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Riverine nutrient loads are among the major causes of eutrophication of the Baltic Sea. This study applied the Soil & Water Assessment Tool (SWAT) in three catchments flowing to the Baltic Sea, namely Vantaanjoki (Finland), Fyrisån (Sweden), and Słupia (Poland), to simulate the effectiveness of nutrient control measures included in the EU’s Water Framework Directive River Basin Management Plans (RBMPs). Moreover, we identified similar, coastal, middle-sized catchments to which conclusions from this study could be applicable. The first modelling scenario based on extrapolation of the existing trends affected the modelled nutrient loads by less than 5%. In the second scenario, measures included in RBMPs showed variable effectiveness, ranging from negligible for Słupia to 28% total P load reduction in Vantaanjoki. Adding spatially targeted measures to RBMPs (third scenario) would considerably improve their effectiveness in all three catchments for both total N and P, suggesting a need to adopt targeting more widely in the Baltic Sea countries. Electronic supplementary material The online version of this article (10.1007/s13280-020-01393-x) contains supplementary material, which is available to authorized users.

There exist numerous ecotechnologies for recovery and reuse of carbon and nutrients from various waste streams before they are lost to runoff. However, it remains largely unknown how growing implementation of such ecotechnologies affect nutrient emissions to surface waters at catchment scale. Here, this knowledge gap is addressed by application of SWAT model in three case study catchments draining to the Baltic Sea: Vantaanjoki (Finland), Fyrisan (Sweden) and Slupia (Poland). Sustainability analysis with Multi-Criteria Analysis was applied in the stakeholder workshops in the case study areas to assess different ecotechnology alternatives. The following ecotechnologies received the highest sustainability scores: in Vantaanjoki anaerobic digestion, based on mostly agricultural residues; in Fyrisan source-separation of wastewaters; in Slupia nutrient extraction within the wastewater treatment process. The effect of application of digestate on agricultural soils in the Vantaanjoki catchment was simulated by adjusting the model parameters describing the organic carbon content and physical properties of soil. The results showed small reductions of nutrient loads to the Gulf of Finland. Larger reductions of nutrient loads to Lake Malaren in Sweden and the Baltic Sea in Poland were achieved as a result of the wastewater treatment upgrades. In the Fyrisan catchment, higher relative reductions were simulated for TN than TP, and in dry years than in wet years. Although the studied ecotechnologies did not show as high effectiveness in nutrient load reduction as combinations of traditional Best Management Practices reported in literature, they do have other multiple benefits including crop yield increase, electricity, heat and bio-based fertilizer production.

Highlights • A concept for a water-smart Circular Economy (CE) is introduced. • Elements of a water-smart CE are presented. • Instruments to support the transition to a water-smart CE are analysed. • Drivers for and barriers to the transition to a water-smart CE are identified. The Circular Economy (CE) is a concept that has gained considerable global attention during the past decade amongst private and public sector actors, politicians and policymakers, citizens and media, and scientific communities. Water and water-related ecosystems, despite their vital role in practically all human activities, have been largely missing from conceptualisations and scientific definitions of the CE. Therefore, this paper presents a definition and concept for a water-smart CE that incorporates water and water-related ecosystems. A water-smart CE would (i) reduce losses of water, energy and valuable substances, (ii) improve water efficiency and productivity, (iii) reuse treated wastewater, and (iv) better protect and lessen pressure upon water-related (both aquatic and groundwater) ecosystems. The paper also touches upon the potential risks of the CE to water-related ecosystems. Policy instruments that could be used to promote a transition towards a water-smart CE in Finland – the setting of the present study – and beyond were also sought. Additionally, actors who provide and/or use water-smart CE solutions were interviewed to shed light on their perceptions about the drivers of, barriers to and potential policy instruments for promoting a transition towards a water-smart CE. Based on the analyses of policy instruments and stakeholder interviews, a mixed use of economic, regulatory and informative instruments is suggested to support the desired transition towards a water-smart CE in Finland and elsewhere.

Funding Information: The shares of financing of the investigated TSCs are reported in Table S9. The differences in financing illustrate the absence of a systematic nationwide approach for financing TSCs. The farmers’ share of the costs was rather low in the six pilot studies, averaging less than 10%. Most financing has been arranged through individual, externally funded research and development projects. Currently, in Finland, a TSC project may obtain state financial support in the form of either a drainage subsidy from Agrifood Research and Development Fund (MAKERA) managed by the ELY Centers (Regional State Authority) or from CAP-AES’s non-productive investments as wetland investment and maintenance allowance. However, overlapping subsidies cannot be received for the same drainage area. Support can cover no more than 40% of the costs, but environmentally friendly (i.e., nature-based) solutions, and particularly expensive structures, may increase the support percentage. In recent years, MAKERA has granted approximately 2.5 million €/year of state support for about 50 dredging projects. Funding Information: Funding: This research was funded by the Joint Research Centre of European Commission (contract no. 939642), Academy of Finland (grant no. 330217), the Finnish Cultural Foundation (grant no. 00201229) and by the Valumavesi project. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Conventional dredging of ditches and streams to ensure agricultural drainage and flood mitigation can have severe environmental impacts. The aim of this paper is to investigate the potential benefits of an alternative, nature-based two-stage channel (TSC) design with floodplains excavated along the main channel. Through a literature survey, investigations at Finnish field sites and expert interviews, we assessed the performance, costs, and monetary environmental benefits of TSCs in comparison to conventional dredging, as well as the bottlenecks in their financing and governance. We found evidence supporting the expected longer-term functioning of drainage as well as larger plant and fish biodiversity in TSCs compared to conventional dredging. The TSC design likely improves water quality since the floodplains retain suspended sediment and phosphorus and remove nitrogen. In the investigated case, the additional value of phosphorus retention and conservation of protected species through the TSC design was 2.4 times higher than the total costs. We demonstrate how TSCs can be made eligible for the obligatory vegetated riparian buffer of the European Union agri-environmental subsidy scheme (CAP-AES) by optimising their spatial application with respect to other buffer measures, and recommend to publicly finance their additional costs compared to conventional dredging at priority sites. Further studies on biodiversity impacts and long-term performance of two-stage channels are required.

