ROCZNIKI GLEBOZNAWCZE (SO Il. SCIENCE A NNUAL) SU1TL. T. XLIV. W ARSZAW A 1994: 9 5 -1 0 0
B A R B A R A ( ’.W OREK
ZEO LITES O F TH E ЗА AN D 5А TY PE
AS FA CTO RS IN A C TIV A TIN G ZIN C IN SO ILS
C O N TA M IN A TE D W ITH THIS M ETA L
D epartm ent o f S o il S c ien ce, W arsaw Agricultural U n iversityIN T R O D U C T IO N
Accumulation of toxic elements in soil, including zinc, affects significantly its properties formed earlier. Changes in the chemical composition of soils are the cause disturbance of normal chemical equilibrium in plants, what leads to an excessive concentration in them, among other things, of heavy metals.
An excess of these metals in plants affects negatively their growth course, worsens their biological value and sometimes destroys totally the plant cover. Thus heavy metals affect the state of environment and the health of men.
Results of investigations concerning zinc inactivation in anthropogenicsoils contaminated with this element by means of introduction into them formed synthetic alumosilicates-zeolites of the ЗА and 5A type are presented in the paper. Content of zinc in lettuce and oats was assumed as the index of its inactivation in soils.
M A T E R IA L A N D M ETH O D S
Investigations concerning zinc inactivation in soils were carried out in a greenhouse, in 1988-1990 in pots of 4 kg volume. Anthropogenic soil taken from the area of Warsaw city, of the granulometric composition of slightly loamy sand, pH (1 N KC1) 6.4 and the total zinc (Zn) content of 1060 mg/kg was used in the experiments.
96 В. G worek
The soil was fertilized before the experiment with 0.20 g N per kg of soil d.m., 0.28 g P per kg, 0.30 g К per kg, 0.06 g Mg per kg in the form of NH4N 0 3, KH2P 0 4 and M g(N 03)2. Upon mixing the soil was left for 6 days and then 1 or 2 weight % in relation to the soil bulk of formed synthetic zeolite of ЗА (treatments 2, 3) or 5A type (treatments 4, 5) were added.
As a control treatment the above anthropogenic soil fertilized with macroe lements without addition of zeolites (treatment 1) has been assumed. On such mixture of soil with and without zeolites oat of the "Dragon” variety was sown. Lettuce of the "Cud V olburgif variety in the form of 2-week seedlings was planted into pots. Plants were watered during their growth up to 60% of maximal field capacity with redistilled water. Oats in the tillering stage and lettuce in the 3rd week of growth were fertilized with nitrogen in the form of water solution of NH4N 0 3 in the amount of 0.1 g/kg of soil bulk. Lettuce (Li) was cut upon reaching the consumption maturity, i.e. after 6 weeks of growth. Roots were separated from soil. Then lettuce (Lu) was planted into the same pots and processed further on like with the lettuce (Lj). Upon cutting the lettuce (Ljj) the lettuce (Lju) was planted with the same procedure like in case of the lettuce (Li) and (Lu).
Oat upon reaching full maturity was cut and divided for the analysis into roots, straw, glumes and grains. The material upon washing and drying at the temperature below 60°C was ground and burnt in the muffle oven at the temperature of 480°C. Ash was dissolved in the concentrated HC1. Zinc was determined directly from the solution with the absorption spectrophotometry method.
Statistical calculations were performed by the two-factorial analysis of variance using the Tukey's test.
R ESU LTS
Results of investigations concerning the zinc content in lettuce leaves (Fig. 1) prove that the cultivation of lettuce on soil with added zeolites led to a reduction of the metal in question by 65% as compared with the control (no zeolites).
The maximum reduction of the zinc content in lettuce leaves was obtained in the IInd planting as compared with control; it amounted to 65% at the 2% dose of the ЗА type zeolite in relation to the soil mass. At application of the 5A type zeolite the maximum Zn reduction in the lettuce leaves was obtain at the III rd planting of lettuce. Also the maximum reduction of Zn in the lettuce roots was obtained at the Illrd planting; it amounted to 52% as compared with the control (Fig. 2). These results suggest that the potassium-sodium zeolite (ЗА type) inactivated better and higher the amounts of zinc than thecalcium-sodium zeolite (5A type).
