Treated ballast water and its impact on port water quality
Concerns have been raised by state environmental protection authorities about the prospect of large volumes of chemically treated ballast water, above, being discharged in Australian ports.
Authors: Rupert Summerson, Nathaniel Bloomfield and Tony Arthur
Summary
The International Convention for the Control and Management of Ships' Ballast Water and Sediments, sponsored by the International Maritime Organisation (IMO), came into force on the 8 September 2017. The Convention regulates the treatment of ballast water to address concerns that ballast water facilitates the spreading of harmful aquatic organisms and pathogens (IMO, 2004). Australia has recently amended the Biosecurity Act 2015 to ratify the Convention and when it comes into force will require domestic and international ballast water to be managed to the Convention’s standards (DAWR, 2016).
Concerns have been raised by state environmental protection authorities about the prospect of large volumes of chemically treated ballast water being discharged in Australian ports. ABARES has been commissioned by the Aquatics and Marine Pests Unit in Biosecurity Animal Division to research environmental concerns arising from this transition in ballast water management. The aims of this report are:
Determine the chemical discharges from each of the 41 ballast water management systems (BWMS) approved by the IMO that use active substances and group the systems by chemical discharge type. Assess the likely concentrations of chemicals discharged by normal operation of these systems.
Assess the likely numbers of vessels visiting Australia that use each BWMS type, the destination ports and likely volumes of ballast water to be discharged.
Run three case studies of ports using the MAMPEC software package for modelling the distribution and fate of chemical discharges.
Port Hedland
Port Phillip Bay
Port of Brisbane
MAMPEC (Marine Antifoulant Model for Predicted Environmental Concentration) is a software package built by Deltares, an environmental consulting company based in the Netherlands, and the Institute for Environmental Studies at the VU University in Amsterdam. The software is used in the IMO approval process for BWMS that use active substances to justify that the BWMS discharge concentrations pose ‘no unacceptable’ environmental risk. MAMPEC is a 2D hydrodynamical steady state and chemical fate model, which means that the maximum concentration predicted will likely be less than actuality, as it cannot account for heterogeneous discharge scenarios. The average concentrations will be accurate, however.
Guidelines for freshwater and marine water quality have been published by the Australian and New Zealand Environment Conservation Council (ANZECC). Trigger values have been set for a range of potentially toxic compounds and are intended to trigger a management response should the specified concentration be exceeded.
As trigger values for many of the DBPs identified in the IMO reports have not yet been derived or are not yet available, equivalent trigger values from the IMO literature were used in many cases. These are not compliant with the ANZECC guidelines, but the method used to derive them is similar to how low reliability ANZECC trigger values are derived.
As such these trigger values should be considered ‘interim working levels’ until more reliable trigger values are derived. The half-lives of DBPs are highly variable and it is therefore uncertain how accurately the maximal discharge concentrations for the BWMS reported in the IMO literature will capture discharge concentrations in the field.
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Key Findings
Concentrations that might cause environmental problems occurred under a worst-case scenario. This assumed all vessels used a hypothetical worst case BWMS, which discharged the maximum concentration of disinfectant by-products (DBPs) observed in approved systems.
Using a more realistic scenario, which took into account the specific BWMS being used by ships visiting a port and their relative frequencies, it was predicted that the environmental concentrations of most DBPs would likely be below trigger levels for most of the compounds modelled.
Three compounds were found to potentially exceed environmentally safe levels: dibromoacetonitrile, monochloroacetic acid and dibromoacetic acid.
A physical sampling plan is recommended to determine the actual concentration of these chemicals as a result of BWMS discharge. It is also recommended that the environmental risk of BWMS is reviewed at some point in the future, as shipping traffic is forecast to increase and new technologies will emerge on the BWMS market with different DBPs and discharge rates.
Introduction
The worldwide transhipment of port water as ballast in shipping has been implicated in the transfer of many marine species, which have become invasive when released in the receiving port environments (Carlton and Geller, 1993, Bax et al., 2003). For example, the northern Pacific seastar (Asterias amurensis), a major invasive marine species in Australia, was probably first introduced to south-eastern Tasmania as larvae in ballast tanks of vessels visiting from Japan (Byrne et al., 2013).
Most modern ships carry ballast water. Three types of vessel carry large volumes of ballast water when they are not carrying cargo, to maintain stability, manage internal stresses in the vessel and to keep the propeller under water (Snell et al., 2015):
Bulk carriers, including wood chip carriers;
Tankers; and
Liquefied Natural Gas (LNG) and Liquefied Petroleum Gas (LPG) carriers.
Other types of ships carry ballast water that is largely retained on board and used for maintaining trim and balancing loads. Container ships are the most numerous of this type of ship. Container ships almost invariably carry cargo as they load and discharge at every port they visit and ballast water is largely retained on board for trim purposes, is infrequently discharged, and then only in relatively small volumes (Verling et al., 2005).
The International Convention for the Control and Management of Ships' Ballast Water and Sediments, sponsored by the International Maritime Organisation (IMO), comes into force on the eighth of September 2017. The Convention regulates the discharge of ballast water to address concerns that ballast water facilitates the spreading of harmful aquatic organisms and pathogens (IMO, 2004). Australia has recently amended the Biosecurity Act 2015 to ratify the Convention and when it comes into force will require domestic and international ballast water to be managed to the Convention’s standards (DAWR, 2016).