Highlights • Participation of local stakeholders is important part of sustainability assessments. • Scale of implementation can determine whether the benefits to outweigh the costs. • Implementation of innovations can be less sustainable than current systems. • Stakeholders did not prioritize technical performance of innovations. Sustainability assessments can be a powerful tool in decision-making regarding technical innovations. In this study, a sustainability assessment of technical systems for recovering nutrients and carbon from domestic wastewater is presented. Multi-criteria analysis was used to calculate a sustainability score of three different technical systems compared to a baseline in two case-studies: the Fyriså river catchment in Sweden and the Słupia river catchment in Poland. Two participatory workshops with local stakeholders were held in each case-study, the first to co-develop the system alternatives and sustainability criteria and the second to collect stakeholder weighting of the criteria. Although the systems assessed in both case studies were similar, the resulting sustainability scores were different. In Fyris, although the differences in scores was small, the preferred alternative was introduction of source-separation followed by a large redesign of the treatment and phosphorus extraction from incinerated sludge was the least sustainable alternative. For the Słupia systems the scores varied more, and the preferred system was a large redesign of the wastewater treatment followed by ammonia stripping of the reject water and the source-separation alternative received the lowest score. In both case-studies, the more costly system received highest sustainability score indicating the large potential benefits of enhancing resource recovery from domestic wastewater. Stakeholders did not prioritize technical aspects over the other sustainability criteria, yet most of research on resource recovery interventions is focused on technical performance.

Constructed wetlands (CWs) are recognized as a useful method to reduce sediment and nutrient loading from arable land to surface waters. Automatic monitoring systems with continuously measuring sensors were utilized for several years to obtain accurate, up-to-date information of the retention performance of two differently dimensioned and located CWs in agricultural catchments in southern Finland. Here, results derived from the data recorded by the sensors measuring height, turbidity and nitrate-nitrogen (NO3-N) concentration of the water entering and exiting the Hovi (established in 1998) and Rantamo-Seitteli (est. in 2009) CWs are presented. Study periods ended in autumn 2014 and they lasted 7 years at Hovi and 4.5 years at Rantamo-Seitteli. Annual total suspended solids (TSS), total phosphorus (TP) and total nitrogen (TN) per cent retentions were much higher in the older, more generously dimensioned (CW-to-catchment area ratio 5%) Hovi CW (TSS 74%, TP 58% and TN 54% on average during 7 years) than in the newer, more scantly dimensioned (CW-to-catchment area ratio 1.3%) Rantamo-Seitteli CW (TSS 7%, TP 12% and TN 9% on average during 4.5 years). Moreover, the annual retentions of the Rantamo-Seitteli CW appeared to decrease with increasing runoff, while the retentions at Hovi were not affected by runoff fluctuations. In terms of TSS and TP retentions in the Hovi CW, they were in this study at similar levels to those observed shortly after the establishment of the CW. Meanwhile, the retention of dissolved nutrient fractions, i.e. NO3-N and dissolved reactive P (DRP, based on water sampling) at Hovi were clearly higher in this than in the previous study. The results confirm the importance of CW dimensioning and locating near the sources of loading, and refer to improved performance as CWs get older with increasing vegetation and biological activity. Our experiences of CW measurements with sensors have been positive. The information obtained with new technology has provided retention estimates that are more accurate than they would have been if they were derived from sparse grab sampling.

Science-informed, reductionist policy has systematically failed to address wicked situations. Such situations are highly interconnected and unpredictable. As a consequence, the implementation of so-called desirable interventions can lead to the export of vulnerabilities within and across different societal domains, sectors, intersections and scales. Systemic practice is an emerging field, and highlights the need to enrich scientific inquiry and policy actions through action learning with an “extended peer community'' as a means to navigate wicked situations. In this paper, we report on the potential of game co-design as a systemic practice to improve the situation of Baltic Sea nutrient enrichment. Findings from water catchments in Finland, Sweden and Poland suggest that the co-design of serious games can both enhance the comprehension of wicked situations, and foster self-organized concerted action without imposing a convergence of perspectives amongst diverse stakeholders.

This paper summarizes key findings from a series of systematic reviews and comprehensive efforts to collate evidence and expert opinions on circular solutions for recovery and reuse of nutrients and carbon from different waste streams in the agriculture and wastewater sectors. We identify established and emerging approaches for transformation towards a more circular nutrient economy with relevance to SDGs 6 and 14. The paper cites the example of the Baltic Sea Region which has experienced decades of fertilizer overuse (1950s–1990s) and concomitant urban sources of excessive nutrients. Regulations and incentive policies combining the nitrogen, phosphorus and carbon cycles are necessary if circular nutrient technologies and practices are to be scaled up. Pricing chemical fertilizer at levels to reflect society’s call for circularity is a central challenge. Highlights • Development of a circular nutrient economy in the EU is reviewed. • The socio-economic value of organic waste products from agriculture & municipalities needs to increase. • Opportunities are found in the new EU Circular Economy Package & Fertilizing Products Regulations. • Further implementation is possible with the Common Agriculture Policy (nutrient management tool) and Waste Framework Directive for recycling. • The Baltic Sea Region case is explored being sensitive to eutrophication with ongoing international efforts to introduce nutrient circularity.

Potential influences of climate change on water quality, riverine suspended sediments, nitrogen and organic matter loads in temporally frozen rivers, which have ice-covered flow and snow-affected basins, are poorly understood. However, before being able to understand potential future changes, the impact of ice and snow needs to be investigated more thoroughly for years which were hydrologically different. We investigated seasonal and event scale concentration-discharge (C-Q) dynamics of total suspended solids/turbidity, nitrate-N (NO3-N) and chemical oxygen demand (COD), which is indicative of the amount of organic matter in river water. In particular, the influence of ice cover, contrasting spring thaw, and soil frost conditions on intra-annual fluxes and the C-Q response of the three solutes are detected based on over four years of hourly data. Seasonally flow-weighted suspended solids and NO3-N concentrations were at their highest in either the autumn or spring thaw, but COD concentrations were the highest each year in autumn. NO3-N and COD levels typically decreased during winter. The ice-covered river water was less turbid compared to open-channel water at an equivalent river discharge likely due to in-stream factors. Storms during the freshet period introduced flushing of organic matter and suspended solids. The ratio of organic matter yield to water yield was similar each freshet and was independent of the amount of precipitation as snow or soil frost status. The freshet NO3-N yield per water yield was higher during the years with a thick snowpack and the consequent thawed soil compared to a year with soil frost and minor snowpack. 91 storm events studied revealed differences and similarities in storm dynamics in between the three variables. Anti-clockwise hysteresis was most common for the variables, with turbidity peaking faster than the COD or NO3-N concentration in most of the storms. Snowmelt storms showed highly variable C-Q responses inbetween the variables. However, spring thaw-related COD concentration peaks abated more slowly compared to turbidity or NO3-N. NO3-N showed a strong dilution pattern during several autumn storms during an extremely wet year, indicating limited N sources for flushing from the catchment. As a result, the flow-weighted mean NO3-N concentration was not the largest during the year of largest water yield instead which was true for suspended solids and COD. We found no evidence that warmer winters with precipitation as rain instead of snow would increase suspended sediment, organic matter and NO3-N load at entire winter-spring season or annual timescales.

