Dissolution of Biosolid-Borne Metals of Soils

Stephanie Lara, Bon-Jun Koo, Chau Nguyen, and Won-Pyo Park Department of Natural and Mathematical Sciences, California Baptist University

Objective of Research

Analysis of soil in Biosolid (BSL) medium in order to determine heavy metal absorption

Different synthetic Organic Acid (OA) Mixture concentrations were used to change pH and absorption rate of metals in Biosolid treated soil

Metal availability increased with decrease in pH and OA Mixture available

Introduction

OA Mixtures help with metal extraction

Metal amounts in soil help in uptake of other metals present

Ability of OA Mixture to complex depend on pH– Negatively charged ions vs neutral solution

Materials and Methods

Organic Acid Mixtures (OAs)

Soil Sampling and Total Analysis

Statistical Analysis

Soil Sampling

The entire experimental fields were cultivated for 10 years (1982–1991) following the termination of BSL application

These experiment plots were established in 1976 on a Romona sandy loam soil (fine–loamy, mixed, thermic Typic Haploxeralf) located in the Moreno Field Station of the University of California, Riverside.

The Nu–earth BSL was used contained an average of 40, 600, 475, 250, and 3,547 mg kg-1 of Cd, Cr, Cu, Ni, and Zn, respectively.

Materials and Methods

Soil Preparation

Materials and Methods

Air dried

1.0 mL H2O + 4.5 mL HNO3+ 1.5 mL HCl in

Teflon vessel in microwave digestions

20 min.484 kPa

Total soil analysis

0.3 gSoil

2 mm sieve

Homogenized

Chemical Properties of the Soil

Table 1. Chemical properties of the soil used for the experiment.

BiosolidTreatment† pH‡

Total Concentration (mg kg-1)

Cd Cr Cu Ni Pb Zn

Control 7.7 0.5 37 105 24 25 95

135 Mg ha-1 6.9 11 243 188 88 120 559

1,080 Mg ha-1 6.1 26 596 478 215 396 1466† Obtained at Moreno Field Station of the University of California, Riverside, CA. From 1976 through 1981 composted Biosolids were applied at dry weight rates of 0 (control), 22.5 and 180 Mg ha-1 yr-1, respectively.

‡ 1 : 1 w/v ratio

Materials and Methods

Materials and Methods

Table 2. Mole fraction of OAs collected in root exudates of corn.

Organic Acid Molecular Weight Mole Fraction Ratio

Acetic 60.05 0.287Butyric 88.11 0.209Glutaric 132.12 0.004Lactic 90.08 0.366Maleic 116.07 0.042Oxalic 90.04 0.043

Propionic 74.08 0.010Pyruvic 88.06 0.0004Succinic 118.09 0.006Tartaric 150.09 0.032Valeric 102.13 0.001

Organic Acid Mixtures (OAs)

Instrumental AnalysisMaterials and Methods

1 gSoil

48 hour shaking

Soil centrifuged for 20 min

0.25 mL HNO3

FilteringICP/AAS

OA mixtures extracted

Three OA mixture concentrations 0.001, 0.01, and 0.1 M in 13.5 mM Ca(NO3)2 along with a 13.5 mM Ca(NO3)2 blank were tested

ICP: Inductively Couples Plasma Optical Emission Spectroscopy (ICP-OES)

AAS: Atomic Absorption Spectrophotometry (AAS)

10 mL OA

mixture

1 mL CHCl3

Materials and Methods

Statistical Analysis

All experiments were repeated 4 times. Between–group differences were determined by one–

way analysis of variance (ANOVA), followed by Student–Newman–Keuls test using a probability level of P < 0.05 in all cases.

Tests were performed with SigmaStat 4.01 Software.

Results and Discussion

Formation of OA mixtures-pH of Rhizosphere Soils

Effects of pH on Dissolution of Metals

Metal Solubility by OA Mixtures

Results and Discussion

Table 3. Estimated solution concentrations (16 Week Average) of OAs in root exudates of corn†.

Treatment

Estimated Concentration (mM)

Control   Biosolid 

Mean S.D.   Mean S.D.

Blank  2.05 0.63    3.41 0.87

Planted 5.23 1.21   12.9 2.04† All experiments performed in four replicates for each 2, 4, 8, 12, and 16 weeks. Values

represent means and standard deviation of 20 replicates.

Table 4. Reported pH Ranges of Rhizosphere.Plant Genotype pH Range Reference

Barley Bowman 6.2 – 7.6 Gollany and Schumacher (1993)Primus II 6.0 – 7.8Dorirumugi 4.8 – 7.1 Youssef and Chino (1989)

Corn Pioneer-3737 5.2 – 7.6 Gollany and Schumacher (1993)Pioneer-3732 5.2 – 7.6CM-37 6.0 – 7.6

– 4.8 – 6.7 Fisher et al (1989)Clover Trikkala 6.2 – 7.1 Hinsinger and Gilkes (1996)Daisy fleabane – 5.1 – 6.3 Zhang and Pang (1999)Nectarine tree Maxim 5.3 – 8.2 Tagliavini et al (1995)Oat Hytest 6.0 – 7.6 Gollany and Schumacher (1993)

SD 84104 6.2 – 7.6Rape – 5.7 – 6.4 Ruiz and Arvieu (1990)Rye Standard 5.6 – 7.1 Hinsinger and Gilkes (1996)Sordan S-757 6.0 – 7.6 Gollany and Schumacher (1993)

S-333 6.1 – 7.6Sorghum SC-33-8-9EY 6.3 – 7.6 Gollany and Schumacher (1993)

