Bernal,S., Butturini,A. and Sabater,F.(2006):
Inferring nitrate sources through end member mixing analysis
in an intermittent Mediterranean stream. Biogeochemistry,
81, 269-289.
『地中海沿岸の間欠河川において端成分混合(エンドメンバー・ミキシング)解析により硝酸塩の起源を推定する』
『Abstract
We monitored 24 storms during the period 1998-2002 in order to
elucidate whether the origin of nitrate could be inferred from
water sources in the catchment. The study was performed in the
Fuirosos catchment (10.5 km2) drained by an intermittent
stream. Water sources were estimated through end member mixing
analysis (EMMA) using chloride, sulfate and dissolved organic
carbon as tracers. Three end members were identified in the catchment:
event water, hillslope groundwater and riparian groundwater. Streamwater
data encompassed the mixing space defined by the end members only
during the 12 storms occurred during the wet period (from December
to May). Water sources were related to stream nitrate concentrations
during 6 of the 12 storms indicating a linkage between hydrological
and nitrate sources. However, there was not a consistent pattern
of a particular end member being a source of nitrate. EMMA was
used to determine expected nitrate concentrations in stream water
based on conservative mixing of the different water sources. The
effect of the near- and in-stream zones on stream nitrate was
inferred by comparing predicted nitrate concentrations to measured
stream nitrate concentration. At discharges below 80 l s-1
stream nitrate concentrations were lower than expected from catchment
sources in 82% of the cases suggesting nitrate retention in the
near stream zones. The trend was the opposite at higher discharges.
Keywords: EMMA; Intermittent stream; Mediterranean regions; Nitrate
sources; Streamwater nitrate; Stormflow generation』
Introduction
Study site
Climate
The catchment
Hydrology
Material and methods
Field measurements
Chemical water analysis
Climatic and hydrological data analysis
Mixing model analysis and procedures
Statistical analysis
Results
Hydrological characterization of storm events and groundwater
level dynamics
Chemical characterization of streamwater and end members
Relative contribution of each end member during the wet period
Sources of nitrogen during storm events in the wet period
Discussion
Relative contribution of each end member and variation in
the groundwater component during the wet period
Sources of nitrogen during storm events in the wet period
Effect of near- and in-stream zones on nitrate concentrations
Concluding remarks
Acknowledgments
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