ISSN 1239-6095 (print),   ISSN 1797-2469 (online)
© Boreal Environment Research 2008

Contents of Volume 13 Number 3

Mander, Ü. & Shirmohammadi, A. 2008: Transport and retention of pollutants from different production systems. Boreal Env. Res. 13: 177–184.
Abstract
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Shirmohammadi, A., Chu, T. W. & Montas, H. J. 2008: Modeling at catchment scale and associated uncertainties. Boreal Env. Res. 13: 185–193.
Abstract
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Bärlund, I. & Kirkkala, T. 2008: Examining a model and assessing its performance in describing nutrient and sediment transport dynamics in a catchment in southwestern Finland. Boreal Env. Res. 13: 195–207.
Abstract
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Deelstra, J. & Iital, A. 2008: The use of the flashiness index as a possible indicator for nutrient loss prediction in agricultural catchments. Boreal Env. Res. 13: 209–221.
Abstract
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Søvik, A. K. & Syversen, N. 2008: Retention of particles and nutrients in the root zone of a vegetative buffer zone — effect of vegetation and season. Boreal Env. Res. 13: 223–230.
Abstract
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Mander, Ü., Lõhmus, K., Teiter, S., Uri, V. & Augustin, J. 2008: Gaseous nitrogen and carbon fluxes in riparian alder stands. Boreal Env. Res. 13: 231–241.
Abstract
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Kull, A., Kull, A., Jaagus, J., Kuusemets, V. & Mander, Ü. 2008: The effects of fluctuating climatic conditions and weather events on nutrient dynamics in a narrow mosaic riparian peatland. Boreal Env. Res. 13: 243–263.
Abstract
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Närvänen, A., Jansson, H., Uusi-Kämppä, J., Jansson, H. & Perälä, P. 2008: Phosphorus load from equine critical source areas and its reduction using ferric sulphate. Boreal Env. Res. 13: 265–274.
Abstract
Full text (pdf format)

Sveistrup, T. E., Marcelino, V. & Braskerud, B. C. 2008: Aggregates explain the high clay retention of small constructed wetlands: a micromorphological study. Boreal Env. Res. 13: 275–284.
Abstract
Full text (pdf format)


Mander, Ü. & Shirmohammadi, A. 2008: Transport and retention of pollutants from different production systems. Boreal Env. Res. 13: 177–184.

Transport and retentions of agricultural pollutants both at farm level and catchment scale are key challenges faced by researchers, environmental managers, and regulatory agencies. Researchers have responded to this challenge by either monitoring or modelling strategies. Models, both empirical and theoretical, have been developed and used at different scales trying to evaluate the dynamics of the pollutants as they move from upland agricultural areas to water bodies. Monitoring studies at different scales (plot, field, catchment) have tried to represent the natural system and provide data-base for calibrating and testing mathematical models. Scientists have also used both modelling and monitoring strategies to evaluate the impact of different management practices such as contour cropping, vegetated buffer strips, riparian zones, and constructed wetlands on reduction of pollutant loads to water bodies. Manuscripts presented in this special issue provide results of both modelling and monitoring at different scales as they relate to transport and retention of nutrients in different landscapes. For example, it covers application of SWAT model in Finland to meet the environmental goals of European Water Framework Directive, and application of the same model in the US to meet the Total Maximum Daily Load mandated by US's 1972 Clean Water Act. Also covered are results on nutrient and sediment reduction due to different management practices including vegetated buffer strips, riparian zones, and constructed wetlands. Overall results of monitoring indicate effectiveness of such practices in attenuating sediment and nutrients, thus reducing their entry into the water bodies.
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Shirmohammadi, A., Chu, T. W. & Montas, H. J. 2008: Modeling at catchment scale and associated uncertainties. Boreal Env. Res. 13: 185–193.

This study describes application of a catchment scale model, SWAT (Soil Water Assessment Tool), to a small scale agricultural watershed in northern Maryland. It covers the steps involved in model application and associated model uncertainty as affected by variability in input parameters using Latin Hyper Cube Sampling (LHS) with Constrained Monte Carlo Simulation (MCS). SWAT model predictions of the impact of environmentally friendly practices are discussed within the context of input variability. Results indicate that SWAT is a reasonable monthly predictor of hydrology, but does not provide strong association between measured and simulated nitrate loss at that time scale. SWAT was found to perform very well when used for annual nitrate loss predictions. Results also show that using average input parameter values without considering their variability due to media heterogeneity produces simulation outputs that can be misleading and should not be given 100% confidence. It was concluded that in developing TMDL (Total Maximum Daily Load) plans for a given watershed one has to assert associated uncertainty levels in model’s inputs and simulation results for proper resource management.
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Bärlund, I. & Kirkkala, T. 2008: Examining a model and assessing its performance in describing nutrient and sediment transport dynamics in a catchment in southwestern Finland. Boreal Env. Res. 13: 195–207.

