NUTRIENT
AND
TRACE
VEGETATION
ELEMENTS
IN SOIL
OF SOUTHERN
AND
IDAHO
DESERT
*
SUSAN K. ROPE, W. J O H N A R T H U R , III ** Radiological and Environmental Sciences Laboratory, U.S. Department of Energy, Idaho Falls, Idaho 83402, U.S.A. T I M O T H Y H. C R A I G , andER1CA H. CRA I G Northwest Nazarene College, Nampa, Idaho 83615, U.S.A.
Abstract. Concentrations of thirty elements were measured in strong-acid extracts of soil, sagebrush (Artemisia tridentata ssp.) leaves and perennial grass from the Idaho National Engineering Laboratory (INEL) and two reference sites in southern Idaho. A bicarbonate-chelating extract of soil was used to estimate plant-available concentrations. The results provide baseline data prior to start-up of a coal-fired steam generation facility on the INEL and other developments in the region. In addition, existing impact from effluents from thirty years of a nuclear fuel reprocessing facility on the INEL was evaluated. Based on the spatial distribution of element concentrations, as well as comparison with references sites, we conclude that concentrations of Zn, and perhaps Ni, Cd, and V, are currently elevated around the fuel reprocessing facility. The spatial distribution of these elements is similar to that of t37Cs in soil, a radionuclide which is emitted by the facility. Sagebrush and soil appear more responsive than perennial grass for long-term monitoring of element concentrations in this semi-arid environment.
1. I n t r o d u c t i o n I n c r e a s e d levels o f tr a c e e l e m e n t s h a v e b e e n d e t e c t e d in the e n v i r o n m e n t as a result o f em i s s i o n s f r o m fossil-fuel p o w e r e d facilities, o r e smelters, m u n i c i p a l i n c i n e r a t o r s , a n d a u t o m o b i l e s , as well as the land a p p l i c a t i o n o f sewage sludges an d fertilizers (Klein an d Russell, 1973; N a t u s c h et al., 1974; C o n n o r et al., 1976; C l a r k , 1979; W a n g e n a n d T u r n e r , 1980; K a b a t a - P e n d i a s a n d P e n d i a s , 1984). E n r i c h m e n t o f s o m e a n t h r o p o g e n i c a l l y - d e r i v e d e l e m e n t s even occurs in relatively r e m o t e areas ( D a v i d s o n et a k , 1985). E m i s s i o n s f r o m c o a l - f i r e d plants c a n c o n t r i b u t e a large f r a c t i o n o f the trace m e t a l c o n t e n t o f t h e a t m o s p h e r e (Lee et al., 1975; T u r n e r an d S t r o j a n , 1978). I n v e s t i g a t o r s h a v e c o n d u c t e d studies o n e n v i r o n m e n t a l e n r i c h m e n t o f t r ace e l e m e n t s n e a r coal-fired plants with v a r i a b l e results. B o l t o n et al. (1973), V a u g h n et al. (1975), B r a d f o r d et al. (1978), W a n g e n a n d W i l l i a m s (1978) a n d C r o c k e t t a n d K i n n i s o n (1979) f o u n d little or n o e l e m e n t a l increases t h a t c o u l d be a t t r i b u t e d to p o w e r p l a n t emissions. H o w e v e r , o t h e r researches h a v e related e l e m e n t e n r i c h m e n t in soil a n d v e g e t a t i o n to a t m o s p h e r i c em is s i o n s f r o m c o a l - f i r e d facilities (Klein a n d Russell, 1973; A n d e r -
* This manuscript is a contribution of the Idaho National Engineering Laboratory Radioecology and Ecology Programs, Idaho Falls, ID 83402, funded by the U.S. Department of Energy, Office of Health and Environmental Research. ** Currently: Uranium Mill Tailings Remedial Action Project, U.S. Department of Energy, Albuquerque Operations Office, Albuquerque, New Mexico 87115, U.S.A. Environmental Monitoring and Assessment 10 (1988) 1-24. 9 1988 by Kluwer Academic Publishers.
