Monitoring the effects of climate and agriculture intensity on nutrient fluxes in lowland streams: a comparison between temperate Denmark and subtropical Uruguay
Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Conference abstract in journal › Research › peer-review
Climate is changing towards more extreme conditions all over the world.
At the same time, land use is becoming more intensive worldwide and
particularly in many developing countries, whereas several developed
countries are trying to reduce the impacts of intensive agricultural
production and lower the excessive nutrient loading and eutrophication
symptoms in water bodies. In 2009, we initiated a comparative research
project between the subtropical region (Uruguay) and the temperate
region (Denmark) to compare the hydrology and nutrient fluxes in paired
micro-catchments with extensive production or intensive agriculture. The
four selected streams drained catchments of similar size (7 to 19 km2).
We have established similarly equipped monitoring stations in the four
micro-catchments in spring (November 2009, Uruguay; March 2010, Denmark)
to monitor the effects of land use and agriculture intensity on stream
hydrology and nutrient concentrations and fluxes under different climate
conditions. We have conducted high frequency measurements in the four
lowland streams with underwater probes (turbidity, pH, conductivity and
oxygen measured every 15 minutes), fortnight grab sampling of water and
automatic sampling of composite water samples for nutrient analysis
(total and dissolved nitrogen and phosphorus; sampled every four hours
and accumulated fortnightly). Moreover, water level and meteorological
information (precipitation, air temperature, global radiation, humidity)
has been recorded every 10 minutes and instantaneous flow measurements
have been conducted at regular intervals, to facilitate the calculation
of instantaneous discharge from continuous records of water level
(stage-discharge relationships). We will show results of ca. 2 years
from this comparative study between Uruguay and Denmark, and the
importance of differences in climate and land use will be discussed.