R O C ZN IK I G L EB O Z N A W C Z E T. X X I V , Z. 2, W A R SZ A W A 1973
ALINA KABATA-PENDIAS
U P T A K E OF C O BA LT AND C O PPER B Y CLOVER FROM M IN ERA LS
IM PREG N ATED B Y T H ESE CATIONS 1
Trace Element Laboratory, Institute of Soil Science and Cultivation of Plants in Puławy
Much evidence indicates that ability of plants to utilize particular m icronutrients depends to a high degree on their forms of occurrence in soil [1, 8 - 1 0 , 12]. F ixation and release of trace elements by soil form ing m inerals is one of the principal factors governing their supply to plants.
The influence of certain clay m inerals commonly occurring in fine soil fractions (clay and silt) on copper and cobalt uptake by clover was investigated. The approach used in this research w as based on the total quantities of these elem ents that w ere released by m inerals and uptaken by clover through a dialysis m em brane.
EXPERIM EN TA L PROCEDURE
M A T E R IA L S
The following m inerals w ere used: W yoming bentonite, Cornvalis kaolinite, biotite separated from the granite and fine fraction of the basaltic soil. Besides, am orphous compounds of F e -A l m ixed hydroxides w ere prepared. The m ixed hydrous oxides w ere obtained by co-precipi tation of FeC l3 w ith HCl solution obtained from the dissolution of kaoli
nite. The proportion of FeC l3 and kaolinite w as calculated for the m olar
ratio S i 02/F e203 = 1. The detailed preparation was proceeded accord
ingly to the description given by Herbillon and T r a n V i n h [3]. The co-precipitates w ere washed several tim es w ith redistilled w ater,
1 This research has been financed in part by grant made by the U.S.D.A. un der the programme of P.L. 480.
274 A. K abata-Pendias
using the sedim entation method and later w ere allowed to age and purify at 20°C in a cellulose dialysis bag for 4 days w ith renew ed w ater daily. These co-p recip itates are called in the paper: F e -A l compounds or amorphous compounds.
M IN ER A L PR E PA R A T IO N
Silt fraction ( < 20 |i) was separated from each natural m ineral samples and from the basaltic soil. The m inerals w ere satu rated w ith CuCl2 and CoCl2 a t the concentration of 100 ppm, in suspension w ith 0 .1 N CaCl2 w ith a ratio of clay to solution 1:2 0. The suspension w ith pH of 6 w as shaken for 5 hours and after a 24-hour interval w as shaken again for 2 hours. A fter the first centrifugation, the suspension was centrifugated and washed several tim es w ith redistilled w ater until the disappearance of C l" in the supernatant liquid. The m ineral and soil fraction samples w ere dried a t 75°C and used for the experim ent.
Ta bl e 1 Trace elem ents in m in erals used f o r th e experim ent
M ineral and treatm en t
Content o f m inerals Amount introd uced w ith m ineral to 1 pot
Fe % Zn Cu Co Fe ms Zn Cu Co ppm /ug K a o lin ite Co - b * 0 .3 6 45 23 2.50 18 225 115 1 2 .5 Co - a 0 .3 3 35 1 .0 0 17 175 5 .0 Си - Ъ 0 .3 5 35 20 0 .7 5 18 175 100 3 .8 Cu - a 0.32 35 0 .6 9 16 175 3 .5 blank 0 .2 7 35 20 1 .0 4 14 175 100 5 .2 B i o t it e Co - b 9 .5 290 141 6 3 .6 2 475 1450 705 3 1 8 .1 Co - a 2 .5 25 8 3 .6 2 125 125 40 1 8 .1 Cu - b 9 o 290 125 2 7 .5 6 475 1450 625 1 37.8 Cu - a 2 .3 25 10 0 .3 1 120 125 50 1 .6 blank 9 .6 300 83 2 9 .6 2 480 1500 415 1 4 8 .1
Ben ton ite
Co 1 .9 90 14 2 5 .8 7 95 450 70 I29.4 Cu 2 .1 100 35 1 .2 5 105 500 165 6 .3 blank 2 .0 70 6 0 .7 5 100 350 30 3 .8 S o i l f r a c t io n Co 5 .0 100 155 39 .1 2 25О 500 775 19 5 .6 Cu 4 .5 80 155 2 8 .8 1 225 400 775 1 4 4 .1 blank 5 .2 80 113 27 .7 9 260 400 565 I39. I Fe-A l comp. Co 634 340 53 0 .5 Cu 634 890 3 0 .5 blank 65 40 3 .1 3 634 340 3 0 .5
Uptake of Co and Cu by clover from minerals... 275
The F e -A l compounds w ere saturated d irectly w ith CuCl2 and CoCl2
solution at the proportion of 500 jag of the cation per each individual sample which w ere placed sep arately in the dialysis bag.
