrocarbons level and destruction of marine ecosystem in coastal areas of Karachi. Although pyrogenic sources sufficiently contributed with it, however, hydrocarbons contamination level in study areas reduced with the passage of time.
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