1Departments of Earth Sciences, The University of Waikato, Private Bag 3105, Hamilton, New Zealand. Email: email@example.com
2Departments of Biological Sciences, The University of Waikato, Private Bag 3105, Hamilton, New Zealand.
3Forest Research, Sala Street, Private Bag 3020, Rotorua, New Zealand.
Soils may be used as a means of disposal of industrial and municipal wastes, which can have detrimental impacts on both the terrestrial environment and also the wider receiving environment. The pulp and paper industry generates as much as 60m3 of effluent per tonne of paper produced. Biosolids are removed from effluent via primary and secondary treatment. The predominant timber species harvested in NZ is Pinus radiata which contain resin acids released in the paper making process. Resin acids present in treated biosolids have been shown to be toxic to aquatic organisms. Microorganisms remove nutrients and contaminants during secondary treatment. As a result of anaerobic metabolism some toxic resin acid metabolites (e.g. fichtelite, dehydroabietin and retene) are formed in secondary biosolids. The terrestrial toxicity of pulp and paper biosolids is not well understood.
Assessment of environmental risk posed by toxic substances cannot be satisfactorily accomplished using chemical analysis alone, because this does not allow estimation of the bioavailable fraction, or the effect on soil-dwelling organisms. Biological sensors integrate long-term sub-lethal effects that chemical analyses of single samples cannot. A suite of bioassay organisms were chosen to represent different functional and structural groups as well as having ecological relevance. Bioassays using these organisms have been conducted to assess chronic and acute effects of paper pulp biosolids on a forestry ecosystem. Quantifying the toxicological impact of applying biosolids to land is necessary in order to set protective limits and provide information on its relative merits compared to other disposal methods currently employed.