Initial contents of F e, Zn, Cu and Co and those, a fte r the m ineral treatm en t w ere determ ined by spectrophotom etric and atom ic absorp tion m ethods. Analysis of the tra ce elem ent content of the sam ples a fter the grow th of clover was also m ade for kaolinite and biotite (Table 1).
W A T E R C U L T U R E E X P E R I M E N T
Red clover T rifolium pratense L. variety hruszowska was grown in
w ater culture in betw een Feb ru ary 1 and Ju n e 6.1971. The m ajor nu
trien t solution was prepared accordingly to the description of H o a
-g l a n d and A r n о n. Thy only sources of trace elem ents w ere
various m inerals saturated w ith copper and cobalt.
5 g of oven dried m ineral and soil fraction sam ples, and 9.8 g of F e -A l compounds w ere placed in cellulose dialysis tubes of diam eter 3 cm , w ith porous size at a range of 20 - 80 A. The tubes w ith saturated and blank m inerals w ere put into pots w ith nutrien t solution of a vo lume of 800 ml.
The treatm en t for each m ineral was the following: — saturation w ith Co,
— satu ration w ith Cu, — blank.
E ach treatm en t was m ade in 4 replicates. Besides, control pots w ithout any m ineral and w ith a m ajor n u trient solution w ith an addi tion of em pty cellu'loze dialysis bags w ere conducted.
Two crops of red clover w ere harvested during the experim ental
period (Table 2). A fter the term ination of the experim ent roots w ere
also taken for chem ical analyses. Plan t m aterial was tw ice washed w ith redestilled w ater, directly after cutting, and dried a t 70°C .
RESULTS AND DISCUSSION
The technique of cellulose dialysis bags was developed by which the release of cobalt and copper by im pregnated m inerals and their uptake by clover from the ionic solution was exam ined. The m ineral samples placed in the dialysis bags released fixed cations to the nutrien t solution due to reactions of exchange and hydrolyses. No other reactions of the im m ediate root-m inerals contact could occur. The experim ental condi tion protected the plant against the uptake of copper and cobalt from other sources than those released in ionic form s by m inerals.
276 A. Kabata-Pendias
Ta bl e 2 Y ield of red c lo v e r grown in the water c u ltu re
with sa tu ra ted m inerals /in £•/
Treatment I crop I I crop Roots T o ta l
K a o lin ite Co 3 . 5 0 7 . 5 0 5 .0 0 1 5 .6 0 Cu 3 .4 0 8 .5 0 4 .5 5 1 6 .2 5 blank 5 .7 5 6 .0 5 5 .9 0 1 5 . 7 0 Bentonite Co 2 .0 5 6 .4 5 4 .1 0 1 4 .6 0 Cu 2 .9 5 8 .0 5 4 .0 5 1 5 .0 5 olani: 2 .3 2 6 .9 0 4 .0 5 1 5 . 7 7 B io t it e Co 2 . 7 0 1 5 . 1 5 5 .2 0 2 1 .0 5 Cu 2 . 7 5 1 4 .9 5 5 .3 5 2 5 .5 5 blank 2 . 7 0 1 0 .9 5 5 .0 5 1 5 . 7 0 Fe-A l conp. Co 1 .0 5 5 .4 0 5 .2 0 9 .6 5 Cu 2 .8 0 1 4 .2 5 6 .5 0 2 3 .5 5 blank 5 .2 5 1 2 .0 0 6 .5 5 2 1 .8 0 S o i l fr a c t io n Co 5 .4 5 8 . 3 С 4 .5 0 1 6 .5 5 Cu 5 . 5 - 1 0 .5 5 5 .9 0 1 9 .7 5 blank 5 .2 0 5 .7 0 2 .4 5 9 . З 5 Control I 1 .6 5 0 .8 5 1 .5 5 4 .0 5 ! I I 1 . 7 5 5 .7 5 5 . 1 5 1 0 .6 5
It is well known that the ability of a particular soil m ineral to fix and release cations of heavy m etals differs significantly. The quantities of the fixed copper and cobalt by th e investigated m inerals differed accordingly within the order and range established by the author in the oth er studies [7]. Figures presented in Table 3 show that the highest am ount of these elements was fixed by biotite and the lowest by kaoli nite. Cobalt was fixed in higher quantities by bentonite than by soil fraction, while the retention of copper was reverse. The release of ele m ents by m inerals to the nutrient solution was in a different proportion (Table 4). A high cobalt sorption and release by bentonite w as associated w ith a specific capacity of m ontm orillonite to fix cations of heavy m e tals reported by the other authors [4, 10, 14].
