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The watershed areas and buffer zones at Asusuo, Sudenalho, Murtsuo, Kirvessuo, Tulilahti, Hirsikangas and Kallioneva.
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Does the use of ripar-ian buffer zones in forest drainage sites to reduce the transport of solids simultaneously increase the export of solutes? Boreal Env. Res. 10: 191–201. Riparian buffer zone areas (BZAs) effectively reduce sediment transport and are considered as the most important water protection method in forest drainage sites in Finland. H...
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... all about 13 million hectares of peatlands and paludified mineral soil sites have been drained for forestry in the Nordic (Finland, Sweden, Norway) and Baltic (Estonia, Latvia, Lithuania) countries and Russia. Forestry drainage has been particularly intensive in Finland (> 5 million hectares), where the portion of drained peatland forests from the total forestry area is almost 20%. Although drainage has greatly increased the area of productive forestry sites, it is on the other hand considered the most harmful forestry measure from the viewpoint of water quality protection. It has been shown that especially the concentrations of suspended peat and mineral soil particles in discharge waters from peatlands increase after drainage. High loads of suspended solids (SS) are usually associated with the actual ditching work (Heikurainen et al . 1978, Joensuu et al. 1999), but even afterwards, high concen- trations may occur due to erosion of bare soil surfaces in the ditches (Heikurainen et al . 1978, Hynninen and Sepponen 1983). High SS loads have numerous adverse effects on aquatic ecosystems (Fairchild et al . 1987, Newcombe and MacDonald 1991). For example, high SS concentrations reduce the numbers and diversity of aquatic invertebrates and different fish species, especially salmon. High SS loads also reduce primary production by decreasing light penetration and disrupting plant cells and respiratory surfaces. Furthermore, sediments play an important role in the sorption, storage, transport, and release of various contaminants. To decrease the transport of SS to water courses in practical peatland forestry in Finland, riparian buffer zone areas (BZAs) are presently being created downstream from drainage areas. Buffer wetlands are usually created by simply conducting discharge waters from drained peat- lands to pristine mires or, occasionally, also to paludified mineral soils. However, because most peatlands in Finland have been drained, a common practice is to create buffer zones by restoring and rewetting sections of drained peat- lands by filling in or blocking the main drainage ditches (Silvan 2004). The sizes of BZAs used in practical forestry may vary considerably but rarely exceed one hectare. If only productive forestry land is available for the construction of the buffer, narrow (generally < 10-m wide) riparian buffer strips may be used (Liljaniemi et al. 2003). As a deviation from those strips, we here define BZAs as areas where the size of the protective, intact area between drainage area and water-course is at least several hundreds of square meters. BZAs have proven to be an effective means in decreasing the transport of SS. Sufficiently large and correctly designed BZAs may capture 70%–100% of the sediment in the through-flow water (Sallantaus et al. 1998, Vasander et al . 2003, Nieminen et al . 2005). However, although BZAs effectively decrease SS transport, they may on the other hand increase the export of soluble phosphorus (P) (Gehrels and Mulamoot- til 1989, Vasander et al . 2003). A BZA created by rewetting and restoring a former peatland drainage area reduced SS concentration from about 100 mg l –1 to 1 mg l –1 , but increased P con- centrations in downstream waters from a level of < 25 μg l –1 to a peak concentration of as high as 300 μg l –1 (Sallantaus et al. 1998). However, another BZA in that study had no effect on P concentrations in discharge waters and it is still unclear whether the BZA-induced P leaching is a common problem. It is also unclear if BZAs act as a sink or source for other soluble nutrients, heavy metals and soluble organic substances. In this study, we monitored water inflow and outflow at seven BZAs in peatland dominated watersheds in south-central Finland, and studied if BZAs had significant effects on the concentra- tions of dissolved organic carbon (DOC), P, iron (Fe) and aluminium (Al) in through-flow water. The study was carried out at seven watershed areas in south-central Finland. At each watershed there was an old peatland drainage area and a buffer zone area (BZA) was designed below it (Fig. 1 and Table 1). The Asusuo, Sudenalho, Murtsuo, Kirvessuo and Hirsikangas BZAs were constructed by filling in the main outlet ditch from the upstream drainage area and conducting the water