Antarctic snow: metals bound to high molecular weight dissolved organic matter

• Published in: Chemosphere
• Main Authors: Pietrantonio, M., Nardi, E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Ltd 2017
• Subjects: Heavy metal; High molecular weight organic substance; Ultrafiltration; Antarctic snow; Antarctic; The Antarctic; Antarc*
• Online Access: https://hdl.handle.net/20.500.12079/1760; https://doi.org/10.1016/j.chemosphere.2017.02.052; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013414399&doi=10.1016%2fj.chemosphere.2017.02.052&partnerID=40&md5=a9d5b6cf199277cdd80336787d698d67

In this paper we studied some heavy metals (Cu, Zn, Cd, Pb, As, U) probably associated to high molecular weight organic compounds present in the Antarctic snow. Snow-pit samples were collected and analysed for high molecular weight fraction and heavy metals bound to them by means of ultrafiltration treatment. High molecular weight dissolved organic matter (HMW-DOM) recovered by ultrafiltration showed a dissolved organic carbon concentration (HMW-DOC) of about 18–83% of the total dissolved organic carbon measured in Antarctic snow. The characterisation of HMW-DOM fraction evidenced an ageing of organic compounds going from surface layers to the deepest ones with a shift from aliphatic compounds and proteins/amino sugars to more high unsaturated character and less nitrogen content. The heavy metals associated to HMW-DOM fraction follows the order: Zn > Cu > Pb >> Cd ∼ As ∼ U. The percentage fraction of metals bound to HMW-DOM respect to total metal content follows the order: Cu >> Pb > Zn, Cd in agreement with humic substance binding ability (Irwing-William series). Going down to depth of trench, all metals except arsenic, showed a high concentration peak corresponding to 2.0–2.5 m layer. This result was attributed to particular structural characteristic of organic matter able to form different type of complexes (1:1, 1:2, 1:n) with metals. © 2017 Elsevier Ltd