Sulfur amendments to soil decrease inorganic arsenic accumulation in rice grain under flooded and nonflooded conditions: Insights from temporal dynamics of porewater chemistry and solid-phase arsenic solubility
| Autor: | Netisuk Chooaiem, Natthapol Chittamart, Nuchanart Rangkadilok, Iso Christl, Surachet Aramrak, Worachart Wisawapipat, Sumontha Nookabkaew, Jutamaad Satayavivad |
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| Rok vydání: | 2020 |
| Předmět: |
Environmental Engineering
010504 meteorology & atmospheric sciences Amendment chemistry.chemical_element 010501 environmental sciences 01 natural sciences Arsenic chemistry.chemical_compound Soil Environmental Chemistry Humans Soil Pollutants Solubility Waste Management and Disposal 0105 earth and related environmental sciences Arsenite fungi Extraction (chemistry) food and beverages Oryza Pollution Sulfur Soil conditioner chemistry Environmental chemistry Chicken manure |
| Zdroj: | The Science of the total environment. 779 |
| ISSN: | 1879-1026 |
| Popis: | Rice cultivation under flooded conditions enhances arsenic (As) solubility and favors As accumulation in rice grain that poses an indisputable threat to human health worldwide. The reduction of sulfur may induce processes that decrease As solubility, but its impact on rice grain As species remains unresolved. Herein, we investigated the influence of sulfur (S)-containing materials, including chicken manure and elemental sulfur powder on As accumulation and speciation in rice grain as well as the dynamics of the porewater chemistry and solid-phase As solubility throughout the entire growth stage under continuous flooding and intermittent flooding conditions in pot experiments. The S amendments (200 mg S kg−1) to the soil significantly decreased inorganic As in rice grain under continuous flooding (~65% decrease) as well as under intermittent flooding (~70% decrease). The chicken manure amendment promoted sulfur reduction and enhanced dissolvable Mn, Fe, and As at an earlier growth stage. The sequential extraction results corroborated a decrease in the soluble and exchangeable As (F1) and an increase in residual As (F5) fractions in the S-amended treatments. Solubility data suggested that As adsorption onto Fe oxides was the primary mechanism controlling As solubility rather than the formation of As Fe sulfides. Porewater As, considered to represent the most bioavailable As fraction, failed to explain the grain As accumulation. The time-averaged concentration of oxalate-extractable As explained grain arsenite best, suggesting that poorly crystalline Fe oxides may be the primary dissolvable reactive phases that control As bioavailability in the soil-rice system. Our results suggest that the application of S-containing soil amendments can effectively decrease inorganic As accumulation in rice grains grown under the flooded conditions, which are most widely applied in paddy rice production. |
| Databáze: | OpenAIRE |
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