R O C Z N IK I G L E B O Z N A W C Z E T. X X V II , N r 1, W A R S Z A W A 1976
A L IN A K A B A T A -P E N D IA S
COPPER RELEASED FROM SOILS TREATED WITH C u S 04
T race E lem en ts L aboratory
In stitu te o f S o il S cien ce and C u ltiv a tio n of P la n ts, 24-100 P u ła w y
It has been recently observed a growing content of certain heavy m etals in soils due to an environmental pollution. Although copper is not very toxic and both plant and animal organisms show a high to lerance to that m etal its growing content in contaminated soils may have an impact on behaviour of other chemical elem ents and also on microbiological activity. An influence of Cu addition to various soils on chemical composition of soil solutions was investigated in the work reported in this paper.
M A T E R IA L S A N D M ETH OD S
The investigation was conducted on various kind of soil materials from the surface horizons of nine soils described in details elsewhere [2]. These soils are cultivated in the same w ay since 1880 year in microplots located in Puław y.
To each 500 g air dried soil sample was added 250 m g Cu as
C u S 04 • 5H20 in water solution (0.25%). Air dried samples w ith Cu
addition were carefuly m ixed and trasfered into 250 m l plastic tubes, then m oistened to the calculated field moisture content. Closed tubes w ith soil samples were incubated in aerobic conditions at 25 °C for three days and centrifugated for 20 m inutes at 3000 r.p.m. A fter the first centrifugation each soil sample was incubated for the follow ing periods 10, 31, 52 and 87 days in two conditions: m oistened to the field m oisture content and air dried (drying lasted about 24 hours in warm air jet). Dry soil samples were moistened for three days before each centrifu gation.
The concentration of Cu, Mn, Zn, Fe, Ca, Mg and К in soil solutions was analysed by atomic absorption using Perkin-Elm er Spetrometer 403. К content was determined by flam e emission on Unicam SP 90 apparatus.
Prior to analyses soil solution was evaporated and oxidized with H202 and dissolved in 1:1 HC1. Two soil fractions of < 2 \i and 2— 20 \x were separated by sedim entation from the water dispersed soil materials at pH 9 adjusted with NH4OH. Air dried powder specimens were analysed by an X-ray diffracion w ith Ni filtred CuKa radiation.
R E SU L T S A N D D ISC U SSIO N
A brief description of the materials shows a high variation in m e chanical and chemical composition of the soils (Table 1). The mineral
T a b l e 1 V a r ia t i o n in pH and volum e o f s o i l s o l u t i o n s c e n t r i f u g a t e d fro ci th e s o i l s d u r in g w et and d ry in c u b a t io n s flo. o f s o i l K inci o f s o i l S o i l c o n t e n t to pH i nS o i l addedHpO * Range o f ch an ge s o l u t i o n pH i n Range o f i s o l u t i o n change in volum e ■**"* С aCO^ o r g .С 1 К KCl g w et dry w et dry I* -** F * * * I F 1 F 1 F 1 s a n d 0 0 .6 2 3 .9 124 3 . 9 4 . 9 3 .8 4 . 7 86 81 86 81 2 l i g h t loam 0 0 .6 5 4 .2 1 3 0 3 .7 5 .1 3 .7 5 .1 85 73 85 81 5 l i g h t loam y r e n d z in a 8 .2 3 2 . 0 0 7 . 4 190 7 . 6 7 . 2 7 . 6 7 . 6 72 63 72 72 4 medium loam 4 .3 2 1 .3 0 7 . 1 194 7 . 8 7 . 7 7 . 8 7 . 7 55 61 5? 46 5 l o e s s 0 1 . 1 0 5 .4 190 5 .9 7 . 5 5 . 9 7 . 2 73 63 73 82 6 medium loam 8 .4 0 3 .8 5 7 . 5 2 0 0 7 . 7 8 . 3 7 . 7 8 . 4 70 65 70 73 7 aar-d 0 0 . 5 0 4 . 5 105 4 . 0 7 . 3 3 . 9 6 . 9 80 70 80 86 8 s i l t 0 .1 0 1 .1 5 6 . 6 140 6 . 3 7 . 0 6 . 4 7 . 3 66 57 67 72 9 l i g h t loam 0 1 .5 0 5 .2 150 4 . 9 6 . 4 4 . 9 6 . 4 i 87 67 80 79 * Amount o f w a te r added i n t o 5 0 0 g a i r m o iß tu r e c a p a c i t y d r ie d s o i l s a m p le s c o r r e s p o n d s t o t h e f i e l d ** E x p r e s s e d in p e r c e n ta g e o f t h e w a ter added 1 - f i r s t and F - f i n a l c e n t r i f u g a t i o n
composition of two fine fractions was also different especially as concern
kaolinite and calcite content (Fig. 1). In two soils (Nos 3 and 6) where
carbonates occur was indentified a relatively high content of calcite
m ainly in 2— 20 \i fraction and a negligible amount of clay minerals.
