Characterization of arsenic occurrence in the water and sediments of the Okavango Delta, NW Botswana

P. Huntsman-Mapila, T. Mapila, M. Letshwenyo, P. Wolski, C. Hemond

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Detailed chemical analyses were performed on surface water, groundwater and sediment samples collected from the Okavango Delta between February and November 2003 in order to examine the distribution and geochemistry of naturally occurring As in the area. Surface water in the Okavango Delta, which is neutral to slightly acidic and has high dissolved organic C (DOC), was found to be slightly enriched in As when compared to a global value for stream water. Of the 20 new borehole analyses from this project, six were found to have values exceeding 10 μg/L, the current World Health Organization provisional guideline value for As. The results from field speciation indicate that As(III) is slightly more predominant than As(V). There is a positive correlation between As and pH and between As and DOC in the groundwater samples. For the sediment samples, there is a positive correlation between As and Co, As and Fe, As and loss on ignition (LOI) and between As and the percent fines in the sample. Reductive dissolution of oxides and hydroxides in the sediments with organic C as an electron acceptor is the likely mechanism for the release of As from the sediments into the groundwater.

Original languageEnglish
Pages (from-to)1376-1391
Number of pages16
JournalApplied Geochemistry
Volume21
Issue number8
DOIs
Publication statusPublished - Aug 1 2006

Fingerprint

Arsenic
arsenic
Sediments
Groundwater
Water
Surface waters
sediment
groundwater
Hydroxides
surface water
water
Geochemistry
World Health Organization
Boreholes
Oxides
hydroxide
Ignition
Dissolution
borehole
geochemistry

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Pollution
  • Geochemistry and Petrology

Cite this

Huntsman-Mapila, P. ; Mapila, T. ; Letshwenyo, M. ; Wolski, P. ; Hemond, C. / Characterization of arsenic occurrence in the water and sediments of the Okavango Delta, NW Botswana. In: Applied Geochemistry. 2006 ; Vol. 21, No. 8. pp. 1376-1391.
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Characterization of arsenic occurrence in the water and sediments of the Okavango Delta, NW Botswana. / Huntsman-Mapila, P.; Mapila, T.; Letshwenyo, M.; Wolski, P.; Hemond, C.

In: Applied Geochemistry, Vol. 21, No. 8, 01.08.2006, p. 1376-1391.

Research output: Contribution to journalArticle

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