WSP00720

• File Number: 8149.900
• Description: Miscellaneous Small Projects and Project Studies - Holly BMP's
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 11/1/1997
• Author: Various
• Title: Holly BMPs
• Water Supply Pro - Doc Type: News Article/Press Release

O A~remediacion of Se-Iaden soils ac-
OD &JrJ.'pHmarily via three mechanisms: up-
take of Se and subsequent accumulation
inco plant tissue (Banuelos and Meek
1989) volatilization of Se. by plantS and
(Frankenberger, Jr., and Karlson 1990),
stimulation of microbial volatilization of
Se in che rhizosphere. Idcally, the removal
or-Se from soil is the drainage effluent. In
chis article we shall consider the first [\vo
mechanisms: uptake and volacilizarion of
Se by che planr.

Uptake and accumulation of
selenium in plant tissues

Initial t.esearch on phytoremediacion of
soil Sc by Banuelos and associates (Banue-
los and Scho1e 1989; Banuelos and Meek
1990) demonstrated chac different plane
species. especially members of the Brossi.

caCMe family, accumulated Se and reduced
soil Se by almost 50% under greenhouse
condicions (Table 1). They concluded chac
Bram'ca spp.. chac are sulfur (5) accumulat-
ing planes, have a better capacity co absorb
Se because of the chemical similarity be-
tween absotbing sulface (SO/-) and sele-
nate (50/-) ions. Therefore, a $-accurnu-
lacing plane species might accumulate high
concentrations of Se if grown in soils con-
taining' high concentrations of soluble
50/-, Banuelos and associates (Ba.ii.uelos ec
01. 1993a) then conducted long-tetm Stud,
ies using Brassica and ocher species [0 de-
termine the effectiveness of the planes co
lower soil Se concentrations under low
S04!. field conditions, Their resules
showed a ner reduction of almost 40% in
(mal soH Se inventory co a depth of 60 em
(24 in) (Table 2). Mass-balance calcula-

Table 1. Accumulation of selenium and changes in soil selenate concentrations under
greenhouse conditions

Se concentrations found in-
Plant species Preplant Postharvest Shoots Unaccounted Percentage
soW soli for Set of soil Se
removed'
( mg Se kg" soil) (mg Se kg' DM) (%) (%)
Canola 2.00(0.02) 0.85(0.04) 315(11) 40 57
Indian mustard 3.50(0.02) 0.91(0.02) 274(14) 25 74
Birds foot trefoil 2.00(0.02) 1.31(0.02) 130(17) 45 34
Tall fescue 2.00(0.02) 1.25(0.03) 35(3) 35 37
Tall fescue 3.50(0.02) 2.05(0.10) 52(6) 36 41
Kenai 2.00(0.02) 1.40(0.03) 92(6) 43 30

. Values are rhe means from:i minimum of 10 replications followed by the n~d:ird error in parenrhesis
'Soil spiked with Se:LS N02Se041.
'l.osses oEsoi! Se which are not accounred for ill dried plam tissue (leaves. nerns and roots)
'Bast:d on difference in soil Se concentration from preplanc co poseharvesr

Table 2. Accumulation of selenium and changes in native soil selenium concentrations
under greenhouse and field conditions

Sa concentrations found in.
Preplant Postharvest
soil soil
(mg Se kg" soil)
Canola' 43.0(3)' 32.0(2)
Canola 1.17(0.04) 0.81(0.03)
Indian mustard 1.17(0.04) 0.89(0.04)
Indian mustard 1.12(0.04) 0.60(0.05)
(Iield grown)
Tall fescue!
Tall fescue
Tall fescue
(Iield.grown)
Kenaft .
Kenaf
(Iield grown)
Birdsloot trefoil 0.98(0.08)
(lield.grown)

Plant species

43.0(3)
1.17(0.04)
1.25(0.06)

38.0(2)
0.72(0.02)
0.87(0.03) .