2
S U S A N K. R O P E E T A L .
son et al., 1975; Connor et al., 1976; H o r t o n et al., 1977). In particular, Be, Co, F, Se, Sr, Ti, U, V, and Zn may be enriched around coal-fired facilities which burn western coal (Connor et al., 1976; Wangen and Wienke, 1976; Wangen and Williams, 1978; Wangen and Turner, 1980). Liquid and solid wastes from coal-fired facilities, particularly coal ash, are also potential sources of trace elements (Dreesen et al., 1977). Critical elements from coal-fired facilities, as determined from mass balance and toxicity considerations, have been ranked by a National Academy of Sciences panel (referenced in Valkovic, 1983). Most critical are B, As, Se, Mo, Cd, Hg, and Pb. Fluoride, V, Cr, Ni, Cu, and Zn are of moderate concern. In 1982-1983, a Coal-Fired Steam Generation Facility (CFSGF) was constructed on the Idaho National Engineering Laboratory (INEL) in southeastern Idaho. The CFSGF, which began operation in March 1984, consists of two atmospheric fluidized bed combustion (AFBC) units, each capable of generating steam at 30 600 kg h r - i. Particulate emissions from the single 46-m stack are controlled by cyclones and a bag house; collected fly ash and spent bed material are disposed in slurry form to a 2.3-ha ash pit. At least one other ash pit will be required during the operationaI life o f the facility (25 y). The total heat input (approximately 0.17 T J h r - 1) is small compared with a typical 300 MW(e) commercial generating station with a heat input of approximately 3.3 TJ h r - t (U.S. Department of Energy, 1980); however, it is large compared with pilot plants of the AFBC type in the United States. The AFBC process, which operates in the range of 800-900 ~ is expected to result in different airborne emissions and ash characteristics than most commercial-scale plants which operate at higher temperatures (Fennelly, 1984). The CFSGF was built to supply steam for the Idaho Chemical Processing Plant (ICPP), which has reprocessed and recovered uranium from spent nuclear fuels since the mid-1950's. In addition to releases of SOx, NOx, and low-level radioactive effluents into the atmosphere, the I C P P has emitted unknown quantities of trace elements, including Cd, Hg, F, and B (Burr et aL, 1983). As a result of radionuclide effluents from the ICPP, vegetation (unpublished data) as well as tissues of various wildlife species such as mourning doves (Zenaida macroura) (Markham and Halford, 1982), sage grouse (Cetrocercus urophasianus) (Connelly and Markham, 1983), pronghorn (Antilocapra americana) (Markham et aL, 1979, 1980, 1982), jackrabbits (Lepus californicus) (Fraley et aL, 1982), and raptors (Craig el al., 1979) in the vicinity of the I C P P contain higher radionuclide concentrations than do corresponding biota off the INEL. Improved filtration of airborne effluent from the I C P P in 1975 resulted in significant reductions in 137Cs in pronghorn near the plant (Markham and Halford, 1985). An aerial radiotogical survey (Boyns, 1984) in 1982 showed t37Cs contamination up to about 4 km from the I C P P in the downwind directions and to < 1 km in the crosswind directions. Prior to this study, the vast majority of contaminant-related environmental studies on the INEL were involved with radionuclides. Because of the potential for trace element contamination due to past and future INEL operations, this study of nutrient and trace elements in soil and vegetation was undertaken to: (1) provide baseline
NUTRIENT
AND TRACE ELEMENTS IN SOIL AND DESERT VEGETATION
3
measurements prior to start-up of the C F S G F and other projects, and (2) analyze for enrichment of trace elements around the I C P P due to past airborne effluents, 2. M a t e r i a l s a n d M e t h o d s 2.].
STUDY AREAS
The study was conducted at the INEL and at two reference sites in Twin Falls and Lemhi Counties (Figure 1). All three Idaho sampling locations are representative of a cool sagebrush (Artemisia tridentata ssp.) steppe. Soils and vegetation types of the 2300-km z INEL site have been described by McBride et al. (1978). Average annual
i
IDAHO
10 20 30 Miles
20 40 Kilometers
L
~:a~:~::3~;:~:~-~;~:'" f
I.~L
+.r.,.~;-- J
Ii
//// // /
t
295" // /
/
\
\
"~.
