『Abstract
Soil-water interactions in coastal tundra soils are a potential
source of nutrients for surrounding fjordal and coastal ecosystems.
Changes in water chemistry and stable isotope composition from
three streams in west Spitsbergen were examined to assess the
sources and losses of nitrogen, sulfur and carbon in thin organic
tundra soils overlying sediments. Studies were undertaken from
snowmelt (mid June) through to the end of the summer (September)
in both 2001 and 2002. Drainage water chemistry was dominated
by the solution of Ca-Mg carbonates withδ13C values
in the waters being uncharacteristically high (approx. -2‰ at
the end of the season), reflecting a largely open system in which
the CO2 is derived equally from the atmosphere
and plant/soil sources. Early melt waters had δ34S
values dominated by sea salt reflecting the close proximity to
the ocean. However, as the season progressed the marine influence
lessened. Extrapolation of the data suggests that the origin of
non-sea salt δ34S was the oxidation of reduced sulfur
from coal particles in the subsoil. Concentrations of inorganic
N in stream waters were generally very low. However, NO3-
values were found to increase as the season progressed, possibly
through increased microbial activity in the soil and the early
senescence of tundra plants reducing demand. Dual isotope analysis
of δ15N and δ18O suggested that the vast
majority of snow-pack NO3- was
assimilated by the soil microbial biomass before being released,
recycled and lost to drainage waters. Organic N concentrations
in drainage waters were generally equal to or greater than losses
of inorganic N from tundra soils. The study demonstrated the effectiveness
of stable isotope data for understanding biogeochemical cycling
and soil-water interactions in tundra ecosystems. The implications
of the results are discussed in relation to climate warming.』
1. Introduction
2. Site description and methods
2.1. Streams
2.1.1. Stream 1
2.1.2. Streams 2 and 3
2.2. Sampling and analysis
2.2.1. Post sample collection procedures
2.2.2. Chemical analysis
2.2.3. Stable isotope analysis
3. Results
3.1. Snow at Site 1
3.1.1. Chemistry
3.1.2. Isotope data
3.2. Stream 1
3.2.1. Flow
3.2.2. Chemistry
3.2.3. Isotope data
3.3. Stream 2 and Stream 3
4. Discussion
4.1. General chemistry
4.2. Sulfur oxidation
4.3. Carbonate solution
4.4. Nitrogen
4.4.1. Nitrate
4.4.2. Ammonium
4.4.3. Organic nitrogen
5. Conclusions and implications
Acknowledgments
References