Selenium speciation in ground water

Technical Report · Tue Jul 10 04:00:00 EDT 1990

OSTI ID:5713875

Atalay, A

Selenium occurs in four oxidations states ({minus}II, O, +IV, and +VI) as selenide, elemental selenium, selenite (SeO{sub 3}{sup {minus}3}) and selenate (SeO{sub 4}{sup {minus}2}). Of the selenium species occurring, selenate is reported as more soluble and less adsorbed than selenite. Selenate is more easily leached from soils and is the most available form for plants. Increased mobility of Se into the environment via anthropogenic activities, and the potential oxidation-reduction behavior of the element have made it imperetive to study the aquatic chemistry of Se. For this purpose, Se species are divided into two different categories: dissolved Se and particulate Se typically suspended sediment and other suspended solids. Element and colloidal phase, not truly dissolved, but passing through the filter is deemed to consist of selenium ({minus}2,0). In dissolved state selenium may exist in three of its four oxidation states; Se({minus}II), Se(+IV), and Se(+VI). Particulate Se may exist in the same oxidation states as dissolved Se and can be found in different phases of the particulate matter. In sediments, Se may be within the organic material, iron and manganese oxides, carbonates or other mineral phases. The actual chemical forms of Se may be adsorbed to or co-precipitated with these phases (primarily selenite, SeO{sub 3}{sup 2{minus}} and selenate, SeO{sub 4}{sup 2{minus}}). Selenide, Se(-II), can be covalently bound in the organic portion of a sediment. In addition, Se may be found in anoxic sediments as insoluble metal selenide precipitates, an insoluble elemental Se or as ferroselite (FeSe{sub 2}) and Se containing pyrite. 22 refs., 6 figs., 2 tabs.

• Research Organization: Oklahoma Univ., Norman, OK (USA). School of Civil Engineering and Environmental Science
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: FG22-89PC89782
• OSTI ID: 5713875
• Report Number(s): DOE/PC/89782-T2; ON: DE91011293
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
CHEMICAL REACTIONS
CHEMISTRY
CONTAMINATION
DISSOLUTION
DOCUMENT TYPES
ELEMENTS
GROUND WATER
HYDROGEN COMPOUNDS
LEACHING
OXYGEN COMPOUNDS
POLLUTION
PROGRESS REPORT
REDOX REACTIONS
SEDIMENTS
SELENIUM
SEMIMETALS
SEPARATION PROCESSES
WATER
WATER CHEMISTRY
WATER POLLUTION