Single-step chemical extraction procedures and chemometrics for assessment of heavy metals behaviour in sediments samples

MÓNICA B. ALVAREZ ; CLAUDIA E. DOMINI; MARIANO GARRIDO; ADRIANA G. LISTA; BEATRIZ S. FERNÁNDEZ-BAND

JOURNAL OF SOILS AND SEDIMENTS (PRINT)

SPRINGER HEIDELBERG

Lugar: Berlin; Año: 2011 vol. 11 p. 657 - 666

1439-0108

Abstract Purpose The objective of this research was to study the 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 (EDTA), trans-1,2-diaminocyclohexane-N,N,N?,N?-tetraacetic acid  (CDTA), nitrilotriacetic acid (NTA)- with increasing extracting power were simultaneously applied to coastal surface sediment samples. Also, three certified reference materials for total metal concentrations were analysed. The studied metals were cadmium, chromium, copper, lead and zinc because of their hazardous potential and related abundance in the estuary. The concentration of metals was determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). 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 - 3.01, 18.6 - 35.6, 55.6 - 102, 20.4 - 79.2 and 70.2 - 508 mg kg?1 for Cd, Cr, Cu, Pb and Zn, respectively. PARAFAC models with two factors describe appropriately the data sets (explained variance of 64.1 % and core consistency of 95.4 %). Cd appears in the surface sediment samples of Bahía 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 proportion 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 made it possible to get useful information about the sediment samples and to achieve a better understanding about the heavy metals 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.