The fractions of all the other soils are fairly similar but it m ay be
noticed that sandy and light loamy soils (Nos 1, 2 and 7) content less
kaolinite and illite in < 2 \i fraction than medium loamy and silty soils.
There was not observed a significant difference between w et and dry conditions of incubation in the variation of pH of the soil solutions and of the total cations removed by five succesive extractions (Tables 1
Copper released from soils 5
Fig. 1. T he X -r a y d iffraction patters usin g C uKa rad iation for air dried u n orien ted clay fraction s sep arated from th e soils.
I — i llit e , К — k a o li n it e , Q — q u a r tz , F — fe ld s p a r s , С — c ^ lc ite
and 2). Therefore the results obtained for the w et incubation only are
discussed in this publication.
Initial pH of soil solution after C u S 04 addition was fairly similar
to those values obtained for soil samples in 1 N KC1 (Table 1). But further incubation led to a growth of the pH values in all the soils with an exception of calcareous ones. The soil pH reflecting in solution pH seems to be the most important factor influencing an extractability of the cations. Cumulative curves for Cu released from the soils during five extractions show clearly a difference between the studied soils
(Fig. 2). The first extraction of Cu from the loamy and silty soils with
pH above 7 was very low and did not exceed a concentration 20 (.imoles/1. The final concentration of these solutions was also negligible (Table 3). A higher rate of Cu extracion was obtained from the light silty soils
with pH about 5 to 6, giving the Cu concentration of the first extraction
from 36 to 157 um oles/1. The highest Cu concentration ranging from 4262 to 7400 umoles/1 was in the first solution of the sandy soils with
T a b l e 2
C a t io n s rem oved by f i v e s u c c e s i c e e x t r a c t i o n s from t h e s o i l s a f t e r Cu a d d i t i o n a t th e l e v e l 500 ppm / f i g u r e s e x p r e s s e d i n ppm o f s o i l m a t e r i a l / No. o f Cu Zn Mn Fe Ca Mg 1I i l w et * d ry * w et d ry w et d ry w et d ry w et d ry w et d ry w et d ry 1 3 50 381 78 7 9 142 1 3 4 16 7 7 1 9 731 17 18 59 67 2 4 75 434 59 50 148 119 23 2 6 7 4 689 16 13 59 57 3 4 . 4 5 . 3 1 . 6 0 . 9 46 32 4 1 1 7 7 4 1511 4 9 43 135 138 4 1 .3 1 . 9 0 . 6 0 . 4 22 11 1 1 1 6 8 8 1582 75 63 90 89 5 15 15 18 19 7 4 69 6 4 1 1 8 6 1220 60 61 59 58 6 1.8 2 . 9 0 . 8 0 . 8 22 9 10 1 I9OI I5 7 I 56 38 85 77 7 4 6 0 4 7 9 36 38 129 102 12 0.8 67 9 652 17 16 71 71 8 6 8 6 7 107 7 4 4 5 1221 121<«i 1 39 148 56 61 9 25 25 16 16 125 117 8 7 I2 3 2 I229 4 0 36 82 82 * C o n d it io n s o f t h e i n c u b a t io n «0 о Б <0 0 ü — 1--- 1--- 1---1 3 10 31 5 2 8 7 Days
Fig. 2. T he cu m m u la tiv e cu rves o f Cu rele a sed from th e so ils by fiv e su ccesiv e w a te r ex tra ctio n (recalcu lated in [xmoles/1)
pH below 4.5. The concentration of the further exctractants was also much higher for those soils than for less acid soils. A sim ilar proportion in the solubility was noticed for the other micronutriens (Table 3), w hile the solubility of Ca, Mg and К was much more constant for all the soils (Table 4).
