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Bjørn Kløve - One of the best experts on this subject based on the ideXlab platform.

  • Long-term purification efficiency and factors affecting performance in Peatland-based treatment wetlands : an analysis of 28 Peat Extraction sites in Finland
    Ecological Engineering, 2018
    Co-Authors: Kaisa Heikkinen, Heini Postila, Satu Maaria Karjalainen, Hannu Marttila, Raimo Ihme, Mirkka Hadzic, Anssi Karppinen, Mikko Tolkkinen, Bjørn Kløve
    Abstract:

    Abstract Peatland-based treatment wetlands that purify incoming water by means of natural physical, chemical and biological processes belonging to the Peatland ecosystem are widely used at Finnish Peat Extraction sites. They can comprise either undrained or drained overland flow areas (OFAs or DOFAs), with the OFAs representing the best available technology (BAT) for Peat Extraction. We analyse here the long-term treatment performance of these OFAs and DOFAs and factors affecting this performance. Data on 14 OFAs and DOFAs in different parts of Finland were taken from the extensive long-term environmental pollution control databases. Nearly half of these wetlands had been monitored for at least 4 years and seven for 8–23 years. The results indicated that Peatland-based treatment wetlands purify drainage water as efficiently as other natural treatment wetlands on soils in general, the common challenge being phosphorus retention. Iron was also efficiently retained. The average reductions were highest in OFAs with good hydraulic function, and these also showed long-term water protection performance. An important factor affecting purification efficiency was the hydraulic loading rate. Important system design elements in this regard were the size of the wetland in relation to its catchment area, its gradient, the length of the water flow route within the wetland, and the efficient flow area of the wetland. The results regarding the latter two design elements strongly indicate that not all the areas potentially suitable in DOFAs for water purification are yet being used efficiently.

  • Predicting organic matter, nitrogen, and phosphorus concentrations in runoff from Peat Extraction sites using partial least squares regression
    Water Resources Research, 2017
    Co-Authors: Tapio Tuukkanen, Hannu Marttila, Bjørn Kløve
    Abstract:

    Organic matter and nutrient export from drained Peatlands is affected by complex hydrological and biogeochemical interactions. Here, partial least squares regression (PLSR) was used to relate various soil and catchment characteristics to variations in chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) concentrations in runoff. Peat core samples and water quality data were collected from 15 Peat Extraction sites in Finland. PLSR models constructed by cross-validation and variable selection routines predicted 92, 88, and 95% of the variation in mean COD, TN, and TP concentration in runoff, respectively. The results showed that variations in COD were mainly related to net production (temperature and water-extractable dissolved organic carbon (DOC)), hydrology (topographical relief), and solubility of dissolved organic matter (Peat sulfur (S) and calcium (Ca) concentrations). Negative correlations for Peat S and runoff COD indicated that acidity from oxidation of organic S stored in Peat may be an important mechanism suppressing organic matter leaching. Moreover, runoff COD was associated with Peat aluminum (Al), P, and sodium (Na) concentrations. Hydrological controls on TN and COD were similar (i.e., related to topography), whereas degree of humification, bulk density, and water-extractable COD and Al provided additional explanations for TN concentration. Variations in runoff TP concentration were attributed to erosion of particulate P, as indicated by a positive correlation with suspended sediment concentration (SSC), and factors associated with metal-humic complexation and P adsorption (Peat Al, water-extractable P, and water-extractable iron (Fe)).

  • Can limestone, steel slag or man-made sorption materials be used to enhance phosphate-phosphorus retention in treatment wetland for Peat Extraction runoff with low phosphorous concentration?
    Ecological Engineering, 2017
    Co-Authors: Heini Postila, Satu Maaria Karjalainen, Bjørn Kløve
    Abstract:

    Abstract This study examined possibilities to enhance phosphorus (P) retention in wetlands using different materials that could enhance removal of phosphate P (PO 4 -P) from runoff waters with fairly low P concentrations (P tot average 80–90 μg L −1 and PO 4 -P 25–30 μg L −1 ) typical for Peat Extraction runoff. The retention potential of sorption materials, that had previously shown good retention capacity was first studied in laboratory batch tests using steel slag (basic oxygen furnace slag (BOF)), Filtralite ® P (high Ca and Mg clay), CFH 12 (ferrihydroxide), limestone, Phoslock ® (95% bentonite clay material + 5% lanthanum) and iron gypsum in year 2010. Based on batch test results and material properties (column tests not suitable for fine clay materials such as Phoslock ® ), steel slag, CFH 12 and iron gypsum products were selected for column tests. The columns experiments were run for almost three months during spring 2011. Steel slag and Phoslock ® were selected for further testing in situ in a treatment wetland. In the laboratory set-ups, all materials tested retained PO 4 -P (70–90% in batch tests and approximately 10–80% in column experiments). However, in the field scale set-up, neither steel slag nor Phoslock ® successfully retained PO 4 -P. The reasons may be e.g. for steel slag, too low pH, too large grain size, and too short retention time. Also, for some set-up, the given instruction were not followed during construction works. Further studies are needed to test different particle sizes and new potential materials for retaining P in treatment wetlands with high hydraulic loading rate, low P concentration and low pH.

