Saturday, November 27

Inter-island ferries are the most likely cause of harmful gas emissions, new study finds

A sensor on Picton beach captures roughly the same amount of sulfur dioxide in the air as a sensor off Tauranga harbor.

03052021 NEWS PHOTO MARLBOROUGH EXPRESS SCOTT HAMMOND / STUFF Police search for ferries after a bomb scare at the Picton ferry terminal.  Bluebridge lingers on the dock during the search,


In fact, it often picks up more sulfur dioxide, a gas that occurs naturally in volcanoes. It also comes from burning coal or diesel.

Port Marlborough exported around 770,000 tonnes of logs last year from Shakespeare Bay, near Picton. Last year, the Port of Tauranga exported 6.3 million tons of logs. In that sense, it is about 80 times bigger than Port Marlborough.

So why the similar levels of the noxious gas? It is likely due to the thick clouds of white smoke pouring into Picton from the inter-island ferries.

That’s according to a new study, which basically echoes what residents have been saying for years.

The study was presented to the Marlborough District Council’s environmental committee last week, prompting councilors to request an air basin in Picton, so that air quality could be monitored over the long term. Marlborough’s only existing air basin was at Blenheim.

The council decided to conduct a 14-month study to see what “major and worrying pollutants” were blowing around Picton after residents became increasingly concerned that fumes from visiting ships would seriously affect their health.

He installed three sensors, one on the beach, one on the main highway into town, and one at the local high school, to track sulfur dioxide, nitrogen dioxide, carbon monoxide, and air pollution.

Each pollutant could cause human health problems ranging from shortness of breath and coughing to asthma attacks, bronchitis, cardiovascular and respiratory diseases or premature death. The risk was higher among vulnerable people such as children, asthmatics or the sick. The study was carried out from July 2019 to August 2020.

The worst offender was found to be sulfur dioxide.

The team of air scientists analyzing the data said the beach appeared to have higher sulfur dioxide levels on average than New Zealand’s largest port, Tauranga. However, ports had different recording devices, weather patterns, types of visiting vessels, and traffic levels.

“The consistently higher baseline in the shoreline data is likely associated with regular ferry movements as opposed to cargo ships staying offshore for longer periods,” the report said.

18072018 News Photo: Scott Hammond / Stuff Pollution Picton.  Cook Strait broadcasts local complaints about high levels of toxic exhaust gases.  InterIslander Kaitaki

A close-up view of the funnel of an inter-island ferry.

Global studies had shown that emissions from shipping affected the air quality of adjacent coastal areas, “negatively affecting the local environment and human health,” the scientists said.

“Emissions are not only produced while the ferry is docked, but also while it is arriving and departing. Exhaust emissions can be clearly visible along Queen Charlotte Sound for a considerable time after a ferry has left its berth and is on its way. towards Wellington, similarly when ferries arrive at the [Marlborough] Sounds from Wellington. “

Council environmental scientist Sarah Brand said it was “interesting” to see a similar pattern of sulfur dioxide, given that the port of Tauranga was “substantially larger” than the port of Picton.

Interislander CEO Walter Rushbrook said KiwiRail welcomed the findings and was working to ensure its ferries reduce any impact on Picton’s air quality.

He said KiwiRail was in the process of switching its Interislander ferries to cleaner burning diesel, while waiting for its larger and greener ferries to be built and delivered.

The new diesel would reduce sulfur emissions.

“In the long term, the Interislander will bring two new ferries, one in 2025 and one in 2026. These ferries will reduce the Interislander’s emissions by 40 percent overall compared to existing ships and eliminate emissions while in port when they will run on battery or shore power, “Rushbrook said.

Director of the Kiwirail Project for Recovery Walter Rushbrook.

New ferries to be delivered in the next five years will reduce emissions, says Interislander CEO Walter Rushbrook.
Photo: RNZ / Rebekah Parsons-King

Bluebridge was contacted for comment.

The report showed that the amount of sulfur dioxide in the atmosphere remained mostly within safe levels for breathing during the spring and summer, before suddenly skyrocketing in May last year on the beach and on the main highway into the city.

This resulted in multiple violations of New Zealand’s air quality laws. By the end of the study, Picton had approached or exceeded the limit once every five days.

Scientists weren’t sure what caused the “sharp rise” in winter, but Brand thought it indicated that dozens of Picton residents still used charcoal to heat their homes. The council did not know how many houses in Picton had charcoal burners.

The results also showed that nitrogen dioxide, an emission produced by fossil fuels, was stronger around the beach than on the main road into town, which the scientists said was “unexpected” because it was exposed to less traffic. .

Emissions were particularly high in summer, not enough to break public health guidelines, but close enough for scientists to conclude that this could happen in the future.

“One possible explanation for the increase in summer is the increased use of local diesel-powered boats in the port immediately adjacent to the beach site, and there is a fuel dock in the area. However, it would be required. more research to confirm this hypothesis. “

Each of the sensors also registered an increase in pollution in late spring, around the same time that acacia and pine trees began to drop their pollen, which blanketed the city in yellow.

Brand told councilors last week that the study showed Picton was in danger of violating national air quality laws from particulate pollutants, sulfur dioxide and nitrogen dioxide.

“It is necessary to work more on the sources of the pollutants, how they behave, how they move.”

Several councilors were surprised by the findings. Councilman Gerald Hope said the study indicates that something needs to be done “sooner rather than later.”

“If it weren’t for the wind, we would probably have more complaints.”

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Local Democracy Reporting is a public interest news service endorsed by RNZ, the News Publishers Association, and NZ On Air.

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