Copper r ele a sed from so ils 7
T a b l e ^
C u, Z n , Mn and Fe rem oved by f i v e s u c c e s i v e e x t r a c t i o n s from t h e s o i l s a f t e r Cu a d d i t i o n a t t h e l e v e l 5 0 0 p .p .m . /w e t in c u b a t i o n / No. Cu Zn N'n Fe o f F L ■r F L T F L T F L ? s o SF SF i l
y u m o le s /l ^ u n o les y u m o le s /l ^UlP.ClCL- ^ im o le s/1 w m oles yimn1Le s / 1 H ^ cle s 1 4 2 6 7 57 5 5 0 8 77 9 5 6 10 1 193 80 1760 34 25 8 5 68 164 21 2 86 57 2 554-7 5 0 7 4 7 5 74 6 6 0 7 9 0 - 73 1 6 9 6 57 2 6 9 4 62 173 43 4 1 1 '♦2 3 20 10 69 28 6 6 24 25 178 62 83 7 21 25 22 78 32 4 6 4 21 28 2 2 9 22 58 39 4 0 0 1«» 7 11 25 28 5 9 4 14 2 3 6 39 1 41 2 2 7 5 51 501 55 234 0 21 35 29 107 32 6 6 4 28 21 3 1 12 25 23 96 4 0 0 6 21 98 179 11 7 7 4 0 0 23 7 2 3 9 88 567 3 5 5 0 34 2 1 2 7 3 ° 23 4 8 90 229 4 4 214 83 8 3 6 18 9 4 38 5 4 4 91 59 5 5 4 10f- I947 28 55 20 71 63 9 1 57 35 39 3 39 1 0 9 5 2 4 4 44 945 127 2 2 7 5 41 21 8 4 14 J 14 E x t r a c t i o n s : F - f i r s t / t h i r d f o r F e / L - l a s t T - t o t a l f o r f i v e e x t r a c t i o n s g iv e n in ^ u m o le s /k g s o i l F SF - s o l u b i l i t y f a c t o r c a l c u l a t e d a s ^ x 100 r a b 1 e 4 C a, Mg and К rem oved by f i v e s u c c e s i v e e x t r a c t i o n s from t h e s o i l s
a f t e r Cu a d d i t i o n a t t h e l e v e l 5 0 0 p .p .m . 4 e t i n c u b a t i o n / N o. o f s o i l Ca Mg К F L * F L T F L •*? nmol«î s/ 1 Lllf:0 lo 5 r .m o le s /1 :.:n oles .mmole s / 1
1 12 O.O9 17 70 0 . 5 6 0 .0 1 0 . 6 9 81 0 . 8 0 0 . 1 8 1 . 5 0 53. 2 12 0 . 0 5 16 75 0 . 4 8 0 . 0 1 0 .6 5 73 0 . 7 6 0 . 0 6 1 . 5 0 5 0 3 16 0 . 8 9 4 4 36 О. 7 4 0 . 1 8 2 .0 1 36 1 .1 5 0 . 2 0 3 . 4 5 33 4 11 0 . 8 9 4 2 26 0 . 9 8 О. 2 3 3 . 0 0 32 0 .6 3 0 . 1 4 2 . 3 0 27 5 13 О. 2 9 29 44 1 .0 0 0 . 0 3 2 .4 6 40 0 . 4 8 0 . 0 2 1 . 5 0 32 6 16 2 . 3 9 47 34 0 . 5 8 0 . 4 0 2 .3 0 25 0 .5 5 0 . 1 5 2 .1 7 25 7 12 0 . 1 3 16 75 0 . 6 3 0 . 0 1 0 .6 9 79 1 .2 8 0 . 0 8 1 .8 1 59 8 16 0 . 8 2 3 0 53 3 .5 7 О. 2 9 5 .7 1 53 0 .6 7 0 . 1 1 I.4 3 46 9 13 О .3 О 3 0 43 O .9O 0 . 0 3 1 . 4 6 61 0 . 7 8 0 . 1 8 2 . 0 9 37 E x t r a c t i o n s : F - f i r s t L - l a s t T - t o t a l f o r f i v e e x t r a c t i o n s g iv o n in y u m o le s /k g s o i l F SF - s o l u b i l i t y f a c t o r c a l c u l a t e d a s — - x 1 0 0
In oxidizing and slightly acid solution Cu cannot precipitate, for the compounds of Cu2+ w ith the common anions of a soil solution are solu ble [4]. Therefore Cu is highly m obilized by such a solution percolating