  • Physical properties of Peat soils under different land use options
    Soil Use and Management, 2016
    Co-Authors: Pirkko Mustamo, Anna-kaisa Ronkanen, Maarit Hyvärinen, Bjørn Kløve
    Abstract:

    Pristine Peat soils are characterized by large porosity, low density and large water and organic matter contents. Drainage and management practices change Peat properties by oxidation, compaction and mineral matter additions. This study examined differences in physical properties (hydraulic conductivity, water retention curve, bulk density, porosity, von Post degree of decomposition) in soil profiles of two Peatland forests, a cultivated Peatland, a Peat Extraction area and two pristine mires originally within the same Peatland area. Soil hydraulic conductivity of the drained sites (median hydraulic conductivities: 3.3 × 10−5 m/s, 2.9 × 10−8 m/s and 8.5 × 10−8 m/s for the forests, the cultivated site and the Peat Extraction area, respectively) was predicted better by land use option than by soil physical parameters. Detailed physical measurements were accompanied by monitoring of the water levels between drains. The model ‘DRAINMOD’ was used to assess the hydrology and the rapid fluctuations seen in groundwater depths. Hydraulic conductivity values needed to match the simulation of observed depth to groundwater data were an order of magnitude greater than those determined in field measurements, suggesting that macropore flow was an important pathway at the study sites. The rapid response of depth to groundwater during rainfall events indicated a small effective porosity and this was supported by the small measured values of drainable porosity. This study highlighted the potential role of land use and macropore flow in controlling water table fluctuation and related processes in Peat soils.

  • Long-term purification efficiency of a wetland constructed to treat runoff from Peat Extraction.
    Journal of environmental science and health. Part A Toxic hazardous substances & environmental engineering, 2016
    Co-Authors: Satu Maaria Karjalainen, Kaisa Heikkinen, Raimo Ihme, Bjørn Kløve
    Abstract:

    Peat Extraction increases the phosphorus, nitrogen, organic matter, suspended solids, and iron concentrations in runoff, resulting in negative effects on downstream water bodies. Wetlands are commonly used as natural cost-effective solutions to mitigate these negative effects. This study analyzed changes in the quality of runoff water from Peat Extraction areas and the long-term efficiency of constructed wetlands. The results indicate that the quality of runoff water changed after the initial drainage and during Peat Extraction. Nitrogen leached at high concentrations in the early stages of Peat Extraction following drainage, whereas the leaching of iron and phosphorus increased after Peat Extraction from deeper layers. Comparison of water quality and impurities retained immediately after treatment wetland construction and 14 years later showed that the treatment wetland remained functional, with good retention capacity, over a long period.

Heini Postila - One of the best experts on this subject based on the ideXlab platform.

  • Characteristics of sulfide bearing soil materials in Peat Extraction areas in N-Finland
    Journal of Geochemical Exploration, 2021
    Co-Authors: Miriam Nystrand, Heini Postila, Raimo Ihme, Mirkka Hadzic, Anneli Wichmann, Anssi Karppinen, Peter Österholm
    Abstract:

    Abstract Concern has been raised about the potential formation of acid sulfate soils and associated environmental problems related to Peat Extraction and, thus, Peat, sediment and till characteristics of 15 well drained Peat Extraction fields were investigated in northern and northwestern Finland. The aim was to identify and characterize the occurrence/abundance of potential acid (hypersulfidic) and actual acid sulfate soil materials as well as metals with regards to their depositional environment (marine/non-marine), black schists and soil material properties. Sulfide-bearing marine sediments were commonly found; the highest contents and thickness of sulfide sediments were found in areas 100 m a.c.s.l.). The highest content of sulfides in sediments was typically found just below the Peat layer. The sulfides existed mostly as pyrite (up to 3.5 wt% S) but were occasionally also mixed with more reactive metastable sulfide (Fe:S ratio in the order of 1:1), which coincide with high Fe concentrations, indicating that an abundance of Fe2+ can diminish the rate of pyrite formation. Sediments contained very high amounts of potential acidity, but in-field oxidation of the sediments was very limited. Although the sulfur contents were much lower (max 0.3% S), several of the till samples still became acidic (pH

  • Long-term purification efficiency and factors affecting performance in Peatland-based treatment wetlands : an analysis of 28 Peat Extraction sites in Finland
    Ecological Engineering, 2018
    Co-Authors: Kaisa Heikkinen, Heini Postila, Satu Maaria Karjalainen, Hannu Marttila, Raimo Ihme, Mirkka Hadzic, Anssi Karppinen, Mikko Tolkkinen, Bjørn Kløve
    Abstract:

    Abstract Peatland-based treatment wetlands that purify incoming water by means of natural physical, chemical and biological processes belonging to the Peatland ecosystem are widely used at Finnish Peat Extraction sites. They can comprise either undrained or drained overland flow areas (OFAs or DOFAs), with the OFAs representing the best available technology (BAT) for Peat Extraction. We analyse here the long-term treatment performance of these OFAs and DOFAs and factors affecting this performance. Data on 14 OFAs and DOFAs in different parts of Finland were taken from the extensive long-term environmental pollution control databases. Nearly half of these wetlands had been monitored for at least 4 years and seven for 8–23 years. The results indicated that Peatland-based treatment wetlands purify drainage water as efficiently as other natural treatment wetlands on soils in general, the common challenge being phosphorus retention. Iron was also efficiently retained. The average reductions were highest in OFAs with good hydraulic function, and these also showed long-term water protection performance. An important factor affecting purification efficiency was the hydraulic loading rate. Important system design elements in this regard were the size of the wetland in relation to its catchment area, its gradient, the length of the water flow route within the wetland, and the efficient flow area of the wetland. The results regarding the latter two design elements strongly indicate that not all the areas potentially suitable in DOFAs for water purification are yet being used efficiently.