Highlights • A procedure for the compilation of the highly disaggregated national water accounts, and a data quality framework is described. • Sectoral data coverages and sources of error are reported and discussed. • Water accounts for self-abstracted water and mains-water are reported for 195 industries of the Finnish economy. • The accounts are primarily based on actual water supply and use rate data. • Data are reported separately for mains water, groundwater, fresh surface water, brackish water, and cooling water. This paper introduces a novel procedure for the compilation of highly disaggregated water accounts by using Finland as a case example. The procedure is based on combining the use of existing standard economic statistics and other registers and databases with a dataset on water supply and use collected in the present study. As an outcome, water supply and use accounts are presented for 195 industries in the Finnish economy in 2010. The water accounts presented are based primarily on actual water supply and use rates and distinguish between various raw water sources and uses: groundwater, fresh surface, brackish water self-abstracted for own use, and mains-water supply and use. Separate accounts for cooling water are presented. The paper covers flow accounts from the environment to the economy and within the economy excluding all return flows. Data coverage issues and potential sources of error are reported in detail and discussed together with the applicability of the procedure in other countries. Implications for the System of Economic-Environmental Accounting for Water (SEEA-Water) framework are assessed.

Livestock-derived phosphorus (P) loading values are largely based on studies performed in small experimental fields, leading to uncertainties when applying the results at larger scale. This five-year study estimated annual loads of P, nitrogen (N), dissolved organic carbon (DOC) and total suspended solids (TSS) in a small 3.2 km2 agricultural and forested catchment by monitoring water quality and discharge in four ditches reflecting different land uses. The monitored catchment has intensive livestock production, with proportions of grassland, cereal and forest area typical for east-central Finland. Typically, spring runoff started in early April under snow cover and peaked during snowmelt. There was great variation in the amount and pattern of discharge between years. Mean annual total P (TP) load (± SD) from an agricultural sub-catchment was 1.0 ± 0.37 kg ha−1. Mean TP load from a forested (PS) sub-catchment was 0.4 ± 0.17 kg ha−1 when a point source of pollution (PS) was included and 0.06 kg ha-1 when it was excluded. The point source of pollution contributed 12 % of the TP load from the whole 3.2 km2 catchment. The proportion of dissolved reactive P (DRP) to TP load varied between 34 % and 67 % in the study period (largest for the forested (PS) sub-catchment and smallest for the whole catchment). Observed erosion rates were very low when measured as TSS, with the highest (115 ± 103 kg ha−1) and lowest (3.4 ± 2.3 kg ha−1) mean annual erosion rate in the agricultural and forested (PS) sub-catchments, respectively. In the agricultural sub-catchment, the relationship between TP and DOC tended to be stronger than that between TP and TSS. Mean annual total N load from the agricultural sub-catchment was 19.0 ± 7.2 kg ha−1 and from the whole catchment 10 ± 2.7 kg ha−1, while mean annual DOC load was 45 ± 13 kg ha-1 and 92 ± 28 kg ha−1, respectively. These results are important in developing, implementing and targeting mitigation measures to control agricultural nutrient losses to surface waters.

With conventional water quality monitoring based on grab sampling, usually carried out once a month, it is quite challenging to obtain reliable sediment and nutrient loading estimates, which is a pre-requisite for testing of water quality models. Despite the growing availability of high-frequency water quality monitoring data obtained by using modern sensors, their use in the calibration of water quality models is still limited. The main objective of this study is to evaluate six years of continuous, high-frequency water quality monitoring data set from a case study carried out in a medium-sized, boreal catchment in southern Finland to be used as a source for the calibration and testing of the Soil & Water Assessment Tool (SWAT). This objective is accomplished by developing a set of ‘sub-sampling’ scenarios focused on quantifying the effect of the sampling frequency (12 vs. 26 samples per year) and strategy (regular vs. flow-proportional sampling) on the model performance and output uncertainty. The goodness-of-fit of the model calibrated against high-frequency data (‘benchmark’), evaluated using the Kling-Gupta Efficiency index for total suspended solids (TSS), nitrate and total nitrogen (NO3-N and TN) and total phosphorus (TP) daily loads ranged between 0.76 and 0.83 (0.69 and 0.73 in validation period). Overall, the model calibrated against low-frequency data performed worse when evaluated against high-frequency data and compared with the benchmark model for each of the studied water quality parameters. The results show that increasing the sampling frequency from 12 to 26 samples per year leads to an improvement in the model performance, particularly for TSS and TP loads. In contrast to the sampling frequency, the evidence for the effect of the sampling strategy on the model performance was much weaker. The model output uncertainty due to different realizations of sub-sampling scenarios was high for four analysed output indices: basin-averaged, long-term average annual values of soil erosion rate, denitrification rate, NO3-N yield and soluble P yield. This study demonstrates that more attention should be paid to the calibration data as a source of uncertainty in model predictions. It also provides evidence for either a wider adoption of modern sensors providing high-frequency data, or for increasing the grab sampling frequency to reduce the uncertainty of loading estimates, particularly in rivers with flashy flow regime such as the Vantaanjoki River.

Monitoring of water quality should not be solely based on laboratory samples. Such activity, although producing reliable results, cannot provide an accurate enough temporal coverage for water quality monitoring. The Finnish Environment Institute, SYKE, has therefore established numerous online water monitoring stations that continuously monitor water quality. The problem with the automatic monitoring, however, is that the recorded values are not reliable as such and need to be subject to quality control and uncertainty estimation. Here, as the main contribution, we present a computational service that we have implemented to automate and integrate the water quality monitoring process. We also present a case study regarding the river Väänteenjoki and discuss the obtained uncertainty results and their implication.

This paper in a uniform manner examines temporal trends in phosphorus (P) concentrations and losses from small and well-monitored agricultural catchments in the Nordic and Baltic countries. Thirty-four catchments (range 0.1-33 km(2)) in Norway (8), Denmark (5), Sweden (8), Finland (4), Estonia (3), Latvia (3) and Lithuania (3) were selected for the study. The time series ranged from 10 (2002-2011) to 21 years (1989-2009). The monthly P concentration and loss time series were tested for significant monotone trends (p

Long-term data from a network of intensively monitored research catchments in Finland was analysed. We studied temporal (1981-2010) and spatial variability in nitrogen (N) and phosphorus (P), from 1987 losses, both from agricultural and forestry land. Based on trend analysis, total nitrogen (TN) concentrations increased in two of the four agricultural sites and in most of the forested sites. In agricultural catchments, the total phosphorus (TP) trends were decreasing in two of the four catchments studied. Dissolved P (DRP) concentrations increased in two catchments and decreased in one. The increase in DRP concentration can be a result of reducing erosion by increased non-plough cultivation and direct sowing. In forested catchments, the TP trends in 1987-2011 were significantly decreasing in three of the six catchments, while DRP concentrations decreased significantly in all sites. At the same time, P fertilisation in Finnish forests has decreased significantly, thus contributing to these changes. The mean annual specific loss for agricultural land was on average 15.5 kg ha(-1) year(-1) for N and 1.1 kg ha(-1) year(-1) for P. In the national scale, total TN loading from agriculture varied between 34,000-37,000 t year(-1) and total P loading 2400-2700 t year(-1) These new load estimates are of the same order than those reported earlier, emphasising the need for more efforts with wide-ranging and carefully targeted implementation of water protection measures.

