Natural input of arsenic into a coral-reef ecosystem by hydrothermal fluids and its removal by Fe(III) oxyhydroxides

Journal Article · Sat May 01 04:00:00 EDT 1999 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es980949+· OSTI ID:354339

Pichler, T; Veizer, J; Hall, G E.M. ^[1]

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1. Univ. of Ottawa, Ontario (Canada). Ottawa-Carleton Geoscience Centre

The coral reef that circles Ambitle Island, Papua New Guinea, is exposed to the discharge of a hot, mineralized hydrothermal fluid. The hydrothermal fluids have a pH of {approximately}6 and are slightly reducing and rich in As. Seven individual vents discharge an estimated 1500 g of As per day into an area of approximately 50 x 100 m that has an average depth of 6 m. Despite the amount of As released into the bay, corals, clams, and fish do not show a response to the elevated values. The authors analyzed hydrothermal precipitates for their chemical and mineralogical composition in order to determine As sinks. Two mechanisms efficiently control and buffer the As concentration: (1) dilution by seawater and (2) incorporation in and adsorption on Fe(III) oxyhydroxides that precipitate when the hydrothermal fluids mix with ambient seawater. Fe(III) oxyhydroxides contain up to 76,000 ppm As, by an order of magnitude the highest As values found in a natural marine environment. Following adsorption, As is successfully retained in the Fe(III) oxyhydroxide deposits because oxidizing conditions prevail and high As activity allows for the formation of discrete As minerals, such as claudetite, arsenic oxide, and scorodite.

• OSTI ID: 354339
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 9 Vol. 33; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AQUATIC ECOSYSTEMS
ARSENIC
CORALS
IRON HYDROXIDES
MONITORING
NEW GUINEA
SEAWATER
WATER CHEMISTRY
WATER POLLUTION