MSGID: 1:317/3 6489427e   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Marine environment at risk due to ship emissions    
      
     Date:   
         June 13, 2023   
     Source:   
         Chalmers University of Technology   
     Summary:   
         Researchers used four different types of port environments   
         to investigate the levels of contaminants emitted from five   
         different sources. They found that the combined emissions of metals   
         and environmentally hazardous substances is putting the marine   
         environment at risk. Ninety per cent of the harmful emissions came   
         from ships fitted with scrubbers, whose purpose is to clean their   
         exhaust gases.   
      
      
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   FULL STORY   
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   In a recently published study from Chalmers University of Technology,   
   Sweden, the researchers used four different types of port environments   
   to investigate the levels of contaminants emitted from five different   
   sources. They found that the combined emissions of metals and   
   environmentally hazardous substances is putting the marine environment   
   at risk. Ninety per cent of the harmful emissions came from ships fitted   
   with scrubbers, whose purpose is to clean their exhaust gases.   
      
   The combined emissions of metals and other environmentally hazardous   
   substances from ships is putting the marine environment at risk according   
   to a new study from Chalmers University of Technology, Sweden. When the   
   researchers calculated the contaminant load from these emissions into   
   the marine environment in four ports, it was found that water discharged   
   from ships' scrubbers, whose purpose is to clean their exhaust gases,   
   accounts for more than 90 per cent of the contaminants. "The results speak   
   for themselves. Stricter regulation of discharge water from scrubbers   
   is crucial to reduce the deterioration of the marine environment," says   
   Anna Lunde Hermansson, a doctoral student at the Department of Mechanics   
   and Maritime Sciences at Chalmers.   
      
   Traditionally, environmental risk assessments (ERA) of emissions from   
   shipping are based on one source at a time. For example, the ERA might   
   look at the risk from copper in antifouling paints. But as with all   
   industries, shipping is an activity where there are multiple sources   
   of emissions.   
      
   "A single ship is responsible for many different types of emissions. These   
   include greywater and blackwater, meaning discharges from showers, toilets   
   and drains, antifouling paint, and scrubber discharge water. That is why   
   it's important to look at the cumulative environmental risk in ports,"   
   says Anna Lunde Hermansson who, with colleagues Ida-Maja Hassello"v and   
   Erik Ytreberg, is behind the new study that looked at emissions from   
   shipping from a cumulative perspective.   
      
   A scrubber can be described as a cleaning system for the exhaust gases   
   arising from the combustion of heavy fuel oil, which has been the   
   most common fuel used in ships since the 1970s. Seawater is pumped up   
   and sprayed over the exhaust gases to prevent emissions of airborne   
   sulphur reaching the air. Scrubbers mean that ships can comply with   
   the requirements introduced by the International Maritime Organization   
   (IMO) in 2020. The only problem is that the water not only takes up the   
   sulphur from the exhaust gases, leading to acidification of the scrubber   
   water, but also other contaminants such as heavy metals and toxic organic   
   compounds. The contaminated scrubber water is then often pumped directly   
   into the sea.   
      
   Hundreds of cubic metres of contaminated water every hour "There is no   
   cleaning step in between -- so up to several hundred cubic metres of   
   heavily contaminated water can be pumped out every hour from a single   
   ship.   
      
   Although new guidelines for ERAs of scrubber discharges are in progress,   
   the ERAs still only assess one source of emissions at a time, which means   
   that the overall assessment of the environmental risk is inadequate,"   
   says Lunde Hermansson.   
      
   In this new study, the researchers at Chalmers looked at four different   
   types of port environments to determine contaminant concentrations from   
   five different sources. Actual data from Copenhagen and Gdynia were used   
   for two of the ports. They were selected due to high volumes of shipping   
   traffic, and a substantial proportion of these ships having scrubbers.   
      
   The results showed that the cumulative risk levels in the ports were,   
   respectively, five and thirteen times higher than the limit that   
   defines acceptable risk. Port descriptions used internationally in   
   ERAs were utilised for the other two port environments. One of these   
   environments has characteristics typical of a Baltic Sea port, while   
   the other represents a European port with efficient water exchange due   
   to a large tidal range.   
      
   The researchers found that three out of the four port environments were   
   prone to unacceptable risks according to the assessment model used. They   
   also saw that it was emissions from antifouling paint and scrubber   
   discharge water that accounted for the highest levels of hazardous   
   substances in the marine environment and had the highest contribution to   
   the risk. More than 90 per cent of the environmentally hazardous metals   
   and PAHs (polycyclic aromatic hydrocarbons) came from scrubber discharge   
   water, while antifouling paints accounted for the biggest load of copper   
   and zinc.   
      
