- Global Statistics on Oil Spill and the Nigeria River Delta
Despite recent advancements in shipbuilding technology, the oil spill in the Gulf of Mexico has become one of the most recently publicized environmental fiascos in 2010. In the 1970s the number of oil tanker accidents has decreased significantly (i.e. below 138,000 tons of oil inputs in the ocean). The results were even better in 2009 where the amount of oil entering the ocean is estimated at about 63,000 tons (Jernelov, 2010).
However, mishaps in tankers are not the only source of oil spill in the ocean. In fact, the amount of oil that spills from tanker accidents is negligible compared to that of the operational discharges of oil to include tank washing and fuel-oil sludge. Besides operational discharges, ageing pipelines are also one of the root causes of oil leakages. While the statistics of oil tanker accidents decreased with the development of cutting-edge technologies, the average incidence of pipeline leaks and ruptures increased from 47 per year to 188 ruptures and 228 leakages after the 1970s.
In Africa, particularly in the Niger River Delta, poor maintenance and the current corrosive state of pipelines lead to several ruptures. Pipelines also became a special target of the military forces during an uprising or a tribal war. The destruction of pipelines along the Niger River Delta regularly occurs thereby becoming the site of reoccurring oil pollution (Jernelov, 2010). Several pipelines and pumping stations connecting 600 oilfields to include storage and tanker loading ports traverses the landscape of the Niger River Delta. In the consolidated reports of WWF, IUCN, Federal Ministry of Abuja and the Nigeria Conservation Foundation (2006 as cited by Jernelov, 2010), there is an estimated 1.5 million tons of oil inputs in the river delta in more than 50 years. The Federal Government claimed that there are about 2000 major and small spillage sites. In a study of Osuji and Opiah (2007), Oshire-2 oil spill in the delta indicates a high level of contamination having an average of 1.99 – 103 mg/kg of petroleum hydrocarbon in the soil.
Some Effects of Oil Spills to the Environment and to the People
The high level soil contamination in the Niger Delta resulted to low soil pH or high acidity and low electrical conductivity that are important aspects of soil fertility (Osuji and Opiah, 2007). Such result affects the livelihood of the people living close to the site of oil spillage. Because of the contamination, the agricultural productivity of the farmers is affected as well as their source of drinking water. Often, farmers and fishermen are compelled to eat and drink contaminated resources.
Summary of the results of soil analysis of two oil spillage sites in Nigeria. The data were adopted from the studies of Osuji and Opiah (2007) and Osuji and Esebuiro (2006).
The effect of oil spill in the marine environment is also documented in a study of the mangrove floor in the intertidal region of the Niger Delta basin after a series of oil spillage in Obiafu. Findings are consistent to the results of the study of Osuji and Opiah (2007) in Oshire-2 in which the soil samples yielded a low pH range of 4.28 – 4.36 suggesting a relatively high acidic condition. The low electrical conductivity of the soil (i.e. 31.75μS/cm) suggests a low salt content. Further, the extracted hydrocarbon content affected the degradation of the mangrove system. Although the mangrove floor may not be relevant in the farming activity of the people in the village, the effect on the fishing activity is indicated by such decrease in the productivity in terms of fish catch (Osuji and Esebuiro, 2006).
This diagram shows how leak in pipelines contaminates the water table and soil. Adopted from: http://en.wikipedia.org/wiki/Pipeline_transport.
References:
Jernelöv, A. (2010). The threats from oil spills: Now, then, and in the future. Ambio, 39(5), 353-66.
Osuji, L. C., & Ezebuiro, P. E. (2006). Hydrocarbon contamination of a typical mangrove floor in Niger Delta, Nigeria. International Journal of Environmental Science and Technology : (IJEST), 3(3), 313-320.
Osuji, L. C., & Opiah, U. C. (2007). Hydrocarbon contamination of a terrestrial ecosystem: The case of oshire-2 oil spill in Niger Delta, Nigeria. Environmentalist, 27(3), 337-340.
