Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica
Penguin colonies from permanently cold environments have a strong impact on their surrounding ecosystem because their excrements provide ample nutrients to the soils and sediments. The high phosphate content of the penguin guano directly affects primary productivity. However, phosphate solubility is...
Main Author: | |
---|---|
Format: | Thesis |
Language: | English |
Published: |
Université d'Ottawa / University of Ottawa
2008
|
Subjects: | |
Online Access: | https://dx.doi.org/10.20381/ruor-12182 http://www.ruor.uottawa.ca/handle/10393/27646 |
id |
ftdatacite:10.20381/ruor-12182 |
---|---|
record_format |
openpolar |
spelling |
ftdatacite:10.20381/ruor-12182 2023-05-15T13:32:37+02:00 Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica Perez Rojas, Nadejda 2008 https://dx.doi.org/10.20381/ruor-12182 http://www.ruor.uottawa.ca/handle/10393/27646 en eng Université d'Ottawa / University of Ottawa Biology, Ecology. Biogeochemistry. Agriculture, Soil Science. Environmental Sciences. Text Thesis article-journal ScholarlyArticle 2008 ftdatacite https://doi.org/10.20381/ruor-12182 2021-11-05T12:55:41Z Penguin colonies from permanently cold environments have a strong impact on their surrounding ecosystem because their excrements provide ample nutrients to the soils and sediments. The high phosphate content of the penguin guano directly affects primary productivity. However, phosphate solubility is dependent on the presence of iron and other metals, which can form stable PO4-rich minerals. Phosphate can also be sorbed onto minerals, including iron oxides. The present study investigated the biogeochemistry of phosphorus in a 42 cm-deep soil profile on Gardiner Island in Antarctica in order to assess the effect of penguin excrements on P partitioning in the solid and aqueous phases. The results indicate that the porewaters were slightly acidic (pH 5-6) and contained extremely high levels of dissolved organic carbon (DOC; 120 mM), PO4 (120 mM), SO4 (27 mM), NO3 (18 mM), Cl (320 mM), F (2 mM), Sr (0.10 mM), Ca (18 mM) and Mg (150 mM) at the top of the soil profile. Dissolved iron concentrations were generally low (< 0.04 mM) and increased at a depth of 15-20 cm and at the bottom of the profile. Chemical extraction revealed the presence of two zones of reactive phosphorus (P-ascorbate extractable fraction) in the soil profile, i.e., at the surface and between 16 and 20 cm. Enriched reactive and crystalline iron fractions were also present at a depth of 16-20 cm, but fluctuated throughout the profile. The Fe(II)/Fe(III) molar ratio of the soil was greater than 1 at the surface of the profile and declined with depth. X-ray diffraction analysis showed that the soil likely contained berlinite, strengite and vivianite, along with silicates and quartz. Saturation index calculations also indicated that Ca and Mg-rich phosphate minerals were likely present in the soil. Based on the above results, the presence of penguin colonies on Gardiner Island strongly impacted the geochemical and mineralogical composition of the soil, as observed in other studies on bird guano impacted (ornithogenic) soils. In addition, the presence of both Fe(II) and Fe(III) points to the fact that the soil undergos redox changes, likely as a result of seasonal water table fluctuations. Microcosm experiments with selected samples from the soil profile and an iron-reducing bacterium indeed showed that iron and phosphorus were released into solution as a result of microbial iron reduction. However, abiotic systems also showed a release of phosphorus indicating that non Fe-rich phosphate minerals are soluble under the conditions prevailing in the growth medium. Thesis Antarc* Antarctica DataCite Metadata Store (German National Library of Science and Technology) Gardiner ENVELOPE(-150.950,-150.950,-86.317,-86.317) Guano ENVELOPE(141.604,141.604,-66.775,-66.775) |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
English |
topic |
Biology, Ecology. Biogeochemistry. Agriculture, Soil Science. Environmental Sciences. |
spellingShingle |
Biology, Ecology. Biogeochemistry. Agriculture, Soil Science. Environmental Sciences. Perez Rojas, Nadejda Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica |
topic_facet |
Biology, Ecology. Biogeochemistry. Agriculture, Soil Science. Environmental Sciences. |
description |
Penguin colonies from permanently cold environments have a strong impact on their surrounding ecosystem because their excrements provide ample nutrients to the soils and sediments. The high phosphate content of the penguin guano directly affects primary productivity. However, phosphate solubility is dependent on the presence of iron and other metals, which can form stable PO4-rich minerals. Phosphate can also be sorbed onto minerals, including iron oxides. The present study investigated the biogeochemistry of phosphorus in a 42 cm-deep soil profile on Gardiner Island in Antarctica in order to assess the effect of penguin excrements on P partitioning in the solid and aqueous phases. The results indicate that the porewaters were slightly acidic (pH 5-6) and contained extremely high levels of dissolved organic carbon (DOC; 120 mM), PO4 (120 mM), SO4 (27 mM), NO3 (18 mM), Cl (320 mM), F (2 mM), Sr (0.10 mM), Ca (18 mM) and Mg (150 mM) at the top of the soil profile. Dissolved iron concentrations were generally low (< 0.04 mM) and increased at a depth of 15-20 cm and at the bottom of the profile. Chemical extraction revealed the presence of two zones of reactive phosphorus (P-ascorbate extractable fraction) in the soil profile, i.e., at the surface and between 16 and 20 cm. Enriched reactive and crystalline iron fractions were also present at a depth of 16-20 cm, but fluctuated throughout the profile. The Fe(II)/Fe(III) molar ratio of the soil was greater than 1 at the surface of the profile and declined with depth. X-ray diffraction analysis showed that the soil likely contained berlinite, strengite and vivianite, along with silicates and quartz. Saturation index calculations also indicated that Ca and Mg-rich phosphate minerals were likely present in the soil. Based on the above results, the presence of penguin colonies on Gardiner Island strongly impacted the geochemical and mineralogical composition of the soil, as observed in other studies on bird guano impacted (ornithogenic) soils. In addition, the presence of both Fe(II) and Fe(III) points to the fact that the soil undergos redox changes, likely as a result of seasonal water table fluctuations. Microcosm experiments with selected samples from the soil profile and an iron-reducing bacterium indeed showed that iron and phosphorus were released into solution as a result of microbial iron reduction. However, abiotic systems also showed a release of phosphorus indicating that non Fe-rich phosphate minerals are soluble under the conditions prevailing in the growth medium. |
format |
Thesis |
author |
Perez Rojas, Nadejda |
author_facet |
Perez Rojas, Nadejda |
author_sort |
Perez Rojas, Nadejda |
title |
Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica |
title_short |
Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica |
title_full |
Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica |
title_fullStr |
Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica |
title_full_unstemmed |
Biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in Antarctica |
title_sort |
biogeochemistry of iron and phosphorus in soils impacted by penguin colonies in antarctica |
publisher |
Université d'Ottawa / University of Ottawa |
publishDate |
2008 |
url |
https://dx.doi.org/10.20381/ruor-12182 http://www.ruor.uottawa.ca/handle/10393/27646 |
long_lat |
ENVELOPE(-150.950,-150.950,-86.317,-86.317) ENVELOPE(141.604,141.604,-66.775,-66.775) |
geographic |
Gardiner Guano |
geographic_facet |
Gardiner Guano |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_doi |
https://doi.org/10.20381/ruor-12182 |
_version_ |
1766028698612400128 |