Selenium speciation in ground water. Quarterly report

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

DOI:https://doi.org/10.2172/10165850· OSTI ID:10165850

Atalay, A

Selenium toxicity diseases in animals may occur when the intake exceeds 4 mg/kg and selenium deficiency symptoms may occur when dietary intake is less than 0.04 mg/kg. Since the selenium dietary requirement is very close to toxic concentration, it is important to understand the distribution of selenium in the environment. Selenium occurs in four oxidation states (-II, 0, +IV, and +VI) as selenide, elemental selenium, selenite and selenate. 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 imperative to study the aquatic chemistry of Se. For this purpose, Se species are divided into two different categories: dissolved Se (in material that passes through filters with 0.45 u openings) and particulate Se (in material of particle size > 0.45 mm) 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 (-2,0). In dissolved state selenium may exist in three of its four oxidation states; Se(-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 coprecipitated 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.

• Research Organization: Oklahoma Univ., Norman, OK (United States). School of Civil Engineering and Environmental Science
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG22-89PC89782
• OSTI ID: 10165850
• Report Number(s): DOE/PC/89782-T8; ON: DE92018429
• Resource Relation: Other Information: PBD: 10 Jul 1990
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
GROUND WATER
CHEMICAL COMPOSITION
SELENIUM
ECOLOGICAL CONCENTRATION
TOXICITY
PROGRESS REPORT
CHEMICAL STATE
SPATIAL DISTRIBUTION
INTAKE
PHASE DIAGRAMS
PH VALUE
SELENITES
SELENATES
SELENIDES
OXIDATION
REDUCTION
SOILS
LEACHING
AVAILABILITY
EXPERIMENTAL DATA
OKLAHOMA
PLANTS
ANIMALS
WATER CHEMISTRY
LIQUID COLUMN CHROMATOGRAPHY
540320
CHEMICALS MONITORING AND TRANSPORT