Environmental Engineering Reference
In-Depth Information
Toxicity of Paints, Antifouling Coatings, and Other Chemicals
Biofouling (growth on external surfaces by algae, barnacles, mussels, and other
marine organisms) will occur rapidly in ocean applications (Langhamer, 2005;
Wilhelmsson and Malm, 2008). Sundberg and Langhamer (2005) observed that a
3-m-diameter buoy may accumulate as much as 300 kg of biomass on the buoy and
mooring cables, whereas siting devices in deeper water with even slight currents will
exhibit reduced biofouling. The encrustation of biofouling organisms could cause
undesirable mechanical wear or changes in the weight, shape, and performance of
energy conversion devices that would require increased maintenance or the applica-
tion of antifouling measures. Encrustation by barnacles and other organisms could
increase corrosion and fatigue and decrease electrical generating efficiency.
There are three options for removing marine biofouling: (1) use of antifouling
coatings, (2)
in situ
cleaning using a high-pressure jet spray, and (3) removal of the
device from the water for cleaning on a floating platform or onshore (Michel et
al., 2007). Antifouling coatings hinder the development of marine encrustations by
slowly releasing a biocide such as tribuyltin (TBT), copper, or arsenic. As the coat-
ings wear away, they must be reapplied periodically. There are concerns about the
immediate toxicity of these biocides to other, non-targeted organisms, and numer-
ous countries and organizations have called for the ban of TBT as an antifoul-
ing coating (Antizar-Ladislao, 2008). As a result, alternative coatings are being
explored. The release of toxic contaminants from a single unit may be relatively
minor, but the cumulative impacts of persistent toxic compounds from dozens or
hundreds of units may be considerable (Boehlert et al., 2008). Accumulations of
biofouling organisms (e.g., barnacles) removed from the project structures may alter
nearby bottom substrates and habitats.
Accidental releases of hydraulic fluids and lubricating oils from inside the energy
conversion device or from vessels used to install and service the equipment could
have toxic effects. At the least, leaks of inert (non-toxic) oils could cause physical/
mechanical effects by coating organisms and blanketing the sediments.
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Energy developments will add new structures to rivers and oceans that may affect
the movements and migrations of aquatic organisms. Hydrokinetic devices, and their
associated anchors and cables in a river, could attract or repel animals or interfere
with their movements. In addition to seabed structures (e.g., anchors, turbines), many
of the ocean energy devices would use mooring lines to attach a floating generator
to the ocean bottom and electrical transmission lines to connect multiple devices
to each other and to the shoreline. For example, the Minerals Management Service
(2007) estimated that wave energy facilities may have as many as 200 to 300 moor-
ing lines securing the wave energy devices to the ocean floor (based on 2 to 3 moor-
ing lines per device and a 100-device facility). Mooring and transmission lines that
extend from a floating structure to the ocean floor will create new fish attraction
devices in the pelagic zone (i.e., the entire water column of the water body), pose
a threat of collision for entanglement to some organisms, and potentially alter both
local movements and long-distance migrations of marine animals (Nelson, 2008;