"~ "c~
.55"
LosttRT'~ ~River \\
TRABIg
Y ./
'\
",,,
',,
7 0 2 4 6 8 I t 1 , I : I i I
Kilometers
e0~12
Fig. 2. Location of permanent sampling stations (e) at the Idaho National Engineering Laboratory. T R A = Test Reactor Area; I C P P = Idaho Chemical Processing Plant; C F A = Central Facilities Area. The wind rose is the annual average for C F A at a height of 76.2 m.
6
SUSAN K. ROPE ET AL.
(IAEA) were submitted 'blind' to the laboratory. Results of vegetation analyses were also cross-checked with those determined on splits of the same samples by the University of California Laboratory of Biomedical and Environmental Sciences in Los Angeles. Physico-chemical characteristics o f soil (pH, ~ organic matter, cation exchange capacity, and %o sand/silt/clay) were measured on one sample from each station by the Colorado State University Soils Testing Laboratory. In addition, this laboratory estimated the 'plant-available' element concentrations by extracting the soils with sodium bicarbonate-DTPA, followed by inductively coupled argon plasma for 17 elements, hydride generation for Se and As, and cold vapor analysis for Hg. The analytical techniques are described in Soltanpour and Workman (1981). Cesium-137 was measured in soil samples using a lithium-drifted germanium detector coupled to a computerized multichannel analyzer. Samples were counted for at least 50min, resulting in a minimum detectable concentration (MDC) of approximately 7 mBq g - ~. 2.4.
DATA
ANALYSIS
Data sets were checked for normality by visual examination o f probability plots. Many sets of trace element concentrations were found to be approximately log-normally distributed. Thus, significance testing was performed on these data after the values had been transformed via natural logarithms. Both geometric means (antilog o f the mean of the transformed values) and arithmetic means were calculated and reported. When data sets contained some values less than the MDC, the mean and standard deviation were determined from probability plots (Waite, 1982). A 95% confidence 'interval' on the mean o f transformed data sets was determined by finding the upper and lower confidence limits of the transformed values and then transforming back to the original units. Because the log-normal distribution is skewed, the untransformed 95% confidence 'interval' is asymmetrical with respect to the mean value. One-way analysis of variance (ANOVA) was used to compare concentrations of elements among the three Idaho locations and also among four location groups on the INEL. These four groups were: (1) downwind-close, (2) crosswind-close, (3) downwind-far, and (4) crosswind-far, where 1 and 2 km from the ICPP were 'close' and 55 ~ and 215 ~ were 'downwind'. Duncan's New Multiple Range Test was used as a follow-up comparison procedure. Data sets containing some concentrations below the MDC were analyzed using a Kruskall-Wallis Rank Sum Test. Results of all statistical analyses were considered significant if P ~ MDC (n total) a
Location and significant differences b
AI
22300 15000 13600
21600 14300 12900
18700-25000 13100-15600 10800-15400
15 (15) 48 (48) 15 (15)
T
18000 17100 11200
17200 16200 10800
14400-20600 14800-17800 9100-12700
15 (15) 48 (48) 15 (15)
T
7320 6310 3400
7000 6200 3310
6430-7610 5540~930 2880-3800
48 (48) 15 (15) 15 (15)
I
