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Characterizing phosphorus speciation of Chesapeake Bay sediments using chemical extraction, 31P NMR, and X-ray absorption fine structure spectroscopy.
Environ Sci Technol. 2015 Jan 06; 49(1):203-11.ES

Abstract

Nutrient contamination has been one of the lingering issues in the Chesapeake Bay because the bay restoration is complicated by temporally and seasonally variable nutrient sources and complex interaction between imported and regenerated nutrients. Differential reactivity of sedimentary phosphorus (P) pools in response to imposed biogeochemical conditions can record past sediment history and therefore a detailed sediment P speciation may provide information on P cycling particularly the stability of a P pool and the formation of one pool at the expense of another. This study examined sediment P speciation from three sites in the Chesapeake Bay: (i) a North site in the upstream bay, (ii) a middle site in the central bay dominated by seasonally hypoxic bottom water, and (iii) a South site at the bay-ocean boundary using a combination of sequential P extraction (SEDEX) and spectroscopic techniques, including (31)P NMR, P X-ray absorption near edge structure spectroscopy (XANES), and Fe extended X-ray absorption fine structure (EXAFS). Results from sequential P extraction reveal that sediment P is composed predominantly of ferric Fe-bound P and authigenic P, which was further confirmed by solid-state (31)P NMR, XANES, and EXAFS analyses. Additionally, solution (31)P NMR results show that the sediments from the middle site contain high amounts of organic P such as monoesters and diesters, compared to the other two sites, but that these compounds rapidly decrease with sediment depth indicating remineralized P could have precipitated as authigenic P. Fe EXAFS enabled to identify the changes in Fe mineral composition and P sinks in response to imposed redox condition in the middle site sediments. The presence of lepidocrocite, vermiculite, and Fe smectite in the middle site sediments indicates that some ferric Fe minerals can still be present along with pyrite and vivianite, and that ferric Fe-bound P pool can be a major P sink in anoxic sediments. These results provide improved insights into sediment P dynamics, particularly the rapid remineralization of organic P and the stability of Fe minerals and the ferric Fe-bound P pool in anoxic sediments in the Chesapeake Bay.

Authors+Show Affiliations

Department of Plant and Soil Sciences, University of Delaware , Newark, Delaware 19716, United States.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

25469633

Citation

Li, Wei, et al. "Characterizing Phosphorus Speciation of Chesapeake Bay Sediments Using Chemical Extraction, 31P NMR, and X-ray Absorption Fine Structure Spectroscopy." Environmental Science & Technology, vol. 49, no. 1, 2015, pp. 203-11.
Li W, Joshi SR, Hou G, et al. Characterizing phosphorus speciation of Chesapeake Bay sediments using chemical extraction, 31P NMR, and X-ray absorption fine structure spectroscopy. Environ Sci Technol. 2015;49(1):203-11.
Li, W., Joshi, S. R., Hou, G., Burdige, D. J., Sparks, D. L., & Jaisi, D. P. (2015). Characterizing phosphorus speciation of Chesapeake Bay sediments using chemical extraction, 31P NMR, and X-ray absorption fine structure spectroscopy. Environmental Science & Technology, 49(1), 203-11. https://doi.org/10.1021/es504648d
Li W, et al. Characterizing Phosphorus Speciation of Chesapeake Bay Sediments Using Chemical Extraction, 31P NMR, and X-ray Absorption Fine Structure Spectroscopy. Environ Sci Technol. 2015 Jan 6;49(1):203-11. PubMed PMID: 25469633.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characterizing phosphorus speciation of Chesapeake Bay sediments using chemical extraction, 31P NMR, and X-ray absorption fine structure spectroscopy. AU - Li,Wei, AU - Joshi,Sunendra R, AU - Hou,Guangjin, AU - Burdige,David J, AU - Sparks,Donald L, AU - Jaisi,Deb P, Y1 - 2014/12/17/ PY - 2014/12/4/entrez PY - 2014/12/4/pubmed PY - 2015/9/15/medline SP - 203 EP - 11 JF - Environmental science & technology JO - Environ Sci Technol VL - 49 IS - 1 N2 - Nutrient contamination has been one of the lingering issues in the Chesapeake Bay because the bay restoration is complicated by temporally and seasonally variable nutrient sources and complex interaction between imported and regenerated nutrients. Differential reactivity of sedimentary phosphorus (P) pools in response to imposed biogeochemical conditions can record past sediment history and therefore a detailed sediment P speciation may provide information on P cycling particularly the stability of a P pool and the formation of one pool at the expense of another. This study examined sediment P speciation from three sites in the Chesapeake Bay: (i) a North site in the upstream bay, (ii) a middle site in the central bay dominated by seasonally hypoxic bottom water, and (iii) a South site at the bay-ocean boundary using a combination of sequential P extraction (SEDEX) and spectroscopic techniques, including (31)P NMR, P X-ray absorption near edge structure spectroscopy (XANES), and Fe extended X-ray absorption fine structure (EXAFS). Results from sequential P extraction reveal that sediment P is composed predominantly of ferric Fe-bound P and authigenic P, which was further confirmed by solid-state (31)P NMR, XANES, and EXAFS analyses. Additionally, solution (31)P NMR results show that the sediments from the middle site contain high amounts of organic P such as monoesters and diesters, compared to the other two sites, but that these compounds rapidly decrease with sediment depth indicating remineralized P could have precipitated as authigenic P. Fe EXAFS enabled to identify the changes in Fe mineral composition and P sinks in response to imposed redox condition in the middle site sediments. The presence of lepidocrocite, vermiculite, and Fe smectite in the middle site sediments indicates that some ferric Fe minerals can still be present along with pyrite and vivianite, and that ferric Fe-bound P pool can be a major P sink in anoxic sediments. These results provide improved insights into sediment P dynamics, particularly the rapid remineralization of organic P and the stability of Fe minerals and the ferric Fe-bound P pool in anoxic sediments in the Chesapeake Bay. SN - 1520-5851 UR - https://www.unboundmedicine.com/medline/citation/25469633/Characterizing_phosphorus_speciation_of_Chesapeake_Bay_sediments_using_chemical_extraction_31P_NMR_and_X_ray_absorption_fine_structure_spectroscopy_ L2 - https://doi.org/10.1021/es504648d DB - PRIME DP - Unbound Medicine ER -