Monitoring of nutrient losses to surface waters at the small agricultural catchment scale has been carried out in seven Nordic and Baltic countries for the past two decades, with the aim of obtaining information on agricultural activities and their impact on surrounding waters. The monitoring methods have been harmonised and in almost all 35 catchments currently being monitored, water samples are taken flow-proportionally, water discharge is measured continuously and information on crops grown and crop management is collected yearly. Here, we evaluate and discuss uncertainties in data and their consequences for fulfilling the aim of the monitoring systems. We also suggest methods and priorities for future monitoring. Although the catchments altogether cover major variations in climate, soil texture and farm type, there is a bias towards more intensive agricultural production compared with the surrounding agricultural regions. For applicability of the results to larger agricultural areas, the representativity of the selected catchments should be stated. The determination of nutrient loads is affected by uncertainties in water discharge measurements, water sampling and chemical analyses, but these uncertainties may decrease over time due to improvements in the methods used. This would improve the possibility to detect trends in the naturally large variation in nutrient loads. For wider applications, the level of nutrient loads at the catchment stream outlet must be related to catchment characteristics such as proportion of agricultural land and contribution from other land uses and point sources. These sources are often estimated based on limited information, but should be included regularly in monitoring schemes. Also data on agricultural activities are related to uncertainties such as coverage of crop management information and nutrient content in manure and harvested products. When data are missing, standard values are used, further contributing to uncertainties. However, intensive monitoring increases awareness of sources of uncertainty in data, and hence the possibility to reduce these uncertainties. Therefore, the intensive monitoring approach should be maintained and rather extended, for example by using sensors for high resolution water quality measurements so that the variations can be identified and related to catchment activities and to processes in streams and groundwater. To further understand these processes and crop management systems, modelling should be closely related to monitoring. With harmonised monitoring programmes where differences in methods are known, focus can be put on the evaluation of data so that further knowledge on the impact of agriculture on the environment can be obtained.

Nitrogen (N) transport and retention in streams are largely determined by hydrological characteristics (e.g. water runoff, baseflow index (BFI) and flashiness index (FI)) in the catchment. It is important to know the impact of catchment characteristics such as land use, subsurface drainage intensity, elevation difference and catchment size on the hydrological properties and N loss. This paper presents a comparison of the magnitude and variation of the baseflow and flashiness in streams in relation to the selected geographical and drainage characteristics for thirty studied agriculture dominated catchments in the Nordic and Baltic countries and the effects it can have on N loss. The analysis included measured data from the total discharge and nitrogen loss at the catchment outlets for the period from the beginning of 1993 to 2011, although there is variation in the length of periods among catchments and countries. The study revealed that the rate of subsurface drainage systems and drainage intensity (given as lateral tile drainage spacing) were statistically significant explanatory variables in explaining differences in hydrological characteristics between catchments. There is a considerable increase in the FI, almost by a factor of three, when using hourly discharge values instead of average daily values, indicating that large diurnal variation in discharge can occur, especially at higher FI values. The analysis also showed that there is a negative relation between FI and the BFI, i.e. a high BFI corresponding to a low FI and vice versa. In general, there seems to be a positive relationship between long-term average runoff and N loss, with the highest runoff and N loss occurring in the Norwegian catchments. However, flow path can have a significant influence on the N loss.

This case study summarizes the current knowledge in Finland on the efficiency of constructed wetlands to improve water quality at the same time providing multiple benefits. The efficiency is highly dependent on the wetland’s relative size compared to the upstream catchment area, and on the amount of agricultural land in the upstream catchment. The case study analyses the incentives designed to motivate landowners to construct wetlands in Finland such as the non-productive investment support and the agri-environment payment support for wetland management. Farmers think that the support system is heavy and bureaucratic, and thus the target number of new constructed wetlands is far from being met. Individual projects have been more successful in wetland construction than the official support system. General wetland plans drafted for hotspot areas is an example of enabling factors and strict eligibility rules form one of the barriers of wetland construction identified in this case study. In spite of the criticism of the current wetland incentives, a support system for wetland construction is needed. One option would be to give regional authorities more freedom to select priority areas according to e.g. River Basin Management Plans.

The empirically based VIHMA model is intended for evaluation of agricultural loading and mitigation measures at the catchment scale. As a starting point for the model construction, results of relevant Finnish long-term field experiments were collected as the database of the model. From the database, specific loading values for different cultivation and tillage methods were calculated using the values of respective tillage methods and conditions (slope, soil texture, hydrological year type) and – in cases of missing empirical data – interpolation and expert judgment. Moreover, based on the data collected in studies carried out at Finnish constructed wetlands (CWs) and at experimental fields with buffer zones (BZs), the model is able to evaluate the environmental benefits achieved by these water protection measures at the catchment scale. The model points out the origin of loading as well as the needs of targeting the protective measures and their load-reducing effects. The use of VIHMA is bound to the distribution of actual information of field cultivation in the target area. Hence, calculations based on changed tillage practices can be assessed only within the limits determined by the lines of production in local farms. On the other hand, the need to decrease the loading is determined by the target state of the recipient body of water. By changing the input data, the potential change in loading, e.g. by increasing the number of BZs or CWs, can be simulated by VIHMA. Influences of different hydrological years with different flow regimes due to different meteorological conditions are taken into account by the choice of the respective empirically-based specific loadings in the model data. The results calculated by VIHMA were found to be well in line with the reported results from long-term catchment monitoring. The model was able to reliably calculate the influences of mitigation measures in large scale in spite of high variation due to different hydrological years.

Automatic on-line measurement stations for water quality components and water level were equipped with dataloggers and GSM transmitters; the stations were installed at two sites in the Yläneenjoki river basin, SW Finland. Measurements during five seasons in 2006–2007 were conducted to find out whether the produced data would provide more accurate estimates of material and nutrient transport than traditional water sampling. Sensor-based monitoring estimates for transport of total suspended solids (TSS) were clearly higher (difference -6–61%), total phosphorus also higher, and that of nitrate (NO3-N) somewhat lower (difference (−51%–4%), as compared with manual sampling based estimates. The winter season studied here was mild i.e. winter-type which is becoming more common in Finland with the changing climate. Sensor-based monitoring proved its benefits particularly in such conditions.

