DE2358953B2 - Process for the treatment of plants with water-soluble complex compounds to limit their content of harmful heavy metals, in particular lead - Google Patents

Description

The invention relates to a method for treating plants during their growth Keeping out and removing harmful heavy metals, especially lead.

Caused by the concentration process of human society and all areas of life (Production: industry, agriculture; trade and commerce; consumption: housing, transport) are among others. the Heavy metals distributed primarily to a harmless extent on earth in the soil, in the water and in the atmosphere is enriched in such amounts that it affects the health of plants, animals and humans threaten. This environmental problem is particularly topical at the moment with lead, mercury, cadmium and zinc, where in terms of quantity the lead plays the biggest role: Due to the high lead content of the gasoline and the Lead precipitation is currently the intensity of motor vehicle traffic in the FRG alone at around 40,000 Tonnes / year to be estimated (report »Lead and Environment« of the Commission for Environmental Hazards of Federal Health Office, Lead Working Group, 1972, p. 38). In addition there is the lead of industrial exhaust gases, especially the lead and zinc smelters. This lead from automobile and industrial exhaust fumes first and foremost down on the plants, as far as the useful plants are concerned. Humans and animals as food or Serve feed. By feeding such lead-containing feed, it was already closed in 1972 in Nordenham numerous deaths have occurred in cattle (Die Naturwissenschaften, 60, 1973, p. 161). A corresponding The lead content of small children in this area already experienced an increase and required medical care Measures. Heavily industrialized and Christian highly developed countries, such as some western Europe, North America or Japan, are from the danger of heavy metal contamination of large parts of their long economic groove / flat immediately affected.

It is therefore important and in many cases already indispensable that plants that are human or animal! Diet to be fed before Absorption of harmful heavy metals are preserved. The natural rain or washing with normal Water is not sufficient for this, since heavy metals are adsorbed very firmly on the plant surface or have already been pulled into the interior of the plant.

The first efforts in this direction have already been made by establishing a procedure Treatment of soil / ur fixation of harmful metals in it (German patent specification 22 40 733, 1973). This method does not take into account that by direct atmospheric Contamination of plants with harmful heavy metals - as is the case with lead in cars and cars Industrial exhaust fumes are given - these humans and animals can be harmed to health when consumed can. In such grooves, treatment of the Ground ineffective.

The main aim of the invention is accordingly a method for treating plants which, on the one hand, makes it possible to largely protect plants from the ingestion of lead and other harmful heavy metals (for example zinc, cadmium, mercury, copper, nickel, iron, cobalt, manganese), on the other hand but it is also permitted to subsequently free plants that have already been contaminated with lead and other harmful heavy metals.

The / μ developed this end, methods of treating plants characterized in the Palentansprüchen. Taking into account their already ongoing large-scale production on the one hand and their extremely favorable chemical affinity to heavy metals on the other hand, solutions of water-soluble salts of ethylenediaminetetraacetic acid (ÄDTE) and oligo- or polyphosphoric acid and mixtures thereof are particularly suitable for this purpose according to the invention. Here correspond to the general formula a) the salts of the ethylenediamine tracer acid:

COOH

COOH

CH, CH,

I "I"

N-CH ₂ -CH ₂ -N
CH, CH ₂

COOH

COOH

the hydrogen (H) in at least one of the four carboxyl groups (-COOH) being replaced by an ammonium, alkali, alkaline earth or other metal ion;
b) the salts of oligo and polyphosphoric acid:

OH

HO-P-O-P-O-P-OH

OH

OH

/ 7> 1

where at least one of the hydroxyl groups (- Oll) has the hydrogen (H) replaced by an ammonium, Alkali, alkaline earth or other Mclallion is replaced.