   Total load is what causes the damage "If you look at only one   
   emissions source, the risk level for environmental damage may be low or   
   acceptable. But if you combine multiple individual emissions sources,   
   you get an unacceptable risk. The marine organisms that are exposed to   
   contaminants and toxins don't care about where the contaminants come from,   
   it is the total load that causes the damage," says Lunde Hermansson.   
      
   The only port environment that showed an acceptable risk in the   
   researchers' ERA was the model with the highest water exchange per tidal   
   period, meaning that a high volume of water is exchanged in the port as   
   the tide moves in and out.   
      
   "It's important to remember that the contaminated water doesn't just   
   disappear -- it is transported elsewhere. In the port environments   
   studied, there might be a kind of acceptance of environmental damage --   
   that in this particular environment we have decided that we will have   
   an industry and that it will result in pollution. However, when the   
   contaminated water is washed out to sea, it can end up in pristine sea   
   areas and have even greater consequences. This is something we address in   
   our research. We look at the total load, how much is actually discharged   
   into the environment," says Lunde Hermansson.   
      
   Having scrubbers on a ship is not a requirement. They are installed and   
   used as an alternative to switching to a cleaner and more expensive fuels   
   that emit lower volumes of metals and PAHs. Scrubbers allow ships to   
   continue using the much cheaper and more polluting heavy fuel oil. Heavy   
   fuel oil is a residual product in the distillation of crude oil, and is   
   now used only in maritime transport.   
      
   Economical to install scrubbers Since the mid-2010s, the number of ships   
   with scrubbers installed has increased. In a study conducted in 2018,   
   it was found that there were 178 ships with scrubbers operating in the   
   Baltic Sea. Today, the researchers estimate that there is triple that   
   number. Globally, there are about 5,000 such ships, representing around   
   five per cent of the total fleet.   
      
   "But it's the large ships with high fuel consumption that install   
   scrubbers, because it is more economical for them to do so. So we   
   anticipate that they would account for somewhere around 30 per cent of   
   total fuel consumption in shipping," says Lunde Hermansson.   
      
   She points out that the use of heavy fuel oil as a ship fuel also   
   contradicts the commitments that the IMO has said it wants to make,   
   such as reducing greenhouse gas emissions from shipping by 50 per cent by   
   2050. The Swedish Agency for Marine and Water Management and the Swedish   
   Transport Agency have submitted a proposal to the Swedish Government to   
   prohibit the discharge of scrubber water into internal waters, that is,   
   waters that lie within the Swedish archipelago.   
      
   "It's a step in the right direction, but we would have liked to see   
   a stronger ban that extends across larger marine areas, while we   
   also understand the challenge for individual countries to regulate   
   international shipping," says Erik Ytreberg, an associate professor at   
   the Department of Mechanics and Maritime Sciences at Chalmers.   
      
   How the risk assessment in the four ports was carried out The work to   
   assess the environmental risk in the ports was carried out following a   
   bottom-up approach.   
      
   In Step 1 (at the bottom), the loads from various emission sources   
   from shipping were calculated. The volumes were estimated using STEAM,   
   a model that assesses emissions from ship traffic. The volumes were   
   combined with specific concentrations of the substances within each   
   emissions source to calculate the load of the different substances.   
      
   In Step 2, the daily load was used to estimate the resulting   
   concentrations in the environment, called PEC or predicted environmental   
   concentration, using the MAMPEC model. The model calculates PEC for a   
   defined environment (in this case a port), using the properties of the   
   substances (in this case of 9 metals and 16 polycyclic hydrocarbons)   
   and the daily load of the substances (from Step 1).   
      
   MAMPEC calculates PEC for one substance at a time at a constant load.   
      
   In Step 3, the results were then combined to enable the inclusion of   
   more substances as well as loads from different emissions sources   
   simultaneously. To calculate the environmental risk, the PEC is   
   compared with the limit values that represent the concentration that   
   can be considered safe, in other words, where no negative effect on the   
   marine environment is found. This is also known as the PNEC (Predicted   
   No Effect Concentration). If the PEC is higher than the PNEC, it is said   
   that there is an unacceptable risk.   
      
   In Step 4, the risk characterisation ratios (RCRs) from multiple   
   substances were added together, which means you can calculate the   
   cumulative risk and present a more comprehensive environmental risk   
   assessment within an area.   
      
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   Story Source: Materials provided by   
   Chalmers_University_of_Technology. Note: Content may be edited for style   
   and length.   
      
      
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   Journal Reference:   
      1. Anna Lunde Hermansson, Ida-Maja Hassello"v, Jukka-Pekka Jalkanen,   
      Erik   
         Ytreberg. Cumulative environmental risk assessment of metals   
         and polycyclic aromatic hydrocarbons from ship activities in   
         ports. Marine Pollution Bulletin, 2023; 189: 114805 DOI: 10.1016/   
         j.marpolbul.2023.114805   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230613110059.htm   
      
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