A range of wood products are produced in Aotearoa.
Chemical treatment of wood
The frequent use of toxic chemical contaminants for the preservation of processed wood is a considerable environmental issue for the industry. Pine, for example, is chemically treated because it is a soft wood and therefore prone to attack by fungi that will discolor the woods surface, or alternatively, insects and fungi can cause decay or bore into the timber after felling. In the past, chemicals used in the treatment of timber products frequently led to contamination of soils and aquatic environments. Revised standards have resulted in the deregistration of some of these chemicals, including pentachlorophenol (PCP), a preventative for fungi which was found to contaminate timber treatment and storage sites. Over 1 million cubic metres of timber, including round wood is preservative treated in New Zealand each year. The Timber Preservation Council is responsible for maintaining standards in the industry.
Wastewater effluent from sawmills is generated through runoff from log yards and log ponds as organic and inorganic contaminants. Wastewater is also generated from chemical coating of wood. The principal environmental problem of runoff is usually the high concentration of organic substances originating from the wood and bark, some of which are toxic to aquatic life. Nutrients like phosphorus can also be a problem potentially causing eutrophication of waterways. The toxicity of the runoff varies greatly, and depends on the species of tree stored, the amount of water the wood has been in contact with and the degree of runoff treatment.
Waste products discharged into waterways have the potential to impact water quality and the health of mahinga kai species. The magnitude, extent, and effects of which are expected to vary depending on management practices and the level of treatment employed by the saw mills and manufacturers.
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