Single-step chemical extraction procedures and chemometrics for assessment of heavy metal behaviour in sediment samples from the Bahia Blanca estuary, Argentina

Purpose The objective of this research was to study heavy metal mobility and availability in sediment samples. A rapid diagnosis about metal behaviour was performed using the combination of several single-step extraction procedures and multi-way chemometric tools. Materials and methods Several single-step procedures for metal lixiviation-ammonium acetate, acetic acid, hydrochloric acid, ethylenediaminetetraacetic acid, trans-1,2-diaminocyclohexane- N, N, N', N'-tetraacetic acid, nitrilotriacetic acid-with increasing extracting power were simultaneously applied to coastal surface sediment samples. Also, three certified reference materials for total metal concentrations were analysed. The metals studied were Cd, Cr, Cu, Pb and Zn because of their hazardous potential and related abundance in the estuary. The concentrations of metals were determined by inductively coupled plasma optical emission spectrometry. Parallel factor analysis (PARAFAC) was used to obtain a better visualization of the experimental data. Results and discussion Total heavy metal content in the sediment samples ranged from 1.19 to 3.01, 18.6 to 35.6, 55.6 to 102, 20.4 to 79.2 and 70.2 to 508 mg kg(-1) for Cd, Cr, Cu, Pb and Zn, respectively. PARAFAC models with two factors describe the data sets appropriately (explained variance of 64.1% and core consistency of 95.4%). Cd appears in the surface sediment samples of Bahia Blanca estuary as the most easily interchangeable, pointing to a possible anthropogenic origin. However, the fraction extracted with ammonium acetate under neutral conditions is low. On the other hand, acetic acid seems to be able to efficiently extract Cd, Cu and Zn. The largest proportions of metals that can be mobilized by complexing reagents belong to the sample S2; Cd, Pb and Zn, and Cu to a lesser extent, appear to be efficiently separated by complexation. Cr appears to be the most difficult to extract, indicating a low mobility of coastal sediments. Conclusions The combination of single-step lixiviation procedures and multivariate techniques provided useful information about the sediment samples and a better understanding about heavy metal mobility, availability and hazardousness. The information obtained was similar to the one recovered by sequential extraction procedures, but the time saved with the proposed methodology is significantly higher.