  • Can limestone, steel slag or man-made sorption materials be used to enhance phosphate-phosphorus retention in treatment wetland for Peat Extraction runoff with low phosphorous concentration?
    Ecological Engineering, 2017
    Co-Authors: Heini Postila, Satu Maaria Karjalainen, Bjørn Kløve
    Abstract:

    Abstract This study examined possibilities to enhance phosphorus (P) retention in wetlands using different materials that could enhance removal of phosphate P (PO 4 -P) from runoff waters with fairly low P concentrations (P tot average 80–90 μg L −1 and PO 4 -P 25–30 μg L −1 ) typical for Peat Extraction runoff. The retention potential of sorption materials, that had previously shown good retention capacity was first studied in laboratory batch tests using steel slag (basic oxygen furnace slag (BOF)), Filtralite ® P (high Ca and Mg clay), CFH 12 (ferrihydroxide), limestone, Phoslock ® (95% bentonite clay material + 5% lanthanum) and iron gypsum in year 2010. Based on batch test results and material properties (column tests not suitable for fine clay materials such as Phoslock ® ), steel slag, CFH 12 and iron gypsum products were selected for column tests. The columns experiments were run for almost three months during spring 2011. Steel slag and Phoslock ® were selected for further testing in situ in a treatment wetland. In the laboratory set-ups, all materials tested retained PO 4 -P (70–90% in batch tests and approximately 10–80% in column experiments). However, in the field scale set-up, neither steel slag nor Phoslock ® successfully retained PO 4 -P. The reasons may be e.g. for steel slag, too low pH, too large grain size, and too short retention time. Also, for some set-up, the given instruction were not followed during construction works. Further studies are needed to test different particle sizes and new potential materials for retaining P in treatment wetlands with high hydraulic loading rate, low P concentration and low pH.

  • Wintertime purification efficiency of constructed wetlands treating runoff from Peat Extraction in a cold climate
    Ecological Engineering, 2015
    Co-Authors: Heini Postila, Anna-kaisa Ronkanen, Bjørn Kløve
    Abstract:

    Abstract With climate warming, snowmelt and runoff will occur more frequently during winter months. For efficient removal of runoff loads, water pollution protection methods such as constructed wetlands must also function during winter runoff periods. This study evaluated the purification efficiency and function of constructed wetlands in treating Peat Extraction runoff in all seasons, using collected data on inflow and outflow concentrations and wetland properties from 14 treatment wetlands in Finland. The runoff water flows partly on top of the Peat layer as surface flow and partly as horizontal subsurface flow. In three of these wetlands, seasonal ground frost depth was also observed in two winter periods. In winter, the surface Peat in constructed wetlands was mostly frozen (0–42 cm depth) but in some parts of the wetland the water flowed as overland or near-surface flow. Chemical oxygen demand (COD Mn ) and ammonium nitrogen (NH 4 -N) purification efficiency varied seasonally, with NH 4 -N purification efficiency being highest during the warm summer period and COD Mn purification efficiency being lowest during summer and winter. For other water quality parameters (N tot , P tot , PO 4 -P, Fe, and SS), no influence of season was noted.

  • Can treatment wetlands be constructed on drained Peatlands for efficient purification of Peat Extraction runoff
    Geoderma, 2014
    Co-Authors: Heini Postila, Jaakko Saukkoriipi, Kaisa Heikkinen, Satu Maaria Karjalainen, Minna Kuoppala, Hannu Marttila, Bjørn Kløve
    Abstract:

    Abstract Peat Extraction for energy purposes causes major changes in the aquatic and terrestrial environment. According to national strategies for extracting Peat in Finland, new Peat Extraction areas should be established on previously drained Peatlands. On such areas it is difficult to find the natural, intact Peatland required for treatment wetlands or so-called overland flow areas, which are considered the best available technology for runoff water purification. Therefore treatment wetlands must be constructed on drained Peatland. It is known that drainage causes physical, biogeochemical and hydraulic changes in the Peat layer, as well as changes in vegetation. It is probable that these changes affect the purification efficiency of wetland treatment systems in many ways. This study evaluated the function and characteristics of drained Peatland areas for purification of Peat Extraction runoff water. Study sites were established on 11 drained wetlands and their purification efficiency was evaluated. Detailed measurements of Peat physical properties and hydraulic conductivity, as well as studies on vegetation, were also made in the study areas. The results showed that wetlands constructed on drained Peatland areas can purify Peat Extraction runoff. However, leaching of phosphorus (P) and iron (Fe) was observed in some areas. Leaching is influenced e.g. by pH and the soil P pool. The chemical oxygen demand was also observed to increase in runoff water from the wetland. The results indicated that low (Fe + aluminium (Al) + manganese (Mn))/P ratio (≤ 25) and quite high P content (> 1200 mg/kg) in the surface Peat characterised those areas where P leaching was observed. The presence of a dense tree stand in a drained Peatland area also seemed to indicate release of nutrients from the area after its rewetting and use as a treatment wetland. Thus, potential nutrient release from a drained Peatland area intended for use as a treatment wetland can be assessed by studying the characteristics of the Peatland area, especially the Peat mineral content, and the vegetation, especially tree stand density in the area. Using the findings obtained, a conceptual decision tree was drawn up in order to help to establish and design wetlands in previously drained Peatland areas.

