Marine pollution can be a blend of chemicals and trash, most of which comes from land and is washed or blown into the seas. This pollution effects the marine environment, the health of all organisms, and economic structures worldwide. As we see, there are two components of marine pollution, we will be focusing on the chemical pollutants and how they can affect the marine environment. As we all know about 90 percent of the chemical trade is being carried out by sea, accidentaly dumping, spilling or discharging of toxic chemicals in sea is inevitable. To regulate this chemical pollution, there are certain conventions laid down by International Maritime Organization named as International Convention for the Prevention of Pollution from Ships (MARPOL).
MARPOL Annex 2 laid by International Convention for the Prevention of Pollution from Ships deals with Regulation for the Control of Pollution by Noxious Liquid Substances in Bulk which details the discharge criteria and procedures for the control of pollution by noxious liquid substances carried in bulk. It came into force on April 6th, 1987. This annex does not apply to harmful substances carried in any kind of packaging, this only applies to noxious liquid substances and chemical carried in bulk.
This annex require all chemical tankers built after July 1st 1986 to follow the International Bulk Chemical Code (IBC Code). IBC is a book which is to be carried by all vessels which are carrying noxious liquid substances and chemicals in bulk by sea. It contains some safety standards which are to be maintained while carriage of these dangerous chemicals and noxious liquid substances. This also sets out minimum design and construction standards of these vessels.
Before understanding the details of this convention we must know that a noxious liquid substance means. Any harmful or poisonous substance, if discharged in the sea causing a devastating effect on marine environment is considered as noxious substance. By convention, it means any liquid substance mentioned within the Pollution Category column of chapter 17 or 18 of the International Bulk Chemical Code(IBC) or provisionally assessed under the regulation 6.3 as belonging into category X, Y or Z.
The NLS are segregated into four main categories:
- Category X
- Category Y
- Category Z
- Other Substances
These are divided on the basis of the harm that they can cause to the marine environment.
According to the regulation 6.1 annex 2, NLS which, if discharged into the sea from tank cleaning or de-ballasting operations, are deemed to present a major hazard to either marine environment or human health and, therefore, they are prohibited to be discharged into the sea.
NLS fall under category Y, when discharged into the sea from tank cleaning or de-ballasting operations, present a hazard to either marine environmen or human health or cause harm to amenities or other legitimate uses of the sea and therefore there is a limitation on the quality and quantity of the discharge into the sea.
NLS fall under category Z, if discharged into the sea after tank cleaning or de-ballasting operations, present a minor hazard to either marine environment or human health and therefore there are even less stringent restrictions which are to be followed and they can be discharged into the sea keeping in mind the quality and quantity of the discharge.
OS are considered to present no harm to the marine environment, human health, amenities or other legitimate uses of the sea when discharged into the sea from tank cleaning or de-ballasting operations.
(Below is the summary of all the substances)
There are some parameters of discharge of noxious liquid substances (NLS) or chemicals on which their discharge standards are based on.
- The maximum quantity of substances per tank which may be discharge into the sea
- The speed of the ship during the discharge
- The minimum distance from the nearest land during discharge
- The minimum depth of water at sea during discharge
- Whether the discharge is being carried out below the waterline or above the waterline.
- The ship is proceeding at speed of at least 12 knots in the case of self-propelled ships or at least 4 knots in the case of ships which are not self-propelled.
- The discharge is made below waterline through the underwater discharge outlet not exceeding the maximum rate for which the underwater discharge outlet is designed.
- The discharge is made at a distance of not less than 12 nautical miles from the nearest land in a depth of water of not less than 25 meters.
Special area is a sea area where due to certain oceanographic conditions, environmental conditions and traffic conditions certain regulations need to be implemented for the environmental protection of that area. As per annex 2, there is just a single special area which is the Antarctic area.
Procedure and Arrangement Manual
As per annex 2, every ship which is carrying Noxious Liquid Substances in bulk and complying with annex 2 of MARPOL needs to carry a “P & A Manual” which is the Procedure and Arrangement manual which is approved by the administration.
The procedure and arrangement manual contain some important guidelines and the operational procedures which need to be followed during cargo operations, tank cleaning, sloth handling and cargo tank ballasting and de-ballasting operations.
Cargo Record Book(CRB)
Every ship to which is carrying noxious liquid substances in bulk needs to carry a Cargo Record Book. This cargo record book contains specific entries which are to be made on the basis of cargo handling. Each entry of the cargo record book has to be signed by the officer in charge and each page has to be signed by the master of the vessel. The cargo record book shall be kept in such a place as to be readily available at all reasonable times for inspection and it shall be preserved for a period of three years after the last entry has be made.
Below is the list of entries which are to be made in the cargo record book:-
- Loading of Cargo
- Internal Transfer of Cargo during the voyage
- Unloading of cargo
- Mandatory pre wash in accordance with the ship’s P & A manual
- Cleaning of cargo tanks
- Discharge into the sea of tank washings
- Ballasting of cargo tanks
- Discharge of ballast water from cargo tanks
- Accidental or other exceptional discharge
- Control by authorized surveyors
- Additional Operational Procedures and Remarks
It is an integral part of regulation for the control of pollution by noxious liquid substances carried in bulk. Every vessel of 150 gross weight tonnage and above carrying noxious liquid substances in bulk needs to carry on board a SMPEP approved by the Administration.
What does this plan consist of?
This plan contains:
- Procedure to be followed to report a noxious liquid substance pollution incident.
- The list of authorities or persons to be contacted in case of NLS pollution incident.
- A detailed description of the action to be taken immediately by the persons on board to reduce or control the discharge of NLS following the incident.
- The procedure and point of contact on the ship for coordinating shipboard action with national and local authorities in combating and reducing the extent of pollution.
Authored By:- Cdt. Rohan Sharma, TMI