Lability of copper bound to humic acid

Mao, Lingchen; Young, Scott D.; Bailey, Elizabeth H.

doi:10.1016/j.chemosphere.2015.03.035

Cited by 16 publications

(23 citation statements)

References 38 publications

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“…2b) is in agreement with previous explanations of more mobile geocolloidal particles in the soil solution at higher pH values (Lombi et al, 2003;Nolan et al, 2009;Marzouk et al, 2013b). The presence of non-labile soluble Cu has also been shown to arise from strong adsorption of Cu on humic acid (Mao et al, 2015) whereas other trace metal ions (Cd, Ni, Pb and Zn) are more likely to be associated with colloidal Fe, Al and Mn oxides (Lombi et al, 2003;Ma et al, 2006a;Nolan et al, 2009). However, in this work no significant correlation (p > 0.05) was observed between the ratio of ME:MEr and solution concentration of Fe, Al, Mn or DOC measured in 0.01 M Ca(NO3)2 (solid: solution ratio 1 g : 30 mL).…”

Section: Effect Of Non-labile Soil Colloidal Particles On Measured E-valuesupporting

confidence: 90%

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

Mao

Young

Tye

et al. 2017

Environmental Pollution

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Metal-salt amended soils (MA, n = 23), and historically-contaminated urban soils from two English cities (Urban, n = 50), were investigated to assess the effects of soil properties and contaminant source on metal lability and solubility. A stable isotope dilution method, with and without a resin purification step, was used to measure the lability of Cd, Cu, Ni, Pb and Zn. For all five metals in MA soils, lability (%E-values) could be reasonably well predicted from soil pH value with a simple logistic equation. However, there was evidence of continuing time-dependent fixation of Cd and Zn in the MA soils, following more than a decade of storage under air-dried conditions, mainly in high pH soils. All five metals in MA soils remained much more labile than in Urban soils, strongly indicating an effect of contaminant source on metal lability in the latter. Metal solubility was predicted for both sets of soil by the geochemical speciation model WHAM-VII, using E-value as an input variable. For soils with low metal solution concentrations, over-estimation of Cd, Ni and Zn solubility was associated with binding to the Fe oxide fraction while accurate prediction of Cu solubility was dependent on humic acid content. Lead solubility was most poorly described, especially in the Urban soils. Generally, slightly poorer estimation of metal solubility was observed in Urban soils, possibly due to a greater incidence of high pH values. The use of isotopically exchangeable metal to predict solubility is appropriate both for historically contaminated soils and where amendment with soluble forms of metal is used, as in toxicological trials. However, the major limitation to predicting solubility may lie with the accuracy of model input variables such as humic acid and Fe oxide contents where there is often a reliance on relatively crude analytical estimations of these variables. Trace metal reactivity in urban soils depends on both soil properties and the original source material; the WHAM geochemical model predicts solubility using isotopically exchangeable metal as an input.

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Section: Effect Of Non-labile Soil Colloidal Particles On Measured E-valuesupporting

confidence: 90%

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

Mao

Young

Tye

et al. 2017

Environmental Pollution

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“…Likewise, the great role of SOM in decreasing the contents of dissolved Cu in soil was documented in previous studies. 38,39 Here, the concentration of Cu in pore water from soil treated with CuSO 4 also decreased with an increasing dose of CuSO 4 (Figure 1), providing reasonable support for our proposal. On the other hand, we also observed the soil pH slightly increased as a result of adding Cu(OH) 2 nanopesticide to soil (Table S1 of the Supporting Information), wherein an alkaline condition would mitigate the bioavailability of copper.…”

Section: ■ Materials and Methodssupporting

confidence: 81%

Assessing the Impacts of Cu(OH)₂ Nanopesticide and Ionic Copper on the Soil Enzyme Activity and Bacterial Community

