Solubility of trace metals in two contaminated paddy soils exposed to alternating flooding and drainage

Pan, Yunyu; Bonten, L.T.C.; Koopmans, G.F.; Song, Jian; Luo, Yongming; Temminghoff, E.J.M.; Comans, R.N.J.

doi:10.1016/j.geoderma.2015.07.011

Cited by 84 publications

(26 citation statements)

References 61 publications

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“…3) via downward transport during the saturation of the potted soil by adding deionized water at the top of the soil surface. In a previous column experiment with the same paddy soil, as described in Pan et al (2014, 2016), the opposite trend was found for the initial sampling occasion, with trace metal and DOC concentrations clearly decreasing with depth. However, this could be explained by Pan et al (2014, 2016) by upward transport because the columns in their experiment were saturated from the bottom.…”

Section: Resultsmentioning

confidence: 60%

“…In a previous column experiment with the same paddy soil, as described in Pan et al (2014, 2016), the opposite trend was found for the initial sampling occasion, with trace metal and DOC concentrations clearly decreasing with depth. However, this could be explained by Pan et al (2014, 2016) by upward transport because the columns in their experiment were saturated from the bottom. In this study, the solubility of Cu, Cd, Pb, Zn, and Ni in all soil layers decreased markedly during the first flooding period, which might be due to Cu, Cd, Pb, Zn, and Ni precipitation in the form of poorly soluble sulfide minerals after SO 4 2− had been reduced to S 2− (Weber et al 2009; de Livera et al 2011; Fulda et al 2013).…”

Section: Resultsmentioning

confidence: 60%

“…The Ni concentrations in the bottom soil layer are remarkably high. Since Ni is the trace metal which is the least likely to form sulfide minerals among the five trace metals considered here (Weber et al 2009; Pan et al 2016), Ni solubility in this paddy soil might not have been controlled by Ni sulfide minerals but rather by binding of Ni to organic matter in the form of DOM and SOM. The elevated DOC concentrations in the bottom soil layer (Fig.…”

Section: Resultsmentioning

confidence: 94%

“…In this study, the solubility of Cu, Cd, Pb, Zn, and Ni in all soil layers decreased markedly during the first flooding period, which might be due to Cu, Cd, Pb, Zn, and Ni precipitation in the form of poorly soluble sulfide minerals after SO 4 2− had been reduced to S 2− (Weber et al 2009; de Livera et al 2011; Fulda et al 2013). With x ranging between 1.22 and 1.29 for Cu x S mineral stoichiometry (Pattrick et al 1997; Pan et al 2016) and a stoichiometry of 1:1 for Cd:S, Pb:S, Zn:S, and Ni:S minerals (Allison et al 1991), there would be enough sulfur in this paddy soil to fully precipitate the reactive forms of all five trace metals as sulfide minerals when all available S–SO 4 2− would be reduced to S 2− (Table 1). Additionally, the increase in pH during flooding (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In our previous work, we investigated how alternating flooding and draining conditions affected redox chemistry and solubility of heavy metals in two field-contaminated soils with similar properties but a contrasting pH (Pan et al 2014, 2016). The primary objective of our current study is to investigate the relationship between the solubility of trace metals and their uptake by rice plants over time.…”

Section: Introductionmentioning

confidence: 99%

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Temporal variability in trace metal solubility in a paddy soil not reflected in uptake by rice (Oryza sativa L.)

Pan

Koopmans

Bonten

et al. 2016

Environ Geochem Health

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Alternating flooding and drainage conditions have a strong influence on redox chemistry and the solubility of trace metals in paddy soils. However, current knowledge of how the effects of water management on trace metal solubility are linked to trace metal uptake by rice plants over time is still limited. Here, a field-contaminated paddy soil was subjected to two flooding and drainage cycles in a pot experiment with two rice plant cultivars, exhibiting either high or low Cd accumulation characteristics. Flooding led to a strong vertical gradient in the redox potential (Eh). The pH and Mn, Fe, and dissolved organic carbon concentrations increased with decreasing Eh and vice versa. During flooding, trace metal solubility decreased markedly, probably due to sulfide mineral precipitation. Despite its low solubility, the Cd content in rice grains exceeded the food quality standards for both cultivars. Trace metal contents in different rice plant tissues (roots, stem, and leaves) increased at a constant rate during the first flooding and drainage cycle but decreased after reaching a maximum during the second cycle. As such, the high temporal variability in trace metal solubility was not reflected in trace metal uptake by rice plants over time. This might be due to the presence of aerobic conditions and a consequent higher trace metal solubility near the root surface, even during flooding. Trace metal solubility in the rhizosphere should be considered when linking water management to trace metal uptake by rice over time.

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