Published on October 9th, 2013 | by Ellen R Delisio0
Saving the Baltic Sea
There are no shortages of ideas and action plans to re-oxygenate the deep water quality of the Baltic Sea. The region’s dependence on the 377,000 km² brackish body of water for commerce and recreation – especially Sweden – is as high as the anxiety level about the consequences if conditions fail to improve.
Some proposals are more controversial than others, such as one to install wind-powered underwater pumps in the deeper parts of the Baltic to “mix” the water to speed oxygenation. Some scientists fear that the mixing could negatively affect plants and animals in the shallower waters.
Decades of environmental issues
About 60,000 km2 of the Baltic’s seafloor, amounting to about 16% of its total area, is now a “dead zone.” The sea is experiencing eutrophication at its deepest depths, caused by an overload of dissolved nutrients, from phosphates and nitrates. The nutrients grow algae, and when the algae die, it sinks to the bottom of the ocean. There the algae consumes oxygen as it decomposes, leading to low levels of oxygen in deeper water, causing bottom organisms to die and interfering with the production of new fish.
The nutrients are the result of decades of poorly-treated waste water and runoff from farms flowing into the sea. The condition also has led to algae blooms during peak recreation use times in the summer.
“It is a very sensitive area, with not much water flowing in and out, intensive shipping and no wastewater treatment plants built in some of the large cities, and there still is a problem with farming and small water treatment plants,” said Thomas Johansson, who is the head of unit for sustainable use and maritime affairs for the Swedish Agency for Marine and Water Management (SwAM), which has adopted regulations and drafted plans for Baltic Sea improvement.
Wind turbine project
SwAM announced a plan to install a demonstration wind turbine-driven pump in the Southern Baltic to pump oxygen down to the deepest levels and accelerate water quality improvement. The wind turbine project is now in the technical development phase, according to Johansson. “The oxygen pump is one solution to take care of phosphorous,” he said.
A report on the use of wind turbine-driven pumps was developed by Professor Anders Stigebrandt of Gothenburg University and Holger Eriksson of the Inocean AB in May 2011.Daniel Conley, professor of Biogeochemistry at the Department of Geology at Lund University, has shared his concerns for the plan, saying the long-term impact of mixing is unknown.
“You just don’t know what is going to happen in terms of consequences,” Conley said. “Mixing water downward could have severe consequences for biogeochemical cycling elements and for organisms. Taking less salty, warmer water and moving it downwards affects salinity, which could affect certain fish such as cod. During the winter, water could mix down to 120 meters and bring up nitrogen and phosphorus nutrients that could lead to larger algae blooms.”
No permanent solution
Also, the pumps do not provide a permanent solution, according to Conley. “If you stop mixing, the nutrients and phosphorous would just resurface.” The project also could be extremely expensive. “If you set up 100 windmills in the Baltic, you still need to bring electricity back to the land and pay the cost of maintaining them, and the windmills only have 20-year lifetimes.”
Installing wind turbines is “taking money away from solving the problem,” Conley maintained. “We know we need to reduce nutrients. The more money we put into questionable technology, the less we have to put into reducing nutrients.” Conley supports the current strategy: continue to minimize runoff from multiple sources while involving stakeholders. “We need to reduce the nutrients from different sources and need to follow the plan agreed upon by the governments surrounding the Baltic Sea.”
But Stigebrandt said his research has not identified any problems associated with the pumps. “We have investigated several proposed risks, but so far we cannot see any severe risks,” he said. “But we see large positive effects of oxygenation. We are in the process of writing scientific papers that describe various effects of oxygenation of the deepwater. This is a necessary step because establishing a system of pumps for deepwater oxygenation will require extensive Environmental Impact Studies (EIAs). It is a problem that a lot of people claim there are supposed risks without having made the slightest attempts to really evaluate the claimed risks. It is therefore very important for our project to evaluate the proposed risks.”
The pumping he has suggested will not use surface water that is warm in summer, Stigebrandt added. Instead the water intake will be at about 50 meter depth where the water always is cold and oxygen saturated; the so-called winter water. “It is typical that our opponents say that we are planning to pump down surface water, in spite of the fact that from the beginning we suggested that one should use the cold winter water in the Baltic,” Stigebrandt said. “We are investigating how the commercially important cod will be affected. It seems that oxygenation will be beneficial for cod recruitment, based on work in progress. And oxygenation will lead to colonization of now dead bottoms, which will lead to a new feed source for bottom living fish like cod, also based on work in progress. The whole idea behind oxygenation is to decrease the flux of phosphorus from the deepwater to the surface layers. We are working on a paper that shows how this works. So, pumping will not lead to increased flux of phosphorus to the surface layer. Instead, it will lead to a decreased phosphorus flux and therefore to less algae bloom in the spring.”
Preliminary estimates suggest that oxygenation by pumping will be a very cost-effective method to decrease the phosphorus loading and eutrophication of the Baltic Sea, Stigebrandt noted. “When a trade system for phosphorus removal for the Baltic Sea has been developed, I am convinced that it might be very good business to run oxygenation systems in the Baltic Sea.”
Turning off the oxygenation system might lead to increased fluxes of phosphorus from the bottom, if the bottoms become anoxic, according to Stigebrandt. “However, when the eutrophication has been reversed, one might turn off some or all pumps for shorter or longer periods and instead deliver the wind power to electrical grids in the surrounding countries.”
Baltic Sea Action Plan
The primary agency overseeing the Baltic Sea recovery, the Helsinki Commission (HELCOM), currently does not have a position on wind turbine-pumps, “an interesting new technology; however, requiring more investigation,” according to Johanna Laurila,
HELCOM’s information secretary. “HELCOM implements the Baltic Sea Action Plan (BSAP) that stresses measures such as improved wastewater treatment and the addressing of diffuse sources, such as pollution loads from agricultural activity.”
HELCOM adopted and oversees the BSAP, which outlines goals and strategies for 2007 to 2021. All nine Baltic Sea coastal countries and the European Union have representation on HELCOM. The action plan aims to have the Baltic return to Good Environmental Status by 2021. Overall, phosphorus loads into the Baltic Sea have been cut by about a half from 1970 to 2008, noted HELCOM.
The real issue behind the wind turbine proposal, according to Conley, is an interest in using clean technology, which he supports. “If there is a technology that could be used that would not harm the ecosystem, then let’s look at it,” he added. “I think a lot of scientists agree with that as well.”