The X -r a y diffraction patterns made for the m inerals used (with the exception of the high purity kaolinite) indicate their composition (Fig. 1). B iotite flakes w ere altered slightly giving sm all reflections for chlorite
(14.25 A ) and for kaolinite (7.08 A ). Bentonite w as composed alm ost en
tirely of m ontm orillonite (15.5; 4.48 and 2.57 A ) with sm all am ounts
of quartz (3.34 A ). The m ineralogical composition of soil fraction was
Uptake of Co and Cu by clover from minerals... 277
T a b l e 3 R eten tio n o f copper and c o b a lt by v ario u s m ineral a t 100 ppm ad d itio n
/ in per cen t o f the added amount/
ISineral Cu Co Z a o lin ite 3 1 .5 • B i o t it e 58 3 5 .0 B en ton ite 29 2 5 .1 S o i l f r a c t io n 42 1 1 .3 T a b l e 4 Copper and c o b a lt conten t of n u tr ie n t so lu tio n , t h e i r r e la t i v e s o l u b i l i t y
and uptake by c lo v e r Treatment ! Content o f so lu tio n in ppb S o l u b i l i t y in per c e n t* Uptake by c lo v e r in p er c e n t* * Co j Cu Co Cu Co I I I I ! j E a o lin ite ! iI Co 15.8 1 0 .0 1 .6 9 O.45 1 5 .7 1 3 .5 8 .5 9 .6 Cu 2 0 .0 1 2 .5 0.91 0 .1 2 2 6 .0 19.2 19.0 1 5 .7 blank 1 0 .0 8 .8 0 .1 5 0 .1 8 I5.O 5 .0 1 2 .0 1 1 .5 B e n to n ite Co 4 7 .5 5I.5 7 8 .4 7 5.9I 9O.O 4 4 .0 5O.O 1 4 .9 Cu 5 6 .5 5 5 .0 I.45 0 .6 1 4 4 .2 1 .1 I5 .7 1 2 .0 blank 2 6 .3 6 .2 1 .1 1 0 .5 5 8 6 .2 0 .8 1 6 .7 1 6 .3 B i o t it e Co 2 3.3 1 2 .5 5 0.77 I.45 4 .1 8 .1 1 .7 5 .1 Cu 2 2 .5 8 .8 1 .2 3 O.45 4 .0 1 .0 1 .9 0 .5 blank I5.8 1 0 .0 1 .0 8 0 .3 9 4 .6 0 .8 2 .1 0 .1 Fe-A l comp. Co 275.O 2 6 .3 3 0 3.12 4 .8 1 6 1 .8 4 6 .4 1 2 .3 6 .5 Cu ! 8 1 .5 I7 .5 9 .3 8 O.91 9 .8 2 6 .9 6 .6 3 5 .7 blank i 45.O 7 .5 5 .6 3 0.51 1 0 .7 1 6 .1 8 .2 7 .1 S o i l f r a c t io n Co i 2 8 .8 1 6 .3 i 1 3 .7 0 I I.50 4 .6 1 0 .3 6 .1 4 .2 Cu 3 5 .0 1 2 .5 7 .3 3 З.90 4 .9 6 .2 2 .4 0 .8 blank 1 1 6 .3 1 1 .3 6 .4 7 3 .9 5 5 .7 6 .0 0 .7 0 .6 Control I XI ; u . 5 6 .2 i 7 .5 7 .5 0 .2 4 0 .2 6 0 .1 6 0 .1 8 1 1 * Cu and Co c o n cen tra tio n in n u tr ie n t s o lu tio n given in the percentage o f t o t a l amount
introduced to p ots with m in erals
* * Amounts o f Cu and Co uptaken by the t o t a l y ie ld o f c lo v e r /tops and ro o ts/ , l e s s c o n tro l v a lu e s, in th e percentage o f amount introduced to p ots with the m inerals *■** I , I I - f i r s t and second crops r e s p e c tiv e ly
278 A. Kabata-Pendias 3,38 1005 Amorphe us Compounds 2,54 3,32 5,30 40 30 20 10 Degrees 2 9
Fig. 1. X -ra y diffraction patterns (CuKa) for the minerals and soil fraction used in the w ater culture
Uptake of Co and Cu by clover from minerals.., 279
v e ry broad reflection at about 15 A. It indicates a higher degree of in terstratification of m ontm orillonite. The X -r a y diffraction p attern for F e -A l co-precipitates shows th at the m aterial was very amorphous and had a high content of hydrous iron oxides, influencing a high F eb ack -ground. The broad sm all reflections a t 7.2; 6.7 and 5.3 A indicate the presence of some alum inium silicates. The other reflections m ay be of some silicates (3.47 and 3. 32 A) and iron compounds (2.54 A).