through out Cu contaminated soil or other spoil m aterials [5, 6]. К r a u- s к о p f [4] has reported that as the pH of dilute solution becomes higher than about 6.5 the complex CuOH+ becomes dominant and above 7 any of several precipitates m ay apear. This is a case in the soils with carbonates which solutions contain 87 times less Cu than the solutions of acid soils (Table 5). In all these soils with an exception of black earth
(No. 6) is observed a slight increase in Cu solubility after 87 days of
T a b l e 5 A v era g e c o n c e n t r a t i o n o f c a t i o n s i n t h e s o l u t i o n s o f f i v e s u c c e s i v e e x t r a c t i o n s c a l c u l a t e d f o r tw o s o i l g r o u p s v ;ith v a r i o u s pH / i n ppm/ Cu Zn Mn ?e Ca М3 j К j S o i l s w it h pH !>■ 6 . 4 5 . 5 3 9 .8 i-r, 3 1440 7 3 ! 80 S o i l s w it h pH <C 5 . 5 2 8 6 .8 4 1 . 8 I3 2 . 6 i 1 3 . 4 846 27 65 R a t io 01 a c id t o a l k a l i n e s o i l s 8 6 .9 1 1 .9 3 . 1 j 2, 9 0 . 6 C .3 : 0 . 3 * S o l u b i l i t y f a c t o r : a l k a l i n e s o i l s ,n 40 2 4 37 41 42 37 a c i d s o i l s 69 71 62 49 61 6? j 48 1 i * S o l u b i l i t y f a c t o r i s c a l c u l a t e d a s a r a t i o o f c o n t e n t i n t h e f i r s t s o l u t i o n to t o t a l amount e x t r a c t e d 1 b I e 6 I n f l u e n c e o f Cu a d d i t i o n on r e l a e s e o f c e r t a i n c a t i o n s e x p r e s s e d a s a r a t i o o f t h e i r m o la r c o n c e n t r a t i o n i n s o i l s o l u t i o n from t.Ue f i r s t e x t r a c t i o n t o a n a t u r a l c o n t e n t i n t h e s o l u t i o n s * î:o. o f . s o i l Mn Zn :--э 1 1 2 37 0 2 1 1 19 --ï'3 3 16 2 23 4 89 2 9 5 5 c-0 4 6 33 г 3 ; 7 20 5? 8 1 1 0 1 iA 9 . . . 2 1 1 ? 1 I 4 1 Ca Ks К 7 6 i 4 6 : 4 3 3 5 4 2 j 4 з 5 j 6 з 3 3 2 8 7 з 3 3 5 7 i 1 8 4 N a t u r a l c o n t e n t i n t h e s o l u t i o n s was d e te r m in e d b e f o r e th.« tr a a tc -.r n t. J e s u i t s a rc g iv e n e ls e w h e r e / 2 /
Copper released from soils 9 incubation, although the pH of those solutions did not decrease signi ficantly.
A relative solubility calculated as a ratio of the concentration of the first solution to the total amount extracted indicates a distinguish difference between alkaline and acid soils for both micro and major nutrients (Table 5). The earlier investigation on the natural solution of these soils have also indicated that total concentration of micronu trients in loam y alkaline soils is about five tim es smaller than that value for sandy acid soils [2].