9900 5920 3520
8460 5400 2520
7270-9900 4340-6720 1980-3730
48 (48) 15 (15) 15 (15)
I
4650 3700 3640
4510 3490 3400
3890-5220 3170-3840 2760-4190
15 (15) 48 (48) 15 (15)
T
1170 816 420
1110 812 411
1020-1200 760-860 364--464
48 (48) 15 (15) 15 (15)
I
901 481 401
889 474 379
811-974 429-523 345-417
15 (15) 15 (15) 48 (48)
T
937 811 542
907 762 520
784-1050 686-846 439-616
15 (15) 48 (48) 15 (15)
T
489 350 209
470 343 195
423-522 294-400 144-264
31 (31) 10 (10) 10 (10)
1
319 271 152
296 250 138
239-367 200-314 122-157
15 (15) 15 (15) 48 (48)
L
303 244 156
298 238 153
268-332 222-255 136-172
15 (15) 48 (48) 15 (15)
T
89.7-104 63.8-72.3 43.3-52.4
48 (48) 15 (15) 15 (15)
I
Fe
Mg
Ca
K
P
Mn
Ti
F
Na
Ba
Zn
100 68.3 48.3
96.7 67.9 47.6
I L
I L
T L
T L
1 L
T L
L I
I L T L
T 1
I L
T L
9
N U T R I E N T A N D T R A C E E L E M E N T S 1N S O I L A N D D E S E R T V E G E T A T I O N
Table II (continued) Element
Sr
V
Ni
Cu
Cr
Pb
B
As
Cd
Be
Se
Hg
Arithmetic mean
Geometric mean (GM)
95% Confidence interval on GM
n > MDC (n total) a
Location and significant differences b
43,0 42.1 27,8
41.3 41.2 27.1
38.2-44.7 36.3-46.7 23,9-30.8
48 (48) 15 (15) 15 (15)
I
40,9 31.3 21,0
39.2 30.4 20.1
36.0-42.7 26,6-34.9 16.6-24.2
48 (48) 15 (15) 15 (15)
I
24.0 18,4 12,2
23.4 18.0 11.8
22,0-24.9 15.8-20.5 10,1-13.7
48 (48) 15 (15) 15 (15)
I
21,2 18,3 13,7
20.8 18.0 13.4
18,4-23.5 17,0-19.1 11.9-15.1
15 (15) 48 (48) 15 (15)
T
23.3 18.9 7.0
20.0 18.0 6.7
16,2-24.7 15,0-21.6 4, 1-10.9
48 (48) 15 (15) 10 (15)
I
14.0 12.6 10.1
13.7 12.2 10.2
12.4-15.2 9.4-15.7 7.7-13.5
37 (48) 11 (15) 7 (15)
I
10.1 4.7 --
9.8 4.6 --
16 (16) 4 (5) 2 (5)
I
9.7 6.8 5.2
9.3 6.7 5.1
6.4-13.5 6.0-7.5 4.0--6.5
5 (5) 16 (16) 5 (5)
L
0.62 0.61 0.47
0.61 0.61 0.46
0.53-0.69 0.544).68 0.36--0.60
16 (16) 5 (5) 5 (5)
I
0.67 0.61 0.58
0.65 0.60 0.57
0.52-0.81 0.53-0.67 0.53-0.60
11 (15) 15 (15) 46 (48)
T
13 (30)
I
8.4-11.4 2.8-7.5
AND
TRACE
VEGETATION
ELEMENTS
IN SOIL
OF SOUTHERN
AND
IDAHO
DESERT
*
SUSAN K. ROPE, W. J O H N A R T H U R , III ** Radiological and Environmental Sciences Laboratory, U.S. Department of Energy, Idaho Falls, Idaho 83402, U.S.A. T I M O T H Y H. C R A I G , andER1CA H. CRA I G Northwest Nazarene College, Nampa, Idaho 83615, U.S.A.
Abstract. Concentrations of thirty elements were measured in strong-acid extracts of soil, sagebrush (Artemisia tridentata ssp.) leaves and perennial grass from the Idaho National Engineering Laboratory (INEL) and two reference sites in southern Idaho. A bicarbonate-chelating extract of soil was used to estimate plant-available concentrations. The results provide baseline data prior to start-up of a coal-fired steam generation facility on the INEL and other developments in the region. In addition, existing impact from effluents from thirty years of a nuclear fuel reprocessing facility on the INEL was evaluated. Based on the spatial distribution of element concentrations, as well as comparison with references sites, we conclude that concentrations of Zn, and perhaps Ni, Cd, and V, are currently elevated around the fuel reprocessing facility. The spatial distribution of these elements is similar to that of t37Cs in soil, a radionuclide which is emitted by the facility. Sagebrush and soil appear more responsive than perennial grass for long-term monitoring of element concentrations in this semi-arid environment.