1990-luvun loppuvuosilta saakka todettu leutojen ja sateisten talvien toistuminen saattaa olla ensimmäisiä maataloutta koskevia konkreettisia seurauksia ilmastonmuutoksesta. Sen vaikutusten arviointi maatalouden aiheuttamaan vesistökuormitukseen on keskeinen tehtävä jo ennen kuin ilmasto muuttuu pysyvästi erilaiseksi. Tämän tutkimuksen tavoitteena oli selvittää, miten ilmastonmuutos vaikuttaa kiintoaine- ja ravinnekuormitukseen viljelytoimenpiteiden jatkuessa muuttumattomina ja kuinka paljon vaihtoehtoiset toimenpiteet ja toimenpideyhdistelmät vähentävät kuormitusta nykyilmastossa sekä muuttuneissa ilmasto-oloissa neljän erilaisen ilmastoskenaarion perusteella. Tutkimus perustui kuormitusmallien käyttöön, joilla laskettiin eroosion, fosforin ja typen kuormituksen muutoksia.INCA-N-mallin tulosten mukaan koko peltoalueen viherkesannointi vähentää valuma-alueen epäorgaanisen typen kuormitusta nykyilmastossa n. 50 %. Tulevaisuuden ilmastossa vähenemä olisi keskimäärin vain 26 % nykytilan kuormitukseen verrattuna. Tämä johtuu valunnan ja osittain typen mineralisaation lisääntymisestä etenkin kasvukauden ulkopuolella myös viherkesantokasvustossa (Granlund ym. 2010). Viljelykasvin ominaisuuksien pysyessä nykyisinä, COUP-mallin mukaan typen huuhtoutuminen kaksinkertaistuu sekä 2025 että 2085 skenaarioissa. Typen huuhtoutumista kohottavat sekä lämpötilan nousun vauhdittama maan typen mineralisaatio että talviaikaisen valunnan lisääntyminen.Toholammille tehtyjen ICECREAM-mallin simulaatioiden mukaan pintavalunnan ajoittuminen muuttuu ratkaisevasti. Jatkossa ei ole enää selkeää kevätvaluntapiikkiä, joka on yleensä tullut pintavaluntana, ja pohjavalunnan määrä (suureksi osaksi salaojiin) kasvaa jonkin verran. Torjunta-aineiden huuhtoutumisriski tulevaisuudessa todennäköisesti kasvaa johtuen monista syistä: 1) skenaarioiden mukaiset syys- ja talvisateet lisäävät pelloilta vesistöihin poistuvan veden (joko pintavalunta tai salaojavalunta) määrää 2) pelloilla seisova lammikoitunut pintavesi irrottaa maahan normaalisti tiukastikin sitoutuvat aineet ja 3) torjunnan ja torjunta-aineiden käyttötarve ajoittuu syksyyn syysmuotoisten kasvien yleistyessä.Viljelyalueiden valumavesien hallintamallin (VIHMA) laskentatulosten mukaan maatalouden nykyiset peltotoimenpiteet ovat alentaneet koko peltoalalla, kun hydrologinen vuosivaihtelu jätetään huomiotta, eroosiota ja partikkelifosforin kuormitusta yhteensä 20 %, kokonaisfosforikuormitusta 12 %ja typpikuormitusta 6 %. Jos nykyisten toimenpiteiden vaikutuksia arvioidaan hydrologisesti kuormittavien vuosien olosuhteissa, eroosio ja partikkelifosforin kuormitus on pienentynyt n. 7 % ja kokonaisfosforin ja -typen kuormituksessa ei ole tapahtunut lainkaan muutoksia.Ilmastonmuutos lisää riskiä peltomaan ravinteiden huuhtoutumiselle leutojen talvien yleistyessä. Peltojen vesitalouden ja rakenneongelmien hallintaan tulee kehittää uusia teknisiä ratkaisuja kastelun ja kuivatuksen tarpeiden muuttuessa. Luonnonmukaisen vesistörakentamisen periaatteiden soveltaminen peruskuivatuksessa voidaan nähdä peltojen kuivatustarpeen ja tuottoedellytysten sekä vesistöjen tilatarpeen integroivana toimenpiteenä. Kosteikot kuuluvat järjestelmään välttämättöminä uoman osina.Sekä peltokasvien satoisuuden että ympäristön kannalta optimaalinen ravinnetalous edellyttää maaperän omien ravinnevarastojen mahdollisimman tarkkaa hyödyntämistä. Tavoitteena tulee olla fosforilukujen alentaminen kestävälle tasolle ja kasvien typen käytön tehostaminen mineralisaatioprosessien kiihtyessä myös syys- ja talvikaudella. Intensiivisen maanmuokkauksen korvaaminen pysyvän kasvipeitteen kaltaisilla vaihtoehdoilla on keskeinen toimenpide kuormitusherkillä alueilla.

