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An environmental clean-up project says plastic bags have largely been eliminated from the water in Sydney Harbour.
Key points:
- There has been a 70 per cent reduction in the number of plastic bags collected by Seabin
- A state government ban on the bags is credited with driving the fall
- Experts say microplastics need to be addressed at their source
Seabin operates 34 bins around the harbour which filter the water to capture microplastics and large plastics.
The company say they collect up to 13,000 plastic items in the harbour every day.
Seabin CEO Pete Ceglinski told ABC Radio Sydney the impact has been dramatic since businesses were banned from giving out lightweight plastic bags in June last year.
"We've seen a reduction by 70 per cent of plastic shopping bags floating around in Sydney Harbour," Mr Ceglinski said.
"With only 12 months of enforced plastic bag ban, it's pretty staggering results in a very positive way."
The group has filtered 15 billion litres of water and collected more than 100 tonnes of litter from the harbour since a trial with City of Sydney in July 2020.
Despite the progress, Mr Ceglinski says the biggest waste issue is microplastics which has made up 44 per cent of the contents picked up by the bins.
"We need to understand better what the problem is to address the lack of accountability and governance of plastic pollution in Sydney Harbour," Mr Ceglinski said.
"I'm feeling very positive ... that collectively we can turn the tide on this plastic pollution problem and especially in Sydney Harbour."
The state government also banned the single-use plastic straws, cutlery and cotton buds in November 2022.
Microplastics need to be addressed at source
There are up to 5,000 microplastics per square metre in Sydney Harbour's shorelines, says Scott Wilson who is part of the Australian Microplastic Assessment Project (AMAP) which measures the problem.
Dr Wilson says since AMAP began counting the fibres, pellets and foam on the shore in 2018, there has not been any improvement in the amount of microplastics in the harbour.
"Most of what we're finding in the harbour is coming from our urban catchments; it's washing through the stormwater," he said.
He believes government regulation of plastics and the industry designing better products are key to reducing microplastics in the marine environment.
"There's a role for us as citizens and community members to choose better products, but ultimately it's industry, in designing better products, and governments to regulate the better products," Dr Wilson said.
"We need to reduce how much of that product there is."
Branded offenders
Confectionary wrappers keep turning up in the marine waste collection bins.
Mr Ceglinski says rubbish with Cadbury branding most frequently appears in their bins, accounting for 32 per cent of the branded litter.
Loading...Cadbury is then followed by Mars Wrigley packaging, making up 13.8 per cent, while Perfetti Van Melle (whose brands include Chupa Chups and Mentos), Nestle and Coca-Cola make up 11.9 per cent, 10.6 per cent and 7.8 per cent respectively.
Mr Ceglinski was interested to discover cheese-flavoured Smith's chip packs were more likely to turn up than original-flavour ones.
He said rubbish was not always the result of deliberate littering but may have been blown out of bins by the wind or garbage falling out of overfilled receptacles.
Water quality issues stem from heavy rainfall
The Sydney Institute of Marine Science's Martina Doblin says the water quality of the harbour has generally improved but is at greater risk of climate change, which brings more intense rainfall.
Heavy rainfall events bring debris and negative effects to the harbour's water quality.
"Stormwater enters our urban waterways and carries with it grease from roads, dust and debris left in gutters, organic material from our garden fertilisers, pesticides, and emissions from vehicles," Dr Doblin said.
"There are sometimes releases, because of mounting pressure in the system, where untreated water is released into the harbour."
Dr Doblin says improving the ageing stormwater and wastewater infrastructure would help prevent degradation of the harbour's water quality.
The institute is also working on a project to install living seawalls in the harbour to regrow mussel and oyster populations, which can filter the harbour water and improve water quality.