The addition of a high amount of Cu2+ and SO42“ ions to the soils
led to an effect on solubility of all other elem ents studied. Ratios of the elem ent concentrations in the first soil solutions obtained after C u S 04
addition to their contents in natural soil solutions determined earlier |2]
show a higher solubility, especially of heavy m etals (Table 6). It may
have a pollution implications because these two ions are common contaminants of soils of certain industrial areas. In soils with a higher content of Cu2+ and S 0 42“ ions m ay be expected a growing solubility of certain micro and major nutriens. That phenomena m ay lead to an unfavourable effect on root m etabolism and ground water pollution [3, 8]. M a s s e y and B a r n h i s e l [6] have reported that black shales asso ciated with coal deposits contain usualy a high concentration of Zn, Ni and Cu. Revegetation conducted on that spoil material may suffered from the toxic level of heavy metals and A1 highly soluble in acid con dition. M a s s e y [5] has also established a correlation between the concentration of Zn, Cu and Ni in soil solution and the solution pH. Much closer negative relationship was obtained in this study for those parameters. The regression equations indicate that of all elem ents stu died Zn is most likely to mobile under an influence of pH (Table 7). The solubility of Cu as a function of the pH shows also a high relation ship what can be seen on Fig. 3. Those curves indicate also that both pH of the solutions and of the soils have similar influence on Cu so lubility. It is noteworthy a low correlation between Fe solubility and the solution pH (Table 7). A low m obility of Fe is confirmed by its absent in all the solutions from two first centrifugations. A relatively high stability of Fe should be explained by the fact that at pH above 5 no Fe can exist in oxidizing solutions at the concentration above 0.01 ppm except in the form of organic complexes or of colloidal hydroxides [4]. M a s s e y and B a r n h i s e l [6] have also found that the highest Fe concentration in natural solutions ranging from 11 000 to 37 500 ppm
occured in samples with pH below 2.2. Those values are much higher
than figures obtained in these studies for Fe concentration in the soil
solutions (Table 2).
The content of clay fraction in the soils is another factor controlling m obility of Cu. Values of two indices, first of Cu solubility (1RS) and
T a b l e 7 2 * R e g r e s s io n e q u a t io n and г v a l u e s f o r h e a v y m e t a l s and Ca s o l u b l e a s a f u n c t i o n o f s o l u t i o n pH i n 9 s o i l s / f o r n = 4 5 / E le m en t I n c u b a t io n . R e g r e s s io n E q u a tio n r 2 Cu w et l o g ppm Cu = 6 . 0 0 - 0 . 7 5 pH 0 . 9 6 d ry l o g ppm Cu = 4 . 6 8 - 0 . 5 9 pH 0 . 9 7 Zn w et l o g ppm Zn = 4 . 7 5 - 0 . 6 1 pH 0 .9 7 d ry l o g ppm Zn = 3 . 7 О -О .5 О pH 0 .9 7 Mn w et l o g ppm Mn = 3 . 4 7 - 0 . 2 6 pH O.90 d ry l o g ppm Mn = 3 . 0 0 - 0 . 2 1 pH O.90 Fe w et l o g ppm Fe = 2 . 3 3 - 0 . 2 4 pH 0 . 8 2 d ry l o g ppm Fe = I .92-O .I9pH 0 . 8 4 Ca w et l o g ppm Ca = 2 .4 2 + 0 .1 0 pH О.92 d ry l o g ppm Ca = 2 .6 0 + 0 .0 7 pH О.92 ■* C a l c u l a t i o n w as done f o r t h e c a t i o n s i n e a c h s o l u t i o n e x t r a c t e d
F ig. 3. C oncentration o f Cu in th e so il so lu tio n s as a fu n ctio n o f fin a l so il and so lu tio n pH during w e t and dry in cu b ation s
a — s o lu t io n p H a n d d r y in c u b a t io n , fc> — s o il p H a n d d r y in c u b a tio n , с — s o lu t io n p H a n d
w e t in c u b a t io n , d — s o il p H a n d w e t in c u b a tio n
second of Cu concentration (IRC) were plotted against the content of < 2 0 \i fraction (Fig. 4). The curve shows that both Cu solubility and Cu concentration in the soil solutions are the negative functions of the content of clay fractions. The spots occured above the curve are related to the soil w ith a high carbonates content.
Copper released from soils 11
F ig. 4. R elea se o f Cu from th e soils as a fu n ctio n o f cla y fra ctio n co n ten t (both in d e x v a lu e s g iv e n for 3 d ays w e t incubation)
1R S — i n d e x o f r e l a t iv e s o l u b i l i t y c a lc u la te d a s a p e r c e n t a g e r a tio o f C u r e m o v e d b y e x t r a c t io n s to 500 m g C u a d d e d to t h e s o ils , IRC — i n d e x o f C u c o n c e n t r a t io n c a lc u la t e d a s a r a t io o f C u c o n c e n tr a tio n in t h e s o lu tio n s o f th e f ir s t e x t r a c t io n to n a t u r a l s o i l s o lu tio n s
Several authors have reported observations on a growing tolerance of plants to a high concentration of heavy metals, especially of С и Д , 3, 9]. It has also been recently established that the concentration of nutrients in the soil solutions is one of a major factor controlling the translocation of nutrients from soil to root [7]. Plant uptake of several elem ents m ay
be a function of their concentration in the nutrient solution [3, 8]. Thus
each chemical contamination of soils m ay lead to an unfavourable effect on salt concentration in the soil influencing root metabolism and ground water pollution.