to an adjacent undisturbed and flat mire area (at Hirsikangas, Murtsuo and Sudenalho via a distribution ditch). No active BZA con- struction operations were needed at Kallioneva and Tulilahti, where the outlet ditches from the drainage areas ended in undrained areas through which the waters had been flowing long before the monitoring in the present study was started. According to a careful leveling of the BZAs and the watershed areas upstream, the sizes of BZAs varied from 0.09 to 1.03 hectares, accounting for 0.05%–4.88% of the area of the watershed. The Sudenalho, Hirsikangas and Kallioneva BZAs were pristine, treeless mires. Except for the areas next to the in-filled ditch, the Asusuo BZA was also classified as an undrained, pris- tine mire according to the site type classification of peat soils used in Finland (Heikurainen and Pakarinen 1982). It was covered by a dense, < 10-m-tall birch stand ( Betula pubescens Ehrh.). Due to drainage the ground vegetation at the Murtsuo and Kirvessuo BZAs had transformed from the pristine state and they were classified as drained peatland forests. The Murtsuo BZA was dominated by a dense birch ( B. pubescens ) stand, but in connection with building a new electricity line about half of the area was clear- cut in 1999. The Kirvessuo BZA was character- ized by a mixed spruce ( Picea abies Karst.), pine ( Pinus sylvestris L.) and birch ( B. pubescens ) stand and a relatively large open area in the middle. The Tulilahti BZA was a paludified mineral soil forest of the Vaccinium vitis-idaea type (Cajander 1926) and it had been cut in a seed tree position a few years before the start of the study. Except for the areas near the surround- ing mineral soils, the depth of the peat layer was > 1 m at all 6 peatland dominated BZAs. The only BZA on a mineral soil site (Tuli- lahti) was characterized at its lowest parts by a number of big rocks and the waters from the upstream drainage area mostly traveled as chan- nel flow between these rocks and bulk soil (silty till). Most of the water flow at the other BZAs occurred as overland flow (or sheet flow) across the relatively flat buffer areas. Generally, the contribution of channel flow to total surface flow at the BZAs constructed on peat soils appeared to depend largely on the size of BZA, i.e. channel flow was considerable at small BZAs, but almost totally absent at Hirsikangas and Kallioneva. Similarly, the importance of subsurface flow may be expected to be strongly related to BZA size and considerable subsurface flow unlikely occurs at the very small BZAs, such as Sude- nalho and Kirvessuo. At each BZA, sampling of inflow and outflow waters was started as soon as the BZA construc- tion operations were finished. This was in spring 1995 at Murtsuo and Asusuo, 1996 at Kirvessuo, Tulilahti and Sudenalho and 1998 at Kallioneva and Hirsikangas. The sampling (twice a week in spring, weekly during other seasons) continued until the end of 2000 (Sudenalho and Tulilahti) or 2001 (all other BZAs). The inflow samples were taken either from the overflow of a V - notched weir (Asusuo, Murtsuo, Kallioneva) or directly from flowing water in the inlet ditch. Outflow water sampling also occurred at a V - notched weir (Kallioneva and Hirsikangas) or at a natural flow channel. In the laboratory, the samples were filtered through 1.0 μm fibre-glass filters and the filtrates analysed for dissolved P, Al and Fe by ICP/AES; ARL 3580, and for DOC, with Shimadzu carbon analyser. The total number of samples collected from the Asusuo BZA was 129 for both inflow and outflow water. The numbers of samples for the other areas were: Murtsuo 213, Kirvessuo 128, Sudenalho 71, Tulilahti 119, Hirsikangas 81, and Kallioneva 78. Owing to the small size of the BZAs relative to the areas of the watersheds, no differences in runoff between inflow and outflow water sampling positions were assumed. Thus, the change in through-flow concentration (mg l –1 ), rather than in solute load (kg ha –1 ), was used as the parameter for determining the impact of BZAs on the transport of solutes. This was also because, in the absence of defined outflow water channels at Asusuo and Kirvessuo, it was not possible to measure runoff. Paired-sample t -test was used to test if the differences in DOC, P, Fe and Al concentrations between inflow and outflow samples were statis- tically significant. All samples collected at each BZA were used in the calculations. The two smallest BZAs (Sudenalho and Kirves- suo, 0.05% and 0.09% of the area of watershed, respectively) had very little effect on through- flow quality (Figs. 2–5). A slight increase in P and Fe concentrations in through-flow occurred at Kirvessuo, but no significant differences between inflow and outflows waters were found at Sudenalho (Table 2). The three medium-sized BZAs (Asusuo, Murtsuo and Tulilahti, 0.15%–0.23% of the area of watershed) generally increased the ...
