Time effect on the fractionation of heavy metals in soils

doi:10.1016/j.geoderma.2004.08.002

Geoderma

Volume 125, Issues 3–4, April 2005, Pages 225-234

https://doi.org/10.1016/j.geoderma.2004.08.002 Get rights and content

Abstract

Time effect on the fractionation of Cu, Zn, Pb, and Cd in three typical Chinese soils was investigated. A total of 500 mg kg⁻¹ of Cu, Zn, Pb and 2.5 mg kg⁻¹ of Cd were added to soils as nitrates. Metals in the incubated soils were fractionated termly from 3 h to 8 weeks by the sequential extraction procedure, in which the metal fractions were experimentally defined as exchangeable, carbonate-, Fe–Mn oxide-, organic matter-bound and residual fractions. Results showed that the changes of Cu, Pb and Zn in fraction distribution were biphasic by an initial rapid step followed by a slow one. Metals in exchangeable fraction were increased in the first 3 h, and then decreased, such decreases could be simulated by a diffusion equation and the decrease rate followed the order Pb>Cu>Zn≫Cd. Metals bound to Fe–Mn oxides and organic matter increased consistently in the 8-week incubation. There were almost no changes for the metals in the residual fraction. After 3-h incubation most of Cd added to soils presented in the exchangeable fraction. The content of Cd in each fraction changed slightly in the 8-week incubation. Soil pH played an important role in metal fraction distribution patterns. Jiangxi soil, with low soil pH, tended to keep more metals added in exchangeable fraction and the changes of metals in each fraction were not as remarkable as in other two soils. High organic matter content resulted in the increased organic matter-bound fraction.

Introduction

Soil contamination with anthropogenic heavy metals, which mainly comes from industrial activity, atmospheric deposition and land application of sewage sludge, has received much attention in recent years. The anthropogenic heavy metals are believed to be easily accumulated in the topsoil (Samsoe-Petersen et al., 2002, Baker, 1990), resulting in potential problems such as toxicity to plants and animals (Ma et al., 2002, Berti and Jacobs, 1996), accumulation in food chain, perturbation of the ecosystem and adverse health effects (Forstner, 1995, Stalikas et al., 1997).

Residence time directly relates to the bioavailability of heavy metals in soils (Pedersen et al., 2000, Joner and Leyval, 2001, Alexander, 2000). Generally bioavailability of heavy metals decreases with increasing residence time (McLaughlin, 2001). Such time effect is ascribed to the reactions between metal ions and soils, which mainly include complexation, adsorption, and precipitation of metal ions in the soil particle surface or diffusion into the mesopores and micropores of soil. Although it is often assumed that residence time effect reduced metal mobility and bioavailability, only a few works have been carried out to investigate whether and how time effect influence the metal chemical forms and/or metal fractions in soils (Ma and Uren, 1998, Lim et al., 2002, Bataillard et al., 2003, Davies et al., 2003).

Total elemental contents provide little information on the mobility and bioavailability of the elements of interest. The mobility and bioavailability of heavy metals depend heavily on their physical and chemical forms. Sequential extraction, although operationally defined, can give information about the association of heavy metals with geochemical phases of soil, hence helps to reveal the distribution of heavy metals in fractions and to assess the mobility and toxicity of metals in soils (Tessier et al., 1979, Quevauiller et al., 1993, Ahnstrom and Parker, 1999). Among numerous sequential extraction methods, the method proposed by Tessier et al. (1979) was most widely used. According to this protocol, metals in soil were fractionated into exchangeable, carbonate-, Fe–Mn oxide-, organic matter-bound and residue fractions. Generally, exchangeable form was considered readily mobile and easily bioavailable, while residual form was considered to incorporate into crystalline lattice of soil minerals and appeared to be the most inactive. The carbonate-, Fe–Mn oxide-, and organic matter-bound fractions could be considered relatively active depending on the actual physical and chemical properties of soil.

To fully understand time effect on bioavailability of anthropogenic heavy metals, detailed information is needed on the fractionation of metals after different residence time. The objective of this study was to investigate time effect on the fractionation of Cu, Pb, Zn and Cd added in soils. Differences of the fractionation among the metals and soils and the possible mechanism were discussed.

