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| Titel |
Soil characteristics and fallout and environmental radionuclides on different geomorphological features in Elephant Island for assessing environmental changes in maritime Antarctica |
| VerfasserIn |
Ana Navas, Enrique Serrano, Jerónimo López-Martínez, Leticia Gaspar, Sandra Mink |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074193
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| Zusammenfassung |
| Soils in ice-free areas of Elephant Island (South Shetland Islands, Antarctic Peninsula region)
have been forming since the last deglaciation in an Antarctic maritime climate that is warmer
and more humid than in interior Antarctica. The studied ice-free areas correspond mostly to
coastal promontories and the underlain materials are composed of metamorphic rocks. A
soil survey was carried out in the largest ice-free areas at the western coast of the
island at Stinker Point and Lindsey Cape, as a part of a broader study on soils and
geomorphology in maritime Antarctica. A soil sampling campaign was undertaken with
the aim of characterizing soils developed on different geomorphic features and to
investigate the processes involved in their development following the glacial retreat,
that started in the area probably later than 4000 yr BP. Study sites have glacial
deposits and raised marine surfaces and they include areas with different mosses
and lichens coverage. Profiles were located at altitudes ranging from 30 to 90 m
a.s.l. at Stinker Point and at 140 m a.s.l. at Lindsey Cape. A total of 8 soil profiles
of variable depths were sampled at depth increment intervals of 5 cm until rock
outcrop (15-30 cm). Distinctive geomorphic features have been described at the
study sites to assess the extent of the relationship between soil characteristics and
geomorphology.
The main soil properties analysed were: pH, electrical conductivity, carbonate content,
bulk density, soil texture and soil fertility indicators (organic matter and soil organic carbon
content, nitrogen, available phosphorous and potassium). Analyses of stable elements and
activities of fallout (FRN’s) and environmental radionuclides (ERN’s) were also performed in
the interval samples. The studied Cryosols are stony with no clear horizon differentiation and
the soil texture is mostly silty loam. The soils have in general low contents of organic matter
(0.3-2.7 %), carbon (0.16 – 1.6 %) and nitrogen (< 0.33 %). Available K and P
contents and N vary largely among the profiles in relation to ornithogenic activity.
Carbonate contents are very low (< 1.0 %) and average electrical conductivity is 0.14
dS m-1. The pH ranges between 3.9 and 8.6 and variation from acid to alkaline
profiles is related to the profile position. The major elements Al, Fe, Ca and Na, were
the most abundant in that order, followed by Mg, K, Mn and then Pb, Ba and Sr
whereas Cr, Zn, Li, Co, Ni and Cd are present as trace elements. In two profiles on
intermediate marine platforms, the FRN’s concentrate at the topsoil, where 137Cs
and 210Pbex activities are 11 and 20 Bq/kg, respectively. The depth distribution of
ERN’s is quite homogeneous, especially for 226Ra and 232Th activities, whereas
larger variations are observed for 40K and to less extent for 238U. The absence of
137Cs and depleted levels of 210Pbexin soils on till materials of moraines is likely
related to the age of ice retreat but soil disturbance can not be disregarded. Cryogenic
processes triggering the mechanical disintegration of bedrock by freezing-thaw
cycles within the soil active layer and wetting-drying are main processes involved in
soil development in Elephant Island. This research provides information on past
environmental changes of interest to understand the soil response to actual changes. |
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