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SITES Water monitoring program

There are several types of data collected within SITES Water, which is divided into six layers. Each layer, described below, specifies the type of data collected and is divided into a base and an advanced level. The base level apply to all stations, and the advanced level apply to some stations, which often links to other ongoing programs at the station.

Layer 1: Available background information

Base level: High resolution maps of relevant parts of inland waters and their catchments, including elevation, soils, land use, lake bathymetry, and vegetation are available.

Advanced level: Sediment depth and organic C and N content of sediments (Abisko, Svartberget and Skogaryd, Erken), P fractions in sediments and paleolimnological data (Erken) are available or under development.  

Layer 2: Water balance

Base level: Accurate measurements of the main inflowing and outflowing streams, lake water levels, and evaporation from the lake. 

Advanced level: A larger number of flow stations within the catchment for landscape analysis (Svarberget/ Krycklan, Asa and Skogaryd). This data and information can be found within WATER.

Layer 3: Physical variables

Base level: Weather and climate variables are measured (wind speed, wind direction, radiation, air temperature, humidity, and atmospheric pressure and precipitation). The temperature of inflowing and outflowing streams is measured and high frequency temperature profiles will be measured in lakes to be able to determine the thermal structure. The onset, duration, and loss of lake ice cover will be monitored by the use of time lapse cameras. 

Advanced level: Detailed temperature measurements in streams that provide information about ground water input (Svarberget/Krycklan).

Layer 4: Chemical variables

Base level: One stream site and a central lake station will be sampled. Manual grab samples from the stream and the lake for chemical analysis are taken on a biweekly basis during ice-free conditions, and on a monthly basis in the presence of lake/stream ice. The central lake station samples will sample at both epi- and hyplimnion during periods of stratification.

Chemical variables such as turbidity, conductivity, pH, fluorescence, absorbance and concentrations of dissolved O2, dissolved and particulate N and P, dissolved organic carbon (DOC), particulate organic carbon (POC), dissolved inorganic carbon (DIC), cat- and anions and chlorophyll are measured.

Automated high frequency sensor based measurements (on rafts or platforms) measure temperature and oxygen profiles in the lakes and will link the stations to international lake networks, such as GLEON (www.gleon.org).
The Tarfala lake station is treated differently than the other stations due to the short ice free period and limited accessibility. Moreover, the agricultural station Röbäcksdalen will only participate in the stream measurement program.

Advanced level: Additional high frequency profiling measurements are done at lake Erken, including pH, conductivity, turbidity, chlorophyll a and phycocyanine fluorescence and cDOM. Temperature profiles at several sites within the lake (Erken). For Skogaryd pCO2 and pH are measured on towers and rafts.

Layer 5: Biological variables

Basic level: Samples for later DNA analysis (0,2 um filtration) from the water samples are collected according to the sampling scheme of layer 4 and stored in a central DNA archive.

Advanced level: Phytoplankton and zooplankton samples are taken and archived at Erken including determination of species composition of phytoplankton and zooplankton by microscopic counting and bacterioplankton by 16S rRNA gene sequencing (Erken).

Layer 6: GHG and C fluxes

Base level: Floating chambers are used for determining Green House Gas, GHG, (CO2 and CH4) emissions from aquatic systems. The sampling strategy is based on the lake depth structure and is individual for the different stations. It is based on three transects of each 4 chambers located so that the depth intervals from 0.5 to 4 m are covered.  

Advanced level: Micrometeorological eddy covariance flux towers (lakes) are used to measure CO2, CH4, H2O, and heat flux (Svartberget, Erken and Skogaryd). The flux protocol will be harmonized with ICOS. In addition to the vertical GHG emissions, lateral fluxes of dissolved and particulate C species (DOC, POC, DIC) are measured in in- and outflowing streams. Required data (C concentrations and stream discharge) will be generated within layers 2 and 3 and standardized methodology for lateral C flux calculations will be used.