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To tackle the symptoms of eutrophication in the open Baltic Sea and Finnish coastal waters, Finland has agreed to reduce both total nitrogen (TN) and total phosphorus (TP) inputs. Due to large investments in treatment of municipal and industrial wastewaters, TP loads started to decrease already in the mid-1970s and the respective TN loads in the mi...
Citations
... Overflow fields and constructed wetlands are typically employed before the runoff can reach the water bodies (e.g., Joensuu, 2002;Väänänen et al., 2008). Sedimentation-based and flow-control water protection methods can retain coarse-textured mineral soil particles from the runoff waters or prevent ditch erosion in the first place (Liljaniemi et al., 2003;Nieminen et al., 2005a;Eskelinen et al., 2015). However, these water protection methods are not particularly effective in retaining the soluble nutrients. ...
... There are several approaches for water purification (Nieminen et al., 2005a;Jafari et al., 2017;Asfaram et al., 2017), which are generally based on adsorption processes and attempt to adsorb both organic and inorganic impurities (Moussout et al., 2018;Battas et al., 2019). In chemical and water engineering, adsorption has been considered a viable, practical and cost-effective strategy for the removal of contaminants from polluted media (Konneh et al., 2021;Singh et al., 2018). ...
Water quality is significantly affected by the forest logging activities that are carried out in drained peatlands, which causes a notable enhancement in sediment loading and nutrient export to water bodies. Furthermore, the seasonal fluctuations in nutrient concentrations in the runoff further underscore the need for efficient water protection tools in peatland forestry. To address these issues, biochar-based adsorption methods can potentially offer an effective alternative for water protection in peatland forestry. The current thesis investigates the potential for adsorption-based nutrient recovery from clear-cut peatland runoff water using Norway spruce and Silver birch biochars. In particular, the aim is to i) study the adsorption characteristics in relation to biochar properties and nutrient compounds in runoff waters in a small-scale laboratory experiment (Paper I); ii) investigate the adsorption characteristics of nitrogen (N) compounds from runoff water in a meso-scale laboratory experiment that utilises biochar reactors (Paper II); and iii) investigate the dynamics of biochar adsorption and desorption under fluctuating total nitrogen (TN) concentrations in runoff water (Paper III). Biochar made from birch and spruce were shown to efficiently adsorb N compounds from the water. Across all experiments, the TN content declined significantly, irrespective of the scale, or whether the runoff volume ranged from litres (I and III) to hundreds of litres (II). Furthermore, the TN content at the beginning of the experiment declined at the fastest rate. The results indicate that cases of relatively low adsorption capacity were attributed to the low initial TN concentrations in the water. In addition, TN adsorption occurs above a threshold concentration in natural runoff water. The spruce did not adsorb TN when the concentrations in the runoff water fell below 0.4 mg L-1. In this thesis, biochar emerges as a compelling water protection solution, particularly in regions where clear-cut peatlands release substantial quantities of nutrients.
