Jökull - 01.12.2007, Síða 46

McPeek et al.
ÁGRIP
Myndun jarðvegs vegna veðrunar bergs stjórnast af
berggerð, veðurfari, líffræðilegum ferlum og tíma.
Líf- og jarðefnafræðilegar mælingar eru notaðar til
að ákvarða samspils lífveruvirkni og jarðvegsmynd-
unar úr basaltlögum mynduðum á sögulegum tíma.
Jarðvegssýni voru tekin ofan af Eldgjárhrauninu frá
934, Hekluhraunumfrá 1300 og 1554, og Skaftárelda-
hrauni (1783). Kolefnis- (C) og fosfórmagn (P) var
ákvarðað í jarðveginum. Lífrænt efni mældist á bilinu
3, 30, 1,01, 0,80 og 0,21 kg m!2. Lífrænt efni í eld-
fjallajarðvegi (Andisol) er í lægri kantinummiðað við
kolefnismagn (0,1–14,9 kg m!2) í öðrum fjalllendis-
og norðlægum vistkerfum. Meðalkolefnisbinding í
jarðveginum var 1–3 g m!2ár!1 samanborið við 0,8–
11,7 g m!2ár!1 í norðlægum vistkerfum. Lífrænn
P jókst með tíma og mældist 13,7, 8,6, 6,5 og 4,5
mg cm!2 í jarðvegi á hraununum frá 934, 1300, 1554
og 1783 en magn ásogaðs P 44,5, 9,4, 7,7 og 2,7
mg cm!2. Aukið C og P magn í eldri jarðvegi eins og
mældist í þessari rannsókn sýnir að líffræðileg virkni
og heildarveðrun hrauna á Suðurlandi vex með tíma.
REFERENCES
Arnalds, O. 2004. Volcanic soils of Iceland. Catena, 56, 3–20.
Arnalds, O., G. Gudbergsson and J. Gudmundsson 2000. Carbon
sequestration and reclamation of severely degraded soils in
Iceland. Icelandic Agricultural Sciences 13, 87–97.
Blakemore, L.C., P.L. Searl and B.K. Daly 1987. Methods for
chemical analysis of soils. NZ Soil Bureau Scientific Report
80, 21–45.
Chadwick, O.A., L.A. Derry, P.M. Vitousek, B.J. Huebert and
L.O. Hedin 1999. Changing sources of nutrient during four
million years of ecosystem development. Nature 397, 491–
497.
Crews, T.E., K. Kitayma, J.H. Fownes, R.H. Riley, D.A. Herbert,
D. Mueller-Dombois and P. Vitousek 1995. Changes in soil
phosphorus fractions and ecosystem dynamics across a long
chronosequence in Hawaii. Ecology 76, 1407–1424.
Filippelli, G.M. 2002. The global phosphorus cycle. Rev. Miner-
alogy and Geochemistry 48, 35 pp.
Filippelli, G.M. and M.L. Delaney 1996. Phosphorus geochem-
istry of equatorial Pacific sediments. Geochimica et Cos-
mochimica Acta 60, 1479–1495.
Filippelli, G.M. and C. Souch 1999. Effects of climate and land-
scape development on the terrestrial phosphorus cycle. Geol-
ogy 27, 171–174.
Filippelli, G.M., C. Souch, B. Menounos, S. Slater-Atwater, A.J.
Timothy Jull and O. Slaymaker 2006. Alpine lake records
reveal the impact of climate and rapid climate change on the
biogeochemical cycling of soil nutrients. Quaternary Res. 66,
158–166.
Froelich, P.N. 1988. Kinetic controls of dissolved phosphate in
natural rivers and estuaries: A primer on the phosphate buffer
mechanism. Limnology Oceanography 33, 649–668.
Gislason, S.R., S. Arnorsson, S. and H. Armannsson 1996. Chem-
ical weathering of basalt in southwest Iceland: effects of
runoff, age of rocks and vegetative/glacial cover. Am. J. Sci-
ence 296, 837–907.
Gudmundsson, A., N. Oskarsson, K. Saemundsson, O. Sigurds-
son, R. Stefansson, P. Einarsson, B. Brandsdottir, G. Larsen,
H. Johannesson and Th. Thordarson 1992. The 1991 eruption
of Hekla, Iceland. Bull. Volcanology 54, 238–246.
Jakobsson, S.P. 1979. Outline of the petrology of Iceland. Jökull
29, 57–73.
Jóhannesson, H., S.P. Jakobsson and K. Sæmundsson 1990. Geo-
logical map of Iceland, sheet 6, South-Iceland, third edition.
Icelandic Museum of Natural History and Iceland Geodetic
Survey, Reykjavík.
Jóhannesson, H. and K. Sæmundson 1998. Geologic map of Ice-
land (2nd ed), 1:500,000. Bedrock Geology. Icelandic Insti-
tute of Natural History, Reykjavík.
Jurinak, J.J., L.M. Dudley, M.F. Allen and W.G. Knight 1986.
The role of calcium oxalate in the availability of phosphorus
in soils of semiarid regions: A thermodynamic study. Soil
Science 142, 255–261.
Midwood, A.J. and T.W. Boutton 1998. Soil carbonate decompo-
sition by acid has little effect on the d13C or organic matter.
Soil Biol. Biochem 30, 1301–1307.
Oskarsson, H., O. Arnalds, G. Gudmundsson and G. Gudbergs-
son 2004. Organic carbon in Icelandic Andosols: geographic
variation and impact erosion. Catena 56, 225–238.
Oke, T.R. 1987. Boundary Layer Climates. Methuen, London, 44
pp.
Sæmundsson, K. 1979. Outline of the geology of Iceland. Jökull
29, 7–28.
Schlesinger, W.H. 1997. Biogeochemistry: An Analysis of Global
Change. Academic Press, San Diego, 558 pp.
Thordarson, T., D.J. Miller, G. Larsen, S. Self and H. Sigurd-
son 2001. New estimates of sulfur degassing and atmospheric
mass loading by the 934 AD Eldgjá eruption, Iceland. J. Volc.
Geotherm. Res. 108, 33–54.
Thordarson, T. and S. Self 2003. Atmospheric and environmental
effects of the 1783–1784 Laki eruption: a review and assess-
ment. J. Geophys. Res. 108, doi:10.1029/2001JD002042.
Tiessen, H. and J.O. Moir 1993. Characterization of available P
by sequential extraction. Soil sampling methods, Boca Ra-
ton, 12 pp.
Walker, T.W. and J.K. Syers 1976. The fate of phosphorus during
pedogenesis. Geoderma 15, 1–19.
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