43.0(3)
0.96(0.06)

35.0(3)
0.66(0.02)

0.56(0.04)

Shoots
forSe
(mg Se kg" DM)
470(22)
1.3(.07)
1.2(.06)
1.4(.04)

Unaccounted
Sa removed'
(%)
40
>50
>50

Percentage of
soil Se removed
(%)
25
31
24
46

43.0(10)
.94(.03)
.32(.02)

>50
>50

12
38
30

45.0(3)
.60(.03)

>50

19
31

.31(.02)

43

'AlI soils contained less than 25J.1g Se kg" as waecN:xrracrable Se
'Loss~s of soil Se which cannot be accolJnted for in plant rissue grown under gr'eenhouse condidons as a
percentage of apparent soil Se concentr:uion
'Losses of soil Se from prepl~t eo postharvest based on tOtal soil Se analysis
'Respectke plane species grown in soil sediment collecred fiom Kesterson Reservoir (unpublished data;
Baiiudos ~e al. 1996)
T\,fJ..lues ar~, means from :I, minimum of 10 replications followc:d by the srand31d c:rror in p:lrenthesis (Banuelos
~t aJ. J993l
'r~rcc:nrage cannor be approximated undc:r field conditions

tions inferred that significant amounts, buc
not all of the lost soil Se, were accounted
for in plane tissues (Table 2). Thus, the au-
thors indicated thac other processes besides
plane uptake, such as biological volatiliza-
tion and leaching were also contributing to
the removal of soil Se.
Other researchers evaluated the feasibil.
ity of using vegetation in general to re-
move Se from the Se-Iaden sediment at
Kesterson Reservoir (Parker and Page
1994). Based on an estimaced soil Se but-
den ac 15 kg Se hi-' (13.4 pounds" acre-'),
and assuming plane dry (OM) yields of 4-
16 T ha" (9,36 cons"acre-'), they-deduced
that a minimum plane tissue concentra.
cion of 100 mg Se kg" OM (ppm). must
be attained by the selected plant species in
order to achieve significant reduction (1
kg Se ha-' yc) (1.I2 pounds Se pet acre"
pet year) in soil Se by plane uptake. They
also emphasized .that removal of Se by
plane uptake is thus dependent upon a
planes' high growth rate and biomass that
accumulates high levels of Se. In the above
scenario, the potencial role of biological Se
volatilization was not considered.
Utilizing information about Se.accu.
mularing plants. researchers evaluated the
ability of primary. secondary. and non-Se
accumulating plantS to absorb Se under a
variety of conditions (Banuelos et a!.
1993a; Bell ec al. 1992; Mayland ec al.
1989; Parkcr et al. 1991; Patket and Page
1994; Recana ec al. 1993; Rosenfield and
Beath 1964; Wu cc al. 1988; Wu and
Huang 1991). Rosenfeld and Beach
(Rosenfeld and Beath 1964) divided Se-
accumulating plants into three main
groups according co their ability CO accu-
mulate 5e. Group 1 planes, which accu.
mulace from hundreds co even thousands
of milligtams per kilogram (dry we. basis)
(ppm), include some species of Amaga/tls
and Sran/eya. GtOUP 2 planes rarely con-
centrate more than 50 co 100 mg Se kg'
dty matrer (OM) (ppm). These include
some species of Atriplex, Grindelia, and
Guitierrezia. Nonaccumularor plants
make up thc chird and largeSt group. Ie
includes grains and Gramineae chac do nor
usually accumulatc mOte than 50 mg Se
kg" OM (ppm) when gtown on selenifer-
ous soil.
The Se metabolism in Se-accumulating
species in group 1, Le'l Astragalus. is dif-
ferent from that of non-accumulating
species. 5e1enium.accumulaeor species
may avoid 5e toxicity at high concentra-
dons by having mechanisms chac prefer-
entially incorf>orate 5e-comaining amino
acids and noe Se isologues inco proteins
(Wenezel ec aJ. 1993). The incorporacion
of Se inco proteins in plane tissues is be-

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