Ballast water convention
The Convention currently requires that the Ballast Water Exchange Standard is met. This regulation (D-1) requires that either 95 per cent of ballast water in the ship is exchanged with seawater, or that three times the volume of each ballast water tank is pumped through the ships ballast tanks before entering a port. Exchange is required to take place in water at least 200 metres deep and at a minimum distance of 50 nautical miles from the nearest land. This ensures that ballast water taken up at a coastal port is replaced by oceanic water, which will be unlikely to contain diseases and coastal species. The Convention also requires that a ship should not need to delay or deviate from its intended voyage in order to comply with this requirement. For voyages to Australia a delay or deviation should not normally be necessary.
As of the eighth of September 2017, ships will be required to meet the Ballast Water Performance Standard (Regulation D-2), though with some caveats relating to the age of the ship and the date of the ship’s next renewal survey (IMO, 2017a). Regulation D-2 states that ships will discharge less than 10 viable organisms greater than 50 micrometres in any dimension per cubic metre of ballast water, and less than 10 viable organisms per millilitre between 10 and 50 micrometres. There are also a number of indicator microbes, including E. coli, which cannot exceed specified concentrations.
In order to meet this standard, ships will need to install and operate a ballast water management system (BWMS). The Convention states that each BWMS must be approved by the government of the state under whose authority the ship is operating. The IMO Marine Environmental Protection Committee (MEPC) has adopted the G8 guidelines to describe the process under which this approval is granted (MEPC, 2008a). This process ensures that the system meets the Ballast Water Performance Standard, and is called Type Approval by MEPC.
For BWMS that use an Active Substance the Convention states that they must obtain approval from the IMO. An Active Substance is defined as ‘a substance or organism, including a virus or a fungus that has a general or specific action on or against harmful aquatic organisms and pathogens’. The G9 guidelines outline the criteria for this approval and have a two tiered structure, with Basic Approval being granted before Final Approval (MEPC, 2008b). Figure 1 shows a graphical summary of this process.
Figure 1 IMO Approval procedure for BWMS to be compliant with regulation D-3 of the ballast water convention (Lloyd's Register Marine, 2015).Source: ABARES
The joint Group of Experts on Scientific Aspects of Marine Pollution – Ballast Water Working Group on Active Substances (GESAMP-BWWG) was established in 2005 to review proposals submitted to the IMO for approval and report on whether the proposed BWMS could adversely affect ship safety, human health and the aquatic environment according to the G9 guidelines. The process for this approval under the G9 guidelines is given in the Methodology for Information Gathering and Conduct Work of the GESAMP-BWWG, which will be referred to as the Methodology (IMO, 2015).
This is a rigorous process, especially when it comes to considering human health. It covers risks to ship crew and exposure to the public undertaking activities such as swimming and through biomagnification in seafood. For environmental risk assessments, however, only a generic discharge scenario is required to be considered. The applications for Basic and Final approval and reports of the GESAMP-BWWG meetings are publically available from the IMO website. However, these dossiers are incomplete as some of the information has been classified as commercial in confidence and is therefore not available. These dossiers have formed the basis of this report for assessing these BWMS.
Australian water quality guidelines
Australian water quality management is underpinned by the ANZECC water quality guidelines (the Guidelines) (ANZECC, 2000). These guidelines are designed to help determine if the water quality of a particular water resource is sufficient for use by humans, food production or aquatic ecosystems. The document includes trigger values for a number of compounds that can be tailored to suit local requirements and conditions. These values are derived for both fresh and marine waters from toxicity data, and are intended to trigger a management response should the specified concentration be exceeded. Depending on the amount of data available, these trigger values can be classified as low, medium or high reliability. Ballast water discharge in Australia occurs only in marine waters.
There is a large number of disinfection by-products produced by BWMS. These include halogenated organic compounds, and inorganic compounds such as bromate, chlorate and chlorite. Where possible trigger values from the Guidelines were used, although for most compounds discharged in ballast water a relevant trigger value was not available or had not yet been derived.
Disinfection by-products
In addition to the active substances used in or produced by BWMS, the chemical reactions between these substances and the molecules found naturally in sea water produce disinfection by-products (DBPs). (Land-based water treatment facilities often have experience with these treatment by-products.) The G9 guidelines require manufacturers test the discharges from their systems for likely DBPs.
The formation of DBPs has long been recognised as potentially toxic and a risk to human health and the environment (Boorman, 1999). Halo-organics produced from drinking water treatment are recognised as potential carcinogens that can disrupt the replication of cells (Komaki et al., 2014). It has been recognised that bromo-organics are more toxic than their chloro-organic counterparts (Sharma et al., 2014), and this will be of particular of concern in ballast water as the presence of bromide ions in higher concentrations in marine waters facilitates their formation. There is also the potential for halo-inorganic by-products to be produced by these systems such as bromate, chlorate and chloropicrin. These have also been identified as potentially genotoxic and carcinogenic (Richardson et al., 2007).
Project background
Concerns have been raised by state environmental protection authorities about the prospect of large volumes of chemically treated ballast water being discharged in Australian ports. ABARES has been commissioned by the Aquatics and Marine Pests Unit in Biosecurity Animal Division to research environmental concerns arising from this transition in ballast water management. The aims of this report are:
Determine the chemical discharges from each of the 41 systems with Final Approval and group the systems by chemical discharge type. Assess the likely concentrations of chemicals discharged by normal operation of these systems.
Assess the likely numbers of vessels visiting Australia that use each BWMS type, the destination ports and likely volumes of ballast water to be discharged.
Run three case studies of ports using the MAMPEC software package for modelling the distribution and fate of chemical discharges.
With the IMO Ballast Water Convention about to come into force developments in this field are occurring rapidly. As a consequence some elements of this report, such as numbers and types of BWMS installed and volumes of ballast water treated will go out of date quickly.
