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Diagenetic cycling of arsenic in the sediments of eutrophic Baldeggersee, Switzerland

Research output: Contribution to journalJournal article

Published

  • Daniel Fabian
  • Zheng Zhou
  • Bernard Wehrli
  • Gabriela Friedl
Journal publication date09/2003
JournalApplied Geochemistry
Journal number9
Volume18
Number of pages10
Pages1497-1506
Original languageEnglish

Abstract

Sedimentation and benthic release of As was determined in Baldeggersee, a eutrophic lake in central Switzerland. Sediment traps recorded As sedimentation during 1994, including a flood event in spring. Diagenetic processes were studied using porewater profiles at the sediment–water interface and in deeper sediment strata deposited in the mesotrophic lake (before 1885). Sediment cores were used to calculate the accumulation and to construct the balance of sedimentation and remobilisation. The results showed that the lake sediment acts as an efficient sink for As. Only 22% of the particulate As flux reaching the sediment surface was remobilised at the sediment–water interface. The As accumulation in the recent varved section of the eutrophic lake was 40 mg As m−2 a−1. Iron reduction in older sediment caused a remobilisation of 1.2 mg As m−2 a−1. This upward flux from the deeper sediment was quantitatively immobilised in the recent sulfidic sediments. The flood event in spring contributed about 34% of the yearly sediment load and led to distinct peak profiles of dissolved As in the porewater. This evidence for rapid remobilisation disappeared within months.