Evaluating the potential of three Fe- and Mn-(nano)oxides for the stabilization of Cd, Cu and Pb in contaminated soils
Introduction
Commonly used methods of contaminated soil remediation, such as soil excavation, encapsulation, in situ and ex situ washing/flushing, vitrification etc., are not only costly and energy demanding, but also disruptive for the soil in the context of natural site conditions (Kumpiene et al., 2008, Tsang et al., 2007, Tsang and Yip, 2014). Due to the limited funding available for soil remediation and with the emphasis on environmental and landscape protection, research on the stabilization of metals in contaminated soils has become a high priority (Bolan et al., 2014, Geebelen et al., 2006, Komárek et al., 2013, Kumpiene et al., 2008, Mench et al., 2006a, Mench et al., 2006b, Renella et al., 2008). Stabilization of metals and metalloids by decreasing their mobility, bioavailability and bioaccessibility in soils can be achieved using living plants and associated microbial communities in the root zone (phytostabilization), application of various immobilizing amendments (chemical stabilization) or using a combination of both (aided phytostabilization) (Komárek et al., 2013, Kumpiene et al., 2008).
Nano-sized oxides (particle size of 1–100 nm) act as important scavengers for contaminants in soils, mainly due to their high reactivity and large specific surface area (Klaine et al., 2008). To date, research on the use of engineered nanoparticles for remediation purposes has focused mainly on the treatment of contaminated water (Hashim et al., 2011, Tang and Lo, 2013). For example, nano-sized particles of γ-Fe2O3 and Fe3O4 were successfully used for the removal of anionic metal/metalloid species (e.g., Cr(VI) and As(V)) from water (Hu et al., 2004, Hu et al., 2005). Although numerous studies have been published on the use of nanoparticles for water treatment, research on their application in soil remediation is still scarce. Komárek et al. (2013) reviewed recently the use of metal oxides in general for the stabilization of metals and As in contaminated soils and even though the remediation potential of some naturally occurring or synthetic metal oxides has been already tested, these data cannot be easily extrapolated as oxide particles have unique properties on the nano-scale (Mueller and Nowack, 2010, Tratnyek and Johnson, 2006). On the other hand, Mn-oxides were found to be more efficient for adsorbing Pb and Cd compared to Fe-oxides (Dong et al., 2000, O'Reilly and Hochella, 2003). A new amorphous Mn oxide (AMO) has been previously synthesized and tested as a promising amendment for chemical stabilization of metals in soils due to its good adsorption properties and simple preparation (Della Puppa et al., 2013, Ettler et al., 2014).
Environmental effects of engineered nanoparticles are still not much known, as the up-to-date research has been largely limited to their ecotoxicity (Nowack and Bucheli, 2007). Their bioavailability and potential ecotoxicity depends on many factors, such as speciation (dissolved, colloidal or particulate phase) (Klaine et al., 2008), size (Madden et al., 2006), shape (Pal et al., 2007) and surface properties (Yang and Watts, 2005) etc. Auffan et al. (2008) observed a strong impact of the Fe oxidation state on the oxidative stress (and associated cytotoxic effect) towards Escheria coli, as nano zerovalent Fe (nZVI) and magnetite (Fe3O4) generated reactive oxygen species. On the other hand, maghemite (γ-Fe2O3) particles did not cause any cytotoxicity. In vitro experiments are useful tools for elucidating toxicity interactions at the molecular level, yet the behavior and ecotoxicity in complex soil environments is difficult to predict. Nevertheless, simple toxicity tests are useful for a fast evaluation of potential toxicity of stabilizing amendments. The aim of this work was thus to evaluate the potential of two selected Fe nanooxides (maghemite and magnetite) and one amorphous Mn oxide (AMO, Della Puppa et al., 2013) to stabilize metals (Cd, Cu, Pb) in two contaminated soils and examine the interactions of these (nano)oxides in soil environments including their influence on soil microbiota.
