8153

• UCREFRP Catalog Number: 8153
• Author: Jacobs, e. L. W.
• Title: Editor
• USFW Year: Series
• USFW - Doc Type: 1989
• Copyright Material: YES

SELENIUM IN SELENIFEROUS ENVIRONMENTS 23
where it could eventually appear as fallout. However, Se concentrations in
many rivers may be less than the present detection limits, so changes as noted
for As and Cd may not yet be measurable.
SELENIUM IN PLANTS
Accumulators versus Nonaccumulators
Rosenfeld and Beath (1964) and Shrift (1973) divided plants into three
groups on the basis of their ability to accumulate Se when grown on high-Se
soils. The first two groups of plants are referred to as Se accumulator or
indicator plants. These grow well on soil containing high levels of available
Se, and some have been used to locate seleniferous soils. Plants in Group
1 are called primary indicators and include many species of Astragalus,
Machaeranthera, Haplopappus, and Stanleya. These species absorb high con-
centrations of Se that may be in the hundered or occasionally even thou-
sands of milligrams per kilogram, dry wt. (Fig. 2-4).
Plants in Group 2 are referred to as secondary Se absorbers. They be-
long to a number of genera including Aster, some species of Astragalus,
Atriplex, Castilleja, Grindelia, Gutierrezia, some species of Machaeranthera,
and Mentzelia. They rarely concentrate more than 50 to 100 mg Se/kg. Plants
in Group 3 include grains, grasses and many fortis that do not usually ac-
cumulate Se in excess of 50 mg Se/kg when grown on seleniforous soil.
N c
W
J Z
U'O
ZF
>Q
Q !r
2 ~
yZ
W W
J U
aZ
~O
Q U
N d
W N
OZ
Z W
O~
FO
!r Z
OQ
a=
~~
a
Fig. 2-4. Proportion of samples having less than given Se concentration (%). (A) • - • Data
for western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) and Sandberg bluegrass (Poa
secunda Presl.) sampled from seleniferous areas of Montana and Wyoming by H.F. May-
land, (1987, unpublished data); o - n Stanleya spp.; • - • Xylorhiza section of Mach-
aeranthera; ^ - ^Astragalus bisulcatus; X-X Astragalus pectina[us; and o - o Oonopsis
section of Haplopappus; latter data adapted from Rosenfeld & Beath (1964). (B) • - • Data
are for vegetative wheat (Triticum aes[ivum L.); ^ - ^ Astragalus bisulcatus; and • -
Astragalus pectinatus reported in plants from North Dakota by Lakin & Byers (1948).
SELENIUM, mg/kg
SELENIUM, mg/kg