Section snippets

Soil samples

Three topsoil samples (0–20 cm) were collected from Beijing, Jiangxi and Heilongjiang Provinces, China. Soil samples were air-dried and passed through a 2.0 mm sieve, homogenized and stored at 4 °C until use. Soil pH was measured with the soil to water ratio of 1:1 (w/v) (Hendershot et al., 1993a), organic matter (OM) was measured by K₂Cr₂O₇ digestion method (Nelson and Sommers, 1996), cation exchange capacity (CEC) was determined by using a 0.1 mol l⁻¹ BaCl₂ displacement method (Hendershot et

Changes of heavy metal concentrations in different fractions

Table 3, Table 4, Table 5 show the distribution of heavy metals Cu, Zn, Pb and Cd in the five fractions: exchangeable (EXC), carbonate (CA), Fe–Mn oxides (Fe–Mn), organic matter (OM) and residual (RES) fractions in the control and the spiked soils incubated for 3 h, 3 days and 8 weeks. Other values were excluded here otherwise the tables would be too big. In the control soils, the background Cu, Zn, Pb and Cd in each fraction were generally in the order residual>exchangeable>Fe–Mn

Conclusion

The fractionation data monitored during 8-week incubation revealed the distribution patterns of Cu, Zn, Pb and Cd in soils. The soluble metals added were transformed from easily extractable fractions to more stable fractions, little change was observed in residual fraction. Among the heavy metals investigated, the transformation rate was in the order Pb>Cu>Zn≫Cd. No significant decrease of Cd was observed in the exchangeable fraction, indicating most of the anthropogenic Cd entered the mobile

Acknowledgement

This work was funded by the National Natural Science Foundation of China (No. 20377049 and No.20237010).

References (32)

N.A. Davies et al.
The influence of time on lead toxicity and bioaccumulation determined by the OECD earthworm toxicity test
Environ. Pollut.
(2003)
E.A. Forbes et al.
The specific adsorption of inorganic Hg (II) species and Co (III) complex ions on goethite
J. Colloid Interface Sci.
(1974)
Y.B. Ma et al.
Transformations of heavy metals added to soil-application of a new sequential extaction procedure
Geoderma
(1998)
C.D. Stalikas et al.
Multielement concentration in vegetable species grown in two typical agricultural areas of Greece
Sci. Total Environ.
(1997)
Z.S. Ahnstrom et al.
Development and assessment of a sequential extraction procedure for the fractionation of soil cadmium
Soil Sci. Soc. Am. J.
(1999)
M. Alexander
Aging, bioavailability, and overestimation of risk from environmental pollutants
Environ. Sci. Technol.
(2000)
D.E. Baker
Coopper
P. Bataillard et al.
Short-term transformation of lead and cadmium compounds in soil after contamination
Eur. J. Soil Sci.
(2003)
W.R. Berti et al.
Chemistry and phytotoxicity of soil trace elements from repeated sewage sludge applications
J. Environ. Qual.
(1996)
E.M. Carmen et al.
Dissolved and labile concentration of Cd, Cu, Pb, and Zn in aged ferrihydrite-organic matter system
Environ. Sci. Technol.
(1999)

E.M. Carmen et al.

Cd, Cu, Pb, and Zn copreipitates in Fe oxide formed at different pH: aging effects on metal solubility and extractability by citrate

Environ. Toxicol. Chem.

(2001)

Chinese Environmental Protection Agency. 1995. Environmental quality standard for soils. GB...

H.A. Eillott et al.

Competitive adsorption of heavy metal by soils

J. Environ. Qual.

(1986)

U. Forstner

Land contamination by metals—Global scope and magnitude of problem

W.H. Hendershot et al.

Soil reaction and exchangeable acidity

W.H. Hendershot et al.

Ion exchange and exchangeable cations

Cited by (230)