Investigations by the inventor have shown that the above-specified derivatives of Äthylcndiaminletracs-

Acetic acid and oligo- or polyphosphoric acid are able to convert with harmful heavy metal ions - for example lead - on the plant surface, i.e. on the leaf and in the area of the roots, into a chelate form that the plant can hardly absorb. In contrast to the normal SchwermelalMon, this heavy-duty complex can now be washed off the surface of the plant very easily by rain, or it can be effectively removed during technical processing by normal washing with water. Since the affinity of other heavy metals to the above-mentioned chelators - the decadic logarithm of the stability constant pK serves as a measure of this - is similar to that of lead , in most cases even more favorable (for example for ethylenediaminetetraacetic acid: Pb: 18.2; l ^: e ^MI : 25.1 ; I Ig: 21.8; Ni: 18.4; Cu: 18, J: Cd: 16.4; Zn: 16.1: Co: Ifa.l; l'e ": 14.5; Mn: I 3, 4: according to M arte II and C a I ν i η: Die Chemie der Metall-Chclatverbindungen. Verlag Chemie GmbH, Weinheim / Bergstr, 1958, p. 491), the results obtained here with lead can generally be applied scientifically to the By treating the plants in the field according to this method according to the invention, it has been proven that - if carried out correctly - they experience no loss in the uptake of important nutrients ( eg potassium or phosphorus) or even in the amount harvested.

The advantages that can be achieved with the invention are based on the fact that the heavy metal emissions in the area Cultivated crops are no longer harmful to animal or human nutrition can be supplied, in the case of lead also in the immediate area of the roads and Lead-emitting industrial plants grown crops.

The derivatives of ethylenediaminetetraacetic acid and oligo7 polyphosphoric acid can according to the Invention can be applied in several ways:

For example, by spraying the compounds onto the plants in the form of aqueous solutions or together with fertilizers or pesticides dissolved in it using commercially available Sprayers and sprinklers as well as sprinkling systems. Thanks to the heat stability of the connections is also Direct introduction of the corresponding aqueous solutions into the exhaust system is possible (hot fog process) - For example, with lead in the exhaust system of motor vehicles - which is the culprit the heavy metal emissions are used for the heavy metal detoxification of plant-based foods would (polluter pays principle).

Health concerns on the part of the derivatives of ethylenediaminetetraacetic acid are unnecessary if one takes into account that these are used in medicine to remove the lead from the bones remove (M a r t e 11 and Calvin: Die Chemie der Metal chelate compounds. Verlag Chemie GmbH, Weinheim / Bergstr., 1958, p. 457; Th. B e r s i η: Biochemistry the mineral and trace elements. Academic Publishing Company, Frankfurt am Main, 1963, p. 422) or very high doses (4000 mg Ca-ADD / kg live weight) do not cause any damage to health (Comaruid Wassermann: Biological Sciences, Vol. 1, Pergamon Press LTD, 1956, p. 161). - As for the polyphosphates, health Concerns are allayed when one considers this in food production z. B. be intentionally added to the processed cheese and sausage to increase their water content (Th. B e r s i η: Biochemistry of mineral and trace elements. Akademische Verlagsgesellschafl, Frankfurt am Main, 1963, p. 367).

· ■> The law applicable in the present invention amount of Komplexbildncrn, depending on the type and amount of /.u remove heavy metal ions vary over a wide range: In the case of ethylene diamine to Menger should: to each to 5 mol

i "Meiallionenequivalentc of the heavy metal ions to be removed preferred. The maximum acceptable concentration is 5 millimoles / liter of spray or spray. Washing solution. - The salts of oligo-Z-polyphosphoric acid on the other hand, in the mentioned spraying resp.

i ") washing solutions up to a maximum concentration of 1% (= 10,000 ppm) can be used.

I ^: .s follow examples to illustrate the invention, in which the lead content of the plants is given in ppm (based on dry weight). The lead in the plants was determined in three ways:

1. Colorimetrically with dithizone according to W. O e 1 s c h 1 e ge around E. Schwarz: Determination of lead in biological substances. Z. Anal. Chem., 258, No. 3,

>> 1972, pp. 203-207 (Springer-Verlag).

2. By atomic absorption according to W. Oc! Schläger and E. Frenkel: Determination of lead in plant and animal materials as well as in Mineral feed using atomic absorption spectrophotometry. Z. Agricultural research, e.g. Currently

in print.