Modeling tools are needed to assess (i) the amounts of loading from agricultural sources to water bodies as well as (ii) the alternative management options in varying climatic conditions. These days, the implementation of Water Framework Directive (WFD) has put totally new requirements also for modeling approaches. The physically based models are commonly not operational and thus the usability of these models is restricted for a few selected catchments. But the rewarding feature of these process-based models is an option to study the effect of protection measures on a catchment scale and, up to a certain point, a possibility to upscale the results. In this study, the parameterization of the SWAT model was developed in terms of discharge dynamics and nutrient loads, and a sensitivity analysis regarding discharge and sediment concentration was made. The SWAT modeling exercise was carried out for a 2nd order catchment (Yläneenjoki, 233 km2) of the Eurajoki river basin in southwestern Finland. The Yläneenjoki catchment has been intensively monitored during the last 14 years. Hence, there was enough background information available for both parameter setup and calibration. In addition to load estimates, SWAT also offers possibility to assess the effects of various agricultural management actions like fertilization, tillage practices, choice of cultivated plants, buffer strips, sedimentation ponds and constructed wetlands (CWs) on loading. Moreover, information on local agricultural practices and the implemented and planned protective measures were readily available thanks to aware farmers and active authorities. Here, we studied how CWs can reduce the nutrient load at the outlet of the Yläneenjoki river basin. The results suggested that sensitivity analysis and autocalibration tools incorporated in the model are useful by pointing out the most influential parameters, and that flow dynamics and annual loading values can be modeled with reasonable accuracy with SWAT. Sensitivity analysis thus showed the parameters which should be known better in order to result in more realistic parameter values. Moreover, the scenario runs for CWs made with SWAT revealed the high demand of land area for this protective measure to be substantially effective., Mallityökalut ovat osoittaneet tarpeellisuutensa arvioitaessamuun muassa maatalouden aiheuttamaa ravinnekuormaa ja vesiensuojelumenetelmien tehokkuutta. Erityisesti Vesipuitedirektiivin (VPD) täytäntöönpanon myötä mallinnustyölle on asetettu konkreettisia haasteita mallitulosten luotettavuuden suhteen. VPD:n puitteissa tarve soveltaa malleja laajoille alueille on myös kasvanut, vaikka perinteisesti prosessipohjaisia malleja on enimmäkseen sovellettu yksittäisillä valuma-alueilla. Vesiensuojelumenetelmien tehokkuuden arvioinnissa prosessipohjaiset mallit ovat avainasemassa, mutta tulosten yleistäminen yhdeltä valuma-alueelta toiselle on edelleen vaikeaa. Tässä tutkimuksessa parametrisoitiin prosessipohjainen SWAT -malli Yläneenjoen valuma-alueelle, joka edustaa tyypillistä lounaissuomalaista maatalousvaltaista aluetta. Yläneenjoen vedenlaatua on seurattu jo pitkään ja havaintojen määrä on riittävä sekä mallisovelluksen luomiseen että kalibrointiin. Lisäksi alueen viljelykäytännöt ja toteutettujen vesiensuojelutoimenpiteiden määrä ovat hyvin tiedossa. Aiempien tutkimusten perusteella mallista valittiin kolmekymmentä parametria, joille herkkyysanalyysi tehtiin. Näin tunnistettiin tärkeimpiin tulosmuuttujiin, virtaamaan ja sedimenttikuormaan, vaikuttavat parametrit. Virtaaman osalta herkimmät parametrit liittyivät pohja- ja pintavesivaluntaa, haihduntaa ja lumen sulamista kuvaaviin prosesseihin, kun taas vastaavasti sedimenttikuormaa selittivät uomaprosesseja ja eroosion kulkeutumista valuma-alueelta kuvaavat parametrit. Tätä tietoa hyödynnettiin mallin kalibroinnissa Rakennetulla SWAT -sovelluksella arvioitiin joen ainevirtaamaan muutoksia sekä tarkasteltiin kosteikkojen vaikutusta jokiveden laatuun. Tulokset osoittivat, että herkkyysanalyysin perusteella mallin kalibrointia voitiin selvästi tehostaa. Parametrivirityksellä saatiin simuloitu virtausdynamiikka ja ainevirtaamat vastaamaan paremmin mitattuja, tosin ainevirtaamien osalta havaintojen vähäinen määrä rajoitti vertailua. Ainehuuhtoumien kalibroinnissa kannattaakin useimmiten pitää lähtökohtana vuotuisia arvoja, koska pitoisuushavaintoihin sisältyy lukuisia epävarmuustekijöitä, joita mallissa on usein mahdotonta ottaa huomioon. Kosteikkosimulointien perusteella voidaan todeta, että merkittävien (n. 20 %) kuormitusvähenemien aikaansaamiseksi kosteikkopinta-alaa tarvittaisiin huomattavan paljon, satoja hehtaareja. Tämä johtuu siitä, että ollakseen tehokas yksittäisen kosteikon tulee olla yläpuoliseen valuma-alueeseensa nähden suuri (n. 2 % tai enemmän). Simulaatioajojen perusteella tuntuvakaan kosteikkojen lukumäärän lisäys ei auta, jos niiden mitoitus on riittämätön. Suuresta pinta-alavaatimuksesta johtuen ei ole realistista laskea vesiensuojelua rakennettavien kosteikkojen varaan, vaan pikemminkin nähdä ne osana laajaa toimenpidevalikoimaa kokonaisvaltaisessa vesiensuojelun suunnittelussa. Rakennettavien kosteikkojen etuna ovat useat kuormitusvähenemien ohessa saatavat lisähyödyt, kuten maiseman elävöityminen ja luonnon monimuotoisuuden, erityisesti linnuston, lisääntyminen, jotka lisäävät kiinnostusta paikallisen väestön keskuudessa.

Development of new automatic sensor-based techniques has expanded the possibilities for intensive monitoring of water quality in small catchments. In this study turbidity and concentration of nitrate-N were monitored with probes in the Savijoki catchment, which has been observed with traditional methods for decades. Particular attention was paid to implementation of the equipment, calibration of the probes and calculation methods. All equipment functioned technically well during the one year monitoring period. Calibration of turbidity and nitrate-N proved that the sampled values agree well with the probe results. However, it seems that loading estimates made with the traditional method are not very reliable for individual years. The research period in this study was exceptional with its many runoff peaks in winter. It is not possible to catch the peaks with traditional monitoring, why the results and comparisons between automatic probes and traditional monitoring cannot be generalized. However, the results proved that novel monitoring techniques have to be continued and extended. In further studies the calculation methods need developed and improved to be to get reliable loading estimations from the sensor data as simply as possible. In a changing climate, the monitoring, loading estimations, and consequently the assessment of the effect of agricultural water protection measures will probably turn even more difficult and challenging., Lewis, J. 1996. Turbidity-controlled suspended sedimentsampling for runoff-even load estimation. Water Resources research 32: 2299–2310. Mustonen, S. 1965. Hydrologic investigations by the Board of Agriculture during the years 1957 to 1964. Helsinki. 144 p. Puustinen M, Koskiaho J. & Peltonen K. 2005. Influence of cultivation methods on suspended solids and phosphorus concentrations in surface runoff on clayey sloped fields in boreal climate. Agriculture, Ecosystems and Environment 105: 565–579. Puustinen, M., Tattari, S., Koskiaho, J. & Linjama, J. 2007. Influence of seasonal and annual hydrological variations on erosion and phosphorus transport from arable areas in Finland. Soil & Tillage Research 93: 44–55. Rekolainen, S. 1993. Assessment and mitigation of agricultural water pollution. Publications of the Water and Environment Research Institute 12. National Board of Waters and Environment, Helsinki, Finland. 34 p. Seuna, P. 1983. Small basins – a tool in scientific and operational hydrology. Publications of the Water Research Institute 51. National Board of Waters, Finland. 61 p. Turtola, E. 1999. Phosphorus losses in surface runoff and drainage water affected by cultivation practices. Academic Dissertation. University of Helsinki. 47 p. Valkama, P., Lahti, K. & Särkelä, A., 2007. Automated water quality monitoring in the river Lepsämänjoki. Terra 119: 195–206. Vehviläinen, B. & Huttunen, M. 2002. The Finnish watershed simulation and forecasting system (WSFS). Proceedings of the XXIst Conference of the Danubian countries on the hydrological forecasting and hydrological bases of water management. Bucharest-Romania. 2–6 September 2002. Vuorenmaa, J., Rekolainen, S., Lepistö, A., Kenttämies, K. & Kauppila, P., 2002. Losses of nitrogen and phosphorus from agricultural and forest areas in Finland during the 1980s and 1990s. Environmental Monitoring and Assessment. 76: 213–248. SELOSTUS Jatkuvatoimisten antureiden soveltuvuus veden määrän ja laadun seurantaan pienillä valuma-alueilla Jarmo Linjama, Markku Puustinen, Jari Koskiaho, Sirkka Tattari, Helmi Kotilainen ja Kirsti Granlund Suomen ympäristökeskus Automaattisten antureiden viimeaikainen kehittyminen on avannut uusia mahdollisuuksia pienten valuma-alueiden monitorointiin. Tässä tutkimuksessa kymmenien vuosien ajan seuratulle valuma-alueelle, Savijoelle, asennettiin sameus- ja nitraattianturi ja tehtiin kuormituslaskenta sekä antureiden tulosten perusteella että perinteiseen harvaan näytteenottoon perustuvin menetelmin. Huomiota kiinnitettiin erityisesti laitteiden asentamiseen ja antureiden kalibrointiin. Huolellisen asentamisen jälkeen laitteet toimivat vuoden mittaisen havaintojakson ajan teknisesti moitteettomasti. Sameuden ja nitraattikäyrien kalibrointi vesinäytteiden perusteella osoitti, että vesinäytteiden ja anturidatan vastaavuus on erittäin hyvä. Alustavien tulosten mukaan perinteiseen seurantaan perustuva kuormitusarvio ei ole yksittäisten vuosien osalta kovin luotettava. Tämän tutkimuksen seurantavuosi oli kuitenkin poikkeuksellinen useiden talviaikaisten valuntapiikkien vuoksi, joita harvan, perinteisen seurannan vesinäytteet eivät olisi tavoittaneet. Tässä esitettyä automaattiantureiden ja vesinäytteiden tuloksiin perustuvaa kuormituslukujen vertailua ei voida yleistää. Tulos kuitenkin osoittaa, että tämänkaltaista monitorointia on tärkeä jatkaa ja laajentaa. Jatkotutkimuksissa huomiota tulee kiinnittää laskentamenetelmien kehittämiseen, erityisesti siihen, kuinka anturiaineistosta päästään mahdollisimman yksinkertaisesti luotettaviin kuormitusarvioihin. Ilmaston muuttuessa valuma-alueiden seuranta ja kuormitusarviointi ovat todennäköisesti entistä vaativampia ja maatalouden vesiensuojelutoimenpiteiden vaikutusten havaitseminen myös entistä haasteellisempaa.