The Eurajoki basin, including Pyhäjärvi, was chosen as the Finnish test catchment in an EU project on benchmarking models for the Water Framework Directive due to the elevated nutrient concentrations and algal biomass production of the lake. One aim of the project was to test the suitability of models for the assessment of management options proposed to meet the surface water quality targets. Additionally, the benchmarking protocol developed to facilitate the dialogue between a modeller and a water manager in a model selection situation was tested. The catchment scale model SWAT was assessed for its applicability to analyse water and nutrient transport in Finnish environmental conditions. The results indicated that SWAT can be calibrated against measured data, especially for discharge, using a "short list" of key parameters, but further calibration is needed, especially for water quality variables. This result was supported by the attempt to validate using other monitoring points within the catchment since it revealed that the model, in the present setup, cannot reproduce observed catchment dynamics correctly. The model benchmarking guideline proved to give the process of model selection a clear structure and aided communication in a situation where the vocabulary and needs of the different parties were not established.
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Deelstra, J. & Iital, A. 2008: The use of the flashiness index as a possible indicator for nutrient loss prediction in agricultural catchments. Boreal Env. Res. 13: 209–221.

A characterisation of the hydrological behaviour of four small agricultural catchments in Estonia and Norway was carried out using a flashiness index (FI). FI reflects the frequency and rapidity of short term changes in runoff values. A comparison of FIs based on hourly and average daily discharge indicated large within-day variations over very short time intervals. Large differences were observed between the Norwegian and Estonian catchments, irrespective of whether average daily discharge or hourly discharge values were used. A comparison of the FI and the base flow index (BFI) showed that high FI values corresponded to low BFI values. Norwegian catchments with high FI or low BFI values showed high nutrient losses, whereas the contrary was observed for the Estonian catchments. Although the FI does not a priori give information about the flow processes within catchments, we believe that the FI, as well as the BFI, might be helpful in explaining differences in nutrient and soil losses between catchments.
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Søvik, A. K. & Syversen, N. 2008: Retention of particles and nutrients in the root zone of a vegetative buffer zone — effect of vegetation and season. Boreal Env. Res. 13: 223–230.

Vegetative buffer zones (BZs) along streams retain particles and nutrients like phosphorus (P) and nitrogen (N), from agricultural runoff. An experiment with drained soil columns was established to study the retention of particles and nutrients from artificial agricultural runoff. The effect of vegetation (grass versus trees, alder versus aspen) and season was examined. The retention of particles and P was significantly higher in columns with trees as compared with that in column with grass. In general this was also the case for organic carbon (Corg) and N. Columns with aspen and alder had equal retention efficiency for particles, Corg and P, and in most cases also for N. Thus alder and aspen seem to be equally suitable in forest covered BZs. The retention efficiency of nutrients was generally better during spring, summer and early autumn as compared with that during late autumn. Uptake of nutrients in vegetation seemed to be an important retention mechanism.
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Mander, Ü., Lõhmus, K., Teiter, S., Uri, V. & Augustin, J. 2008: Gaseous nitrogen and carbon fluxes in riparian alder stands. Boreal Env. Res. 13: 231–241.

Riparian buffer zones are considered to be important elements of agricultural watersheds, in that they control nutrient and carbon fluxes. Although the water purification effect of riparian ecosystems has been well studied, there is little knowledge of their internal cycling, especially in the area of gaseous emissions. We measured fluxes of nitrous oxide (N2O), dinitrogen (N2), methane (CH4), and carbon dioxide (CO2) in riparian grey alder stands in southern Estonia and black alder stands in Brandenburg, Germany. Dinitrogen emission was the most important component in N retention in the studied riparian grey alder forests. In 2001–2003, the median values of N2 emission in the grey alder sites significantly exceeded the N2 emission rates in the black alder sites, varying from 700 to 1200 and from 360 to 400 kg N2-N ha–1 year–1, respectively. In contrast, the median values of N2O flux were higher in the black alder sites than in the grey alder sites, i.e., 0.9–2.6 and 0.2–0.7 kg N2O-N ha–1 year–1, respectively. The black alder sites acted as a sink for CH4, whereas the grey alder sites emitted a small amount of CH4. The CO2-C flux was higher in the black alder stands. The estimated N2-N emission in the grey alder stands for 1994–1995 was 51.2, whereas N2O-N emission was 0.5 kg N ha–1 year–1. The significant increase in N2 emission from 1994–1995 to 2001–2003 can be related to changes in microbial activity during the succession of the pioneer grey alder stand into a more stable mixed forest community. Due to CO2 fluxes and N2O fluxes from sites with altered water regime, the estimated GWP of the studied riparian alder stands was relatively high. Further investigations should concentrate on the factors that regulate rates of N2O and N2 emission from riparian buffer zones.
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Kull, A., Kull, A., Jaagus, J., Kuusemets, V. & Mander, Ü. 2008: The effects of fluctuating climatic conditions and weather events on nutrient dynamics in a narrow mosaic riparian peatland. Boreal Env. Res. 13: 243–263.