The obtained results indicate that a toxic effect of heavy m etal addition to the soil-plant system depend upon mechanical, chemical and mineral composition of the soils. Data on chemical composition of the natural solutions of spoil materials m ay give some information on a soil resistance to heavy m etals pollution.
*
The author wishes to extend her thanks to Dr. M. Stępniew ski for the X -ray diffraction testing and to Mr. P. Tarłowski for the technical assistance.
REFEREN CES
[1] B r a m s E. A., F i s k e l l J. G. A.: C opper accu m u lation in citrus roots and desorp tion w ith acid. S o il Sei. Soc. A m . Proc. 35, 1971, 772— 775.
[2] K a b a t a - P e n d i a s A.: W p ły w sk ład u ch em iczn ego roztw oru g leb o w eg o na za w a rto ść m ak ro- i m ik ro elem en tó w w zbożach. Rocz. G lebozn., 26, 1975, 75— 88. [3] K a b a t a - P e n d i a s A. , W i ą c e k K.: E ffe c t of h igh con cen tration of copper on its accu m u lation by grass. T rans. 10th Intern. C ongress S o il Sei. 11, 1974, 185— 193.
[4] K r a u s k o p f К . В.: G eoch em istry of m icron u trients. M icronu trien ts in A g r i culture, 1972, 7— 40.
[5] M a s s e y H. F.: PH and solu b le Cu, N i and Zn in E astern K en tu ck y coal m in e sp oil m aterials. S o il Sei. 114, 1972, 217— 221.
[6] M a s s e y H. F., B a r n h i s e l R. I.: Copper, n ick el and zinc relea sed from acid coal m in e sp oil m a teria ls of E astern K en tu ck y. S oil Sei. 113, 1972, 207—
2 1 2.
[7] M e n g e l K.: N u trien t a v a ila b ility and y ield form ation. N eth. J. agric. Sei. 22, 1974, 283—294.
[8] W i k l a n d e r L., A n d e r s o n A.: T he com p osition of th e soil solu tion as in flu en ced by fertiliza tio n and n u trien t u ptake. G eoderm a 11, 1974, 157— 166. [9] W u L i n , B r a d s h o w A. D.: A erial p o llu tio n and the rapid ev o lu tio n of
copper tolerance. N ature 238, i972, 167— 169.
А . К А Б А Т А -П Е Н Д И А С О С ВО БО Ж ДЕН И Е М ЕДИ И З ПО ЧВ Н А С Ы Щ Е Н Н Ы Х CuSOj Л аборатория м икроэлем ентов, О тделение хим ии почв и удобр ен и я растений, И нститут агротехни ки, удобрен и я и почвоведени я в П ул ав ах Р е з ю м е В почвах п од в ер ж ен н ы х пром ы ш ленном у загрязн ен и ю констатируется п о стоянный рост содер ж ан и я т я ж ел ы х металлов. Н есм отря на вы сокую толеран т ность растений в отнош ении вы сок их концентраций м еди в ср еде [3, 9] введение повы ш енны х количеств этого элем ента в почву м ож ет невы годно сказаться на п оведении др уги х хи м и ч еск и х компонентов. В проведенном опы те и зуч алось влияние м еди вносимой в различн ы е почвы на и зм ен ение хим ического состава естеств ен н ы х почвенны х растворов. В 500 г навески почв (9 почвенны х разновидностей, табл. 1) добавляли раствор C u S 0 4 • 5Н20 в количестве эквивалентном 500 мг Си на 1 кг почвы. В ы суш ен н ы е образцы у в л я ж н я л и до капи ллярной влагоем кости и затем ставили в терм остат с тем пературой 25° на 3 -х дневны й срок. П осле я дален и я центреф уги рованием почвенного раствора одн у груп п у образцов вы суш ивали (на в озд у х е) а вторую