... Overflow fields and constructed wetlands are typically employed before the runoff can reach the water bodies (e.g., Joensuu, 2002;Väänänen et al., 2008). Sedimentation-based and flow-control water protection methods can retain coarse-textured mineral soil particles from the runoff waters or prevent ditch erosion in the first place (Liljaniemi et al., 2003;Nieminen et al., 2005a;Eskelinen et al., 2015). However, these water protection methods are not particularly effective in retaining the soluble nutrients. ...
... There are several approaches for water purification (Nieminen et al., 2005a;Jafari et al., 2017;Asfaram et al., 2017), which are generally based on adsorption processes and attempt to adsorb both organic and inorganic impurities (Moussout et al., 2018;Battas et al., 2019). In chemical and water engineering, adsorption has been considered a viable, practical and cost-effective strategy for the removal of contaminants from polluted media (Konneh et al., 2021;Singh et al., 2018). ...
Water quality is significantly affected by the forest logging activities that are carried out in drained peatlands, which causes a notable enhancement in sediment loading and nutrient export to water bodies. Furthermore, the seasonal fluctuations in nutrient concentrations in the runoff further underscore the need for efficient water protection tools in peatland forestry. To address these issues, biochar-based adsorption methods can potentially offer an effective alternative for water protection in peatland forestry. The current thesis investigates the potential for adsorption-based nutrient recovery from clear-cut peatland runoff water using Norway spruce and Silver birch biochars. In particular, the aim is to i) study the adsorption characteristics in relation to biochar properties and nutrient compounds in runoff waters in a small-scale laboratory experiment (Paper I); ii) investigate the adsorption characteristics of nitrogen (N) compounds from runoff water in a meso-scale laboratory experiment that utilises biochar reactors (Paper II); and iii) investigate the dynamics of biochar adsorption and desorption under fluctuating total nitrogen (TN) concentrations in runoff water (Paper III). Biochar made from birch and spruce were shown to efficiently adsorb N compounds from the water. Across all experiments, the TN content declined significantly, irrespective of the scale, or whether the runoff volume ranged from litres (I and III) to hundreds of litres (II). Furthermore, the TN content at the beginning of the experiment declined at the fastest rate. The results indicate that cases of relatively low adsorption capacity were attributed to the low initial TN concentrations in the water. In addition, TN adsorption occurs above a threshold concentration in natural runoff water. The spruce did not adsorb TN when the concentrations in the runoff water fell below 0.4 mg L-1. In this thesis, biochar emerges as a compelling water protection solution, particularly in regions where clear-cut peatlands release substantial quantities of nutrients.
... One of the widely recommended methods to protect water courses from the negative impacts of forest harvesting activities is to divert the runoff through a natural or restored buffer area before it enters the water courses (Silvan et al. 2004a;Nieminen et al. 2005;Väänänen et al. 2008;Vikman et al. 2010). However, in Ireland and the UK, the establishment of riparian buffer areas was not considered during the afforestation of the majority of upland blanket peat catchments and trees were planted up to the edges of streams (Ryder et al. 2011). ...
Forest harvesting activities on peatlands have long been associated with nutrient leaching and deterioration of downstream water quality. This study aims to assess the effect of grass seeding practice on harvested blanket peatlands to immobilize N and reduce its export to water courses. First, a plot-scale field experiment was conducted by seeding with two grass species (Holcus lanatus and Agrostis capillaris) to study the N uptake potential from a harvested area. Secondly, a simulated rainfall experiment was conducted to study the effect of these grasses on reducing N leaching from surface peat using laboratory flume approach. In the end, the role of seeded grasses in removing N from nutrient-rich throughflow water was assessed using simulated overland flow experiment. The results showed that the seeded grasses had the potential to uptake over 30 kg ha⁻¹ of N in the first year after seeding on harvested peatlands, whereas it takes over 2.5 years to establish the same level of N uptake by natural re-vegetation (non-grassed). In the simulated rainfall experiment, the inorganic N (NH4⁺-N and NO3⁻-N) leaching in surface runoff from grassed flumes was 72% lower (453 mg m⁻²) than non-grassed flumes (1643 mg m⁻²). In the simulated overland flow experiment, the N retention by grassed flumes was significantly higher (98%) as compared to non-grassed flumes (70%) in the simulated overland flow experiment. Comparatively higher concentrations of NH4⁺-N and NO3⁻-N in soil porewaters of non-grassed flumes suggest that this N retention by non-grassed flumes is less sustainable and is likely to be leached in runoff in subsequent flow events. The results from all three experiments in this study suggest that seeded grasses are a major sink of N on harvested blanket peatland forests. Immobilization of N onsite using the grass seeding and mini-buffer practice could be an efficient and a feasible mean of reducing N export from harvested blanket peatland forests in order to protect the sensitive water courses. However, the sustainability of retention and immobilization of N by grasses needs to be studied further in long-term field-scale experiments on multiple peatland sites.