Ntot, NO3-N, NO2-N, NH4-N, Ptot, PO4-P, SO4, Fe, Ca, Al, K, Mg and dissolved O2 concentrations, as well as water temperature, pH, Oxidation-Reduction Potential (ORP) and electric conductivity were measured in soil water and ground water sampled from different plant communities located along topo-edaphic gradients from moraine upland to stream valley in two small agricultural catchments in southeastern Estonia. The production rate and the N and P content in plant biomass were also analyzed. The mosaic soil and vegetation pattern had a significant influence on soil water quality. In the arable land, the mean annual concentration of total inorganic nitrogen (NH4-N + NO2-N + NO3-N) in piezometer water was 3–40 mg N l–l, but in the riparian grey alder forest (Alnus incana) total inorganic nitrogen never exceeded 1 mg N l–l. The most significant reduction was in the average concentration of NO3-N content, which was reduced from 25 mg l–1 under the arable land to 0.5 mg l–1 in both the alder forest and the sedge-dominated floodplain. The average Ptot concentration also decreased under the alder stands, being 0.2–1.5 mg P 1–l in the arable land and less than 0.2 mg P l–1 in the alder forest. Wetland herb communities (Carex elata association, Filipendula ulmaria, Cirsium oleraceum and Aegopodium podagraria dominated communities) also had a significant influence on soil water quality, increasing the internal cycling of N and P within the peatland. The plant biomass (the sum of above- and below-ground biomass) of riparian and wetland communities accumulates up to 54.3 g N m–2 and up to 5.3 g P m–2 during the growth season. The following factors have the highest priority in weather-induced changes in the nutrient fluxes in riparian peatlands: (a) the duration of frozen surface, (b) snowpack peak water, (c) the precipitation pattern over the warm period, (d) the duration and continuity of certain weather, (e) the occurrence of night frost events and soil freeze-thaw cycles. When night frost events start, the importance of autumn rainfalls is enhanced, as the high water-table intensifies the denitrification process but also increases Ca, Mg, K, N and P losses released during the frost–thaw cycle.
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Närvänen, A., Jansson, H., Uusi-Kämppä, J., Jansson, H. & Perälä, P. 2008: Phosphorus load from equine critical source areas and its reduction using ferric sulphate. Boreal Env. Res. 13: 265–274.

The increasing number of horses, especially in urban areas has made the phosphorus (P) load of exercise areas (paddocks) more and more obvious but there has been a lack of information regarding how to assess this load and what can be done to lower it. In the surface soil (0–2 cm) of areas that are affected by horse manure, like paddocks, we measured very high extractable P contents. When testing soils from these areas using a rainfall simulator we found a close correlation between the extractable soil P in the surface soil and the dissolved reactive P in runoff water. In a runoff treatment test trial we used ferric sulphate to treat paddock runoff water. The chemical dosage was carried out using a tube doser placed in a well. After ferric sulphate treatment the runoff was discharged into a sedimentation pond and then filtered in a sandbed. The chemical treatment was performed during one year and the reduction of the dissolved P and total P in the runoff was 95% and 81%, respectively. Our Agri-Environmental Programme has not been successful in reducing the total P status in our agriculturally loaded lakes. We suggest that the cost-effective chemical treatment of waters from the high P equine areas should be included in the programme. Also in other countries in the Baltic Sea catchment area reductions of P contents in waters from equine areas should be carried out.
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Sveistrup, T. E., Marcelino, V. & Braskerud, B. C. 2008: Aggregates explain the high clay retention of small constructed wetlands: a micromorphological study. Boreal Env. Res. 13: 275–284.

Earlier studies have shown that small constructed wetlands are more efficient as sedimentation basins for eroded soil material than expected from calculations based on detention time. It has been suggested that this is caused by sedimentation of aggregates. The present microscopic study of thin sections made from undisturbed samples of wetland sediments confirmed that the fine silt and clay fractions are present in aggregated form. Aggregates from the wetland sediments had the same mineralogical composition as those from the corresponding arable land, but were more rounded, indicating erosion during transport. To prevent breakdown of aggregates, wetlands should therefore be constructed as close to the source of erosion as possible. A correct prediction of particle retention in constructed wetlands has to take into account the presence of aggregates. Textural analysis methods, which require clay dispersion pre-treatment, are not suitable for the calculation of the retention of fine silt and clay.
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