Results of investigations concerning the oat cultivation on the soil contami nated with zinc at addition of zeolites prove a possibility of a reduction of the
Factors inactivating^ zinc 97
Fig. 1. Mean concentration o f zinc [m g/kg o f dry matter] in leaves o f lettuce («=12) grown on contaminated soil with and without addition o f zeolites: 1 - control - no zeolites added, 2 -t r e a t
ment with 1% soil w eight zeolite type ЗА, 3 - treatment with 2% soil w eight zeolite type ЗА , 4- treatment with 1% soil w eight zeolite type 5A , 5 - treatment with 2% soil w eight zeolite type 5A ,
LSD - limit significant differentiation at 1%, Li, Ln and Lm - first, second and third planting o f
Fig. 2. Mean concentrations o f zinc [m g/kg o f dry matter] in roots o f lettuce (n= 12) grown on con taminated soil with and without addition o f zeolites: Ki, Кц and Кщ - first, second and third plan
98 В. Gwarek
Zn content in roots, straw, glumes and grain as compared to control (Fig. 3, 4). The greatest Zn reduction was obtained in straw (56%), then in roots (52%), glumes (34%) and grain (26%) of oats cultivated on soil with the 2% addition of ЗА type zeolite. These results confirm the relationship obtained for lettuce, according to which the potassium-sodium alumosilicate inactivated the zinc available to the plants under study to a better and higher degree as compared to the calcium-sodium alumosilicate. This follows from the difference of their ion-exchanging and sorption abilities in relation to zinc. Moreover, zinc can be also occluded in inner canals of minerals. The diameter of canals inside the ЗА zeolites crystal amounts to 0.38 nm and of 5A zeolite to 0.49 nm.
The double dose of zeolites led in most cases to a significant Zn reduction in analyzed parts of plants as compared to the single dose. The 2% addition of zeolite in relation to the soil mass seems to be inappropriate from the economic viewpoint.
Suitably formed zeolites applied in the experiment can be removed at any case out off the soil with absorbed elements, i.e. the soil can be permanently cleaned of heavy metals [Gworek, Borowiak 1990a].
The occurrence of natural zeolites in soil and the zinc sorption by natural and synthetic zeolites in the model investigations have been presented in many works [Borowiak et al. 1983, 1986; Breck 1974; Brogowski et al. 1979,1983; Chelishev, Chelisheva 1981; Czupyrna et al. 1986; Gorokhov et al. 1981; Gworek, Borowiak 1990 a,b; Sandy, Mumpton 1978]. On the other hand, there
Fig.3. Mean concentration o f zin c [m g/kg o f dry matter] in aboveground parts o f oat (n= 12) grown on contaminated soil with and without addition o f zeolites: A - glum es, В - straw, C - grain, 1-5
Factors inactivating zinc
99
is a lack of works concerning the effect of synthetic zeolites on the reduction of heavy metals in plants.
R E C A P IT U L A T IO N
Pot experiments carried out in a gre enhouse proved the possibility of redu cing the zinc accumulation in plants cultivated in soils contaminated with this element. Synthetic zeolites introdu ced into the soil led to a reduction of the Zn content in lettuce leaves by 36-65% in relation to the control. The Zn content in subsequent harvests of lettuce allo wed to estimate the effect of zeolites in a dynamical approach. The results ob
tained suggest that the ЗА type zeolite FiS -4 - Mean concentration of zinc [mg/kg o f , . i c* a dry matterl in roots o f oat grown on contam
i-immobilizes zinc quicker than the 5A
type zeolite. tes, 1-5 and LSD - denotation see F ig .l
Attention deserves also the fact of reduction of the zinc accumulation not
only in vegetative parts of plants, but also in a generative organ - in oat grain.
