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| Format: | Dataset Open Access |
| Language: | en |
| Published: |
PANGAEA
1995
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| Subjects: | |
| Online Access: | https://doi.org/10.1594/PANGAEA.808983 |
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| _version_ | 1867167669837365248 |
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| author | Filippelli, Gabriel M Delaney, Margaret Lois |
| author_facet | Filippelli, Gabriel M Delaney, Margaret Lois |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | We determined phosphorus (P) concentrations in Leg 138 sediment samples from Sites 844, 846, and 851, using a sequential extraction technique to identify the P associated with five sedimentary components. Total concentrations of P (sum of the five components) ranged from 4 to 35 µmol P/g sediment, with mean values relatively similar between the three sites (11, 14, and 12 for Sites 844,846, and 851, respectively). Authigenic/biogenic P was the most important component in terms of percentage of total P (about 75%), with iron-bound P (13%), adsorbed P (2%-9%), and organic P (4%) of secondary importance; detrital P was a minor P sink (1%) in these sediments. Profiles of adsorbed P and iron-bound P show decreasing concentrations with age, indicating that these components have been affected by diagenesis and reorganization of P. A peak in iron-bound P may reflect higher fluxes of hydrothermally derived Fe to eastern equatorial Pacific Ocean sediments from 11 to 8 Ma. Lower detrital P values for western Site 851 reflect a greater distance of this site from a terrigenous source area, compared to that of Sites 844 and 846. Phosphorus mass accumulation rates (P-MARs; units of µmol P/cm**2/k.y.) were calculated using total P concentrations (not including the minor and oceanically unreactive detrital P component) and sedimentation rates and dry-bulk densities averaged over time intervals of 0.5 m.y. P-MARs generally decrease from 17 Ma to the present. Eastern transect Sites 844 and 846 display a decrease in P-MARs from about 30 to 10 in the interval from 17 to 8 Ma, while western transect Site 851 is highly variable during this interval. P-MARs increase to about 45 and stay relatively high from 8 to 6 Ma, then decrease toward the present to some of the lowest values of the record (about 10). The general trend of high P-MARs at about 6 Ma and decreasing values toward the present is correlated with other geochemical and sedimentary trends through this interval and may reflect (1) a change in net sediment and P burial, (2) a reorganization of fluxes with no change of net burial, or (3) a combination of the two. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_808983 |
| institution | PANGAEA |
| language | en |
| publishDate | 1995 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Phosphorus geochemistry of eastern equatorial Pacific Ocean sediments Filippelli, Gabriel M Delaney, Margaret Lois Ocean Drilling Program; ODP We determined phosphorus (P) concentrations in Leg 138 sediment samples from Sites 844, 846, and 851, using a sequential extraction technique to identify the P associated with five sedimentary components. Total concentrations of P (sum of the five components) ranged from 4 to 35 µmol P/g sediment, with mean values relatively similar between the three sites (11, 14, and 12 for Sites 844,846, and 851, respectively). Authigenic/biogenic P was the most important component in terms of percentage of total P (about 75%), with iron-bound P (13%), adsorbed P (2%-9%), and organic P (4%) of secondary importance; detrital P was a minor P sink (1%) in these sediments. Profiles of adsorbed P and iron-bound P show decreasing concentrations with age, indicating that these components have been affected by diagenesis and reorganization of P. A peak in iron-bound P may reflect higher fluxes of hydrothermally derived Fe to eastern equatorial Pacific Ocean sediments from 11 to 8 Ma. Lower detrital P values for western Site 851 reflect a greater distance of this site from a terrigenous source area, compared to that of Sites 844 and 846. Phosphorus mass accumulation rates (P-MARs; units of µmol P/cm**2/k.y.) were calculated using total P concentrations (not including the minor and oceanically unreactive detrital P component) and sedimentation rates and dry-bulk densities averaged over time intervals of 0.5 m.y. P-MARs generally decrease from 17 Ma to the present. Eastern transect Sites 844 and 846 display a decrease in P-MARs from about 30 to 10 in the interval from 17 to 8 Ma, while western transect Site 851 is highly variable during this interval. P-MARs increase to about 45 and stay relatively high from 8 to 6 Ma, then decrease toward the present to some of the lowest values of the record (about 10). The general trend of high P-MARs at about 6 Ma and decreasing values toward the present is correlated with other geochemical and sedimentary trends through this interval and may reflect (1) a change in net sediment and P burial, (2) a reorganization of fluxes with no change of net burial, or (3) a combination of the two. |
| title | Phosphorus geochemistry of eastern equatorial Pacific Ocean sediments |
| topic | Ocean Drilling Program; ODP |
| url | https://doi.org/10.1594/PANGAEA.808983 |