3. Radiometric with Pb-210 (scintillation spectrometry) according to A. Suchodoller: Investigations into the lead content of plants in the vicinity of

Ji roads and on the inclusion and translocation

of lead from plants. Ber. Switzerland. Bot. Ges., 77, pp. 266-308.

I. Examples 1-3
with salts of ethylenediaminetetraacetic acid

example 1

Influence of the disodium salt of ethylenediaminetetraacetic acid (Na ₂ ADTE) on the lead content of ryegrass which has been sprayed with lead nitrate:

In special rearing vessels (Mitscherlich vessels), ryegrass (Lolium perenne) was sprayed in a sand / earth mixture outdoors for 3 weeks twice a day with lead nitrate (10 " ⁴ mol Pb (NO ₃ ) ₂ / liter) (control) Restriction of the lead uptake of the grass, a corresponding variant was additionally _{sprayed with Na 2} ADTE (10- ^! Mol / liter), which can be represented with the following formula:

COONa COONa

I i

CH ₂ CH ₂
N-CH ₂ -CH ₂ -N
CH ₂ CH ₂
COOH COOH

The precipitation during the experiment was 97 mm. - To show that the lead is still there can be subsequently eliminated with Na2ÄDTE, the grass was analyzed a) immediately for lead in both cases, b) beforehand with water or c) with one Na ^ ADTE solution (10 'mol / liter) washed off for 15 min. The lead content of the grass was determined colorimetrically. The results obtained are summarized in Table 1:

Table 1 Table 2

a) - 693

b) water 583

c) Na ₂ ADTE 178

Dry matter
(g / pot)

156
165
136

8.5 8.3

COOH COOH
I. CH ₂ CH ₂ N-CH ₂ - -CH ₂ -N : a ^ "CH ₂ coo ^x 0OC

Washing up with

Washdown with lead content (ppm) of

Ryegrass after spraying> "> from

only Pb (NOj) ₂ Pb (NO ₃ J ₂
(Control) + Na ₂ ADTE

Example 2

Influence of CaÄDTE on the lead content of Weidclgras, which for 3 weeks the lead-containing Motor vehicle exhaust fumes on Charlottenplatz in Stuttgart was exposed:

For 3 weeks, ryegrass was exposed to leaded vehicle exhaust fumes on one of the busiest locations in Germany - Charlottenplatz in Stuttgart. The control was sprayed with water once a day, the corresponding variant, on the other hand, to limit the lead uptake of the grass with CaÄDTE (10 ~ ³ mol / liter), which can be expressed with the following formula:

The precipitation during the experiment was e> o 86 mm. - To also show that the lead can also be removed later with CaÄDTE, the grass was analyzed a) immediately for lead in both cases, b) beforehand with water and c) with a CaÄDTE solution (10 'mol / liter) for 15 min washed. The filei-Gehall of the grass was through Atomic absorption determined. The results obtained are shown in Table 2.

b5 lead content (ppm) of
Willow Igrass after sprinkling
from

Water
(Control)

CaADTI-:

b) water

c) CaÄDTE

Dry matter
(g / pot)

139
97
83

15.2

98
58
58

16.0

Tables 1 and 2 show:

1. that according to the invention by spraying with Na? ÄDTE or CaÄDTE the BJigesehalt of the grass can be reduced considerably, namely in the 1st example from 693 to 156 ppm or in the 2nd example. Example from 139 to 98 ppm,

2. with water

a) normally relatively little lead can be washed off, namely in the 1st example 693 opposite 583 ppm or in the 2nd example 139 compared to 97 ppm,

b) with prior spraying with Na ₂ ADTE or CaÄDTE, however, according to the invention, a great deal of lead can be removed, namely in the 1st example 693 compared to 165 ppm and in the 2nd example 139 compared to 58 ppm,

3. by washing the grass with salt solutions of the ÄDTE after lead contamination can remove a great deal of lead, namely 693 in the 1st example compared to 178 ppm and in the 2nd example 139 compared to 83 ppm,

4. that neither spraying with Na ₂ ADTE (1st example) nor with CaÄDTE (2nd example) has a negative effect on the amount of grass harvested (dry matter) (8.5 versus 8.3 g / pot or 15.2 versus 16.0 g / pot).

