Copper release rate needed to inhibit fouling on the west coast of Sweden and control of copper release using zinc oxide

How zinc oxide influences copper release has been tested and the lowest release rate of copper from various combinations of copper and zinc in a paint matrix evaluated, whilst still deterring macrofouling, including barnacles and bryozoans. Copper (I) oxide was added to a generic AF paint in 0, 8.5, 11.7 or 16.3 wt% copper oxide in combination with 0, 10 or 20 wt% zinc oxide and applied on PMMA panels. The results show that zinc influences the release rate of copper. When 10 and 20 wt% zinc was added, the total amount of copper released significantly increased by on average 32 and 47% respectively. All treatments that included copper were successful in deterring macrofouling, including the treatment with the lowest average Cu release rate, ie 4.68 μg cm^?2 day^?1.     

Effects of pH and heavy metal concentrations in solution culture on the proton release,growth and elemental composition ofAlyssum murale andRaphanus sativus L.

The proton release by a species that can hyperaccumulate nickel (Alyssum murale) and by a non-accumulator (Raphanus sativus L.) was studied at different pH and heavy metal concentrations in solution culture. Both factors influenced the growth and composition of the plants.A. murale was more sensitive than radish to a decrease of pH from 7.0 to 6.0 in the growth medium; plant yield and proton production diminished with decreasing pH. However, yields and proton production of radish only decreased at pH 5.5. The differences in the amounts of protons produced between the hyperaccumulator species and radish were not large enough to conclude that decreasing pH in the rhizosphere ofA. murale is a mechanism for heavy metal solubilization.Nickel concentrations inA. murale followed the typical pattern of an accumulator plant — more Ni was accumulated in the shoots than in the roots. Lower concentrations of Zn and Cd occurred in the shoots than in roots ofA. murale, and also of Ni in radish. The concentrations of Co inA. murale shoots were increased when Zn, Ni and Cd were absent from the nutrient solution. However, Co concentrations in radish shoots were independent of the concentrations of other heavy metals in the growth medium.