1. I n t r o d u c t i o n I n c r e a s e d levels o f tr a c e e l e m e n t s h a v e b e e n d e t e c t e d in the e n v i r o n m e n t as a result o f em i s s i o n s f r o m fossil-fuel p o w e r e d facilities, o r e smelters, m u n i c i p a l i n c i n e r a t o r s , a n d a u t o m o b i l e s , as well as the land a p p l i c a t i o n o f sewage sludges an d fertilizers (Klein an d Russell, 1973; N a t u s c h et al., 1974; C o n n o r et al., 1976; C l a r k , 1979; W a n g e n a n d T u r n e r , 1980; K a b a t a - P e n d i a s a n d P e n d i a s , 1984). E n r i c h m e n t o f s o m e a n t h r o p o g e n i c a l l y - d e r i v e d e l e m e n t s even occurs in relatively r e m o t e areas ( D a v i d s o n et a k , 1985). E m i s s i o n s f r o m c o a l - f i r e d plants c a n c o n t r i b u t e a large f r a c t i o n o f the trace m e t a l c o n t e n t o f t h e a t m o s p h e r e (Lee et al., 1975; T u r n e r an d S t r o j a n , 1978). I n v e s t i g a t o r s h a v e c o n d u c t e d studies o n e n v i r o n m e n t a l e n r i c h m e n t o f t r ace e l e m e n t s n e a r coal-fired plants with v a r i a b l e results. B o l t o n et al. (1973), V a u g h n et al. (1975), B r a d f o r d et al. (1978), W a n g e n a n d W i l l i a m s (1978) a n d C r o c k e t t a n d K i n n i s o n (1979) f o u n d little or n o e l e m e n t a l increases t h a t c o u l d be a t t r i b u t e d to p o w e r p l a n t emissions. H o w e v e r , o t h e r researches h a v e related e l e m e n t e n r i c h m e n t in soil a n d v e g e t a t i o n to a t m o s p h e r i c em is s i o n s f r o m c o a l - f i r e d facilities (Klein a n d Russell, 1973; A n d e r -
* This manuscript is a contribution of the Idaho National Engineering Laboratory Radioecology and Ecology Programs, Idaho Falls, ID 83402, funded by the U.S. Department of Energy, Office of Health and Environmental Research. ** Currently: Uranium Mill Tailings Remedial Action Project, U.S. Department of Energy, Albuquerque Operations Office, Albuquerque, New Mexico 87115, U.S.A. Environmental Monitoring and Assessment 10 (1988) 1-24. 9 1988 by Kluwer Academic Publishers.
2
S U S A N K. R O P E E T A L .
son et al., 1975; Connor et al., 1976; H o r t o n et al., 1977). In particular, Be, Co, F, Se, Sr, Ti, U, V, and Zn may be enriched around coal-fired facilities which burn western coal (Connor et al., 1976; Wangen and Wienke, 1976; Wangen and Williams, 1978; Wangen and Turner, 1980). Liquid and solid wastes from coal-fired facilities, particularly coal ash, are also potential sources of trace elements (Dreesen et al., 1977). Critical elements from coal-fired facilities, as determined from mass balance and toxicity considerations, have been ranked by a National Academy of Sciences panel (referenced in Valkovic, 1983). Most critical are B, As, Se, Mo, Cd, Hg, and Pb. Fluoride, V, Cr, Ni, Cu, and Zn are of moderate concern. In 1982-1983, a Coal-Fired Steam Generation Facility (CFSGF) was constructed on the Idaho National Engineering Laboratory (INEL) in southeastern Idaho. The CFSGF, which began operation in March 1984, consists of two atmospheric fluidized bed combustion (AFBC) units, each capable of generating steam at 30 600 kg h r - i. Particulate emissions from the single 46-m stack are controlled by cyclones and a bag house; collected fly ash and spent bed material are disposed in slurry form to a 2.3-ha ash pit. At least one other ash pit will be required during the operationaI life o f the facility (25 y). The total heat input (approximately 0.17 T J h r - 1) is small compared with a typical 300 MW(e) commercial generating station with a heat input of approximately 3.3 TJ h r - t (U.S. Department of Energy, 1980); however, it is large compared with pilot plants of the AFBC type in the United States. The AFBC process, which operates in the range of 800-900 ~ is expected to result in