First Systematic Voltammetric Measurements of Cd, Pb, and Cu in Hydrofluoric Acid-Dissolved Siliceous Spicules of Marine Sponges: Application to Antarctic Specimens

Abstract

Ultrasensitive Square Wave Anodic Stripping Voltammetry is used for the first time for the systematic determination of Cd, Pb, and Cu in siliceous spicules of marine sponges; the procedure is performed directly in hydrofluoric acid solution, according to a procedure previously established in our laboratory, with the aim of demonstrating the feasibility of such measurements and to improve knowledge of heavy metal distribution in Porifera. The following Demospongiae species are considered: Sphaerotylus antarcticus, Haliclona sp., Kirkpatrickia coulmani, and Inflatella belli from the Ross Sea, Antarctica, and Petrosia ficiformis from the Mediterranean Sea, Italy. The method shows a good accuracy; the analytical variability is approximately ±10% for all the metals studied and for all the measurements performed, showing a good repeatability of the method in consideration of low metal concentrations (order of tenths of µg g⁻¹ dry weight, i.e., of hundreds of ng L⁻¹ in the HF solution). In particular, the concentrations of heavy metals in the body of the sponge vary in the range 0.038–0.93 µg g⁻¹ dry weight (d.w.) for Cd, 0.024–0.52 µg g⁻¹ d.w. for Pb, and 0.32–1.3 µg g⁻¹ d.w. for Cu. Similar ranges of concentration were recorded in the oscula of S. antarcticus and I. belli. Heavy metal concentration in the spicules can vary within and between specimens and, in particular, siliceous spicules of Antarctic sponges show higher concentrations of Cd and Pb and lower concentrations of Cu than those from the Mediterranean.

Keywords:

• Antarctica
• Heavy metals
• Hydrofluoric acid
• Marine sponges
• Mediterranean Sea
• Siliceous spicules
• Voltammetry

Acknowledgments

Financial support from the Italian Programma Nazionale di Ricerche in Antartide in the framework of the project of “Chemical Contamination” titled “Approaches and means for monitoring of chemical pollution: Environmental indicators, Antarctic Environmental Specimen Bank and certified reference materials” is gratefully acknowledged. The authors are grateful to Prof. G. Bavestrello for spongiological advice and for stimulating discussion, to the technical personnel of ENEA (Ente Nazionale Energia e Ambiente) at Terra Nova Bay, and to the scientists of the 2005–2006 expedition (especially Stefano Schiaparelli) for the sampling activities performed on-site.

Notes

Note: Values are mean ± SD obtained from at least 3 measurements.

*Outlier at 95% confidence (Q test).

^{a , b} Means in the same column followed by different letter are significantly different at 95% C.L. (Anova test followed by Fisher's LSD procedure).

Note: Values are mean ± SD obtained from at least 3 measurements.

*Outlier at 95% confidence (Q test).

^{a , b} Means in the same column followed by different letter are significantly different at 95% C.L. (Anova test followed by Fisher's LSD procedure).

Note: Values are mean ± SD obtained from at least 3 measurements.

*Outlier at 95% confidence (Q test).