Raft trial experiments on antifouling paints containing zineb and copper

Abstract

Zineb and copper were incorporated both singly and in various combinations into (a) self‐polishing copolymer (SPC) and (b) eroding (organotin‐free) antifouling compositions, and the degree of fouling on the raft‐immersed paints estimated by chlorophyll a and ashed weight determinations. In the case of both paint systems zineb and copper mixtures were generally more effective in controlling fouling than those with copper alone. Paints containing a ratio of 75% zineb: 25% cuprous oxide by volume were the most effective. Measurements of leaching rates from these paints showed that they generally leached more zineb (measured as zinc) and less copper than the other formulations. They were colonised mainly by diatoms of the genera Amphora, Amphiprora and Navicula. Paints containing zineb alone were completely ineffective. Analysis of the leachate from the most effective zinebxopper combination (in SPC) revealed compounds with identical retention times to 5, 6‐dihydro‐3H‐imidazo (2, 1‐c)‐1, 2, 4‐dithiazole‐3‐thi...