The grow th of red clover in w ater culture differed for the kind of m ineral in the w ater culture system . Fo r all the treatm en ts the first
crop of clover w as m uch sm aller than for the second one (Table 2). The
w orst grow th of clover with some chlorotic sym ptom s was observed for the treatm en t w ith F e -A l compounds and kaolinite during the first crop. On the other hand, the most chlorotic plants of the second crop w ere in the pots w ith bentonite and kaolinite which w as not reflected in the yield. The best grow th and yield of both of the crops w ere observed in the treatm en t w ith biotite. In general, the grow th of the second crop of clover was m uch m ore uniform in all the treatm ents. The clover suffered from both a deficiency (especially pronounced in the control pots) and a to xicity (observed in clover grown in pots w ith F e -A l com pounds especially those, treated with cobalt).
The concentration of Fe, Zn, Cu and Co in clover tissues shows significant differences for each m ineral and treatm ent (Table 5). It was
also found as regards the untreated m inerals (Table 6). The average con
ten t of iron and zinc in clover for all the untreated m inerals was at the level of blank control treatm ents, while a relatively high utilization of copper from F e -A l compounds and of cobalt from F e -A l compounds, soil fraction and bentonite was to be noticed (Table 5).
The addition of copper and cobalt in the form s fixed by various m i nerals greatly influenced both their concentration in the nutrien t solu tion and cobalt in clover tissues (Tables 4 and 5).
The ability of m inerals to replenish the trace elem ents varies and indicates the following orders calculated on the base of th e percentage solubility of the cations in the nutrient solution:
for Co
F e -A l comp. > bentonite > kaolinite > soil fraction > biotite for Cu
bentonite > F e -A l comp. > kaolinite > soil fraction > biotite These proportions well support the earlier results reported for cobalt
by K a b a t a and B e e s o n [1 0]. In both th e cases, th e lowest release
w as found for the soil fraction and biotite.
Alm ost the sam e order was obtained, when m inerals w ere clasified
280 A. Kabata-PencLias
T a b l e 5 M icronu trient conten t o f red clo v e r grown in the w ater c u ltu re
with satu rated e in e r a ls / in ppm/
Tre atment Fs Zn Cu Co I * I I R ** I I I R I 1 I I R I I I R Z e o lin ite Co 100 44 56 17 40 28 6.3 2 .0 5 .5 0 ,3 3 0 .1 8 0 .8 0 Cu 60 28 55 13 36 38 6.3 8 .5 4 .3 0 .0 6 0 .0 3 0 .0 6 blank 53 44 39 27 42 33 8 .5 3 .5 4 .5 0 .0 6 0 .0 2 0 .0 6 Bentonite Co 75 44 65 17 30 38
11.0
4 .6 50.0 6.75 4 .4 2 1 1 .1 3 Cu 72 40 55 24 30 35 1 5.5 7 .0 1 0 .0 0 .27 O .I3 0 .6 9 blank 56 40 55 20 42 30 5 .2 1 .0 5.0 0 .2 00.11
О.54 B i o t it e Co 72 44 100 24 20 36 5 .5 1 .8 9 .8 1 .0 5 1 .1 8 1 2 .3 3 Cu 56 60 196 20 16 28 7 .0 3 .0 4 .5 O .I5 0 .1 6 О.25blank 60 44 80 16 20 26 4 .0 4 .5 3 .4 O.O5 0 .0 8 O.O9
