In non-hydrocarbon compounds. From these polycyclic aromatic hydrocarbons

In previous decades, the incidence of oil spills have became frequent throughout the world. The oil spills produce various detrimental effects on aquatic as well as terrestrial ecosystems. The anthropogenic activities are quite responsible to these oil spills and raised various serious threats to all the living beings. It occurs via land run off, accidental discharge during storage, transportation and bilge discharge etc. The cleanup, recovery and remediation methods for oil spill are very challenging and complex to execute. Therefore, the present work is mainly focused on some important past oil spills and remediation methods.

Keywords: Major oil spill, fate, bioremediation, phytoremediation.

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Introduction

Oil spill is like an environmental disaster which is accidental release of petroleum/crude oil into the surroundings and usually take place during transportation, storage and at the production site. In different ecosystems the oil spill can result into various perturbation to the living beings and even death. The oil spills are mainly categorizes into 4 types: minor oil spill, medium oil spill, major oil spill and disaster (Tewari et al., 2015). The possible reason for such injurious effects is the complex nature of petroleum/crude oil. Chemically, it consists of approximately more than 17000 organic compounds (Brooijmans et al., 2009). The main constituent of petroleum are hydrocarbon complexes which consist of saturated hydrocarbons, aromatic hydrocarbons and non-hydrocarbon compounds. From these polycyclic aromatic hydrocarbons (PAHs) were widely reported in different environments (Guo et al., 2016) and number of PAHs were included priority control pollutants by different organizations (Wang, 2017). Marine ecosystem is prone to the pollution caused by petroleum/crude oil than terrestrial ones. The oil spills may consist crude oils/refined petroleum products. The oil spill affects mainly marine ecosystem, land and ground water. It was reported that approximately 13 million tones of petroleum/crude oil enters to the marine ecosystem annually. Therefore, these is an urgent need of understanding of remediation techniques for the removal of petroleum from marine ecosystem. 

Important major oil spills

All the reported major oil spill are the result of anthropogenic errors, weather conditions and improper designing. The oil spill is not only detrimental in terms of ecology but it also effects the economy. The important major oil spill are summarized in Table 1. Accidental large-scale release of petroleum/crude oil in the form of oil spills represent a significant volume of contaminants throughout the world. The few well known example of oil spills are: The Exxon Valdez spill in Alaska (1989) and the BP Deepwater Horizon spill in the Gulf of Mexico (2010) (Atlas and Hazen 2011; Spier et al. 2013). Moreover, in addition to these, small spills from low-level continuous seeps, offshore exploration are still going (Listed in Table 2) and have raised various serious environmental issues (Yang et al. 2009).

Table 1: List of some major oil spills of world

Sr. No.

Oil Spill

Year

Location

Quantity of oil spill (tones)

1

Torrey Canyon

1967

Scilly Isles, UK

119000

2

Sea Star

1972

Gulf of Osman

115000

3

Jakob Maersk

1975

Oporto, Portgal

88000

4

Urquiola

1976

La Coruna, Spain

100000

5

Hawaiian Patriot

1977

300 nautical miles off Honolulu

95000

6

Amoco Cadiz

1978

Off Brittany, France

223000

7

Atlantic Empress

1979

Off Tobago, West Indies

287000

8

Independenta

1979

Bosphorus, Turkey

94000

9

Ixtox I oil  well

1979

Gulf of Mexico

454000

10

Irenes Serenade

1980

Navarino Bay, Greece

100000

11

Abt Summer

1991

700 nautical miles off Angola

260000

12

Castillo De Bellver

1983

Off Saldanha Bay, South Africa

252000

13

Nova

1985

Off Kharg Island, Gulf of Iran

70000

14

Odyssey

1988

700 nautical miles off Nova Scotia, Canada

132000

15

Khark 5

1989

120 nautical miles off Atlantic coast of Morocco

70000

16

Exxon Valdez

1989

Prince William Sound, Alaska, USA

37000

17

Haven

1991

Genoa, Italy

144000

18

ABT Summer

1991

700 miles of the Angolan coast

260000

19

Aegean Sea

1992

La Coruna, Spain

74000

20

Katina P

1992

Off Maputo, Mozambique

67000

21

Fergana valley

1992

Fergana valley of Central Asia

285000

22

Braer

1993

Shetland Island, UK

85000

23

Sea Empress

1996

Milford Haven, UK

72000

24

Prestige

2002

Off Galicia, Spain

63000

25

Hebei Spirit

2007

Taean, Republic of Korea

11000

26

2014 Israeli Oil spill

2014

Trans-Israel Pipeline, Israel

1948-4300

27

Refugio oil spill

2015

California Coast, USA

330

 

Table 2: List of ongoing oil spills

Sr. No.

Oil Spill

Country

Year

Spilled oil (max. tones)

1.

Ennore oil spill

India, Chennai, Ennore Port
 

28 January 2017 to present

60

2.

OT Southern Star 7

Bangladesh, Sundarbans, Khulna Division

9 December 2014 to present 

300

3.

Napocor
Power Barge 103

Philippines, Estancia, Iloilo

8 November 2013 to present 

520

4.

Taylor Energy wells
Platform 23051v

United States, Gulf of Mexico

16 September 2004 to present 

unknown

(Source: https://en.wikipedia.org/wiki/List_of_oil_spills)

Fate of oil spills

The fate of oil after spill depends upon the composition of oil and environmental conditions (McGenity et al., 2012). The physical and chemical properties of oil are significantly affected after oil spill by the weathering of oil via the action of waves and sunlight. The weathering consists of the spreading, evaporation, drifting, dissolution, photo-oxidation, photolysis, biodegradation, emulsification, adsorption, sinking/sedimentation (shown in Figure 1). These all cause the changes in the oil viscosity, density and interfacial tensions. Sometimes these processes collectively may result into the formation of chocolate mousse, tar ball and formation of oxygenated products which make the recovery of oil difficult (Daling and Strom, 1999).