different airborne emissions and ash characteristics than most commercial-scale plants which operate at higher temperatures (Fennelly, 1984). The CFSGF was built to supply steam for the Idaho Chemical Processing Plant (ICPP), which has reprocessed and recovered uranium from spent nuclear fuels since the mid-1950's. In addition to releases of SOx, NOx, and low-level radioactive effluents into the atmosphere, the I C P P has emitted unknown quantities of trace elements, including Cd, Hg, F, and B (Burr et aL, 1983). As a result of radionuclide effluents from the ICPP, vegetation (unpublished data) as well as tissues of various wildlife species such as mourning doves (Zenaida macroura) (Markham and Halford, 1982), sage grouse (Cetrocercus urophasianus) (Connelly and Markham, 1983), pronghorn (Antilocapra americana) (Markham et aL, 1979, 1980, 1982), jackrabbits (Lepus californicus) (Fraley et aL, 1982), and raptors (Craig el al., 1979) in the vicinity of the I C P P contain higher radionuclide concentrations than do corresponding biota off the INEL. Improved filtration of airborne effluent from the I C P P in 1975 resulted in significant reductions in 137Cs in pronghorn near the plant (Markham and Halford, 1985). An aerial radiotogical survey (Boyns, 1984) in 1982 showed t37Cs contamination up to about 4 km from the I C P P in the downwind directions and to < 1 km in the crosswind directions. Prior to this study, the vast majority of contaminant-related environmental studies on the INEL were involved with radionuclides. Because of the potential for trace element contamination due to past and future INEL operations, this study of nutrient and trace elements in soil and vegetation was undertaken to: (1) provide baseline
NUTRIENT
AND TRACE ELEMENTS IN SOIL AND DESERT VEGETATION
3
measurements prior to start-up of the C F S G F and other projects, and (2) analyze for enrichment of trace elements around the I C P P due to past airborne effluents, 2. M a t e r i a l s a n d M e t h o d s 2.].
STUDY AREAS
The study was conducted at the INEL and at two reference sites in Twin Falls and Lemhi Counties (Figure 1). All three Idaho sampling locations are representative of a cool sagebrush (Artemisia tridentata ssp.) steppe. Soils and vegetation types of the 2300-km z INEL site have been described by McBride et al. (1978). Average annual
i
IDAHO
10 20 30 Miles
20 40 Kilometers
L
~:a~:~::3~;:~:~-~;~:'" f
I.~L
+.r.,.~;-- J
Ii
//// // /
t
295" // /
/
\
\
"~.
"~ "c~
.55"
LosttRT'~ ~River \\
TRABIg
Y ./
'\
",,,
',,
7 0 2 4 6 8 I t 1 , I : I i I
Kilometers
e0~12
Fig. 2. Location of permanent sampling stations (e) at the Idaho National Engineering Laboratory. T R A = Test Reactor Area; I C P P = Idaho Chemical Processing Plant; C F A = Central Facilities Area. The wind rose is the annual average for C F A at a height of 76.2 m.
6
SUSAN K. ROPE ET AL.
(IAEA) were submitted 'blind' to the laboratory. Results of vegetation analyses were also cross-checked with those determined on splits of the same samples by the University of California Laboratory of Biomedical and Environmental Sciences in Los Angeles. Physico-chemical characteristics o f soil (pH, ~ organic matter, cation exchange capacity, and %o sand/silt/clay) were measured on one sample from each station by the Colorado State University Soils Testing Laboratory. In addition, this laboratory estimated the 'plant-available' element concentrations by extracting the soils with sodium bicarbonate-DTPA, followed by inductively coupled argon plasma for 17 elements, hydride generation for Se and As, and cold vapor analysis for Hg. The analytical techniques are described in Soltanpour and Workman (1981). Cesium-137 was measured in soil samples using a lithium-drifted germanium detector coupled to a computerized multichannel analyzer. Samples were counted for at least 50min, resulting in a minimum detectable concentration (MDC) of approximately 7 mBq g - ~. 2.4.