Fe-A l comp. Co 250 68 73 40 40 50 4 6 .3 12.3 4 9 .5 2 9 .6 2 7 .3 3 3 2 .0 4 Cu 100 68 44 36 30 20 3 1 .4 9 .3 I6.3 1 .1 2 O.5I 2 .5 3 blank 87 52 72 40 30 36 1 7 .2 5 .0 1 1 .3 0 .7 3 О.47 3 .? ^ S o il fr a c t io n Co 50 44 75 20 24 33 7 .0 2 .3 6 .0 1 .8 3 1 .1 6 5 .2 0 Cu 66 56 48 20 20 24 1 0 .4 3 .5 7 .0 0 .3 5 0 .2 2 О.34 blank 60 73 140 27 26 50 5 .8 1 .0 5 .6 0 .5 6 0 .4 4 0 .8 0 Control
T
60 52 100 30 26 48 З.З 0 .5 5 .6 0 .0 6 0.0 0 1 0 .1 8 I I 60 52 100 30 26 48 5 .0 1 .2 4 .6 O.O5 0 .0 1 0 .1 8* I , I I - f i r s t and second crop, re s p e c tiv e ly * * ro o ts
Ta bl e 6 Average co n cen tra tio n o f F e , Zn, Cu and Co in red c lo v e r
grov/n in th e treatm en t w ith blank m inerals
Treatment Fe Zn Cu Co I * X X l; * * I 11 Ы X I I Ы I I I u K a o lin ite 53 44 43 27 42 5.4 8 .5 3 .3 5.4 0 .0 6 0 .0 2 0 .0 4 Eer.tonite 56 40 43 20 42 31 ii* JC\ 1 .0 3 .1 0 .2 0 0 . 1 1 O .I5 B i o t it e 60 44 52 16 20 18 4o0 4 .5 4 .3 0 .0 5 O0O8 0 .0 7 Fe-A l comp. 67 52 69 40 30 55 1 7 .2 5 .0 1 1 . 1 0 .7 2 0.4 7 0 .5 9 S o il fr a c t io n 60 73 66 27 26 26 5 .8 1 . 0 3 .4 0.56 0 .4 4 0.50 Control 60 52 56 50 26 28 3 .3 0 .5 1 .9 0 .0 6 0 . 0 0 1 0.03
* I and I I -• f i r s t ; and second crop, r e s p e c tiv e ly * * Kean co n cen tratio n fo r both the c.reps
Uptake of Co and Cu by clover from minerals.., 281
values of cobalt and copper for the m inerals can be presented in the following ord er:
F e -A l comp. > bentonite > soil fraction > biotite > kaolinite Although the relative release of cations by kaolinite was m oderate (Table 4), this m ineral was the poorest source of all the m icronutrients due to its low cation retention (Table 1). The results show th at F e-A l compounds and bentonite w ere th e most im portant sources for m icro nutrient supply to the clover (Table 5).
In general, the concentration of copper and cobalt was higher for the first crop than for the second one (Table 5). How ever, the uptake of these elem ents was higher for the second crop alm ost in all the cases (Table 7). The highest concentration of copper (46 ppm) and cobalt (29 ppm) was found for the first crop of clover from the Со-F e -A l com pound treatm en t. The addition of copper to the amorphous compounds did not influence the copper concentration in clover so strongly. The cobalt and copper content of the second crop decreased several tim es when compared to the first crop. A very high ra te of decrease of co balt and copper concentration in both the plant tissues (Table 5) and the n utrien t solution (Table 4) was due to a weak fixation of these cations by m inerals which presum ably had an influence on the higher root cap acity during the plant grow th before the first crop.
In general an addition of the copper fixed by m inerals did not affect ed its uptake by plants to such a high e x te n t as cobalt. In the case of the F e -A l compounds, the copper concentration in clover was even higher from the C o-treatm ent relative to the C u -treatm en t (Table 5). B u t it w as not true for the total uptake of this n u trient (Table 7). It m ay be a reflection of some implication between a high content of iron and copper in the medium of clover grow th.