Fractionation of metals in soil for strawberry cultivation: Effect on metal migration in food chain and application in risk assessment
2024, Environmental Research
Although trace metals in strawberry production system have attracted growing attention, little is known about metal fractionation in soil for strawberry cultivation. We hypothesized that the metal fractions in soil influenced by strawberry production had significant effect on food chain transport of metals and their risk in soil. Here, samples of strawberries and soil were gathered in the Yangtze River Delta, China to verify the hypothesis. Results showed that the acid-soluble Cr, Cd, and Ni in soil for strawberry cultivation were 21.5%–88.3% higher than those in open field soil, which enhanced uptake and bioaccessible levels of these metals in strawberries. Overall, the ecological, mobility, and health risks of Pb, Zn, Ni, and Cu in soil were at a low level. However, the ecological risk of bioavailable Cd, mobility risk of Cd, and cancer risk of bioavailable Cr in over 70% of the soil samples were at moderate, high, and acceptable levels, respectively. Since the increased acid-soluble Cr and Ni in soil were related to soil acidification induced by strawberry production, nitrogen fertilizer application should be optimized to prevent soil acidification and reduce transfer of Cr and Ni. Additionally, as Cd and organic matter accumulated in soil, the acid-soluble Cd and the ecological and mobility risks of Cd in soil were enhanced. To decrease transfer and risk of Cd in soil, organic fertilizer application should be optimized to mitigate Cd accumulation, alter organic matter composition, and subsequently promote the transformation of bioavailable Cd into residual Cd in soil.
Effect of DOM derived from composting on the changes of Pb bioactivity in black soil
2024, Journal of Environmental Chemical Engineering
Exogenous dissolved organic matter (DOM) plays an important role in the migration and transformation of heavy metals in soil. This study investigated the effect of composting-DOM with different maturity on changes of Pb bioactivity in soil, and evaluated the soil environmental factors driving these changes. The results showed that the activating ability of DOM to Pb in chernozem and dark brown soil increased by 4.11%−22.42% and 13.22%−30.15%, respectively. And the order followed: fresh manure (FDOM) > immature compost (IDOM) > mature compost (MDOM). The pH and dissolved organic carbon (DOC) were the main factors driving the changes in diethylenetriaminepentaacetic acid extraction (DTPA) -Pb in chernozem and dark brown soil, respectively. In chernozem, the input of MDOM can reduce the proportion of easily mobile fractions of Pb. While, DOM promotes the transformation of Pb from organic bound and residual fractions to exchangeable and carbonate bound fractions under other conditions. Moreover, the input of DOM can also drive the transformation of Pb species by regulating soil pH, electrical conductivity (EC), organic matter (SOM), DOC, and enzyme activity.
Stability of exogenous Cadmium in different vineyard soils and its effect on grape seedlings
2023, Science of the Total Environment
Cadmium (Cd) being potentially toxic heavy metal, has become increasingly serious to vineyard soil and grapes in recent years. Soil type is one of the main factors affecting the absorption of Cd in grapes. To investigate the stabilization characteristics and form changes of Cd in different types of vineyard soils, a 90-days incubation experiment was conducted after exogenous Cd addition to 12 vineyard soils from typical vineyards in China. The inhibition of exogenous Cd on grape seedlings was determined based on the pit-pot incubation experiment (200 kg soil per pot). The results demonstrate that Cd concentration in all the sampling sites did not exceed the national screening values (GB15618-2018; i.e., 0.3 mg/kg when pH was lower than 7.5, 0.6 mg/kg when pH was higher than 7.5);. Cd in Fluvo-aquic soil 2, Red soils1, 2, 3 and Grey-Cinnamon soil is dominated by acid-soluble fraction, but was mainly in residual fraction in the remain soils. Throughout the aging process, proportion of the acid-soluble fraction increased and then decreased, while proportion of the residual fraction decreased and then increased, after exogenous Cd was added. The mobility coefficients of Cd in Fluvo-aquic soil 2 and Red soil 1, 2 increased 2.5, 3 and 2 folds, after exogenous Cd addition, respectively. Compared with CK (control), the correlation between total Cd content and its different fractions was relatively weak in the Cd_l (low concentration) and Cd_h (high concentration) groups. Poor Cd stabilization and strong inhibition of seedling growth rate were observed in Brown soil 1, black soil, red soil 1 and cinnamomic soil. Fluvo-aquic soil 2, 3 and Brown soil 2 showed good Cd stability and small inhibition effect on grape seedlings. These results show that Cd stability in soils and inhibition rate of grape seedlings by Cd are strongly influenced by soil type.
Mineral-organic interactions drive the aging and stabilization of exogenous Pb in soils
2023, Geoderma
The interactions of soil components have profound impacts on the speciation, bioavailability and transformation of heavy metals. However, these interactions have not been well included in multi-surface model (MSM) as most of the models adopt component additive method. Here, an incubation experiment was conducted with three contrasting soils spiked with 200 mg/kg Pb and rice straw to investigate the impact of mineral-organic interactions on Pb speciation and to validate the MSM for Pb in soils. With the aid of chemical extraction and instrumental analysis (XANES and SEM-EDS), the results show that metal oxides and soil organic matter are the main scavengers for Pb, accounting for the stabilization of exogenous Pb by ∼ 40% − 80% and ∼ 13% − 30%, respectively. The accumulation of the most stable residual Pb was driven by Fe/Al oxides, which was fostered by organic matter through the formation of amorphous Fe/Al oxides. Unexpectedly, the introduction of straw promoted the activation of metal oxides and the competition from Fe/Al/Ca ions reduced the binding of Pb by soil organic matter. Simulation of organic-Fe/Al/Ca interactions largely improved the accuracy of the MSM model results for the prediction of Pb speciation distribution. Overall, this study highlights that mineral-organic interactions play important role in the stabilization of exogenous Pb in soils, while incorporate of these interactions into MSM is recommended in future heavy metal studies.
Lability, bioaccessibility, and ecological and health risks of anthropogenic toxic heavy metals in the arid calcareous soil around a nonferrous metal smelting area
2022, Chemosphere
Lability and bioaccessibility of anthropogenic toxic heavy metals in arid calcareous soils are critical to understand their ecological and health risks. This study examined toxic heavy metal speciation in the calcareous soil contaminated by nonferrous metal smelting. Results demonstrated that approximately 70 years’ nonferrous metal smelting and mining in Baiyin led to significant contamination of nearby soil down to about 200 cm depth by cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), with more serious contamination in the downwind areas of smelting or mining. More than half of Cd, Cu, Pb, and Zn in the soil was present in the labile fractions while more than 75% of cobalt (Co), chromium (Cr), nickel (Ni), and vanadium (V) was present in the residual fraction. Carbonate minerals in this calcareous soil play an important role in the labile fractions, with approximate 25% of Cd and Pb and 15% of Cu and Zn bound in carbonates. Bioaccessible Cd, Cu, Pb, and Zn in the soil were approximately 49.8%, 29.4%, 12.2%, and 33.8% in gastric phase and 13.5%, 15.9%, 4.3%, and 9.1% in intestinal phase of their total concentrations, respectively. Therefore, Cd and Zn were removed from gastric solution to a greater extent than Cu and Pb by neutral intestine environment. However, bioaccessible Co, Cr, Ni, and V in the soil were less than 3% of their total concentrations. Bioaccessibility of these metals but Cu in this calcareous soil was significantly lower than that for the acidic Ultisols and Alfisols in U.S. The concentrations of Cd, Cu, Pb, Zn, and Ni in each chemical and bioaccessible forms were significantly correlated linearly with their total concentrations in the calcareous soil, while only residual concentration was significantly correlated with the total concentration for Co, Cr, and V. These linear slopes showed that relative lability and bioaccessibility increased for Cd, but decreased for Cu, Pb, and Zn with the increase in their total concentrations in the calcareous soil. Direct oral soil ingestion would not pose a non-carcinogenic health risk to local children. However, very high potential ecological risk would be caused by these metals in the soil. These results provide improved insights into the biogeochemical processes of anthropogenic toxic heavy metals in the arid calcareous soils worldwide.
Diversity, function and assembly of the Trifolium repens L. root-associated microbiome under lead stress
2022, Journal of Hazardous Materials
Root-associated microbial layers provide unique niches that drive specific microbe assemblies. While the rhizosphere microbiome has long received much attention, endophytic microbes remain largely elusive. Characterizing metal-tolerant plants’ strategies for assembling different root-associated microbial layers is important for optimizing phytoremediation. Here, a pre-stratified rhizo-box assay was conducted with Trifolium repens L. under greenhouse conditions with artificial Pb-contaminated soil. Cultivation compensated for the pollution-driven loss of soil microbial biomass carbon, enzyme activities and abundance. The acid-soluble Pb proportion increased in the rhizosphere (from 6.5–13.7% to 7.1–18.0%) compared with bulk soil. Under stress, root-layer variants were a considerable source of variation in the microbiome, with the endosphere representing a unique and independent niche. A core set of root microbes were selected by T. repens, with Proteobacteria and Actinobacteria composed of diverse plant-growth-promoting bacteria (PGPBs) and metal-tolerant members. Cluster analysis revealed endosphere-enriched genera, with Rhizobium, Nocardioides, Novosphingobium, Phyllobacterium, and Sphingomonas being the most dominant. Finally, inferred microbial metabolic pathways suggested that these potential metal-tolerant PGPB species provide critical services to hosts, enabling them to tolerate and even flourish in contaminated soil. Our results provide novel insights for understanding how root-associated microbes help metal-tolerant plants cope with abiotic stress.

