The composition of different grades of oil varies. Typically, oil contains metals like nickel, vanadium, iron, copper, chromium, paraffin, isoparaffins, aromatics, naphthenes, vacuum gas oil, hydrogen sulphide, sulphur, etc. Almost all are toxic. The severity of adverse health effects depend on the exposure level. Those who have received oil splashes directly and have their homes covered with oil are at high risk. In addition, old people, women (especially pregnant women) and children are at high risk, even with relatively low exposure.
In Korangi, raw industrial waste water in the channels and drains is used for growing vegetables. The already-contaminated vegetables irrigated in Korangi, have been further contaminated by water mixed with oil posing a serious health risk.
Soil contamination is reported to be severe in Korangi. Since the presence of oily soil poses threats to human health, urgent measures are required for soil treatment. There are a number of methods for the treatment of contaminated soil. These include bioremediation, soil washing, land-filling, incineration, thermal desorption, chemical addition, and composting.
Bioremediation technique involves adding nutrients to the contaminated soil, to enhance the growth of bacteria naturally present in the environment. These bacteria naturally cause degradation of certain types of toxic hydrocarbons in oil. Bacterial growth can be increased by applying nutrients, which increase the availability of nitrogen and phosphorus, the nutrients bacteria need to utilise hydrocarbons as a food source.
Soil-washing systems comprise adding a wash solution (water and/or a surfactant) to soil to remove contaminants. The contaminants are transferred from the soil to the wash solution, which then must be treated. Water alone is not effective in removing PAHs. Other solutions, such as hydrochloric acid and sodium hydroxide, are also used in soil-washing techniques.
Land-filling is one of the oldest forms of remediation. Contaminated soil is excavated from the site and transported to a landfill, where it remains indefinitely. Incineration is the destruction of contaminants by burning contaminated soil. This method is very expensive and causes air pollution. In thermal desorption, soil is heated to increase the vapour pressure of contaminants causing contaminants to be released from the soil.
In the case of the Korangi spill, soil washing, land-filling and bioremediation methods are suggested in order of priority. For bioremediation, the concerned oil company needs to contact the biological department of the Karachi University, since controlled conditions are required for the growth of bacteria.
In case the land-filling system is adopted for soil treatment, the approval of the environment regulatory agency must be obtained for soil disposal, since improper disposal of contaminated soil has the potential to cause severe environmental impacts, including the contamination of water resources.
Post-oil-spill operations revealed a poor emergency response.
Proper preparedness demands that the oil pipeline route is known to other relevant agencies.