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Dissertation
Attenuation of arsenic in soil and water using iron-enriched compost
Washington State University
Doctor of Philosophy (PhD), Washington State University
2023
DOI:
https://doi.org/10.7273/000005102
Abstract
Arsenic (As) can become enriched in terrestrial environments through human activity, such as mining, pesticide application, phosphate fertilizers, fossil fuel combustion, and smelting. Here, we investigated whether compost feedstocks enriched with ferrous gluconate or ferrous sulfate and then composted would limit the environmental availability of As in soil and water. We hypothesized that increasing concentrations of iron (Fe) in compost would correlate with (1) increased As sorption from solution; (2) increased reduction in ammonium acetate (NH4AOc)-extractable As from spiked soil; and (3) reductions in compost-derived dissolved organic carbon (DOC). We further hypothesized that ferrous gluconate will lead to higher proportions of organically bound Fe and reactive poorly crystalline Fe solid phases in the compost, thereby leading to enhanced As retention, as compared to ferrous sulfate amendments. A compost feedstock was amended with different amounts of ferrous gluconate or ferrous sulfate and then composted for approximately five months. The mature compost was characterized for total elemental concentrations, and the Fe phases were characterized by chemical extractions, Mössbauer spectroscopy, and X-ray adsorption spectroscopy. The effects of Fe-amended composts on As environmental availability were quantified by batch sorption isotherms and ammonium acetate extractions of Fe-compost incubated with As-spiked soil. The results showed (1) Fe(II) gluconate amendments produced comparatively higher amounts of organically bound Fe while higher amounts of Fe(III) precipitates formed in the Fe(II) sulfate amendments; (2) at low pH, high As sorption correlated with both sodium pyrophosphate- and ammonium oxalate-extractable Fe; (3) the highest Fe(II) gluconate- and Fe(II) sulfate-amended compost treatments significantly reduced solution-phase As at pH 6; and (4) the highest Fe(II) sulfate-amended compost showed the greatest reductions in NH4AOc-extractable As compared to untreated soil although no significant treatment differences were observed after 260 days of incubation.
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Details
- Title
- Attenuation of arsenic in soil and water using iron-enriched compost
- Creators
- Patrick Maxwell Freeze
- Contributors
- James B Harsh (Advisor)Markus Flury (Committee Member)Tarah Sullivan (Committee Member)Glenn C Miller (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 103
- Identifiers
- 99901019936601842
- Language
- English
- Resource Type
- Dissertation