Publication Abstract

Increased persistence of antifouling paint booster biocides when associated with paint particles

K. V Thomas, M. Hilton, M. McHugh, M. Waldock

Current regulatory risk assessment procedures only assess the impact of antifouling paint biocides that are released through leaching from a painted surface. Hull cleaning activities can lead to particles of antifouling paint containing biocides to enter the environment. Comparative pseudo-first order anaerobic degradation rate constants and half-lives were determined for a selection of common antifouling paint booster biocides, their degradation products, and associated with paint particles. Anaerobic half-lives of < 0.5 days were calculated for chlorothalonil, dichlofluanid, and SeaNine 211, between 1.5 and 3.6 days for DCPMU and DCPU, between 32 and 50 days for diuron and CPDU, and over 226 days for GS26575 and Irgarol 1051. Increased persistence was observed when the compounds were introduced to sediments associated with antifouling paint particles. An increased half-life of 146 days was calculated for diuron, 18.4 days for SeaNine 211, and 4.4 days for dichlofluanid when introduced as antifouling paint particles. It is suspected that this is due to much of the biocide being initially bound within the matrix of the paint particle that is slowly released through dissolution processes into the sediment pore water prior to degradation. The release of booster biocides associated with paint particles into marinas therefore has the potential to lead to their accumulation unless activities such as hull cleaning are strictly regulated.

Reference:

K. V Thomas, M. Hilton, M. McHugh, M. Waldock, 2003. Increased persistence of antifouling paint booster biocides when associated with paint particles. Environmental Pollution, 123(1): 153-161.