The bulk of the erosion and phosphorus (P) loading from agriculture to surface waters originates in Finland outside the growing season. The annual loading starts after the harvest in autumn and increases cumulatively during winter and spring, while loading during summer remains low. In terms of loading, the condition in which the fields remain after the growing season is crucial. When the (i) the tillage intensity is reduced, (ii) the tillage date is postponed till next spring, or (iii) when the cultivation practice is changed from tillage to no-tillage, the field surface begins to increasingly resemble a permanent crop cover and, consequently, both erosion and particulate P loading strongly decrease when compared with intensive autumnal tillage. On the other hand, the loading of dissolved P tends to increase in such a transition. The effect of annual hydrological variation on the loading is substantial. The suspended solids and particulate P concentrations may double in hydrologically disadvantageous (wet autumn followed by mild and rainy winter) years, thus greatly increasing the erosion and phosphorus loading when compared with “normal” years. A possible increase in runoff will further increase the difference. The levels of suspended solids and particulate P concentrations in fields under permanent crop cover are, particularly during hydrologically disadvantageous years, substantially lower than in fields under intensive tillage. The dissolved P concentrations showed minor variation and remained at their characteristic level regardless of hydrological year or tillage treatment. The annual distribution of loading was similar at the catchment and field scales. The differences among the flow-weighted annual mean concentrations of suspended solids and particulate P tended to strongly even out when the runoff waters from fields were mixed with those from the parts of the catchment with other land-uses. At catchment-scale, it seems that the increase in total runoff rather than in concentrations govern the increases in total loading. The catchment-scale phenomena may, however, cause misconceptions about the character of the loading from fields and the possibilities of mitigation. While it is possible to efficiently reduce the loading from fields, the gained benefit is hard to prove on the base of catchment-scale measurements and, moreover, it often disappears in the variation caused by hydrological conditions. This will pose major challenges for the mitigation measures in a warmer future climate, particularly if the autumn and winter precipitation will increase and the winters will turn milder.

Turbidity datasets recorded by sensors during 2009-2012 were collected in five observation sites in the 2046-km2 Karjaanjoki River Basin in southern Finland. From these and water sample-based data, total phosphorus (TP) and total suspended solids (TSS) fluxes were determined. Based on calculations made with combined sensor- and water sample-based dataset, the annual loading from the Karjaanjoki Basin in 2009-2012 varied between 11,300 and 23,900[corrected] kg of TP and 3300-8400 t of TSS. As compared with two other river basins discharging into the Baltic Sea in southern Finland, the TP loading from Karjaanjoki was low because the summed retention in the two major lakes Hiidenvesi and Lohjanjärvi was high: 48 and 49% of the TSS and TP loadings generated in their upstream catchments, respectively. Depending on how water sampling took place in relation to peak flow events, differences of annual fluxes as determined by "water samples only" vs. "sensors and water samples" data varied between -22 and 26 for TP and -31 and 39% for TSS. This study proved automatic monitoring being useful when spatial differences and lake retention of riverine fluxes are explored. Moreover, the loading estimates calculated on the base of well-functioning and well-maintained automatic monitoring system, supported with water sampling during periods when devices were off, are undoubtedly more accurate than those based on manual grab water sampling only. The findings of this study were in line with, and well contribute to, earlier Finnish and international research on automatic water quality monitoring.

Construction of wetlands is a possible supplement to best management practices (BMP) at the field level to mitigate phosphorus (P) pollution from agricultural areas. In this paper, annual results from 17 intensively studied wetlands in the cold temperate or boreal climatic zone are reported and analyzed. Surface areas varied from 0.007 to 8.7% of the catchment area. The average total phosphorus (TP) retention varied from 1 to 88%, and the dissolved reactive phosphorus (DRP) retention from -19 to 89%. Retention varied substantially from site to site, indicating the existence of site-specific factors in the catchment and wetlands that influenced the P removal. Factors important for P retention in wetlands were evaluated through multiple statistical analyses by dividing P into two fractions: particulate phosphorus (PP) and DRP. Both relative (%) PP and DRP retention increased with wetland surface area. However, PP retention was not as sensitive as DRP in terms of wetland size and retention: specific PP retention (gram P retention per m(2) and year) decreased as wetland area (A(w)) increased, suggesting the existence of a site-specific optimal wetland to catchment area (A(c)) ratio. Particulate P retention decreased with increasing DRP to TP ratio, while the opposite was found for DRP. Dissolved reactive P retention was higher in new than in old wetlands, while increasing age did not influence PP retention negatively. Effective BMP in the catchment is important to keep the P loss low, because the outlet concentration of P from wetlands is often positively correlated to the input concentration. However, wetlands act as the last buffer in a catchment, since the retention often increases as the P concentration in streams increases.