The concentration of cobalt and copper in the nutrient solution r e sulted from their release by the im pregnated m inerals. W ith the excep tion of the exrem ely high value for cobalt and copper concentration (e.g. 275 ppb Cu and 303 ppb Co in Со-F e -A l compounds treatm ent), in the n u trient solution, their concentration was at a sim ilar range as in the soil solution [8]. The degree of the solubility of the trace element differed for each m ineral and treatm en t (Table 4). The percentage so lubility of copper based on the ratio of its quantities found in the nu trien t solution to the am ount introduced to the pot w ith m ineral (Table 1) varied in the range from 3.7 to 90, being the highest for bentonite. The lowest values w ere obtained for the soil fraction and biotite. These values calculated for cobalt differs from 0.8 to 46 in a sim ilar proportion for each m ineral as w as found for copper. In general, an average energy of copper release by m inerals to the n u trient solution was in a higher
T a b l e 7
T o ta l uptake of m içro n u trie n ts by the y ie ld * o f red c lo v e r grown in th e water cu ltu re w ith satu rated m inerals /inyUg/
Treatment Pe Zn Cu Co X ** I I R*+* T «-*■** I I I R T I I I R T I I I R T K a o lin ite Co 330 321 280 931 56 292 140 488 20 15 28 63 1 .1 1 .3 4 .0 6 .4 Cu 204 498 222 924 44 298 153 495 21 71 17 109 0 .2 0 .2 0 .2 0 .6 blank 198 352 152 702 101 338 128 567 32 27 18 87 0 .2 0 .1 6 0.2 3 0 .6 Bentonite Co 153 371 266 790 34 253 155 442 23 39 123 185 1 3 .8 3 7 .3 4 5 .6 9 6 .7 Cu 212 322 222 756 70 241 141 452 46 56 41 143 0 .8 1 .0 2 .3 4 .1 blank 157 276 222 655 56 289 121 466 15 7 20 42 0 .6 1 .4 1 .4 3 .4 B i o t it e Co 194 578 520 1292 118 263 187 568 14 24 51 89 2 .8 I5.5 6 4 .1 8 2 .4 Cu 154 897 1146 2197 55 239 163 457 19 45 26 90 0 .4 2 .4 1 .5 4 .3 blank 162 481 404 1047 43 219 131 393 11 49 17 77 0 .1 0 .9 0 .5 1 .5 Fe-A l comp. Co 262 367 233 862 42 216 160 418 49 66 158 273 3 1 .1 3 9 .6 102.5 173.2 Cu 280 969 286 1535 100 427 130 657 88 133 106 З27 3 1 .4 7 .3 1 6 .4 5 5 .1 blank 282 624 471 1377 130 360 235 725 56 60 74 190 2 3 .7 5 .4 2 1 .2 5 0 .3 S o i l fr a c t io n Co 172 387 322 1302 69 211 141 421 24 202 26 252 6 .3 1 0 .2 2 4 .9 4 1 .4 Cu 283 590 283 1156 66 211 141 418 34 37 41 112 1 .2 2 .3 2 .0 5 .5 blank 192 270 343 805 86 96 122 304 19 4 14 37 1 .8 1 .6 1 .4 4 .8 Control I 111 442 135 688 55 221 64 340 6 0 .4 8 14 0 .1 0 .0 0 1 0 .2 0 .3 I I 105 299 315 719 52 149 151 352 9 7 14 30 0 .0 9 0 .0 6 0 .5 6 0 .7
* Y ield o f clo v e r i s given per 4 pots * * * R - ro o ts
Uptake of Co and Cu by clover from minerals.. 283
proportion (25.8 per cent) than for cobalt (13.7 per cent). A high rela tionship w as found for both, the cobalt and copper betw een their con centration in the nutrient solution and in the clover tissues (Fig. 2). This is positive linear correlation giving r = 0.963 for cobalt and r = 0.911 for copper, w ith significant levels ± 1 %.
0,1 1,0 10 Co in nutrient solution - j i j i b 100 50 100 260 Cu in nutrient solution - j i j i b 280 Fig. 2 Fig. 3
Fig. 2. Relation between the cobalt released to nutrient solution and the concen tration of cobalt in red clover
Fig. 3. Relation between the copper released to nutrient solution and the concen tration of copper in red clover
The results indicate th at the concentration of cobalt and copper in the nutrient solution is one of m ore im portant factors governing their supply to clover. Sim ilar statem ents are also reported in the other publi cations [8, 11, 12].
T here is m uch evidence that organic com plexing agents increase the flow of some heavy m etals into root system s m uch better than an ionic solution of these elem ents [2, 5, 6]. P i o t r o w s k a [13] did not find im portant differences for uptake of zinc and copper by tom ato plants from various m etal organic com plexes and for the ionic solutions. It m ay suggest that the mode of acting of m etal organic com plexing agents as a source of m icronutrients can differ under various conditions of plant grow th. The results of this experim ent show that plants can uptake v ery high quantities of copper and cobalt from their ionic solution, without an influence of organic com plexes. Continuous supply of copper and cobalt by im pregnated m inerals to the nutrien t solution controled a high concentration of their ionic form s highly influencing their uptake by the clover. The results indicate a relatively high relation of copper and cobalt uptake to their content in the nutrient solution.
284 A. Kabata-Pendias
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[13] P i o t r o w s k a M.: Uptake of Zn and Cu by tomato plant from their aerobic and anaerobic lucerne decomposing solutions. Rocz. glebozn. 24, 1973, 2, 291-299.
[14] S p e n c e r W. F., G i e s e k i n g J. F .: Cobalt adsorption and release in ca tion-exchange systems. Soil Sei. 78, 4, 1954, 267 - 277.