R EFER E N C E S
BO R O W IA K M „ G ÓR NY М., KOT B „ LEW ANDOW SKI W ., 1983: Study on distribution o f heavy metals in anthropogenic soil-zeolite system s. Prep. Pap. o f Sei. M eeting PZChem. 2 8 7 , K atow ice [in Polish).
BO RO W IAK M ., CZA R N O W SK A K., LEW ANDOW SKI W ., KOT B.„ 1986: Dynam ics o f changes in the content o f heavy metals in anthropogenic soils in the presence o f zeolites. R ocz.
G lebozn . 37, 4: 67--83 [in Polish].
В RECK D .W ., 1974: Zeolite molecular sieves. N ew York, W illey.
BRO G OW SKI Z., D O BRZA ŃSK I В., KOCOŃ J., 1979: M orphology o f natural zeolites occurring in soil as determined by electron microscopy. Bulletin de L 'A cadem ie P o lo n a ise d e s Sciences. X X V II, 1-2: 1 1 5 -1 1 7 .
BRO G OW SKI Z.,D O BR ZA Ń SK I В., KOCOŃ J., Z ANI EW S К А -CH LI PALS К А E., 1983: The possibility o f zeolites occurrence in the soi Is o f Poland. Zesz. Probl. P ost. N aukR ol. 2 2 0 :4 8 9 -4 9 4 (in Polish).
CH ELISH EV N.F., CH ELISHEVA R.V., 1981: Importance o f ion exchange properties o f natural zeolites for removal o f toxic metals from the digestive canal. Prep. Pap. o f Sei. M eeting, aspir. 2 1 7 -2 2 5 , Bacu (in SU ).
C Z U PY R N A G., LEVY R.D., M C LEAN A.I., GOLD H., 1986: In situ im m obilization o f heavy meta I-conta mined soils. N ew Jersey, Park Ridge, N oyes Data Corporation.
G OR OK H OV V .K ., LYA N P.M ., ISA EV A E.N., K ALAC H EV A L.I., SICHKAR E .V ., 1981: On possible use o f natural sorbents from Sakhalin in agriculture. Prep. Pap. o f Sei. M eeting, aspir.: 1 1 7 -1 2 3 , Bacu (in SU ).
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B. G worekGW OREK В., BOROWI A K M., lQQOa: Model studies on immobilization o f certain heavy metals by synthetic zeolites. Rocz. Glebozn. 42, 1/2: 2 7 -3 5 .
G W OREK B., BO RO W IAK М., 1990b: Patent notification No 283821 (RP).
S A N D Y L.B., M UM PTON F.A., 1978: Natural zeolites. Occurrence, properties, uses. N ew York, Pergamon Press.
B. G w orek
ZEOLITY TYPU ЗА I 5A JAKO CZYNNIK INAKTYWUJĄCY CYNK W GLEBACH ZANIECZYSZCZONYCH TYM M ETALEM
Katedra G leboznaw stw a S G G W w W arszaw ie
STRESZCZENIE
W prowadzenie do gleby zanieczyszczonej cynkiem syntetycznych zeolitów powoduje zm niejsze nie ilości tego pierwiastka w roślinach uprawianych na tej glebie. Syntetyczne zeolity typu ЗА i 5 A stosow ano w daw ce 1 i 2% wag. w stosunku do objętości gleby. W doświadczeniach w azonow ych 2% dodatek zeolitów do gleby zanieczyszczonej cynkiem zm niejszył zawartość tego metalu w liściach sałaty o 65% , w słom ie owsa o 56%, w plewach owsa o 34%, a w ziarnie owsa o 26%. Oznacza to, że zeolity mogą zm niejszać ilość cynku w łańcuchu pokarmowym.
D r hab. B a rb a ra G w orek D e p a rtm e n t o f S o il S cien ce
W a rsa w A g ric u ltu ra l U n iversity - S G G W 0 2 -5 2 8 W arszaw a, R ak o w ieck a 26 /3 0 , P ola n d
