Over 2000 captive seawater sites in the US exhibit copper levels that are toxic to algae, mollusks and other crustaceans, and certain sea grasses. The toxic presence is the result of copper leaching from copper-based paints on ocean going vessels. In fact, toxic copper levels are at a crisis level in bays, harbors, and marinas where industrial boats and pleasure yachts anchor.
Toxic copper enters the water column at high parts per billion levels. The US EPA and numerous state and local water quality boards have mandated limits, known as Threshold Maximum Daily Loads (TMDL’s), to numerous bays and harbors requiring the reduction of toxic copper levels in seawater by specified dates. Responses often focus on either treating the boats, moving the water, and/or by treating the water. Treating boats has had a limited effect on overall copper reduction as documented in controlled studies, and moving the water out to the ocean has also had limited success, since most bays and harbors, whether natural or man-made, have limited water flow.
Factors effecting the ambient toxic copper levels in bays and harbors include the current load of soluble toxic copper and the addition of new total copper loads from boat hulls. Additionally, total copper binds to organic matter in the seawater, eventually chelating upon decomposition and settling in the silt layer. Over time, chelated copper can re-solubilize to the toxic form of copper especially if water levels of soluble toxic copper are depleted.
In response, Red Lion Chem Tech in San Diego pioneered two remedial approaches that work. One employs submersible ballasts to address the soluble toxic copper problem in situ, and the other, involving ‘pump and treat,’ was developed for reduction in new total copper load. Through these advances in proprietary coordination chemistry, Red Lion Chem Tech has demonstrated the removal of >98% copper from seawater. Submersible ballast systems containing proprietary adsorbent materials remove soluble toxic copper via wave action, and ‘pump and treat’ methods remove total copper, including soluble copper, copper absorbed on organic matter, and chelated copper remaining in the water column. After successful lab testing, field trials are now under way in San Diego bay.