DATA
ANALYSIS
Data sets were checked for normality by visual examination o f probability plots. Many sets of trace element concentrations were found to be approximately log-normally distributed. Thus, significance testing was performed on these data after the values had been transformed via natural logarithms. Both geometric means (antilog o f the mean of the transformed values) and arithmetic means were calculated and reported. When data sets contained some values less than the MDC, the mean and standard deviation were determined from probability plots (Waite, 1982). A 95% confidence 'interval' on the mean o f transformed data sets was determined by finding the upper and lower confidence limits of the transformed values and then transforming back to the original units. Because the log-normal distribution is skewed, the untransformed 95% confidence 'interval' is asymmetrical with respect to the mean value. One-way analysis of variance (ANOVA) was used to compare concentrations of elements among the three Idaho locations and also among four location groups on the INEL. These four groups were: (1) downwind-close, (2) crosswind-close, (3) downwind-far, and (4) crosswind-far, where 1 and 2 km from the ICPP were 'close' and 55 ~ and 215 ~ were 'downwind'. Duncan's New Multiple Range Test was used as a follow-up comparison procedure. Data sets containing some concentrations below the MDC were analyzed using a Kruskall-Wallis Rank Sum Test. Results of all statistical analyses were considered significant if P ~ MDC (n total) a
Location and significant differences b
AI
22300 15000 13600
21600 14300 12900
18700-25000 13100-15600 10800-15400
15 (15) 48 (48) 15 (15)
T
18000 17100 11200
17200 16200 10800
14400-20600 14800-17800 9100-12700
15 (15) 48 (48) 15 (15)
T
7320 6310 3400
7000 6200 3310
6430-7610 5540~930 2880-3800
48 (48) 15 (15) 15 (15)
I
9900 5920 3520
8460 5400 2520
7270-9900 4340-6720 1980-3730
48 (48) 15 (15) 15 (15)
I
4650 3700 3640
4510 3490 3400
3890-5220 3170-3840 2760-4190
15 (15) 48 (48) 15 (15)
T
1170 816 420
1110 812 411
1020-1200 760-860 364--464
48 (48) 15 (15) 15 (15)
I
901 481 401
889 474 379
811-974 429-523 345-417
15 (15) 15 (15) 48 (48)
T
937 811 542
907 762 520
784-1050 686-846 439-616
15 (15) 48 (48) 15 (15)
T
489 350 209
470 343 195
423-522 294-400 144-264
31 (31) 10 (10) 10 (10)
1
319 271 152
296 250 138
239-367 200-314 122-157
15 (15) 15 (15) 48 (48)
L
303 244 156
298 238 153
268-332 222-255 136-172
15 (15) 48 (48) 15 (15)
T
89.7-104 63.8-72.3 43.3-52.4
48 (48) 15 (15) 15 (15)
I
Fe
Mg
Ca
K
P
Mn
Ti
F
Na
Ba
Zn
100 68.3 48.3
96.7 67.9 47.6
I L
I L
T L
T L
1 L
T L
L I
I L T L
T 1
I L
T L
9
N U T R I E N T A N D T R A C E E L E M E N T S 1N S O I L A N D D E S E R T V E G E T A T I O N
Table II (continued) Element
Sr
V
Ni
Cu
Cr
Pb
B
As
Cd
Be
Se
Hg
Arithmetic mean
Geometric mean (GM)
95% Confidence interval on GM
n > MDC (n total) a
Location and significant differences b
43,0 42.1 27,8
41.3 41.2 27.1
38.2-44.7 36.3-46.7 23,9-30.8
48 (48) 15 (15) 15 (15)
I
40,9 31.3 21,0
39.2 30.4 20.1
36.0-42.7 26,6-34.9 16.6-24.2
48 (48) 15 (15) 15 (15)
I
24.0 18,4 12,2
23.4 18.0 11.8
22,0-24.9 15.8-20.5 10,1-13.7
48 (48) 15 (15) 15 (15)
I
21,2 18,3 13,7
20.8 18.0 13.4
18,4-23.5 17,0-19.1 11.9-15.1
15 (15) 48 (48) 15 (15)
T
23.3 18.9 7.0
20.0 18.0 6.7
16,2-24.7 15,0-21.6 4, 1-10.9
48 (48) 15 (15) 10 (15)
I
14.0 12.6 10.1
13.7 12.2 10.2
12.4-15.2 9.4-15.7 7.7-13.5
37 (48) 11 (15) 7 (15)
I
10.1 4.7 --
9.8 4.6 --
16 (16) 4 (5) 2 (5)
I
9.7 6.8 5.2
9.3 6.7 5.1
6.4-13.5 6.0-7.5 4.0--6.5
5 (5) 16 (16) 5 (5)
L
0.62 0.61 0.47
0.61 0.61 0.46
0.53-0.69 0.544).68 0.36--0.60
16 (16) 5 (5) 5 (5)
I
0.67 0.61 0.58
0.65 0.60 0.57
0.52-0.81 0.53-0.67 0.53-0.60
11 (15) 15 (15) 46 (48)
T
13 (30)
I
8.4-11.4 2.8-7.5