Zhang

Qian

et al. 2020

J. Agric. Food Chem.

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Nanopesticides are being introduced in agriculture, and the associated environmental risks and benefits must be carefully assessed before their widespread agricultural applications. We investigated the impacts of a commercial Cu(OH)2 nanopesticide formulation (NPF) at different agricultural application doses (e.g., 0.5, 5, and 50 mg of Cu kg–1) on enzyme activities and bacterial communities of loamy soil (organic matter content of 3.61%) over 21 days. Results were compared to its ionic analogue (i.e., CuSO4) and nano-Cu(OH)2, including both the commercial unformulated active ingredient of NPF (AI-NPF) and synthesized Cu(OH)2 nanorods (NR). There were negligible changes in the activity of acid phosphatase, regardless of exposure dose, whereas significant (p < 0.05) variations in activities of invertase, urease, and catalase were observed at a dose of 5 mg kg–1 or higher. Invertase activity decreased with an increasing bioavailable Cu concentration in soil under various treatments. In comparison to CuSO4, both Cu(OH)2 nanopesticide (i.e., NPF) and nano-Cu(OH)2 (i.e., AI-NPF and NR) caused a significant (p < 0.05) inhibition of urease activity, wherein a significant (p < 0.05) increase in the activity of catalase was observed, representing serious oxidative stress. Accordingly, NPF, AI-NPF, and NR differently affected soil bacterial abundance, diversity, and community compared to CuSO4, which could have resulted from the changes in the bioavailable Cu concentration as a result of the distinct nature of copper spiked (i.e., nano form versus salt). Moreover, minor differences in the soil enzyme activity and bacterial community were observed between NPF and AI-NPF, reflecting that the impact of the Cu(OH)2 nanopesticide was primarily attributed to the presence of nano-Cu(OH)2. In total, the impacts of nano-Cu(OH)2 on the soil bacterial community and enzyme activity tested in this study differed from CuSO4, shedding light on the environmental risks of the Cu(OH)2 nanopesticide in the long run.

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“…This is consistent with the claims made in the literature that the dissociation kinetics of metal−HA complexes greatly affects the dynamics of metal ions in the aqueous environment. 6,31,32 The HA concentrations in each fraction (Figure 1b) were determined by UV−vis measurements. It was found that most HA molecules were distributed in less than 5 kDa.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Humic acid (HA) is one of the constituents of soil and aquatic natural organic materials. − It has been reported that HAs, alkaline-soluble and acid-insoluble substances, have high affinity to various metal ions and play a significant role in regulating metal species in aqueous and soil environments. − HA molecules are complex mixtures of polymers of various sizes and chemical functional groups produced by complicated processes . While it is known that HAs have a broad molecular weight (MW) distribution (10 2 to 10 6 Da), determining the composition of these chemical functional groups, their shape, and the degree of polymerization is challenging.…”

Section: Introductionmentioning

confidence: 99%

Stoichiometry between Humate Unit Molecules and Metal Ions in Supramolecular Assembly Induced by Cu²⁺ and Tb³⁺ Measured by Gel Electrophoresis Techniques

Nakano

Marumo

Kazami

et al. 2021

Environ. Sci. Technol.

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Humic acid (HA), a fraction of humic substances, can strongly complex with metal ions to form a supramolecular assembly via coordination binding and other intermolecular forces. However, determining the supramolecular size distribution and stoichiometry between small HA unit molecules constituting HA supramolecules and metal ions has proven to be challenging. Here, we investigated the changes in the size distributions of HAs induced by Cu 2+ and Tb 3+ ions using unique PAGE for the separation and quantification of HA complexes and metal ions bound, followed by UV−vis spectroscopy and excitation−emission matrix−parallel factor analysis. By determining the concentrations of HA and metal ions, it was possible to estimate the stoichiometry of the HA unit molecule to metal ions in supramolecular complexes. It was found that the supramolecular behaviors of Cu 2+ and Tb 3+ complexes with HA collected from peat (PAHA) and deep groundwater (HHA) differed. For example, two HHA unit molecules form a supramolecule via cross-linking by a Cu 2+ ion in the case of Cu 2+ −HHA. Our results suggest that this supramolecular stoichiometry is related to the abundance of sulfur atoms in the elemental composition of HHA. Our experimental results and analysis provide new insights into HA supramolecules formed via metal complexation.

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Lability of copper bound to humic acid

Cited by 16 publications

References 38 publications

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

Assessing the Impacts of Cu(OH)₂ Nanopesticide and Ionic Copper on the Soil Enzyme Activity and Bacterial Community

Stoichiometry between Humate Unit Molecules and Metal Ions in Supramolecular Assembly Induced by Cu²⁺ and Tb³⁺ Measured by Gel Electrophoresis Techniques

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Lability of copper bound to humic acid

Cited by 16 publications

References 38 publications

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability

Assessing the Impacts of Cu(OH)2 Nanopesticide and Ionic Copper on the Soil Enzyme Activity and Bacterial Community

Stoichiometry between Humate Unit Molecules and Metal Ions in Supramolecular Assembly Induced by Cu2+ and Tb3+ Measured by Gel Electrophoresis Techniques

Contact Info

Product

Resources

About

Assessing the Impacts of Cu(OH)₂ Nanopesticide and Ionic Copper on the Soil Enzyme Activity and Bacterial Community

Stoichiometry between Humate Unit Molecules and Metal Ions in Supramolecular Assembly Induced by Cu²⁺ and Tb³⁺ Measured by Gel Electrophoresis Techniques