Physical barriers: an alternative to prevent negative impacts of chemically treated wood

Abstract

There exists a possibility of leaching out of chemicals along with preservative components from chemically treated wood on exposure to water or moisture. Physical barriers have gained much acceptance in this regard as alternative non-biocidal wood protection method as it is supposed to reduce leaching and subsequent negative impacts of wood preservative components to the organisms in vicinity. Fibreglass reinforced plastic (FRP) and epoxy paint was coated over chromated copper arsenate (CCA) treated rubber wood panels and exposed in Cochin estuary for 18 months. Total wet weight biomass and numerical abundance of five most abundant group of foulers viz. hydroids, polychaetes, crustaceans including wood borers, barnacles and bivalves on these panels were studied. Copper, chromium and arsenic concentration in tissues and shells of barnacles were also analyzed. Results indicated significantly high biomass and numerical abundance of foulers on physically protected panels than untreated and preservative treated ones. Physical barriers significantly reduced accumulation of metals in barnacles indicating possibility of reduced leaching. Study can be considered as a lean to the impact studies conducted world over regarding the use of CCA for marine applications. However, CCA treated rubber wood as core material for FRP boats can be a better option as it poses less adverse effect on organisms in the vicinity.