... Vasander et al. (2003) restored a drained Norway spruce mire site covering about 2% of a forested catchment in southern Finland and found highly increased phosphorus exports during the first two years after restoration. However, Nieminen et al. (2005) found no nutrient release from wetland buffers that had been restored about 10 years earlier, suggesting that the increase in nutrient exports caused by restoration may not last long. Similarly, Finnegan et al. (2012) reported no phosphorus release to a receiving stream from a buffer area restored five years earlier in a forested blanket peat catchment in Ireland. ...
We restored small downstream sections of forestry-drained peatland catchments for use as wetland buffer areas and studied the effects of their restoration on the exports of nitrogen, phosphorus, dissolved organic carbon, and dissolved aluminium and iron. Even though the buffer areas were small relative to their catchment areas (0.5–3.5%), buffer restoration clearly increased pollutant exports. Thus, even though restored buffer areas proved later to be efficient in retaining pollutants from their upstream catchment area, turning from an initial restoration-induced pollutant source to their net sink may take a long time. In one restored buffer, the whole concept of restoration to improve water quality was judged questionable due to significantly deteriorated water quality. We presented a hypothesis that high iron content in peat may be a common denominator for the sites with high carbon and organic nutrient exports after restoration of forestry-drained peatlands. We conclude that it may not always be reasonable to restore drained peatlands for use as wetland buffers due to high initial pollution exports.
... It is very likely that climate change will further escalate the problem by enhancing peat decomposition and nutrient release (Nieminen et al. 2017b). While current water protection methods such as sedimentation pits, sedimentation ponds, and peatland buffer areas can reduce the export of suspended solids, these methods are rather ineffective in reducing dissolved nutrient load (Joensuu et al. 2002;Liljaniemi et al. 2003;Nieminen et al. 2005). This calls for new methods in water protection. ...
... Current water protection methods used in forested peatlands, such as sedimentation ponds, sedimentation pits, overland flow fields and peak-flow control methods, retain suspended solids, but are not capable to effectively remove NO 3 − -N from runoff water (Joensuu et al. 2002;Liljaniemi et al. 2003;Nieminen et al. 2005). Furthermore, riparian buffer zones and overland flow fields require large areas, and nutrient retention through plant uptake is restricted to the growing season (Liljaniemi et al. 2003;Nieminen et al. 2005). ...
... Current water protection methods used in forested peatlands, such as sedimentation ponds, sedimentation pits, overland flow fields and peak-flow control methods, retain suspended solids, but are not capable to effectively remove NO 3 − -N from runoff water (Joensuu et al. 2002;Liljaniemi et al. 2003;Nieminen et al. 2005). Furthermore, riparian buffer zones and overland flow fields require large areas, and nutrient retention through plant uptake is restricted to the growing season (Liljaniemi et al. 2003;Nieminen et al. 2005). Available physico-chemical and biological technologies developed for NO 3 − -N removal in turn tend to be expensive and generate additional by-products and NO 3 − -N concentrated waste streams (Bhatnagar and Sillanpää 2011). ...
