Month: November 2024

It has been a busy two days – and we haven’t even left port yet! Firstly, there was equipment to get aboard and stow, and a reception to be organised for local German and Brazilian dignitaries. This included a presentation by the scientists, a tour of the ship and some canapés on the main deck. It all went very well, and we were pleased that all our visitors enjoyed being tested on what they had learned with a short Kahoot, before being taken around and shown what a great ship and crew we have to look after the cruise. Many thanks to all who honoured us with their presence.

It is late afternoon now and everyone is still at work setting up their posts in the labs, and preparing for the long sampling run ahead. This will begin tomorrow, as soon as we leave port, interrupted only by more safety training. Details of individual labs and the work of all the groups will be coming soon – bookmark us to find out more!

All photos Clive Maguire except ‘Reception’ and ‘Presentation of M206’ – Photos Mark Zindorf, with thanks.

Never let it be said that scientists are afraid of getting their hands dirty. Whether it’s wading knee-deep in mud or standing waist deep-in murky waters, it’s all in a day’s work for the dedicated team of scientists of the PROBRAL project. Drawn from Germany and Brazil (Constructor University Bremen, GEOMAR, the University of Oldenburg, Universidade Federal do Pará, and Universidade Estadual do Norte Fluminense) they teamed up this month to analyse water from mangroves, rivers and estuaries in North Brazil.

Making chemistry together

Metals like copper and iron are naturally present throughout oceans, rivers and estuaries, and can act as both nutrients and toxins to living organisms.  The behaviour of the metals is influenced by their size (e.g. are they large particles or dissolved?) and other components of water chemistry, such as salinity, pH (how acidic is the water?) and the presence of dissolved organic matter.  Rivers and estuaries are often rich in organic (carbon-based) matter from plants and soil. Dissolved organic matter often binds to metal ions (when this happens, it’s called a “ligand”), and this can influence their bioavailability (how readily they can be taken up by living organisms).

We love Mangroves

Mangrove swamps are a rich source of dissolved organic matter, nutrients and some metals. The team sampled porewater (water that collects in the ground in the tiny gaps between particles of soil) in both degraded and healthy mangroves. We sampled by digging holes and collecting the water that filled them. Even at low tide, we had to stomp through heavy mud, often sinking in to our knees. We saw lots of tiny crabs, birds, and even a monkey!

We also visited several creeks and rivers, especially the Caeté River that runs through Braganca and northern Brazil in the state of Pará. The Caeté is influenced by diurnal (twice daily) tides, resulting in salinity that changes throughout the day in the regions nearer to the coast. We sampled at multiple sites across the whole salinity gradient, from coastal waters (salinity 35, like seawater), to brackish estuary waters, and riverine freshwater (salinity 0). We sampled both by boat in the Caeté Bay, and from land in the inland rivers and creeks.

Contributing to M206

The PROBRAL campaign will generate lots of great data that will contribute to the M206 cruise, also examining trace metals and organic matter in the Amazon and Pará River estuary, as well as near coastal mangroves to the south-east.

On 30^th November, the Amazon Geotraces-2 interdisciplinary research cruise M206, with RV Meteor, led by Prof. Andrea Koschinsky of Constructor University will sail from the Brazilian port of Fortaleza to begin work examining the distribution of trace elements, organic matter and isotopes discharged into the Atlantic from the Amazon’s mouth. The cruise is carried out in collaboration with GEOMAR in Kiel, the University of Oldenburg, the University of Hamburg, and the Brazilian Universities Universidade Estadual do Norte Fluminense, Universidade Federal de Santa Maria and Universidade Federal do Rio Grande do Sul.

The Amazon Plume

The Amazon River is almost 7.000 km long and in the wet season transports an incredible 300,000 cubic metres of water into the Atlantic Ocean every second. It is responsible for about 20% of the world’s fresh water entering the ocean, and the water spreads into the ocean in a huge plume covering an area of 80,000 square kilometres. As it pushes into the sea, it brings with it huge quantities of trace metals such as iron and copper and dissolved organic materials, and it is these materials and the processes they undergo during mixing of river water and seawater that interest the team.

“We need a much better understanding of the material cycle in the ocean,” says Prof. Koschinsky about the research trip’s aims. “We will only be able to reliably predict the human impact on the cycle if we can succeed in this.” Elements such as carbon, nitrogen, and phosphorus play an important role in our oceans, as they are essential elements for the formation of biomass. However, all life needs iron – even the smallest marine organism. In addition, many other trace elements such as copper, cobalt and zinc are essential while some other elements such as mercury are toxic elements of high environmental concern.

This is the second time the team will have studied the area. In 2018, they visited during the wet season, and this year they will study what happens in the dry season. They will take comparative water and sediment samples throughout the plume area and beyond, at depths from less than 100m to more than 2,000m and across the mixing area from pure seawater to pure freshwater. The research is very important, particularly now, when the whole of the Amazon region has experienced the worst drought in living memory. Humans are intervening in the fragile ecosystem of the Amazon and changing it significantly by building dams and through deforestation, and intensive agriculture. In addition, climate change will alter the fluxes from the Amazon to the ocean. All of this will in turn impact the biological productivity and health of the coastal ocean.

NEW Young Learner Outreach

This year we are focused on helping young learners and their teachers engage with M206, Geotraces, and the wider geoscientific community. In addition to adding regular blog posts here, we will be adding posts we hope students and teachers will find interesting, and building up an online library of free factsheets, fun activities and quizzes, lessons/lesson plans, links and other useful or fun material. Bookmark and keep an eye on the blog, or take a look at our young learner pages here.