Scientist warns of high arsenic content in sargassum

AS JAMAICA and the wider Caribbean brace for another influx of sargassum weed along the islands’ beaches, research is ongoing to find productive uses for this open ocean brown algae, which is free floating and will not attach to the ocean floor.

Sargassum can also be extremely important to particular endangered and migratory species like sea turtles and whales and can play a role in beach nourishment and is an important element in shoreline stability.

However, in excessive amounts of it may result in beach erosion.

Mona Webber, professor of marine biology and director of the Centre for Marine Sciences and Discovery Bay Marine Laboratory at The University of the West Indies, has been spearheading a research project on sargassum and shared some of the findings.

“We started three years ago and part of it involves an analysis of the constituents of the sargassum and potential uses for the algal biomass. It has good potential for making fertiliser and can also be used as a manufacturing raw material. We even tried composting it raw but it had too much sodium (salt) and too much arsenic. It naturally has too much arsenic (a very poisonous metallic element), so it’s not something you can just pick up and use.

“When it rots is produces hydrogen sulfide which is a bad gas, so it has to be handled with care and the information needs to get out there into the coastal communities. That is critical,” Professor Webber advised.

Despite this, indications are that sargassum could have many economic spinoffs, the marine scientist disclosed.

“The Scientific Research Council did a test for me using pig slurry and they were able to produce a bio-methane. So if you live near to the coast and want to invest in a bio-digester, sargassum is in abundance, so it has great potential. In fact, in Barbados it is being used in bio-digesters to generate bio-methane. In another Caribbean island they are now basing a fertiliser production system on the sargassum. The main thing is the removal of the arsenic and they are holding on to that technology, holding it close to their chest. It’s not something that they are publishing or sharing.”

Meanwhile, the National Environment and Planning Agency (NEPA) has warned that some local beaches have already begun to accumulate sargassum and so it has granted permission for hotel/resort owners, beach operators and fishing groups to manually remove the seaweed from their properties. However, the use of heavy-duty equipment such as tractors or front-end loaders is prohibited by NEPA.

In a half-page advertisement carried in the Sunday Gleaner of March 26, the agency sets out guidelines for the proper manual removal and disposal of the sargassum.

For the removal, NEPA advises the use of non-intrusive methods, such as hand-raking or beach-raking equipment with a perforated conveyor belt. It also warns that the removal of sand must be avoided and where this is accidentally removed during raking, it should be returned afterwards. Clean-up activities should also be monitored to ensure that there is little or no disruption of the marine ecosystem, with special care taken to ensure that there is no loss of endangered sea turtles, including nests and hatchlings.

In terms of the disposal of the sargassum, it advises that a stockpile location be identified on-site, preferably on another area of the property. The seaweed should also be turned occasionally to promote drying and the displacement of any sand contained therein. Where it is practical, after a suitable time, the sargassum may be buried at an appropriate location.