Sulfur Fertilization Integrated with Soil Redox Conditions Reduces Cd Accumulation in Rice Through Microbial Induced Cd Immobilization

2021 ◽  
Author(s):  
Quan Zhang ◽  
Hai-Fei Chen ◽  
Daoyou Huang ◽  
Xiao-Bin Guo ◽  
Chao Xu ◽  
...  
Keyword(s):  
Redox Conditions ◽  
Cd Accumulation ◽  
Soil Redox ◽  
Sulfur Fertilization

Influence of soil redox conditions on oxidation of biotite

Clay Minerals ◽  
1986 ◽  
Vol 21 (2) ◽  
pp. 149-157 ◽  
Author(s):  
S. Bouda ◽  
K. P. Isaac
Keyword(s):  
Mössbauer Spectroscopy ◽  
Soil Profile ◽  
Mossbauer Spectroscopy ◽  
Redox Conditions ◽  
Soil Profiles ◽  
Moderate Degree ◽  
Soil Redox ◽  
Mößbauer Spectroscopy

AbstractBiotites from three peaty gleyed podzol soil profiles on ranite bedrock were examined to investigate the oxidation of the octahedral Fe during weathering. Oxidation of these biotites as determined by Mössbauer spectroscopy shows a good correlation with the in situ measured soil Eh values of the sampled horizons. In every soil profile the highest Eh measured is in the A horizon and the lowest in the C horizon. Similarly, biotites from the A horizons are the most oxidized compared with those from the lower horizons. In most of the samples the oxidation is accompanied by loss of K+ from the lattice, as demonstrated by a moderate degree of vermiculitization.

scholarly journals The role of soil redox conditions in microbial phosphorus cycling in humid tropical forests

Ecology ◽  
2019 ◽  
Vol 101 (2) ◽  
Author(s):  
Avner Gross ◽  
Yang Lin ◽  
Peter K. Weber ◽  
Jennifer Pett‐Ridge ◽  
Whendee L. Silver
Keyword(s):  
Tropical Forests ◽  
Redox Conditions ◽  
Phosphorus Cycling ◽  
Soil Redox

Mobilization, release and speciation of arsenic in an As-contaminated gold mine spoil under varied soil redox conditions

2020 ◽  
Author(s):  
Albert Kobina Mensah ◽  
Bernd Marschner ◽  
Jianxu Wang ◽  
Sabry M. Shaheen ◽  
Jörg Rinklebe
Keyword(s):  
Extraction Procedure ◽  
Mineralogical Composition ◽  
Redox Conditions ◽  
Mine Spoil ◽  
Residual Fraction ◽  
Reductive Dissolution ◽  
Gold Mine ◽  
Soil Redox ◽  
Reducing Conditions ◽  
The Impact

<p>Redox-induced release dynamics of arsenic (As) in an abandoned geogenic arsenic-contaminated gold mine spoil in Ghana has never been studied. Therefore, our aim was to investigate the effects of varied soil redox conditions on mobilisation and speciation of As from an abandoned highly contaminated gold mine spoil (with 4,283 mg As/kg soil) using an automated biogeochemical microcosm set-up. We also studied the impact of redox potential (E<sub>H</sub>)-dependent changes of pH, Fe, Mn, Al, S, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, DOC, DIC, DC, DN and SUVA on the release dynamics of As. As mineralogical composition and speciation were further determined using a synchrotron-based X-ray absorption spectroscopy (XANES). Linear combination fits of XANES results indicated that scorodite (FeAsSO<sub>4</sub>) and arsenopyrite (FeAsS) are the two major As-containing minerals in the studied mine spoil. Geochemical fractionation using sequential extraction procedure indicated greater proportions of the extracted As in the amorphous iron oxide fraction III (1390.13 mg kg<sup>-1</sup>, 32.5% of the total As) and residual fraction V (2591.67 mg kg<sup>-1</sup>, 60.5% of the total As). Concentrations of dissolved Fe and SUVA were higher during reducing conditions and decreased under oxidising conditions and both showed negative significant relationships with E<sub>H</sub> (E<sub>H </sub>and SUVA: r = -0.76, <em>P <</em> 0.01; E<sub>H</sub> and Fe: r = -0.75). Mobilisation of As was greater under reducing conditions (dissolved As = 136.68 mg/L) than in oxidising environments (dissolved As = 8.06 mg/L). The release of As under low E<sub>H</sub> can be explained by the associated reductive dissolution of Fe oxides, as demonstrated by the high positive significant relationship between Fe and As (r = +0.97, <em>P <</em> 0.01). Dissolved As release dynamics can also be linked to desorption of aromatic carbon compounds on the surfaces of dissolved organic carbon, as demonstrated by the high positive significant correlation between SUVA and As (r = +0.573, <em>P <</em> 0.01). Further, the release dynamics of dissolved As was also affected by changes in pH (r = -0.4, <em>P <</em> 0.05), but were not affected by redox-induced dynamics of Mn, Al, S, Cl<sup>-</sup>, SO<sub>4</sub><sup>2-</sup>, DOC, DIC, DC, DN. We conclude that conditions such as flooding and high rainfall in this contaminated mine spoil could create reducing conditions, leading to reductive dissolution of the arsenopyrite As-bearing primary mineral and may lead to higher As release into the groundwater, translocation into the food chain with potential impacts on human health.</p><p><strong>Keywords</strong>: Arsenopyrite, redox chemistry, arsenic mobilisation, gold mine spoil, reductive and oxidative dissolution.</p>