Hannu Marttila - One of the best experts on this subject based on the ideXlab platform.

  • Long-term purification efficiency and factors affecting performance in Peatland-based treatment wetlands : an analysis of 28 Peat Extraction sites in Finland
    Ecological Engineering, 2018
    Co-Authors: Kaisa Heikkinen, Heini Postila, Satu Maaria Karjalainen, Hannu Marttila, Raimo Ihme, Mirkka Hadzic, Anssi Karppinen, Mikko Tolkkinen, Bjørn Kløve
    Abstract:

    Abstract Peatland-based treatment wetlands that purify incoming water by means of natural physical, chemical and biological processes belonging to the Peatland ecosystem are widely used at Finnish Peat Extraction sites. They can comprise either undrained or drained overland flow areas (OFAs or DOFAs), with the OFAs representing the best available technology (BAT) for Peat Extraction. We analyse here the long-term treatment performance of these OFAs and DOFAs and factors affecting this performance. Data on 14 OFAs and DOFAs in different parts of Finland were taken from the extensive long-term environmental pollution control databases. Nearly half of these wetlands had been monitored for at least 4 years and seven for 8–23 years. The results indicated that Peatland-based treatment wetlands purify drainage water as efficiently as other natural treatment wetlands on soils in general, the common challenge being phosphorus retention. Iron was also efficiently retained. The average reductions were highest in OFAs with good hydraulic function, and these also showed long-term water protection performance. An important factor affecting purification efficiency was the hydraulic loading rate. Important system design elements in this regard were the size of the wetland in relation to its catchment area, its gradient, the length of the water flow route within the wetland, and the efficient flow area of the wetland. The results regarding the latter two design elements strongly indicate that not all the areas potentially suitable in DOFAs for water purification are yet being used efficiently.

  • Predicting organic matter, nitrogen, and phosphorus concentrations in runoff from Peat Extraction sites using partial least squares regression
    Water Resources Research, 2017
    Co-Authors: Tapio Tuukkanen, Hannu Marttila, Bjørn Kløve
    Abstract:

    Organic matter and nutrient export from drained Peatlands is affected by complex hydrological and biogeochemical interactions. Here, partial least squares regression (PLSR) was used to relate various soil and catchment characteristics to variations in chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) concentrations in runoff. Peat core samples and water quality data were collected from 15 Peat Extraction sites in Finland. PLSR models constructed by cross-validation and variable selection routines predicted 92, 88, and 95% of the variation in mean COD, TN, and TP concentration in runoff, respectively. The results showed that variations in COD were mainly related to net production (temperature and water-extractable dissolved organic carbon (DOC)), hydrology (topographical relief), and solubility of dissolved organic matter (Peat sulfur (S) and calcium (Ca) concentrations). Negative correlations for Peat S and runoff COD indicated that acidity from oxidation of organic S stored in Peat may be an important mechanism suppressing organic matter leaching. Moreover, runoff COD was associated with Peat aluminum (Al), P, and sodium (Na) concentrations. Hydrological controls on TN and COD were similar (i.e., related to topography), whereas degree of humification, bulk density, and water-extractable COD and Al provided additional explanations for TN concentration. Variations in runoff TP concentration were attributed to erosion of particulate P, as indicated by a positive correlation with suspended sediment concentration (SSC), and factors associated with metal-humic complexation and P adsorption (Peat Al, water-extractable P, and water-extractable iron (Fe)).

  • Optimization of Gravity-Driven Hydraulic Flocculators to Treat Peat Extraction Runoff Water
    Journal of Irrigation and Drainage Engineering, 2016
    Co-Authors: Shahram Mohammadighavam, Hannu Marttila, Elisangela Heiderscheidt, Bjørn Kløve
    Abstract:

    AbstractPeatland drainage and Peat Extraction result in runoff water rich in humus, sediments, and nutrients that requires simple purification methods to prevent pollution of surface waters. Chemical treatment of drainage water has been suggested as best management practice. However, good chemical purification results require flocculators to achieve efficient particle aggregation. This study evaluated gravity-driven hydraulic flocculators using full-scale three-dimensional (3D) computational fluid dynamic (CFD) turbulence models to simulate hydraulics, combined with data obtained in jar tests to estimate optimal mixing conditions for coagulation [velocity gradient (G-values)]. The CFD model was first run for several barrier configurations. The optimal structure was then tested for different ratios of distance between barriers [or opening slot width (B)] and flocculator width (W). The relationship between distribution of G-values and the target value of 40–60  s−1 was determined for different designs. The b...