снова ув л аж н я л и и обе группы (серии) образцов оставляли в терм остате па п е р иод 10, 31, 52 и 87 дней. С ухой обр азец смачивали водой на 3 дня п ер ед к аж ды м ц ен треф уги рован и ем раствора. В пол уч аем ы х п очвенны х р астворах о п р ед ел ял и сод ер ж ан и е сл едую щ и х х и м ическ их элементов: Cu, Mn, Zn, Fe, Ca, Mg и К . С одерж ан и е назв ан н ы х э л е ментов равно как и pH растворов не подвергались ди ф ф ер ен ц и а ц и и в зав и си
Copper released from soils 13 мости от условий сухого либо мокрого инк убирования почв енны х образцов. Н а чал ьн ое pH п очвенны х растворов соответствовало pH почвы в вы тяж к е 1 n КС1. Р еак ц и я почв и растворов по-в и ди м ом у является одним и з осн ов н ы х ф ак торов в лияю щ их на растворим ость меди. К оличество м еди растворенной при первом ц ен треф уги рован и и раствора склады валось сл едую щ е для почв с р азличн ой р е- к ацией (рис. 2): pH > 7 — Си в растворе около 20 м икром олей на литр; pH 5-6 — Си в растворе 36 до 157 м икром олей на литр; pH < 4 — Си в растворе 4262 до 7400 м икром олей на литр. П овы ш енное сод ер ж а н и е ионов Си2+ и S 0 42— способствовало повы ш ению растворим ости д р уги х катионов, а особенно т я ж ел ы х м еталлов (табл. 6). И н тен сивность о св обож ден и я катионов о к азал ась вы сш ей в группе к и сл ы х почв (pH < 5,5) н е ж е л и щ ел оч н ы х почв (pH > 6,5) (табл. 5). К онстати рована отрица тельная корреляция м е ж д у количеством о св обож даем ы х т я ж ел ы х м еталлов и р еакци ей раствора (табл. 7). С одер ж ан и е илистой ф р ак ц и и и отчасти ее м инеральны й состав т ож е влияли на интенсивность освобож ден и я м еди и д р уги х катионов из почв. Зависим ость растворим ости м еди от количества илистой ф рак ц и и пок азы вает отрицательную корреляцию (рис. 4). П о данны м нов ей ш и х и сследован ий усвоен и е некоторы х питательны х э л е ментов растениям и м о ж ет являться ф у н к ц и ей и х концентрации в почвенном растворе [3, 7, 8]. П оэтом у сод ер ж а н и е т я ж ел ы х металлов в растворе почв подв ергаю щ ихся пром ы ш ленном у загр язн ен и ю до л ж н о стать предм етом испы таний оп р едел я ю щ и х степень и х хи м и ч еск ой денатурации. Р езул ьт аты проведенного опыта показы ваю т, что степень токсичности т я ж е л ы х м еталлов вводим ы х в почвенную ср еду будет обусл овл ен а зависим остью от хим ического, м инерального и м еханич еского состава почв и и х ув л аж н ен и я. A . K A B A T A - P E N D I A S U W A L N IA N IE M IEDZI Z GLEB T R A K T O W A N Y C H C u S 0 4 L aboratorium M ik roelem en tów , Z akład C hem ii G leb
i N aw ożen ia R oślin IU N G w P u ła w a ch
S t r e s z c z e n i e
W gleb ach narażon ych na zan ieczyszczen ia p rzem y sło w e stw ierd za się stały w zro st zaw artości m eta li ciężkich . M im o dużej toleran cji roślin n a w y so k ie stężen ie m ied zi w środ ow isk u [3, 9] w p ro w a d zen ie w ięk szej ilo ści tego p ierw ia stk a do gleb y m oże być n iek o rzy stn e ze w zg lęd u na zachodzące zm ian y w zach ow an iu się in n ych sk ła d n ik ó w chem iczn ych .