Forest management practices in boreal peatlands increase nutrient export and suspended solids to watercourses calling for development of new water protection methods. One potential solution could be adsorption-based purification of runoff water using biochar. The aim of this study was to determine the adsorption rate and capacity for Norway spruce and silver birch biochars to design a biochar-filled reactor for a ditch drain. In a 10-day laboratory experiment, biochar was stirred with runoff water from a clear-cut peatland forest, and changes in water pH, total nitrogen, nitrate nitrogen, ammonium nitrogen, phosphorus, and total organic carbon concentrations were measured. Based on the concentration changes, adsorption was quantified and adsorption model containing the adsorption rate and capacity was fitted to the data. Our results indicate that biochar effectively adsorbs both inorganic and organic nitrogen from runoff water. Birch biochar had higher adsorption capacity of nitrogen than spruce biochar. This study demonstrates that the adsorption of nitrogen compounds onto biochar surfaces increases with increasing initial concentrations. Thus, aquatic ecosystems exposed to high nutrient loads from fertile peatlands would particularly benefit from biochar-based water purification.
... In addition, the construction of ponds is expensive and must be maintained and emptied regularly where the loads of suspended sediments from the upstream drainage areas or clear-cut sites are high. Buffer zones have also been considered as an inexpensive and maintenance-free means of improving water quality from peatlands drained for forestry purposes [79]. However, the cost-efficiency of buffer zones decreases drastically if we consider the value of the forest stand in the area that becomes ruled outside economic use [80]. ...
Biochar can be an effective sorbent material for removal of nutrients from water due to its high specific surface area, porous structure, and high cation and anion exchange capacity. The aim of this study was to test a biochar reactor and to evaluate its efficiency in runoff water purification and consecutive nutrient recycling in clear-cut peatland forests. The goodness of the method was tested in a meso-scale (water volume thousands of liters) reactor experiment by circulating runoff water through wood biochar-filled columns and by determining water nutrient concentrations in the column inlet and outlet. The pseudo-first and second order kinetic models were fitted to the experimental data and the adsorption rate (Kad) and maximum adsorption capacity (Qmax) of the biochar reactor were quantified. The concentration of total nitrogen (TN) decreased by 58% during the 8-week experiment; the majority of TN adsorption occurred within the first 3 days. In addition, NO3-N and NH4-N concentrations decreased below the detection limit in 5 days after the beginning of the experiment. The maximum adsorption capacity of the biochar reactor varied between 0.03–0.04 mg g−1 biochar for NH4-N, and was equal to 0.02 mg g−1 biochar for TN. The results demonstrated that the biochar reactor was not able to adsorb TN when the water TN concentration was below 0.4 mg L−1. These results suggest that a biochar reactor can be a useful and effective method for runoff water purification in clear-cut forests and further development and testing is warranted. Unlike traditional water protection methods in peatland forestry, the biochar reactor can effectively remove NO3-N from water. This makes the biochar reactor a promising water protection tool to be tested in sites where there is the risk of a high rate of nutrient export after forest harvesting or drainage.
... Significant reduction is not likely to occur from the inflow water with already low nutrient concentrations close to background levels of forested areas. It is therefore not surprising that poor retention efficiencies were reported when the performance of wetland buffers was assessed under such conditions (e.g., Nieminen et al. 2005b). ...
The objective of this study was to evaluate the potential of different water management options to mitigate sediment and nutrient exports from ditch network maintenance (DNM) areas in boreal peatland forests. Available literature was reviewed, past data reanalyzed, effects of drainage intensity modeled, and major research gaps identified. The results indicate that excess downstream loads may be difficult to prevent. Water protection structures constructed to capture eroded matter are either inefficient (sedimentation ponds) or difficult to apply (wetland buffers). It may be more efficient to decrease erosion, either by limiting peak water velocity (dam structures) or by adjusting ditch depth and spacing to enable satisfactory drainage without exposing the mineral soil below peat. Future research should be directed towards the effects of ditch breaks and adjusted ditch depth and spacing in managing water quality in DNM areas.
