Proposal of evaluation of soilorganic matter sorption capacity
Gabriela Barančíková
Soil Science and Conservation Research Institute Bratislava
Regional working place Prešov, Slovakia
E-mail: g. barancikova@vupop.sk

VUPOP Humic Substances in Ecosystems 8, Šoporňa 13.-17.9.2009 Slovakia

Soil organic matter (SOM) is responsible for:
 stable crop production (production function)

 maintaining of good soil quality

SOM has been widely promoted as a key indicator of soil
quality and plays an important role in soil. SOM affects:
 biological chemical physical properties.
Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

SOM
1.organic matter at various 2. completely decomposed
degree of decompositionmaterial (humus)
2.1. nonhumified organic material

2.2. humified organic material(humic substances)

2.2.1. humic acids

2.2.2. fulvic acids
Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

2.2.1. huminThree-dimensional model ofa hypothetical HA (Schulten,1996)

A two-dimensional structure of HA from andosol (Hatcheret al.,1994) in Ecosystems
HumicSubstances
8, Šoporňa 13.-17.9.2009
Slovakia

Humic substances (HS) are amphyphilic with hydrophobic
and hydrophilic, internal and external reactive surfaces
Hypotetical structure of a humic acid macromolecules
include lignin-like backbone (mainly part of model), somepolysaccharide-like components, protein residues, and alkyl
molecules visible in peripheral location
Chestworth, 2008

SOM – high specific surface (up to 800 m2 g-1 )CEC ranging from 150 to 300 cmol kg-1
SOM plays fundamental role in:
Sorption
Binding
Entrapmentof plant macro and micronutrients, variety of chemicals,
including inorganic pollutants (heavy metals) and organicsubstances as enzymes, proteins and xenobiotics
Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Humic substances– amphoteric compounds withpositive and negative charges
Negative charges - disociation of protons fromfunctional groups in the humic molecule
Two the most important functional groups:
Carboxyl (COOH)
Phenolic- hydroxyl (Phe-OH)

Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Functional groups (COOH, phe-OH) are responsible for:
Adsorption
Cation exchangeComplex and chelation reactions

Humic acids - HA
 substantially larger moleculesmore complex structure

Fulvic acids - FA
smaller moleculesless complex

Total acidity : FA > HA
Binding sites : HA > FA
Binding capacity: HA > FA
Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Forces responsible for adsorption reactions ofHS with ionic and non polar substances:
Physical forces
Chemical forces
Hydrogen bonding
Hydrophobic bonding
Electrostatic bonding
Coordination reactions
Ligand bonding
Covalent bonds

Humic Substances in Ecosystems 8, Šoporňa 13.-17.9.2009 Slovakia

Importance of HA chemical structure on HM sorption
Statistically significant Spearman’s coefficients of Cu fraction and selected
HA parameters
HA parameter

Cufraction IV (HM asociated with SOM)

Corg
Cha/Cfa
CH/CCarCaliph
α

0.59*
0.55*
0.6*
-0.72*
0.63*-0.69*
0.59*

Barančíková & Makovníková, 2003

Humic Substances in Ecosystems 8, Šoporňa 13.-17.9.2009 Slovakia

Influence of HA sorption characteristics at soil detoxifications
Cd sorption
Source of HA-COOH

CaliphCar

αmeq/1 g HA%%%

Chernozem 114

4,233,742,255,6Cambisol 55

2,7648,62937,7200180160114

55

Freundlich distribution coeficient KF in contex with pH
hodnota KF.103

hodnota amax. 103

Maximum sorption capacity amax in context with pH

lignit

140
120

90
80
70

114

55

lignit

60
50

100

40

80

3060

2040

102000
pH 3

Madaras et al., 2004

pH 4
oblasti pH

pH 5

pH 3

Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

pH 4oblasti pH

pH 5

Soil and HA parameters
soil
pH (CaCl2 )Corg(%)

CalcaricFluvisol

7.89

0,97

Gleyic Fluvisol

5.46

CalcaricChernozem

Q46

COOH
meq/1gHA

Caliph
(%)

3,73

3,62

41,8

37,2

1,43

4,83

3,1

43,1

34,7

7.77

1,16

3,80

4,2

33,7

42,2

Orthic Luvisol

5.56

1,09

3,96

2,52

46,9

32,8

Dystric
Cambisol

3.63

3,00

6,06

2,76

48,57

28,99

Car
(%)

1412-6sorpcia 10 mol/g sorbentu

Soil type

HA

10864
20KMa

FMmc

ČMcFMGHM

lignitHumic Substances in Ecosystems
sorpcia Cd na.10sorpcia Cd na HK8,pôdyŠoporňa
13.-17.9.2009

Slovakia

Makovníková et al., 2003

2,5copper
2-1

adsorbedamount of Cu[mmol g ]Adsorption
isotherms of soiland HA

1,5

10,500HA

0,050,10,150,2-3

equilibrium concentration of Cu [mol dm ]cadmium90

cadmium-1

adsorbed amount of Cd[mmol kg ]

80
70
60
50
40
3020
10Soil

0HA00,010,02

chernozem fluvisol 1 luvisol fluvisol 2 cambisol lignite
Makovníková et al., 2004

0,03-3equilibrium concentration of Cd [mmol dm ]Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Soil monitoringThe basic network of monitoring sites (300)at 5 years regular interval(agriculture and alpine soils)
The key monitoring sites(21) at 1 year regular interval

Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Monitoring of soil organic matter
Basic monitoring networkquantitative parameter: Soil organic carbon SOC (%)% humus = SOC x 1,724
 basic qualitative parameters: CHA /CFA,Q64

Key monitoring localities
selected parameters of chemical structure of humic acids:
Elemental analyses (C H N)
Carboxylic groups (COOH meq/1 g HA)
UV-VIS spectra (E1%6)
13C NMR spectra

Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Main parameters of soil organic matter which influence
its sorption capacity

Content of soil organic carbon (SOC)
Ratio of HA and FA carbon (CHA/CFA)
Optical parameter of HA (Q46)
Content of carboxylic groups (COOH)
Degree of aromaticity (αα = (Car + Caliph)/Car x 100)

Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Proposal of humus sorption capacity assessment onagricultural soils

category

SOC (%)

CHA/FA

Q46COOH (meq/1g HA)

α(%)

I.

>= 2>1< 4.5>4>50

II.

1.5 - 2

0.8 - 1

4.5 - 5

3–4

40 – 50

III.

< 1.5

< 0.8>5<3< 40

I. – high humus sorption capacity
II.– medium humus sorption capacity
III. – low humus sorption capacity

Notice: Humus belongs to particular category if fulfil minimum three qualitative parameters
Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

I. – high humus sorption capacity

Chernozem
Phaeozems
Andosols

III. Medium sorption capacity

Luvisols
Rendzinas
Regosols
FluvisolsPart of Cambisols

III. – low humus sorption capacity
Planosols
part of Cambisols

Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
Slovakia

Soil Science and Conservation Research Institute
Gagarinova 10,827 13 Bratislava, Slovak Republic
Tel: 02/48206901 Fax: 02/43295487 e-mail: sci@vupop.sk Internet: www.vupop.sk

Thank you for your attention
Humic Substances in Ecosystems
8, Šoporňa 13.-17.9.2009
This work was supported by the Slovak Research and Development Agency under the contract No. APVV-0333-06.
Slovakia