Estimation of pollutant fluxes through river systems calls for accurate and precise load estimation. However, considerable uncertainty is associated with these estimates due to diffuse loading, which sets high requirements not only on sampling frequencies but also on calculation methods. The aim was to examine the variation in load calculations and the reliability of the load estimates of total phosphorus, total nitrogen and suspended solids in 24 Baltic rivers varying in size and land-use characteristics. Reliability of the load estimates was tested by simulation experiments in the river Paimionjoki using a Monte Carlo procedure. The estimates calculated by the most reliable method were compared to the loads estimated by five other methods. The general reliability (RMSE) for P and SS was best by the correlation method and for N by the periodic method. Load calculations varied greatly depending both on the characteristics of the rivers and the calculation method. The flow-stratified method overestimated the P and SS loads by about 20% in large low-lake rivers. In small low-lake rivers, the overestimation was 10% and over 14% for P and SS, respectively. By contrast, the averaging method underestimated P and SS loads by 10% and 21% in small agricultural low-lake rivers. All the methods produced rather similar results for N in each of the river types.

Constructed wetlands are among the eutrophication abatement measures for which farmers may receive public subsidies in Finland. To assess the performance of constructed wetlands under boreal conditions, we monitored the retention of total suspended solids (TSS), total P (TP), dissolved reactive phosphorus (DRP), total N (TN), nitrate+nitrate-N (NOx-N) and ammonium-N (NH4-N) for 15–26 months in three constructed wetlands located in southern Finland. Annual retentions were −5–72% for TSS, −6–67% for TP, −33–33% for DRP, −7–40% for TN, −8–38% for NOx-N and −50–57% for NH4-N. The constructed wetland with the longest water residence time (WRT) showed the best performance, retaining annually about 25 kg of TP and 300 kg of TN per hectare. In contrast, the constructed wetland with the shortest WRT functioned only occasionally and was a net source for DRP and NOx-N. In addition to the WRT, high P sorption capacity of constructed wetland soil and high input concentrations appeared to promote retention. Vegetation had a limited effect, input load being transported mostly outside the growing season. When carefully designed and located, constructed wetlands may efficiently reduce nutrient loading from agriculture.

The use of constructed wetlands (CWs) for the treatment of the runoff waters from field cultivation and peat production in boreal climate is reviewed on the base of the authors' own research experiences and a literature study. The main water purifying mechanisms are presented, and the effectiveness of different types of CWs as well as the design and dimensioning parameters at the bottom of the effectiveness are discussed. In our view, CW area in relation to its catchment and hydraulically efficient CW shape are the main issues that a CW designer should focus on. This is because water purifying processes need time for efficient functioning, and both of these factors increase the actual residence time of water in a CW. Although both these factors stand up to as general guidelines, drawing conclusions from direct comparison of CWs in different locations is often misleading because of the differences in climate, catchment properties etc that highly effect the retention performance. Landscape improvement and increased birdlife are raised as examples of the ancillary benefits of CWs. The potential significance of CWs in water protection is dealt with at catchment scale. Comprehensive catchment management with variety of pollution control measures is needed if sustainable water quality improvement is aspired. When designed and located appropriately, CWs can make a useful contribution to this.

Phosphorus in surface runoff water may cause eutrophication of recipient water. This study clarifies the mechanisms of P removal in the wetland of Hovi, Finland, constructed on arable land in 1998. Before the construction, the surface soil (removed in the construction) and subsoil (the current wetland bottom) were analyzed for Al and Fe oxides (Al ox and Fe ox ) reactive in P sorption, and for the distribution of P between various pools as well as for P exchange properties. Retention of P from runoff water within the wetland was studied from 1999 to 2001 in situ and factors affecting the P removal (O 2 availability and P concentration in water) were investigated in a laboratory microcosm. The processes taking place in the wetland diminished by 68% the total P load and by 49% the dissolved reactive P load. Desorption-sorption tests indicated that without removal of the surface soil, there would have been a risk of the wetland being a source of P, since the equilibrium P concentration of the soil removed was high compared with the mean P concentration of the inflowing water. The subsoil contained less P and high amounts of reactive oxides, which could bind P. Evidently, the P sorption by Al ox played an important role in a first phase removal of P, since the wetland retained P efficiently even under anoxic conditions, where Fe tends to be reduced. Fine-textured, mineral soil on the bottom of the wetland (subsoil of the former arable land) seemed to be very efficient in retaining P from agricultural runoff.

Field-scale modelling is widely used as a means to look into interdependencies of processes and to assess potential effects of agricultural management practices as well as of climate and socio-economic scenarios. Generalisation from field-scale results to cover all agricultural land in a catchment by using typical soilcrop- slope combinations has been restricted by a lack of information for the systematic parameterisation of soils. Data from single experimental fields are seldom representative for the whole respective catchment. In this study typical soil profiles for mineral agricultural soils in Finland are defined. Key parameters describing e.g. the texture and water holding capacity of soils, were generated from existing soil data using expert knowledge and are aimed to be used for field-scale modelling when the target is not to model a particular field but soils of certain type in general. Estimates for water balance and phosphorus losses, obtained with the ICECREAM model by applying these data sets, were realistic and compatible with experimental results measured in Finland., Peltomittakaavaista mallinnusta käytetään yleisesti silloin,kun tarkastellaan prosessien kuten pintavalunnan ja perkolaation välisiä riippuvuussuhteita, arvioidaan toimenpiteitä maataloudesta tulevien huuhtoumien vähentämiseksi tai silloin kun halutaan arvioida ilmasto- tai sosio-ekonomisten skenaarioiden hahmottaman tulevaisuuden mahdollisia vaikutuksia vesitaseeseen, eroosioon ja ravinteiden huuhtoumaan. Peltokohtaisen mallinnustuloksen laajentaminen koskemaan koko valuma-alueen maatalousmaata on teknisesti mahdollista käyttämällä tyypillisen maaperän, pellon kaltevuuden ja viljelykasvin muodostamia yhdistelmiä. Tämän lähestymistavan käyttöä on toistaiseksi rajoittanut tarvittavan tiedon puute maaperän systemaattiseksi parametrisoimiseksi. Yksittäisen kenttäkokeen tulos on harvoin edustava koko valuma-alueen mittakaavassa. Tässä tutkimuksessa esitetään yksi tapa ryhmitellä maaperän fysikaalisia ominaisuuksia siten, että niistä voidaan johtaa useita maaperäkohtaisia tyypillisiä parametrisointeja. Nämä tyyppiprofiiliparametrisoinnit kuvaavat kivennäismaalla sijaitsevien peltojen ominaisuuksia Suomessa. Mallinnusta varten maaperän ominaisuustiedot, kuten tekstuuri ja vedenpidätyskyky, johdettiin olemassa olevasta maaperäaineistosta. Tyyppiprofiiliparametrisointia voidaan käyttää silloin kun tarkoituksena ei ole mallintaa yhtä tiettyä peltoa vaan tiettyä maalajia olevia peltoja laajemmin. Kun tätä parametrisointia käytettiin ICECREAM-mallissa, saadut simulointitulokset olivat vesitaseen ja fosforin osalta realistisia ja vastasivat Suomessa kenttäkokeissa saatuja tuloksia.