  • Purification efficiency of a Peatland-based treatment wetland during snowmelt and runoff events
    Ecological Engineering, 2015
    Co-Authors: Riku Eskelinen, Hannu Marttila, Anna-kaisa Ronkanen, Bjørn Kløve
    Abstract:

    Abstract Purification efficiency of a treatment wetland for a Peat Extraction area in Northern Finland was studied March–October 2012. The focus was on the snowmelt season, with inflow and outflow sampled twice a day. All samples were analysed for stable isotopes of water and various water quality parameters. The wetland inflow and outflow were continuously monitored which in combination of precipitation and evaporation data allowed to study the effect of direct precipitation (dilution) and evaporation (enrichment) on the wetland water balance and water quality. The evaporated water volume was approximately 20% of the inflow on days with small inflows, whereas the proportion of precipitation was more variable. Negative correlations between hydraulic load and water quality at the outlet were found, whereas evaporation, precipitation from/to wetland had a negligible impact on outlet water quality. The observation year was rainier than normal, which complicated application of isotope techniques as the evaporation signal was weak. However, the heavy rain provided ample data on wetland performance under different flow conditions. The wetland reduced concentrations of e.g. suspended solids, phosphate-phosphorus, ammonium and iron, but reduction rate of other dissolved nutrients and organic carbon was low or negative. The observed retention of suspended solids load (28% during snowmelt, 61% during the whole observation period) shows that treatment wetlands can reduce the environmental impact of Peat Extraction areas.

  • Effect of soil properties on Peat erosion and suspended sediment delivery in drained Peatlands
    Water Resources Research, 2014
    Co-Authors: Tapio Tuukkanen, Hannu Marttila, Bjørn Kløve
    Abstract:

    Erosion from Peat Extraction areas is known to cause siltation of water courses and poor water quality. However, the main soil parameters affecting Peat erosion and suspended sediment (SS) yields from different catchments are not well understood. This paper used Peat properties (degree of humification, Peat type, ash content, porosity, moisture content, bulk density, and shear strength) and novel erosion threshold measurements from intact soil cores to explain Peat erodibility and spatial variations in SS concentrations (SSCs) and SS loads (SSLs) at 20 Finnish Peat Extraction sites. The erosion threshold measurements suggested that critical shear stresses for particle entrainment decrease with increasing degree of humification (von Post scale) and are significantly lower in well-decomposed Peat than in slightly or moderately decomposed Peat. Two critical shear stresses were obtained from moderately decomposed Peat samples, indicating a degree of surface armoring by coarse Peat fibers. Monitored long-term average SSC was highest at study sites with well-decomposed Peat, while very fine-grained mineral subsoil explained some of the highest long-term SSC in areas where drainage ditches penetrated below the upper Peat layer. Average SSL (kg d−1) at the study sites was best explained (R2 = 0.89) by average discharge and surface Peat decomposition level. Overall, this study provides new knowledge on Peat erosion and critical shear stresses that can be used in water conservation and sediment management practices for cutover Peatlands and other similar land uses.

Satu Maaria Karjalainen - One of the best experts on this subject based on the ideXlab platform.

  • Long-term purification efficiency and factors affecting performance in Peatland-based treatment wetlands : an analysis of 28 Peat Extraction sites in Finland
    Ecological Engineering, 2018
    Co-Authors: Kaisa Heikkinen, Heini Postila, Satu Maaria Karjalainen, Hannu Marttila, Raimo Ihme, Mirkka Hadzic, Anssi Karppinen, Mikko Tolkkinen, Bjørn Kløve
    Abstract:

    Abstract Peatland-based treatment wetlands that purify incoming water by means of natural physical, chemical and biological processes belonging to the Peatland ecosystem are widely used at Finnish Peat Extraction sites. They can comprise either undrained or drained overland flow areas (OFAs or DOFAs), with the OFAs representing the best available technology (BAT) for Peat Extraction. We analyse here the long-term treatment performance of these OFAs and DOFAs and factors affecting this performance. Data on 14 OFAs and DOFAs in different parts of Finland were taken from the extensive long-term environmental pollution control databases. Nearly half of these wetlands had been monitored for at least 4 years and seven for 8–23 years. The results indicated that Peatland-based treatment wetlands purify drainage water as efficiently as other natural treatment wetlands on soils in general, the common challenge being phosphorus retention. Iron was also efficiently retained. The average reductions were highest in OFAs with good hydraulic function, and these also showed long-term water protection performance. An important factor affecting purification efficiency was the hydraulic loading rate. Important system design elements in this regard were the size of the wetland in relation to its catchment area, its gradient, the length of the water flow route within the wetland, and the efficient flow area of the wetland. The results regarding the latter two design elements strongly indicate that not all the areas potentially suitable in DOFAs for water purification are yet being used efficiently.

  • Can limestone, steel slag or man-made sorption materials be used to enhance phosphate-phosphorus retention in treatment wetland for Peat Extraction runoff with low phosphorous concentration?
    Ecological Engineering, 2017
    Co-Authors: Heini Postila, Satu Maaria Karjalainen, Bjørn Kløve
    Abstract:

    Abstract This study examined possibilities to enhance phosphorus (P) retention in wetlands using different materials that could enhance removal of phosphate P (PO 4 -P) from runoff waters with fairly low P concentrations (P tot average 80–90 μg L −1 and PO 4 -P 25–30 μg L −1 ) typical for Peat Extraction runoff. The retention potential of sorption materials, that had previously shown good retention capacity was first studied in laboratory batch tests using steel slag (basic oxygen furnace slag (BOF)), Filtralite ® P (high Ca and Mg clay), CFH 12 (ferrihydroxide), limestone, Phoslock ® (95% bentonite clay material + 5% lanthanum) and iron gypsum in year 2010. Based on batch test results and material properties (column tests not suitable for fine clay materials such as Phoslock ® ), steel slag, CFH 12 and iron gypsum products were selected for column tests. The columns experiments were run for almost three months during spring 2011. Steel slag and Phoslock ® were selected for further testing in situ in a treatment wetland. In the laboratory set-ups, all materials tested retained PO 4 -P (70–90% in batch tests and approximately 10–80% in column experiments). However, in the field scale set-up, neither steel slag nor Phoslock ® successfully retained PO 4 -P. The reasons may be e.g. for steel slag, too low pH, too large grain size, and too short retention time. Also, for some set-up, the given instruction were not followed during construction works. Further studies are needed to test different particle sizes and new potential materials for retaining P in treatment wetlands with high hydraulic loading rate, low P concentration and low pH.

  • Long-term purification efficiency of a wetland constructed to treat runoff from Peat Extraction.
    Journal of environmental science and health. Part A Toxic hazardous substances & environmental engineering, 2016
    Co-Authors: Satu Maaria Karjalainen, Kaisa Heikkinen, Raimo Ihme, Bjørn Kløve
    Abstract:

    Peat Extraction increases the phosphorus, nitrogen, organic matter, suspended solids, and iron concentrations in runoff, resulting in negative effects on downstream water bodies. Wetlands are commonly used as natural cost-effective solutions to mitigate these negative effects. This study analyzed changes in the quality of runoff water from Peat Extraction areas and the long-term efficiency of constructed wetlands. The results indicate that the quality of runoff water changed after the initial drainage and during Peat Extraction. Nitrogen leached at high concentrations in the early stages of Peat Extraction following drainage, whereas the leaching of iron and phosphorus increased after Peat Extraction from deeper layers. Comparison of water quality and impurities retained immediately after treatment wetland construction and 14 years later showed that the treatment wetland remained functional, with good retention capacity, over a long period.

  • Identification of processes leading to long-term wastewater purification in northern treatment wetlands
    2016
    Co-Authors: Satu Maaria Karjalainen
    Abstract:

    Treatment wetlands (TW) constructed on natural wetlands potentially perform efficient purification of wastewater, but the longevity of TWs at northern latitudes is not well known. This thesis examined processes affecting nutrient and suspended solids (SS) retention in TWs during their lifetime. In total, 15 TWs were studied using water and Peat quality and gas flux data for different TW life lengths, the longest period being 18 years. The TWs commonly retained nutrients and suspended solids efficiently, even after 18 years of wastewater loading. For nitrogen (N) removal, sedimentation, nitrification-denitrification and plant uptake were efficient processes in the wetlands studied. However, emissions of nitrous oxide (N2O) from TWs are not a major contributor to climate change due to the small total surface area of TWs. The significance of anaerobic ammonium oxidation (anammox) and other newly discovered nitrogen processes in TWs remains to be clarified. Phosphorus (P) adsorption capacity in TWs remained efficient over a 12-year study period, the process being continuous when surfaces for adsorption were available or freed up through alternating absorption/desorption/ adsorption. Phosphorus accumulation by Peat accretion was low, but has not been well assessed in northern TWs receiving nutrient-rich waters. Iron (Fe) and aluminium (Al) in Peat Extraction runoff and purified wastewater from sewage treatment plants were of great importance for precipitation of P in TWs. Filtration and sedimentation of organic humic substances with Feor Al-bound P were other probable P retention pathways. In Peat Extraction runoff, Fe was more significant than Al for P retention, but Fe-bound P is susceptible to desorption in anaerobic environments, whereas Al-bound P is more strongly retained. Suspended solids were generally retained well, although there was great variation in percentage retention in individual TWs in different years and different seasons. Changes in discharge affected SS transportation and retention. SS were retained by sedimentation, the rate of which was affected by particle size. It is plausible that smaller particles from old Peat Extraction areas where the extracted Peat has a high humification degree erode more easily than poorly humified particles in surface Peat. Weakened SS retention may also have been caused by development of preferential flow areas (PFA) in TWs, changes in sediment delivery characteristics and sampling involving too few samples to show SS transportation sufficiently accurately for estimating SS retention. Thus TWs are potentially ideal for purification of wastewater and can have high purification efficiency even after long-term use in northern regions. They are also more widely applicable as long as their limitations are understood.

  • Can treatment wetlands be constructed on drained Peatlands for efficient purification of Peat Extraction runoff
    Geoderma, 2014
    Co-Authors: Heini Postila, Jaakko Saukkoriipi, Kaisa Heikkinen, Satu Maaria Karjalainen, Minna Kuoppala, Hannu Marttila, Bjørn Kløve
    Abstract:

    Abstract Peat Extraction for energy purposes causes major changes in the aquatic and terrestrial environment. According to national strategies for extracting Peat in Finland, new Peat Extraction areas should be established on previously drained Peatlands. On such areas it is difficult to find the natural, intact Peatland required for treatment wetlands or so-called overland flow areas, which are considered the best available technology for runoff water purification. Therefore treatment wetlands must be constructed on drained Peatland. It is known that drainage causes physical, biogeochemical and hydraulic changes in the Peat layer, as well as changes in vegetation. It is probable that these changes affect the purification efficiency of wetland treatment systems in many ways. This study evaluated the function and characteristics of drained Peatland areas for purification of Peat Extraction runoff water. Study sites were established on 11 drained wetlands and their purification efficiency was evaluated. Detailed measurements of Peat physical properties and hydraulic conductivity, as well as studies on vegetation, were also made in the study areas. The results showed that wetlands constructed on drained Peatland areas can purify Peat Extraction runoff. However, leaching of phosphorus (P) and iron (Fe) was observed in some areas. Leaching is influenced e.g. by pH and the soil P pool. The chemical oxygen demand was also observed to increase in runoff water from the wetland. The results indicated that low (Fe + aluminium (Al) + manganese (Mn))/P ratio (≤ 25) and quite high P content (> 1200 mg/kg) in the surface Peat characterised those areas where P leaching was observed. The presence of a dense tree stand in a drained Peatland area also seemed to indicate release of nutrients from the area after its rewetting and use as a treatment wetland. Thus, potential nutrient release from a drained Peatland area intended for use as a treatment wetland can be assessed by studying the characteristics of the Peatland area, especially the Peat mineral content, and the vegetation, especially tree stand density in the area. Using the findings obtained, a conceptual decision tree was drawn up in order to help to establish and design wetlands in previously drained Peatland areas.

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  • impact of reed canary grass cultivation and mineral fertilisation on the microbial abundance and genetic potential for methane production in residual Peat of an abandoned Peat Extraction area
    PLOS ONE, 2016
    Co-Authors: Mikk Espenberg, Martin Maddison, Hiie Nolvak, Jarvi Jarveoja, Marika Truu, Jaak Truu, Ülo Mander
    Abstract:

    : This study examined physiochemical conditions and prokaryotic community structure (the bacterial and archaeal 16S rRNA genes and mcrA gene abundances and proportions), and evaluated the effect of reed canary grass cultivation and mineral fertilisation on these factors, in the 60 cm thick residual Peat layer of experimental plots located on an abandoned Peat Extraction area. The archaeal proportion was 0.67-39.56% in the prokaryotic community and the methanogens proportion was 0.01-1.77% in the archaeal community. When bacterial abundance was higher in the top 20 cm of Peat, the archaea were more abundant in the 20-60 cm layer and methanogens in the 40-60 cm layer of the residual Peat. The bacterial abundance was significantly increased, but archaeal abundance was not affected by cultivation. The fertiliser application had a slight effect on Peat properties and on archaeal and methanogen abundances in the deeper layer of cultivated Peat. The CH4 emission was positively related to mcrA abundance in the 20-60 cm of the bare Peat, while in case of reed canary grass cultivation these two parameters were not correlated. Reed canary grass cultivation mitigated CH4 emission, although methanogen abundance remained approximately the same or even increased in different layers of residual Peat under cultivated sites over time. This study supports the outlook of using abandoned Peat Extraction areas to produce reed canary grass for energy purposes as an advisable land-use practice from the perspective of atmospheric impact in Peatland-rich Northern Europe.

  • Impact of water table level on annual carbon and greenhouse gas balances of a restored Peat Extraction area
    Biogeosciences, 2016
    Co-Authors: Jarvi Jarveoja, Martin Maddison, Kaido Soosaar, M. Peichl, K. Vellak, E. Karofeld, A. Teemusk, Ülo Mander
    Abstract:

    Abstract. Peatland restoration may provide a potential after-use option to mitigate the negative climate impact of abandoned Peat Extraction areas; currently, however, knowledge about restoration effects on the annual balances of carbon (C) and greenhouse gas (GHG) exchanges is still limited. The aim of this study was to investigate the impact of contrasting mean water table levels (WTLs) on the annual C and GHG balances of restoration treatments with high (ResH) and low (ResL) WTL relative to an unrestored bare Peat (BP) site. Measurements of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes were conducted over a full year using the closed chamber method and complemented by measurements of abiotic controls and vegetation cover. Three years following restoration, the difference in the mean WTL resulted in higher bryophyte and lower vascular plant cover in ResH relative to ResL. Consequently, greater gross primary production and autotrophic respiration associated with greater vascular plant cover were observed in ResL compared to ResH. However, the means of the measured net ecosystem CO2 exchanges (NEE) were not significantly different between ResH and ResL. Similarly, no significant differences were observed in the respective means of CH4 and N2O exchanges. In comparison to the two restored sites, greater net CO2, similar CH4 and greater N2O emissions occurred in BP. On the annual scale, ResH, ResL and BP were C sources of 111, 103 and 268 g C m−2 yr−1 and had positive GHG balances of 4.1, 3.8 and 10.2 t CO2 eq ha−1 yr−1, respectively. Thus, the different WTLs had a limited impact on the C and GHG balances in the two restored treatments 3 years following restoration. However, the C and GHG balances in ResH and ResL were considerably lower than in BP due to the large reduction in CO2 emissions. This study therefore suggests that restoration may serve as an effective method to mitigate the negative climate impacts of abandoned Peat Extraction areas.

