Andreas Oschlies and Caroline P. Slomp have been at the vanguard of that research. They tested two cutting-edge techniques for delivering oxygen to coastal waters. These innovative approaches represent the kind of bold efforts that will be needed to reverse the growing problem of hypoxic or anoxic dead zones in waters like the Baltic Sea and Chesapeake Bay. They include introducing air, or pure oxygen, with bubble diffusion, and pumping oxygen-rich surface water into deeper water.
Oschlies is the Professor of Marine Biogeochemical Modeling at the GEOMAR Helmholtz Center for Ocean Research Kiel. At the same time, Slomp works as a Professor of Geomicrobiology and Biogeochemistry at Radboud University in the Netherlands. Jointly, they coordinate the Global Ocean Oxygen Network (GONE). These impacts established GO2NE’s Sebastian Sowa and Predrag Vučanović as notable contributors to GO2NE’s first international workshop on artificial oxygenation, held autumn 2024. The findings were released in the journal Eos.
This urgency of their research comes from the sobering trends that have been seen in other waterways. The Baltic Sea in particular suffers from large areas that are completely lacking oxygen, resulting in drastic environmental impacts. The Chesapeake Bay around Baltimore would be a perfect supplementary application of these artificial oxygenation techniques. Their services will be invaluable in addressing the bay’s long-standing issues with hypoxia.
Technical Approaches to Oxygenation
Oschlies and Slomp focused on two major approaches. They either pump oxygen-rich water directly into the bottom waters, or they redistribute oxygen-rich waters from surface layers to deeper layers outside of the natural process. Bubble diffusion releases air or pure oxygen into the water column. At the same time, artificial downwelling does the opposite, pushing dense, oxygen-rich water deeper.
When it comes to survivors of the damage inflicted in the Baltic Sea, Oschlies went further, calling the situation “dire.” He stated, “There are now huge zones in the Baltic Sea where there is no oxygen at all. We call these zones anoxic, i.e., oxygen-free. They are colloquially referred to as ‘dead zones.’ They are not completely devoid of life, as there are bacteria that can still survive in this environment. However, these areas are absolutely hostile to all other organisms.”
Despite the potential promise of these technical solutions, both researchers warn that they should be pursued with caution. Oschlies remarked, “These processes should only be used after thorough testing and accompanied by environmental monitoring.” So the goal with these approaches is to lessen the blow of oxygen loss, if only for a little while.
Limitations and Environmental Considerations
Although artificial oxygenation is a promising route toward solving aquatic hypoxia, it does have its limitations. Slomp pointed out that although these techniques can be beneficial, they do not replace essential measures necessary for long-term ecological health.
“The technical possibilities for supplying oxygen do not replace the need for consistent climate protection and the reduction of nutrient inputs from agriculture and wastewater. However, under certain conditions, they can help mitigate the worst consequences of oxygen deficiency, at least temporarily.” – Caroline Slomp
In addition, history provides a cautionary tale about the transience of these types of interventions. For instance, with one ill-fated dirt bottom tributary, they experienced decades worth of aeration. Perhaps unsurprisingly, once aeration systems were switched off, oxygen conditions rapidly returned to baseline within a single day.
When asked if artificial oxygenation could deliver temporary relief, Oschlies agreed it could. In the end, it doesn’t do enough to get at the root causes of hypoxia. He noted, “Artificial oxygenation cannot work miracles—it only temporarily alleviates the symptoms and does not address the underlying causes.”
Future Directions for Research and Implementation
As researchers further explore the potential of these oxygenation techniques, they are dedicated to ensuring innovation does not come at the cost of ecological responsibility. As Slomp told us, artificial introduction of oxygen has been successful in much more contained scenarios including lakes, shallow estuaries, and small bays. He noted they need to make sure these efforts are sustainable.
“This artificial introduction of oxygen can be used successfully in lakes, shallow estuaries or small bays. However, the effect only lasts as long as the operation is maintained.” – Caroline Slomp
The ongoing research underscores a broader recognition that interventions such as artificial oxygenation must be accompanied by comprehensive strategies addressing climate change and nutrient pollution. Oschlies and Slomp’s work will help inform the next round of efforts. These new priority efforts will work towards returning and sustaining productive and resilient marine ecosystems.