Both in example 1 and in example 2, the sprayed-on lead or the lead of the car exhaust fumes was through the simultaneously sprayed salts of ethylenediaminetetraacetic acid and chelated by the precipitate or washed off by the washing water to a much greater extent than is normally the case with lead he follows. In the same way, the salts become effective when added to the wash water.

Example 3

About the influence of the salts of ethylenediaminetetraacetic acid on the lead uptake of the plant roots and to check their uptake of important nutrients (e.g. potassium or phosphorus), was the following experiment under controlled environmental conditions in climatic chambers of the department for Plant nutrition carried out by the University of Hohenheim:

10-day-old French beans (Phaseolus vulgaris) - popular model plants in agricultural research - were in a complete nutrient solution for 24 hours that also contained IO ^r> mol Pb (NOj) J per liter. In a corresponding manner, graduated amounts of Na; ÄDTE were added to the nutrient solution (0:10 ^h :

5 · IO ^h ; 10 ·: 5 · 10 '; 10 ": 5 · 10 ⁴ mol / liter). After the end of the test period, the plants were radiometric for lead (ppm). Potassium (ipm / mg dry matter)

Table 3

and phosphorus (ipm / mg dry matter) analyzed. The results obtained are summarized in Table 3.

MincralstoffTgchüll of the French beans

10 ⁽⁾

The nutrient solution of the
Added roots
Na ₂ ADTE (mol / l)
Lead (ppm)
Potassium (ipm / mg TS)
Phosphorus (ipm / mg TS)

Table 1 shows that, according to the invention, equimolarc (10 ^r> mol / l) and overequimolarc amounts of NajÄDTE almost completely limit the lead uptake of plants via the roots, while

5 ·! 0

5-10

_ C

10

5 ■ \ 0 ⁴

176 135 93 18th 3 4th 4th 111 107 135 126 127 113 89 78 84 90 68 71 75 71

the uptake of important nutrients, such as potassium or phosphorus, is completely unaffected by this continues normally.

II. Examples 4-6 with salts of oligo / phosphoric acid

example

Influence of sodium polyphosphate (Grahamscbcs salt) on the lead content of ryegrass, which with Blood nitrate was sprayed.

In special rearing vessels (Mitscherlich vessels), ryegrass (Lolium perenne) was sprayed in a sand / earth mixture outdoors for 3 weeks once a day with lead nitrate [10 <mol Pb (NOi) ₂ / liter] (control). To limit the lead uptake of the grass, a corresponding variant was additionally sprayed with sodium polyphosphate (0.1% ^ lOOO ppm), which can be represented with the following general formula:

can be subsequently removed with sodium polyphosphate, in both cases the grass was a) analyzed immediately for lead, b) beforehand with water or c) with a sodium polyphosphate solution (0.1% I ₁ QOO ppm) during Washed off for 15 min. The lead content of the grass was determined by atomic absorption. The results obtained are summarized in Table 4.

Table 4

Washing up with

NaO-P-O-P-O

ONa

ONa

-P-ONa

ONa

Lead content (ppm) of
Ryegrass after spraying
from

only PtXNO ₃ ) ₂ Pb (NO ₃ ) ₂
(Control) + Na polyphosphate

η> I

The precipitation during the experiment was 106 mm. - To show that the lead is still there

a) - 128 65

b) water 70 50

c) Na polyphosphate 62 41

Dry matter 17.2 19.2

(g / pot)

example

Influence of Sodium Polyphosphate on the Blcigchalt von Ercidelgras, which for 3 weeks the lead-containing Motor vehicle exhaust fumes on Charloltcnplatz in Stuttgart was exposed to:

Wcidelgras was the leaded vehicle exhaust gas on one of the busiest for 3 weeks Locations of the FRG - the Charlottenplatz in Stuttgart - exposed. The control was used once a day Sprayed with water, the cntsprcchncdc variant on the other hand / ur restriction of the blci uptake of the grass with Sodium polyphosphate (0.5% = 5000 ppm). Its formula is shown in Example 4. The precipitation during the experiment was 82 mm. - To also it was agreed that the lead can also be removed later with Naliiiim-I'olyphosphal also here in both cases the grass a) analyzed immediately for lead, b) beforehand with water or c) with a Njilriuiii-I'olypliosplial solution (0.1% = 1000 ppm) washed off for 15 min. The lead content of the grass was determined by atomic absorption.

