Characterisation of the dilute HCl extraction method for the identification of metal contamination in Antarctic marine sediments I. Snape a, * , R.C. Scouller a,b , S.C. Stark a ,J.Stark a , M.J. Riddle a , D.B. Gore b a Human Impacts Research, Australian Antarctic Division, 203 Channel Highway, Kingston, Tasmania 7050, Australia b Department of Physical Geography, Macquarie University, NSW 2109, Australia Received 13 August 2003; received in revised form 19 May 2004; accepted 27 May 2004 Abstract Aregionalsurveyofpotentialcontaminantsinmarineorestuarinesedimentsisoftenoneofthefirststepsinapost- disturbance environmental impact assessment. Of the many different chemical extraction or digestion procedures that havebeenproposedtoquantifymetalcontamination,partialacidextractionsareprobablythebestoverallcompromise between selectivity, sensitivity, precision, cost and expediency. The extent to which measured metal concentrations relatetotheanthropogenicfractionthatisbioavailableiscontentious,butisoneofthedesiredoutcomesofanassess- mentorpredictionofbiologicalimpact.AspartofaregionalsurveyofmetalcontaminationassociatedwithAustraliaÕs pastwastemanagementactivitiesinAntarctica,wewantedtoidentifyanacidtypeandextractionprotocolthatwould allowareasonabledefinitionoftheanthropogenicbioavailablefractionforalargenumberofsamples.Fromakinetic studyofthe1MHClextractionoftwoCertifiedReferenceMaterials(MESS-2andPACS-2)andtwoAntarcticmarine sediments,weconcludedthata4hextractiontimeallowstheequilibriumdissolutionofrelativelylabilemetalcontam- inants,butdoesnotfavourtheextractionofnaturalgeogenicmetals.Inaregionalsurveyof88marinesamplesfrom theCaseyStationareaofEastAntarctica,the4hextractionprocedurecorrelatedbestwithbiologicaldata,andmost clearly identified those sediments thought to be contaminated by runoff from abandoned waste disposal sites. Most importantly the 4 h extraction provided better definition of the low to moderately contaminated locations by picking upsmalldifferencesinanthropogenicmetalconcentrations.Forthepurposesofinter-regionalcomparison,werecom- mend a 4 h 1 M HCl acid extraction as a standard method for assessing metal contamination in Antarctica. Crown Copyright Ó 2004 Published by Elsevier Ltd. All rights reserved. Keywords: MESS; PACS; Kinetics; Multivariate analysis; Bioavailable metals 1. Introduction Assessing marine sediments for metal contamination can be difficult when there are no pre-disturbance re- cords (Green, 1979; Peterson, 1993). The most com- monly adopted post-impact strategy, at least as a first 0045-6535/$ - see front matter Crown Copyright Ó 2004 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2004.05.042 * Corresponding author. Tel.: +61 3 6232 3591; fax: +61 3 6232 3158. E-mail address: ian.snape@aad.gov.au (I. Snape). Chemosphere 57 (2004) 491–504 www.elsevier.com/locate/chemosphere