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NATURAL BACKGROUND TOPSOIL ARSENIC CONCENTRATIONS AND SOME IMPLICATIONS FOR APPLYING SGVs (HEALTH). Daniel Moore Mathew Taylor Ministry for the Environment Environment Waikato. Introduction. Acknowledgements
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NATURAL BACKGROUND TOPSOIL ARSENIC CONCENTRATIONS AND SOME IMPLICATIONS FOR APPLYING SGVs(HEALTH) Daniel Moore Mathew Taylor Ministry for the Environment Environment Waikato
Introduction • Acknowledgements • Policy : toxicological vs. natural • Limited published arsenic data • Regional council data request
Timber Treatment Guidelines 1997 “The nominated criterion should not be less than a reasonable background concentration of arsenic. In this regard a value of, say, 30 mg/kg may be appropriate (Spier, 1997) notes that typically background concentrations of arsenic in New Zealand soils range from 2 to 30 mg/kg)”
Arsenic dataset • Collate existing data • Sample density, variability, confidence • Identification of data limitations • Assess key drivers of landscape-scale variation
Data analysis • Data quality • Standardised land use • Standardised soil type • Data desk • Pooled t-test
Data limitations • Variation in the sampling and analysis methodology • Poor land use classification • Representative Background data • Variation due to soil type • The effect of soil bulk density
Conclusions • Bush, indigenous forest, native = background • National As average 6.0 mg/kg • Background As average 4.5 mg/kg • Cropping, horticulture and urban land uses higher concentrations than background. • Waikato region statistical significance
Upcoming • Cadmium • Publish SGV comparisons • Data email: daniel.moore@mfe.govt.nz • Questions?