Climate change makes metals in the ocean more toxic

Did you know our oceans naturally contain tiny quantities of toxic metal elements like lead, mercury, arsenic, and cadmium? It sounds a bit concerning. But these trace elements typically aren’t an issue.

However, human activities such as industry and agriculture have been contributing heftier amounts.

To make matters worse, a new study has found climate change already has an impact on how these elements are distributed and accumulated in our seas. As we move forward, this could have significant implications.

Understanding changes in the ocean

We are well-versed in the impacts of climate change on our oceans: warming temperatures, growing acidity, and loss of oxygen. The newest twist in the tale however is the way climate change affects contaminants in our seas.

The research was led by Dr. Rebecca Zitoun, a marine chemist at GEOMAR Helmholtz Center for Ocean Research Kiel, and Dr. Saša Marcinek from the Ruđer Bošković Institute in Zagreb.

Lead, mercury, cadmium, and other metals don’t just enter our oceans through industrial or fossil fuel burning activities.

As it turns out, natural sources of these elements are undergoing changes due to climate factors such as rising sea levels, rivers overflowing, or drying up, and melting sea ice and glaciers. The result? Increased flow and mobilization of contaminants.

Metal contaminants in the ocean

The research is the product of a working group of the UN Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP), with a focus on metal contaminants in the ocean.

Dr. Sylvia Sander, professor of marine mineral resources at GEOMAR and former head of the Marine Environmental Studies Laboratories at IAEA in Monaco, initiated this working group. German contributor Christoph Völker from the AWI is another member of this group.

“Our working group has focused on the effects of climate change and greenhouse gases on contaminants in the ocean,” explained Dr. Sander.

This rise is mainly due to melting glaciers, thawing permafrost, and coastal erosion. Such an increase in mercury levels poses a significant risk to communities dependent on traditional fishing, as mercury accumulates in the food chain.

The contribution of human activities

“Human activities have increased the global flow of toxic metals such as lead by tenfold and mercury by three to seven times compared to pre-industrial levels,” said Dr. Sander.

“Toxic elements like silver are increasingly detectable in coastal waters, originating from coal combustion and the growing use of silver nanoparticles in antibacterial products.”

It’s not just these elements, but even silver is increasingly detectable in coastal waters, thanks to coal combustion and the growing use of silver nanoparticles in antibacterial products.

The proliferation of plastics and shipping have further contributed to this issue. They can bind heavy metals such as copper, zinc, and lead, which can then enter the food chain. With increasing exploitation of the oceans, the human contribution of these heavy metals could rise even further.

Changing climate and metals

Climate changes, like warming sea temperatures, ocean acidification, and oxygen depletion, impact trace elements in a variety of ways.

For instance, water temperatures directly influence the bioavailability and uptake of trace elements like mercury in marine organisms.

With higher temperatures, metabolism increases, oxygen solubility reduces, and gill ventilation improves, leading to more metals entering organisms and accumulating in their bodies.

Additionally, as our oceans absorb more human-emitted CO2, their pH levels drop, thus increasing the solubility and bioavailability of metals like copper, zinc, and iron.

This can be particularly damaging with copper, which is highly toxic to many marine organisms at increased concentrations.

Changes in ocean contaminants

Human activities have a two-pronged effect on the amount of contaminants in our coastal regions. There is the direct impact where we release pollutants into the environment, and then there is the indirect effect of climate change on natural sources of these elements.

What’s concerning is that there is a significant lack of data on how climate change influences contaminants in the ocean.

The working group argues that we need more research into new and under-studied contaminants. They also stress on the need for better models, as well as updating legislation that controls the impact of contaminants in the seas.

Emerging challenges

The dual threat of climate change and environmental contamination presents a formidable challenge requiring innovative solutions and collaborative strategies.

One burgeoning area of research is the development of advanced models that provide comprehensive insights into the interaction between climate variables and contaminant behavior in marine ecosystems.

Such models would enable scientists to predict shifts in contaminant distribution and, more importantly, devise mitigation strategies that prioritize environmental and human health.

In addition, the integration of satellite technology and big data analytics offers unprecedented opportunities to enhance our understanding and monitoring of marine pollution on a global scale.

Saving oceans from toxic metals

“To better understand the impacts on ecosystems and human health, we need to close knowledge gaps on the interactions between pollutants and climate change and develop standardized methods that provide globally comparable data,” said Dr. Zitoun.

While there is much we still need to learn, the importance of strengthening marine protection and developing sustainable solutions for vulnerable coastal areas cannot be overstated. Climate change and pollution are complex issues, but addressing them is essential for preserving our oceans.

The study is published in the journal Communications Earth & Environment.

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