А . К А Б А Т А -П Э Н Д И А С УСВАИВАНИЕ КОБАЛЬТА И МЕДИ КЛЕВЕРОМ ИЗ МИНЕРАЛОВ НАСЫЩ ЕННЫХ ЭТИМИ КАТИОНАМИ Л аборатория микроэлементов Института агротехники Удобрения и почвоведения в П у л а в а х Р е з ю м е Проведен был опыт с красным клевером (Trifolium pratense L.) в водных культурах, где единственным источником микроэлементов являлись минералы помещенные в мешечках для диализа с пористостью 20-80 À. Форма опыта препятствовала непосредственному контакту корней с минералами и растения могли получить микроэлементы исключительно из растворов. В исследованиях применялись следующие минералы: бентонит (из W yo ming), каолинит (из Cornvalis), биотит выделенный из судетского гранита и
Uptake of Co and Cu by clover from minerals., 285 фракция ила из горизонта (В) почвы образованной из базальта (возле Уне-гощи). Кроме того были использованы аморфные препараты гидроокисей алю миния и железа (рис. 1). Из всех естественных минералов обособляли фрак цию с крупностью частиц < 20 [i, которую обрабатывали СиС12 и СоС12 в кон центрации эквивалентной 100 ppm катионов в водном растворе 0,1 Н СаС12 при pH 6. Суспензию минералов в ростворе (соотношение 1 : 20) взбалтывали в те чение 5-ти часового периода и затем после 24-часового перерыва еще в тече ние 2 часов. Минералы промывали несколькократно, после каждого центри фугирования раствора, до исчезновения реакции на С1~. Затем минералы вы сушивали до постоянного веса в температуре 75°. Суспензию аморфных соеди нений Fe-Al, конденсированных до небольшого объема, насыщали растворами СиС12 и СоС12 в количестве эквивалентном 500 ug катиона на индивидуальную пробу (9,8 г сухого вещества) помещенную в мешечке для диализа. Схема опыта учитывала кроме контрольных серий также сосуды с чистыми минералами и с насыщенными кобальтом и медью. Данные о количестве ми кроэлемента вносимых с минералами в сусуды приводится в табл. 1. Содержание меди и кобальта в клевере (в надземной части и корнях) ока залось дифференцинованным как в вариантах с чистыми минералами так и в вариантах с добавкой испытуемых микроэлементов (табл. 5). Обнаружены были тоже большие изменения концентрации этих элементов в растворе в связи с неодинаковой степенью их десорбирования. Наивысшая концентрация меди (46 ppm) и кобальта (29 ppm) была отме чена в клевере в варианте с Fe-A l соединениями насыщенными кобальтом. В этом-же варианте наибольшим оказался также вынос микроэлементов с об щим урожаем растений (табл. 7). Способность минералов к высвобождению микроэлементов из адсорбиро ванной формы, выраженная в процентах их перехода в раствор, складывает ся в следующий ряд: Fe-A l соединения > бентонит > каолинит > илистая фракция > биотит. Исключение составляет бентонит в случае меди, десорбирующий наиболь шее количество этого элемента (табл. 4). Очень сходный ряд был получен для минералов при учете количеств меди и кобальта усвоенных растениями: Fe-A l соединения > бентонит > илистая фракция > биотит > каолинит. Каолинит, в общем довольно легко десорбирующий микроэлементы, ока зался самым плохим их источником для растений, в следствие своей очень не высокой адсорбционной способности в отношении этих катионов (табл. 1). Обычно медь сильнее подвергалась десорбции (в среднем перешло в раствор 25,8% адсорбированной меди) чем кобальт (аналогичная величина составила 13,7%). Установлено высокую зависимость содержания меди и кобальта в клевере от концентрации этих катионов в растворах (рис. 2). Опыт показал, что клевером могут быть усвоены даже очень большие ко личества меди и кобальта, если эти элементы находятся в истинных растворах в субстрате. С этим явлением может совмещаться опасность токсических кон центраций меди и кобальта в растениях выращиваемых в специфических эко логических средах, подвергнутых загрязнению названными элементами.
286 A. K abata-Pendias
A . K A B A T A - P E N D I A S
POBIERANIE KOBALTU I MIEDZI PRZEZ KONICZYNĘ Z MINERAŁÓW NASYCONYCH TYMI KATIONAMI
L a b o r a t o r i u m M ik r o e le m e n tó w IU N G w P u ła w a c h
S t r e s z c z e n i e
Przeprowadzono doświadczenie z koniczyną czerwoną Trijolium pratense L.
w kulturach wodnych, w których jedynym źródłem mikroelementów były minerały umieszczone w woreczkach do dializy o porowatości 20 - 80 Â. Układ doświadcze nia uniemożliwił bezpośredni kontakt korzeni z minerałami, tak że rośliny mogły pobierać mikroelementy jedynie z roztworów.