W przep row ad zon ym d ośw iad czen iu badano w p ły w m ied zi dodanej do różn ych gleb na zm ian y ch em iczn ego sk ład u n a tu ra ln y ch roztw orów g leb ow ych . D o 500 g próbek g leb o w y ch (9 gleb różnego typ u i rodzaju, tab. 1) w p row ad zon o roztw ór C u S 0 4 • 5H 20 w ilości od p ow iad ającej 500 ppm Cu w gleb ie. W ysu szon e próbki n a w ilża n o do k apilarnej p ojem n ości w od n ej, a n a stęp n ie u m ieszczan o w term o sta cie o tem peraturze 25°C na 3 dni. Po o d w iro w a n iu roztw oru g leb o w eg o jedną serię próbek suszono (p ow ietrznie), drugą n a w ilża n o i oibe serie próbek z o sta w ia no w term ostacie na okres 10, 31, 52 i 87 dni. Sucha próbka b yła n a w ilża n a w od ą na 3 dni przed k ażd ym o d w iro w y w a n iem roztw oru.
W o trzy m y w a n y ch roztw orach g leb o w y ch oznaczano zaw artość n a stęp u ją cy ch p ierw ia stk ó w : Cu, Mn, Zn, Fe, Ca, M g i K. Z aw artość w y m ien io n y ch p ierw ia stk ó w , jak ró w n ież pH roztw orów n ie ró żn ico w a ły się w za leżn o ści od w a ru n k ó w suchej lub m okrej in k u b acji próbek gleb o w y ch . P o czą tk o w e pH roztw orów g leb o w y ch od p ow iad ało pH g leb y oznaczon em u w z a w ie sin ie ln KC1. O dczyn gleb i ro ztw o rów w y d a je się być jed n y m z p o d sta w o w y ch c zy n n ik ó w w p ły w a ją c y c h na roz p u szczaln ość m iedzi. Ilość m ied zi rozpuszczona przy p ierw szy m o d w iro w y w a n iu roztw oru k szta łto w a ła się n astęp u jąco dla gleb o zró żn ico w a n y m o d czyn ie (rys. 2): p H > 7 — Cu w roztw orze około 20 (jimoli/1; pH 5— 6 — Cu w roztw orze 36 do 157 (хтоПЯ; p H < 4 — Cu w roztw orze 4262 do 7400 jxmoli/l.
P o d w yższon a zaw artość w g leb ie jo n ó w Cu2+ i S 0 42~ w p ły n ę ła n a zw ięk szo n ą rozpuszczalność in n y ch k ation ów , a zw łaszcza m e ta li ciężkich (tab. 6). In te n sy w n ość u w a ln ia n ia k a tio n ó w je st w ię k sz a w grupie g leb k w a śn y ch (p H < 5 ,5 ) n iż g leb a lk a liczn y ch (p H > 6 ,5 ) (tab. 5). S tw ierd zon o n eg a ty w n ą k o rela cję p om ięd zy ilością u w a ln ia n y ch m eta li ciężkich a od czyn em roztw oru (tab. 7).
Z aw artość fra k cji ila sty ch oraz częściow o ich sk ład m in era ln y w p ły w a ły ta k że na in ten sy w n o ść u w a ln ia n ia m ied zi oraz in n y ch k a tio n ó w z gleb. Z ależn ość rozp u szczaln ości m ied zi od ilo ści fra k cji ila sty ch w y k a zu je k o rela cję n eg a ty w ą (rys. 4).
Z godnie z o sta tn im i b ad an iam i p ob ieran ie n iek tó ry ch sk ła d n ik ó w p ok arm ow ych przez ro ślin y m oże być fu n k cją ich stężen ia w roztw orach g leb o w y ch [3, 7, 8]. D latego zaw artość m eta li ciężkich w roztw orach gleb p o d leg a ją cy ch za n iecz y szcze n iom p rzem y sło w y m p o w in n a być p rzed m iotem bad ań o k reśla ją cy ch stop ień ich ch em iczn ego skażenia.
W yn ik i przep row ad zon ego d o św ia d czen ia w y k a zu ją , że sto p ień tok syczn ości m eta li ciężkich w p row ad zon ych do środ ow isk a b ęd zie u zależn ion y w dużej m ierze od chem icznego, m in era ln eg o i m ech an iczn ego sk ład u gleb oraz ich u w ilg o tn ien ia .
P r o f . d r h a b . A l i n a K o b a t a - P e n d i a s 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
Z a k ł a d C h e m i i G l e b i N a w o ż e n i a R o ś l i n I U N G , P u ł a w y