The results obtained are shown in Table 5.

Table 5

Washing up with M) a) - Blcigchalt (ppm) of after Spril / .ung b) water Willow grass ⁽ '^r> c) Na polyphosphate from Dry matter Na-poly (g / pot) water phosphate (Control) 78 119 79 121 71 59 19.6 20.1

Tables 4 and 5 show:

! that according to the invention by spraying with sodium polyphosphate the lead hall of the Grass can be limited considerably, namely in the 4th example from 128 to 65 ppm or in the 5th example from 119 to 78 ppm.

2. with water

a) normally relatively little lead can be washed off, namely in the 4th example 128 opposite 70 ppm or in the 5th example only 119 compared to 121 ppm,

b) after previous spraying with nairium polyphosphate, however, a great deal can be found Can remove lead, namely in the 4th example 128 compared to 50 ppm or in the 5th example 119 versus 79 ppm.

3. A lot of lead can still be removed by washing the grass after lead contamination with sodium polyphosphate solution, namely in the 4th example 128 compared to 62 ppm and in the 5th example 119 compared to 59 ppm.

4. that by spraying the grass with sodium polyphosphate the harvested amount of the grass (dry matter) neither in the 4th example (17.2 compared to 192 g / pot) in the 5th example (20.1 opposite 19j6 g / pot) is adversely affected.

Both in example 4 and in example 5 this was sprayed lead or the lead of the car exhaust is chelated by the simultaneously sprayed sodium polyphosphate and by the precipitate or by the Wash water is washed off to a much greater extent than is normally the case with lead. In in the same way the sodium polyphosphate becomes effective when added to the wash water.

Example b

To check the influence of ju Polyphosphalcn on lead capture of plant root, the following experiment was under controlled environmental chambers Umweltbcdingungen in the Department of Plant nutrition carried out by the University of Hohenheim:

10 days all French beans (Phascolus vulgaris) - popular model plants in agricultural research - were in for 24 hours

xi a complete nutrient solution in the also still 10 'moles of Pb (NOi) J per liter were contained. In Correspondingly, graduated amounts of sodium polyphosphate were added to the nutrient solution (0; 5; ! 0; 25; 50 and 100 ppm). After the

2 ^r> test period were analyzed on the plants radiometrically Lead (ppm). The results obtained are summarized in Table 6.

Table 6 0 added to the nutrient solution of the roots Sodium PolypljQjgjhat (ppm) (control) Lead content of French beans (ppm) 273

247

IO

221

165

50

125

From Table 6 it can be seen that according to the Invention Polyphosphates are able to reduce the lead uptake of plants via the root in to a great extent (ultimately by -Vi), whereby in the case of sodium polyphosphate, concentrations of 100 ppm have proven to be optimal.

Claims (3)

Patent claims: 1. Method of treating plants with water-soluble complex compounds for restriction their content of harmful heavy metals, especially lead, characterized by that of harmful heavy metal ions threatened or already affected plants with at least one of the water-soluble salts of ethylenediaminetetraacetic acid and / or the oligo- / Polyphosphoric acid can be sprayed on the cultivated area. 2. The method according to claim 1, characterized in that that the water-soluble salts of ethylenediaminetetraacetic acid the spray solutions in a Amount of up to 5 moles per equivalent weight of the metal ions to be removed, but a maximum of up to a concentration of 5 millimoles / liter can be added. 3. The method according to claim 1, characterized in that the water-soluble salts of the oligo- / Polyphosphoric acid can be added to the spray or washing solutions in an amount of a maximum of 1%.