  • Impact of water table level on annual carbon and greenhouse gas balances of a restored Peat Extraction area
    2015
    Co-Authors: Jarvi Jarveoja, M. Peichl, M. Maddison, K. Soosaar, K. Vellak, E. Karofeld, A. Teemusk, Ü. Mander
    Abstract:

    Abstract. Peatland restoration may provide a potential after-use option to mitigate the negative climate impact of abandoned Peat Extraction areas; currently, however, knowledge about restoration effects on the annual balances of carbon (C) and greenhouse gas (GHG) exchanges is still limited. The aim of this study was to investigate the impact of contrasting water table levels (WTL) on the annual C and GHG balances of restoration treatments with high (Res-H) and low (Res-L) WTL relative to an unrestored bare Peat (BP) site. Measurements of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes were conducted over a full year using the closed chamber method and complemented by measurements of abiotic controls and vegetation cover. Three years following restoration, the difference in the mean WTL resulted in higher bryophyte and lower vascular plant cover in Res-H relative to Res-L. Consequently, greater gross primary production and autotrophic respiration associated with greater vascular plant cover were observed in Res-L compared to Res-H. However, the means of the measured net ecosystem CO2 exchanges (NEE) were not significantly different between Res-H and Res-L. Similarly, no significant differences were observed in the respective means of CH4 and N2O exchanges in Res-H and Res-L, respectively. In comparison to the two restored sites, greater net CO2, similar CH4 and greater N2O emissions occurred in BP. On the annual scale, Res-H, Res-L and BP were C sources of 111, 103 and 268 g C m−2 yr−1 and had positive GHG balances of 4.1, 3.8 and 10.2 t CO2 eq ha−1 yr−1, respectively. Thus, the different WTLs had a limited impact on the C and GHG balances in the two restored treatments three years following restoration. However, the C and GHG balances in Res-H and Res-L were considerably lower than in BP owing to the large reduction in CO2 emissions. This study therefore suggests that restoration may serve as an effective method to mitigate the negative climate impacts of abandoned Peat Extraction areas.

  • Mitigation of greenhouse gas emissions from an abandoned Baltic Peat Extraction area by growing reed canary grass: life-cycle assessment
    Regional Environmental Change, 2013
    Co-Authors: Jarvi Jarveoja, Martin Maddison, Janika Laht, Kaido Soosaar, Ivika Ostonen, Ülo Mander
    Abstract:

    Abandoned Peat Extraction areas are continuous emitters of GHGs; hence, abandonment of Peat Extraction areas should immediately be followed by conversion to an appropriate after-use. Our primary aim was to clarify the atmospheric impact of reed canary grass (RCG, Phalaris arundinacea L.) cultivation on an abandoned Peat Extraction area and to compare it to other after-treatment alternatives. We performed a life-cycle assessment for five different after-use options for a drained organic soil withdrawn from Peat Extraction: (I) bare Peat soil (no management), (II) non-fertilised Phalaris cultivation, (III) fertilised Phalaris cultivation, (IV) afforestation, and (V) rewetting. Our results showed that on average the non-fertilised and fertilised Phalaris alternatives had a cooling effect on the atmosphere (−10,837 and −477 kg CO_2-eq ha^−1 year^−1, respectively), whereas afforestation, rewetting, and no-management alternatives contributed to global warming (9,511, 8,195, and 2,529 kg CO_2-eq ha^−1 year^−1, respectively). The main components influencing the global warming potential of different after-use alternatives were site GHG emissions, carbon assimilation by plants, and emissions from combustion, while management-related emissions played a relatively minor role. The results of this study indicate that, from the perspective of atmospheric impact, the most suitable after-use option for an abandoned Peat Extraction area is cultivation of RCG.

  • reed canary grass cultivation mitigates greenhouse gas emissions from abandoned Peat Extraction areas
    Gcb Bioenergy, 2012
    Co-Authors: Ülo Mander, Martin Maddison, Jarvi Jarveoja, Kaido Soosaar, Ivika Ostonen, Rene Aavola, Jüri-ott Salm
    Abstract:

    We studied the impact of reed canary grass (RCG) cultivation on greenhouse gas emission in the following sites of an abandoned Peat Extraction area in Estonia: a bare soil (BS) site, a nonfertilized Phalaris (nfP) plot, a fertilized Phalaris (fP) plot, and a natural bog (NB) and a fen meadow (FM) as reference areas. The C balance and global warming potential (GWP) were estimated by measuring CO2 ,C H4, and N2O emissions and aboveground and belowground biomass variations. The high CO2 flux from the nfP and fP sites and the low CO2 emission from the BS are due to the enhancement of mineralization by plant growth on planted sites and inhibited mineralization by the recalcitrant C of BS. The NB site emitted 24 kg CH4 ha 1 yr 1 , whereas the almost zero CH4 emission from the Phalaris plots and the BS site was due to the high S concentration in Peat, which probably inhibited methanogenesis. The N2O flux varied from <0.1 kg on the Phalaris plots and the NB to 2.64 kg N2O ha 1 yr 1 on the FM. The highest yield of RCG was obtained in autumn (13.9 t and 8.0 t dw ha 1 on the fP and nfP, respectively). By spring, the biomass yield on the fP and nfP plot was 12.7 and 7.9 t dw ha 1 , respectively. The C balance of nfP and fP plots was negative in comparison to the BS (3322, 5983, and 2504 kg CO2 ha 1 yr 1 , respectively). This indicates that the cultivation of RCG transformed them from a net source of C into a net sink of C. The GWP for the fP and nfP sites was 5981 and 3885 kg CO2 eq ha 1 yr 1 , respectively. The BS site had a total GWP of 2544 kg CO2 eq ha 1 yr 1 .