SC-118-15E 6.6 – 7.6Soybean Hawkeye 5.5 – 7.1 Romheld and Marschner (1984)

4.8 – 7.6 Gollany and Schumacher (1993)PI-54169 5.8 – 7.6 Gollany and Schumacher (1993)Toyosuzu 5.1 – 7.0 Youssef and Chino (1989)

– 4.7 – 7.1 Riley and Barber (1971)

Results and Discussion

4.5 5.5 6.5 7.5

Cd

(mg

kg-1

)

0.0

0.1

0.213.5 mM Ca(NO3)2 0.01 M OA Mixture

pH4.5 5.5 6.5 7.5

Zn (m

g kg

-1)

0.0

1.0

2.0

3.0

pH4.5 5.5 6.5 7.5

Ni (

mg

kg-1

)

0.0

1.0

2.0

3.0

4.5 5.5 6.5 7.5

Cu

(mg

kg-1

)

0.0

1.0

2.0

3.0

Aa AaBb

Da

CbCa

Cb

Ca

Bb

Ab

Ba

Ca

Bb

CaBa

Ab

Ab

AbAa

Bb

Bb

Ba

BaBbBb

Da

Ca

AaBa

Cb CbAa

CbCa

Aa

Bb

Ba

Cb

Ca

Db

4.5 5.5 6.5 7.5

Cr

(mg

kg-1

)

0.0

0.1

0.2

pH

Figure 1. Effects of pH on the extraction of metals in BSL–treated Romona soil (135 Mg ha-1) by 13.5 mM Ca(NO3)2 electrolyte solution and 0.01 M OA mixture†

† Values represent means and standard deviation (in parenthesis) of four replicates. The differences of metal concentrations among the pH values were tested by one–way ANOVA. Values followed by the same upper case letter were not significantly different at P < 0.05. The differences of the metal concentrations between 13.5 mM Ca(NO3)2 and 0.01 M OA mixture were tested by Student–Newman–Keuls test. Values followed by the same lower case letter was not significantly different at P < 0.05.

Results and Discussion

Table 5. Amounts of metal extracted from control and BSL –treated Romona soil by OA mixtures.

ElementExtracted by

13.5 mM Ca(NO3)2 (mg kg-1)Extracted by OA Mixture (mg kg-1)0.001 M 0.01 M 0.1 M

Control Romona SoilCd 8×10-4 1.6×10-3 1.2×10-2 0.04Cr 0.001 0.04 0.08 0.50Cu 0.12 0.20 0.61 3.35Ni 0.03 0.08 0.72 1.71Pb n.d.† n.d.† n.d.† n.d.†

Zn 0.18 0.39 3.20 8.10BSL–treated Romona Soil (135 Mg ha-1)

Cd 2.3×10-2 0.12 0.29 1.46Cr 0.01 0.29 0.80 3.82Cu 0.3 1.37 3.55 14.2Ni 0.2 0.97 2.33 11.8Pb n.d.† 0.07 0.15 1.22Zn 1.32 6.23 40 155

BSL–treated Romona Soil (1,080 Mg ha-1)Cd 0.21 0.53 2.11 3.58Cr 0.11 1.55 3.81 9.72Cu 0.82 4.44 19.0 38.0Ni 0.51 4.48 17.3 30.3Pb 0.03 0.52 1.35 4.08Zn 3.51 36.0 168 354

† Some of the observations were below detection limits of the AAS for Pb = 0.001 mg kg-1.

Results and Discussion

Perc

enta

ges o

f met

al e

xrac

ted

(%)

0.0

0.1

0.2

0.3

0.4

0.5Pb Cr Cd Cu Ni Zn

Perc

enta

ges o

f m

etal

ext

ract

ed (

%)

0

5

10

15

20

Perc

enta

ges o

f m

etal

ext

ract

ed (%

)

0

10

20

30

40

Perc

enta

ges o

f m

etal

ext

ract

ed(%

)

0

2

4

6

8

1013.5 mM Ca(NO3)2 0.001M OA

0.01M OA 0.1M OA

nd

nd

nd

nd Control 135 Mg ha-1 1,080 Mg ha-1

nd Control 135 Mg ha-1 1,080 Mg ha-1

Control 135 Mg ha-1 1,080 Mg ha-1 Control 135 Mg ha-1 1,080 Mg ha-1

Results and Discussion

Figure 2. Percentages of metal extracted (means ± SD where n = 4) from control and BSL–treated Romona soil by the OA mixtures. † Obtained at Moreno Field Station of the University of California, Riverside, CA. From 1976 through 1981

composted BSL were applied at dry weight rates of 0 (control), 22.5 and 180 Mg ha-1 yr-1, respectively. ‡ Some of the observations were below detection limits of the AAS for Pb = 0.001 mg kg-1.

1) Metals treated with BSL-treated soils

2) Metals extracted decreased with increase of pH

3) Cd, Cu, Ni, and Zn more readily extractable -Cr and Pb did not have similar properties

4) Metals extracted correlated with OA mixtures

Conclusion

Acknowledgments

I would like to thank Dr. Koo for his guidance and help throughout the research process.

We would like to express appreciation towards Dr. Park who provided the data tables and help with the machines in analyzing the soils as well as with this presentation.

We would also like to extend our gratitude towards Dr. Chang from UC Riverside as well as Dr. Ferko and Dr. Parker for their contribution to the research project.

Finally, we would like to thank CBU for the micro grant provided to the Natural and Mathematics Department for Dr. Koo and his research.

Questions?