Do badań zastosowano następujące m inerały: bentonit z Wyoming, kaolinit z Cornvalis, biotyt wydzielony z granitu sudeckiego oraz frakcję iłu z poziomu (B) gleby wytworzonej z bazaltu koło Uniegoszczy. Ponadto spreparowano bezposta ciowe wodorotlenki glinu i żelaza (rys. 1). Ze wszystkich minerałów naturalnych wydzielono frakcję ziarnową o wymiarze < 20 u, którą traktowano CuCl2 i CoCl2 w stężeniu odpowiadającym 100 ppm kationów w wodnym roztworze 0,ln CaClv, 0 pH 6. Zawiesina minerałów w roztworze (stosunek 1 : 20) była wytrząsana przez 5 godzin, a następnie po 24-godzinnej przerwie jeszcze przez 2 godziny. Minerały przemywano kilkakrotnie, po każdorazowym odwirowaniu roztworu, aż do zani ku reakcji na Cl- . Następnie minerały wysuszono do stałej wagi w temperaturze 75°C. Zawiesinę bezpostaciowych związków Fe-A l, zagęszczonych do możliwie m a łej objętości, nasycono roztworam i CuCl2 i CoCl2 w ilości odpowiadającej 500 jig kationu na indywidualną próbkę (9,8 g suchej masy) umieszczoną w woreczku do dializy.
Schemat doświadczenia obejmował, oprócz serii kontrolnych, wazony z mine rałami czystymi oraz nasyconymi kobaltem i miedzią. Mikroelementy wprowadzone wraz z minerałami do wazonów podano ilościowo w tabeli 1.
Zawartości miedzi i kobaltu w koniczynie (w częściach nadziemnych 1 w ko rzeniach) są zróżnicowane zarówno w seriach z samymi minerałami (tab. 6), jak 1 w kombinacjach z dodatkiem badanych mikroelementów (tab. 5). Stwierdzono również duże zmiany koncentracji tych pierwiastków w roztworach, związane z róż nym stopniem ich desorpcji.
Najwyższa koncentracja miedzi (46 ppm) i kobaltu (29 ppm) wystąpiła w ko niczynie w serii doświadczenia z Fe-A l związkami nasyconymi kobaltem. Z tej też kombinacji rośliny pobrały największą ilość mikroelementów w całkowitym plonie (tab. 7).
Zdolność minerałów do uwalniania obu mikroelementów z form zasorbowa-nych, wyrażona w procentowym ich przechodzeniu do roztworu, może być przed stawiona w następującym szeregu:
Fe-A l związki > bentonit > kaolinit > frakcja ilasta > biotyt.
W yjątek stanowi bentonit w przypadku miedzi; uwalnia największe ilości pier wiastka do roztworu (tab. 4).
Bardzo zbliżony szereg uzyskano dla minerałów, klasyfikując je pod względem ilości miedzi i kobaltu pobranych przez rośliny:
Fe-A l związki > bentonit > frakcja ilasta > biotyt > kaolinit.
Kaolinit, mimo dość łatwego uwalniania mikroelementów do roztworu, okazał się najgorszym ich źródłem dla roślin, ze względu na bardzo małą pojemność sorp
Uptake of Co and Cu by clover from minerals.., 287
cyjną w stosunku do tych kationów (tab. 1). Na ogół miedź uległa silniejszej desorp cji (średnio przeszło do roztworu 25,8% zasorbowanej miedzi) niż kobalt (analo giczna wartość wynosi 13,7%).
Stwierdzono dużą zależność zawartości miedzi i kobaltu w koniczynie od stę żenia tych kationów w roztworach (rys. 2).
Doświadczenie wykazało, że koniczyna może pobrać bardzo duże ilości miedzi i kobaltu, jeżeli składniki te znajdują się w roztworach właściwych w podłożu. Ze zjawiskiem tym związane może być niebezpieczeństwo toksycznych stężeń miedzi i kobaltu w roślinach rosnących w specyficznych środowiskach ekologicznych, n a rażonych na zanieczyszczenie wymienionymi pierwiastkami.
D o c . d r h a b . A l i n a K a b a t a - P e n d i a s W p ł y n ę ł o d o P T G w s t y c z n i u 1972 Z a k ł a d C h e m i i R o l n e j i G l e b o z n a w s t w a
L a b o r a t o r i u m M i k r o e l e m e n t ó w I U N G — P u ł a w y
