How do you cope with 9m tonnes of suffocating seaweed?

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How do you deal with 9m tonnes of suffocating seaweed?


The Nice Atlantic Sargassum Belt, first detected by Nasa statement satellites in 2011 and now identified to be the world’s largest bloom of seaweed, stretches for five,500 miles (8,850km) from the Gulf of Mexico to the western coast of Africa.

Hundreds of thousands of tonnes of floating Sargassum seaweed in coastal waters smother fragile seagrass habitats, suffocate coral reefs and hurt fisheries. And as soon as washed ashore on Mexican and Caribbean seashores, this foul-smelling, rotting seaweed goes on to devastate the vacationer trade, stop turtles from nesting and harm coastal ecosystems, whereas releasing hydrogen sulphide and different poisonous gases because it decomposes.

Seaweed blooms are exacerbated by fertilisers washing into the ocean, in addition to by warming sea temperatures. “Sargassum blooms on the Atlantic gyre [tidal current] have gotten a lot worse in recent times partly as a consequence of rising intensive agriculture discharging fertiliser into the ocean by way of rivers such because the Mississippi and Amazon,” says Prof Mike Allen, of the College of Exeter and Plymouth Marine Laboratory. “Fertiliser makes the seaweed develop quicker and this inflow of biomass simply shouldn’t be there in that abundance – it’s uncontrolled.” In Might this 12 months, 8.7m tonnes of Sargassum had been noticed throughout the Atlantic.

Allen is a part of a analysis staff led by the schools of Exeter and Bathtub that believes it might have discovered a strategy to rework this environmental mess right into a golden financial alternative – by growing an affordable and easy strategy to pre-process seaweed on an industrial scale earlier than changing it into high-quality, low-cost sustainable fertiliser, fuels and chemical substances.

“It’s free and there’s a lot of it, so it is sensible to transform it into helpful merchandise,” says Allen. “However changing marine biomass like seaweed normally requires eradicating it from salt water, washing it in contemporary water and drying it. That’s very costly, so we would have liked to discover a methodology that will be each economically and environmentally viable.”

His staff has devised an preliminary “fractionation” or separation course of that gives “a vital lacking step in the direction of creating a real salt-based marine biorefinery” through the use of acidic and alkaline catalysts to interrupt down the salty seaweed. The sugars produced can be utilized to feed a yeast that produces a palm oil substitute, whereas the remaining seaweed biomass is then able to be subjected to extraordinarily excessive temperature and stress in a course of referred to as hydrothermal liquefaction (HTL), and break up into totally different merchandise. The ensuing liquid bio-oil may be processed additional into gasoline and an aqueous, nutrient-rich fertiliser precursor, whereas heavy metals which can be probably recyclable are separated right into a strong char, and carbon dioxide may be captured.

However harvesting enormous volumes of seaweed poses enormous challenges. “The timings, sizes and actual places of those seaweed blooms are unpredictable, plus its composition modifications each day because it rots,” explains Prof Chris Chuck, the venture’s lead chemical engineer on the College of Bathtub. “So we’d like versatile know-how to deal with the heterogeneous nature of the fabric. Simply because the crude oil trade creates liquid gasoline, plastics and fertilisers, we will profit from related flexibility. By altering the situations to supply totally different quantities of particular by-products, we will meet variable demand.”

With HTL, even plastic waste and lifeless animals discovered entangled among the many seaweed may be transformed.

The inspiration for the venture got here from Allen’s youngsters, Rosie, 12, and Archie, 9, who helped him acquire seaweed samples for trial research alongside England’s south Devon coast. “Whereas we had been painstakingly eradicating fishing gear entwined across the seaweed, Rosie requested me: ‘Dad, can’t you simply convert the plastics alongside the seaweed?’” remembers Allen. “At first, we thought it was a foolish thought, however her remark triggered a stream of analysis and now we embrace the plastic.”

Throughout the Caribbean, scientists are growing different sustainable options to this golden tide. Dr Jayaraj Jayaraman, professor of biotechnology and plant microbiology on the College of the West Indies in St Augustine, Trinidad and Tobago, is formulating biofertiliser and different merchandise – as a consequence of be prepared for commercialisation inside two years. He proposes harvesting Sargassum from the floor of the ocean earlier than it rots on the seashores and turns into more durable to wash, however acknowledges that that is “a really costly operation”.