scholarly journals Dynamic hydrology and plant-mediated effects reduce greenhouse gas emissions and alter wetland microbial communities

2020 ◽  
Author(s):  
Regina B. Bledsoe ◽  
Ariane L. Peralta
Keyword(s):  
Microbial Community ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Redox Status ◽  
Gas Production ◽  
Redox Conditions ◽  
Gas Emissions ◽  
Soil Redox ◽  
Microbial Function ◽  
Mediated Effects

AbstractWhile wetlands represent a small fraction (~7%) of the world’s land surface, it is estimated that one third of wetlands have been lost due to human activities. Wetland habitat loss decreases ecosystem functions such as improving water quality and mitigating climate change. These microbially mediated functions are dependent on particular soil redox conditions, which are altered by soil hydrology and the presence of plants. Differences in microbial physiology allow certain taxa (aerobes and facultative anaerobes) to adapt to fluctuating (dry/wet) hydrologic conditions, while other taxa (obligate anaerobes) are better adapted to continually saturated conditions. Therefore, the duration of hydrologic periods can affect soil microbial community structure and function. Further, plant-derived carbon, nutrients, and air are released by diffusion belowground which also impacts microbial activity in soils. In this study, we hypothesized that redox status due to continuous flooding would support greater abundance of microbial taxa involved in methanogenesis (obligate anaerobes), but plant-mediated oxygen transport would decrease methane emissions. Using a mesocosm design, we manipulated duration of hydrologic condition (i.e., stable dry, stable flooding, and alternating wet/dry) and presence of plants to induce soil redox changes in wetland soils. We measured soil redox status, used targeted amplicon sequencing to characterize the bacterial and archaeal communities, and measured greenhouse gas production to assess microbial function. Hydrology and to a lesser degree plant presence influenced soil redox conditions. Hydrologic history strongly influenced microbial community composition, but plant presence and hydrologic treatment altered microbial function to a great degree. As predicted, plant presence decreased greenhouse gas production in the wetland mesocosms. While previous studies do not often include plants when assessing greenhouse gas emissions, this study highlights that plant-mediated decreases in greenhouse gas emissions are significant. If plant-mediated effects are not considered when estimating the carbon balance of ecosystems, then wetland carbon storage could be underestimated.

scholarly journals Azolla incorporation under flooding reduces grain cadmium accumulation by decreasing soil redox potential

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chen Liu ◽  
Bin Guo ◽  
Hua Li ◽  
Qinglin Fu ◽  
Ningyu Li ◽  
...  
Keyword(s):  
Redox Potential ◽  
Cadmium Accumulation ◽  
Soil Redox Potential ◽  
Cd Accumulation ◽  
Soil Redox ◽  
Rice Yields ◽  
Double Rice ◽  
Late Rice

AbstractCadmium (Cd) presents severe risks to human health and environments. The present study proposed a green option to reduce bioavailable Cd. Rice pot experiments were conducted under continuous flooding with three treatments (T1: intercropping azolla with rice; T2: incorporating azolla into soil before rice transplantation; CK: no azolla). The results showed that azolla incorporation reduced soluble Cd by 37% compared with the CK treatment, which may be explained by the decreased soil redox potential (Eh) (r = 0.867, P < 0.01). The higher relative abundance of Methylobacter observed in azolla incorporation treatment may account for dissolved organic carbon increase (r = 0.694; P < 0.05), and hence decreased the Cd availability for rice. Azolla incorporation increased the abundance of Nitrospira, indicating the potentially prominent role of nitrogen mineralization in increasing rice yields. Further, lower soluble Cd decreased the expression of OsNramp5, but increased OsHMA3 levels in rice roots, which decreased Cd accumulation in grains. Through these effects, azolla incorporation decreased Cd concentrations in rice grains by 80.3% and increased the production by 13.4%. The negligible amount of Cd absorbed by azolla would not increase the risk of long-term application. Thus, intercropping azolla with early rice and incorporating azolla into soil before late rice transplantation can contribute to safe production at large scales of double rice cultivation.

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