Mercury and sulphur speciation in contaminated coastal sediments (Kastela bay, Croatia)

摘要

It is well known that the sulphur cycle greatly influences mercury speciation and consequently its mobility and toxicity in aquatic sediments. However, many questions regarding the interaction between Hg and S in sediments are still unanswered. For example, it was recently suggested that the formation of pure metal sulphides may not necessarily occur even in sulphidic sediment (MORSE et al., 1999), implying that a presumption of Hg immobilisation as HgS in such sediments may not be valid. Also, it was recently hypothesised, that HgS(aq) is the form available for methylation in sulphidic porewater, but this assumption still requires confirmation by field measurements (BENOIT et al., 2001). In this work, solid speciation of sulphur and mercury in marine sediments contaminated by mercury was investigated. The study was performed in the Kastela bay (located in the central part of the eastern Adriatic coast), that received mercury inputs from a chlor-alkali plant operating from 1949 to 1989.