Within the open ocean, Sargassum offers a precious habitat for breeding fish and different marine life, in accordance with Dr Debbie Bartlett, ecologist and principal lecturer in environmental conservation on the College of Greenwich in south London. “The elimination of seaweed earlier than it reaches shore would require an evaluation of dangers to wildlife, akin to turtles. Assortment at sea might hurt wildlife, but additionally any growth put in to maintain the seaweed from touchdown on seashores can simply be broken throughout hurricane season,” says Bartlett, who’s investigating the potential use of Sargassum discovered on the seashores of the Turks and Caicos Islands for biogas manufacturing and composting utilizing anaerobic digestion.

Preliminary outcomes point out biogas manufacturing is unlikely to be a really perfect resolution, and Bartlett explains that as a result of most meals are imported to the Turks and Caicos Islands, demand for seaweed-based compost could be restricted to decorative gardens round lodges. “It’s extremely difficult. There’s no joined-up strategy and we’re unlikely to get one as a result of there are such a lot of totally different international locations concerned.”

This monumental quantity of biomass is devastating the vacationer trade, economic system and atmosphere

Chris Chuck, College of Bathtub

Bartlett lately discovered that the bloom is a mixture of totally different variants of Sargassum. “The blended mats of seaweed comprise three totally different ‘morphotypes’, every with its personal chemical make-up,” explains Bartlett. “To transform it successfully, we have to know the way a lot of every one is current within the combine and the way each reacts to processing.” Researchers on the College of Greenwich additionally discovered that the doable presence of marine pollution akin to arsenic and different heavy metals in Sargassum samples could make the seaweed unsuitable for meals or prescription drugs and warned that use in feed and fertilisers must be restricted.

However Allen and Chuck argue that they don’t face these issues as a result of they will convert a variable biomass. “This monumental quantity of biomass is devastating the vacationer trade, economic system and atmosphere, however we’re making a extra round economic system by recycling these vitamins again right into a renewably sourced fertiliser and merchandise that would displace crude oil,” says Chuck, who’s estimating the prices of scaling up the operation whereas finishing up trials with a Mexican fertiliser firm to check the efficacy of fertilisers made utilizing Sargassum. “If we will get the economics proper, we’re trying to commercialise quickly.”



a large body of water: Sargassum covers the beach in Playa del Carmen, Mexico. Photograph: Victor Ruiz/AP


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Sargassum covers the seashore in Playa del Carmen, Mexico. {Photograph}: Victor Ruiz/AP

There’s a huge worldwide effort to repair these seaweed invasions due to their impression on tourism, notably in Mexico. But when Sargassum will get collected at sea, maybe by cellular processing models or a tanker with a biorefinery on board, Allen believes that funding wouldn’t be so forthcoming and that extra worldwide cooperation could be required.

“Because it stands, extra localised, decentralised and cooperative operations are extra beneficial, and as soon as [this industry becomes] extra established, large-scale offshore multinational operations producing enormous volumes of lower-value biofuels is perhaps possible,” explains Allen.

Wave Crookes, co-founder of SeaGrown, the UK’s first large-scale industrial seaweed farm, is worked up by the proposed know-how: “Seaweed is so versatile, and this Sargassum is an efficient pure useful resource, however the practicalities of utilizing it are usually not straightforward.

Associated: Huge Sargasso seaweed: 5,500-mile algae belt retains on rising

“Creating a biorefinery at sea is an efficient choice. It makes excellent sense to take out the high-value compounds earlier than you find yourself with different merchandise akin to bio-char and fuels, if it may be made financially viable with out hurt to the wildlife feeding in or breeding on the floating Sargassum. However clearly, there are key challenges relating to predictability, repeatability and possession of the seaweed.”

If these obstacles may be overcome, Allen and Chuck’s staff believes there may be monumental scope for the know-how to have many environmental purposes. “We’ve created a set of options that may be deployed globally at totally different places for various functions,” says Allen, who argues that the strategies might probably be used to deal with plastic air pollution on seashores, clear up invasive water hyacinth in Lake Victoria, Africa, and eradicate heavy-metal contaminants akin to these within the lakes round Hanoi in Vietnam.

However with reviews that one other 500 tonnes of Sargassum hit Mexican seashores in storms earlier this month, the seaweed is the primary risk to deal with.

Discover extra age of extinction protection right here, and comply with biodiversity reporters Phoebe Weston and Patrick Greenfield on Twitter for all the newest information and options



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