Section snippets
Soil properties
Two soils from the vicinity of a Pb (Haplic Udept) and Cu smelter (Dystric Udept) were chosen for the experiment, mainly due to their increased content of Pb, Cd and Cu and varying characteristics. Soil samples were collected from the superficial layer (0−20 cm), air-dried, homogenized and sieved through a 2-mm stainless sieve. Particle size distribution was determined using the hydrometer method (Gee and Bauder, 1986). Soil pH was measured in suspension using a 1:2.5 (w/v) ratio of soil and
Soil properties
Basic physico-chemical properties and metal contents in the studied soils are summarized in Table 2. Dystric Udept has a coarse texture (62% sand, 30% silt and 8% clay), has a lower pH value and a higher SOM content compared to the Haplic Udept. Concentrations of trace elements exceeded their limit values for agricultural soils set by the Ministry of the Environment of the Czech Republic (1994) in the case of Pb and Cd in the Haplic Udept and Cu and Cd in the Dystric Udept. According to the
Conclusions
Results from batch and column experiments coupled with adsorption tests proved that the AMO was the most effective treatment for the stabilization of metals in the studied soil samples at the given w/w ratios (1 and 2%, w/w). Metal stabilization resulted from combined specific adsorption onto the AMO surface together with an increase in soil pH promoting the adsorption of metallic cations. On the other hand, no impact on soil pH was found for the Fe oxides. Furthermore, the AMO had a positive
Acknowledgement
This work was supported by the Czech Science Foundation (projects GAČR P503/11/0840 and GA14-01866S). Zuzana Michálková is thankful for the support from the Czech University of Life Sciences Prague (project CIGA 20134209) and Ondřej Vaněk for the support from Charles University in Prague (project UNCE 204025/2012). The authors thank two anonymous reviewers for their valuable suggestions and comments.
References (44)
- et al.
Remediation of heavy metal(loid)s contaminated soils – to mobilize or to immobilize?
J. Hazard. Mater.
(2014) - et al.
Rapid and cost-effective multiparameter toxicity tests for soil microorganisms
Sci. Total Environ.
(2000) - et al.
Is the dehydrogenase assay invalid as a method to estimate microbial activity in copper-contaminated soils?
Soil. Biol. Biochem.
(1991) - et al.
Adsorption of copper, cadmium, lead and zinc onto a synthetic manganese oxide
J. Colloid Interface Sci.
(2013) - et al.
Adsorption of Pb and Cd onto metal oxides and organic material in natural surface coatings as determined by selective extractions: new evidence for the importance of Mn and Fe oxides
Water Res.
(2000) - et al.
Stability of a novel synthetic amorphous manganese oxide in contrasting soils
Geoderma
(2014) - et al.
Evaluation of cyclonic ash, commercial Na-silicates, lime and phosphoric acid for metal immobilisation purposes in contaminated soils in Flanders (Belgium)
Environ. Pollut.
(2006) - et al.
Remediation technologies for heavy metal contaminated groundwater
J. Environ. Manag.
(2011) - et al.
Removal and recovery of Cr(VI) from wastewater by maghemite nanoparticles
Water Res.
(2005) - et al.
Chemical stabilization of metals and arsenic in contaminated soils using oxides – a review
Environ. Pollut.
(2013)
Assessment of zerovalent iron for stabilization of chromium, copper and arsenic in soil
Environ. Pollut.
Stabilization of As, Cr, Cu, Pb and Zn in soil using amendments – a review
Waste Manag.
Evaluation of the effectiveness of various amendments on trace metals stabilization by chemical and biological methods
J. Hazard. Mater.
In situ fixation of metals in soils using bauxite residue: chemical assessment
Environ. Pollut.
Insights for size-dependent reactivity of hematite nanomineral surfaces through Cu2+ sorption
Geochim. Cosmochim. Acta
Biochemical parameters and bacterial species richness in soils contaminated by sludge-borne metals and remediated with inorganic soil amendments
Environ. Pollut.
Progress in assisted natural remediation of an arsenic contaminated agricultural soil
Environ. Pollut.
Occurrence, behaviour and effects of nanoparticles in the environment
Environ. Pollut.
Lead sorption efficiencies of natural and synthetic Mn and Fe-oxides
Geochim. Cosmochim. Acta
Operationally defined extraction procedures for soil and sediment analysis I.
Stand. Trends Anal. Chem.
Long-term effects of aided phytostabilisation of trace elements on microbial biomass and activity, enzyme activities, and composition of microbial community in the Jales contaminated mine spoils
Environ. Pollut.
Trace element stabilisation in a shooting range soil: mobility and phytotoxicity
J. Hazard. Mater.
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