View all citing articles on Scopus

View full text

Time effect on the fractionation of heavy metals in soils

Abstract

Introduction

Section snippets

Soil samples

Changes of heavy metal concentrations in different fractions

Conclusion

Acknowledgement

Environ. Pollut.

J. Colloid Interface Sci.

Geoderma

Sci. Total Environ.

Development and assessment of a sequential extraction procedure for the fractionation of soil cadmium

Soil Sci. Soc. Am. J.

Aging, bioavailability, and overestimation of risk from environmental pollutants

Environ. Sci. Technol.

Coopper

Short-term transformation of lead and cadmium compounds in soil after contamination

Eur. J. Soil Sci.

Chemistry and phytotoxicity of soil trace elements from repeated sewage sludge applications

J. Environ. Qual.

Dissolved and labile concentration of Cd, Cu, Pb, and Zn in aged ferrihydrite-organic matter system

Environ. Sci. Technol.

Cd, Cu, Pb, and Zn copreipitates in Fe oxide formed at different pH: aging effects on metal solubility and extractability by citrate

Environ. Toxicol. Chem.

Competitive adsorption of heavy metal by soils

J. Environ. Qual.

Land contamination by metals—Global scope and magnitude of problem

Soil reaction and exchangeable acidity

Ion exchange and exchangeable cations