... For example in forestry areas, leaving discontinuities in the drainage network, sedimentation ponds, flow control dams, prohibiting tree felling in riparian zones and constructed wetlands have become common requirements when the drainage network is being maintained or new drainage ditches dug e.g. (Hökkä et al. 2011, Joensuu et al. 1999b, Nieminen et al. 2005, Vaananen et al. 2008). In the peat extraction industry, flow control dams, sedimentation ponds and treatment wetlands are currently mandatory, although some wetlands areas can be replaced with chemical purification e.g. ...
This thesis examined hydrological processes such as snowmelt and groundwater discharge in drained peatland areas in the boreal zone. The studied processes were measured in situ using environmental tracers. Further, performance of a treatment wetland was studied during snowmelt and high flow. A GIS model was developed to estimate groundwater seepage areas in peatland systems surrounding eskers.
It was found that soil frost had a clear impact on water quality during snowmelt. This was evident as lower suspended sediments, water colour and dissolved organic carbon concentrations, among other changes. The treatment wetland was found to reduce the suspended solids load during the snowmelt period and late autumn, while reductions in phosphorus and nitrogen loads occurred during summer. A sampling algorithm was built to test how different sampling frequencies affected the estimation of suspended solid loads from the constructed wetland. The results showed increasing uncertainty for sparser sampling (from weekly to monthly sampling), but the uncertainty remained high even at weekly sampling. The GIS model was tested on two eskers and shown to give a fair estimate of groundwater discharge locations. It can thus be used for improving aquifer protection in boreal eskers related to the drainage networks surrounding them. However, to be applied more widely, further efforts are required.
The findings in this thesis could be used to develop better water management policies for peat extraction areas, or other industries operating in similar soils and climate. For example, meltwater could be allowed to temporarily bypass treatment facilities in areas with deep soil frost penetration. The wetland study showed that peatland-based wetlands are a suitable approach for improving water treatment performance even under variable hydraulic loads. The uncertainty in the estimated load from a small peat extraction catchment was high, which might limit the use of such data for some purposes. Load estimation methods using the concentration data collected during previous years might be able to reduce the uncertainty, but if the uncertainty needs to be lowered substantially use of sensor technology might be the only viable approach.
... Peatlands are present in almost all parts of the world (Gore, 1983). In pristine state, they provide many ecological functions such as acting as filters for water (Nieminen et al., 2005), storing and sequestering carbon (C) (Turunen et al., 2002;Yu et al., 2010;Joosten et al., 2012) and maintaining biodiversity (Chapman et al., 2003). They have, however, been exploited for various goals, such as peat extraction, agriculture and forestry (Joosten & Clarke, 2002). ...
... Detrimental effects have been observed, for example by Vasander et al. (2003), who reported increased export of PO 4 from a restored buffer zone, and Sallantaus (2004), who reported an increase in P concentration from 10 to 160 µg l −1 in a lake whose catchment included 30% of restored peatlands. Nieminen et al. (2005) reported elevated concentration of DOC in runoff from a forestry-drained peatlands restored for a forestry buffer. Rewetting of peat from drained peatlands has also been found to cause significant release of DOC and nutrients, particulariry P, in laboratory incubation studies on agricultural (e.g. ...
... However, in the same study some of the TWs released PO 4 -P, especially during the first years after their establishment. Phosphorus release after rewetting of drained peatlands in wetland restoration has also been observed in other studies (Kieckbusch and Schrautzer, 2007;Koskinen et al., 2011;Nieminen et al., 2005). P leaching may partly occur due to reduction of iron (Fe) under anaerobic conditions, resulting in PO 4 3− releases (Reddy and DeLaune, 2008). ...
This study examined possibilities to enhance phosphorus (P) retention in wetlands using different materials that could enhance removal of phosphate P (PO4-P) from runoff waters with fairly low P concentrations (Ptot average 80–90 μg L−1 and PO4-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 PO4-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 PO4-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.
