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In order to reduce odor emissions and surface water pollution while storing manure in field heaps near a barn, there is a challenge in properly designing manure-storage areas. Therefore, it is important to assess what solutions and conditions, considering environmental requirements, should be considered when storing manure in field heaps. The goal of the research is to determine the impact of various factors on the risk of nutrient leaching, soil, and gas emissions from solid manure heaps, considering climatic factors in the environment. Through various scientific studies, a manure pile model has been developed and evaluated for its impact on the risk of potential leaching and odor emissions (using hyperspectral gas emission analysis mass flow method) from manure and the dynamics of the 0–80 cm soil layer properties (nitrate (N-NO3) and nitrite (N-NO2), ammonia (NH3), mineral, and total N). Based on the research results, requirements for manure management and storage during the prohibited fertilization period were established, considering the requirements for nitrates from agricultural sources in Lithuania. An optimal new manure heap model has been identified—a layer of not less than 20 cm of compacted straw (density 150–200 kg m−3) or a 10 cm layer of peat for absorbing manure slurries is formed on the soil surface, the manure heap is surrounded by an earth embankment not less than 30 cm high, the manure heap is covered with a layer of finely chopped straw not less than 10 cm thick, or 5 cm of sawdust, or 5 cm of peat. The manure is stored in the heap for 6–12 months. Following the research results, requirements for manure management and storage during the prohibited fertilization period were established, considering the requirements for nitrates from agricultural sources in Lithuania, applicable to the northern part of the temperate climate zone and applying similar requirements to the relevant countries. [ABSTRACT FROM AUTHOR]

Recently, the number and intensity of hydrological droughts have been increasing; thus, it is necessary to identify and respond to them quickly. Since the primary hydrological data in Lithuania are water levels, and converting these data into discharge takes additional time, there is a need to develop a methodology or adapt these data to analyze and detect hydrological droughts. This paper examines the concept of the standardized water level index (SWLI) calculation, which is based on the standardized precipitation index (SPI) and streamflow drought index (SDI) methods. SDI and SWLI data were compared; SWLI was used to analyze the situation in the past and future. A total of 15 main sub-basins were considered, and the future discharge of three rivers was estimated; SWLI showed good compatibility with SDI. To better analyze droughts, the use of severe drought threshold values (SDTV) was suggested as some river data (especially those for small rivers) needed to be corrected due to dense riverine flora. The dry years and trends identified by SWLI are consistent with previous studies. [ABSTRACT FROM AUTHOR]

The study evaluated climate change impact on water flows and nutrient loads to surface water bodies in Lithuania by applying the SWAT model. Seven RCM and GCM combinations were selected and RCP4.5 and RCP8.5 climate change representative concentration pathways were selected for the study. The study concluded that an annual and winter increase in most river water flows are expected. The change will be driven by rising precipitation, mainly in the regions where it is already high. Less snow would result in less surface runoff, substituted by increased lateral and groundwater flows because of more water percolating through the soils. As a result, water flows could be expected to increase by 9.7% for RCP4.5 and by 35.4% for the RCP8.5 climate scenario by the end-century. Whereas sediment transport and phosphorus loads would tend to decline a little bit (median results are -11.4% and -5.6% respectively for the RCP4.5 scenario, -13.3% and -7.4% for the RCP8.5 by the end of century). Conversely, temperature driven nutrient mineralization and increased leaching are expected to cause a significant increase in nitrogen loads (by 23.1% for the RCP4.5 scenario and by 64.4% for the RCP8.5 by the end of century). Overall, it could be concluded that climate change related hydrometeorological and water quality changes were found to be the most profound for the end-century RCP8.5 climate change scenario. [ABSTRACT FROM AUTHOR]

A mathematical model of nitrate removal in woodchip denitrification bioreactor based on field experiment measurements was developed in this study. The approach of solving inverse problem for nonlinear system of differential convection-reaction equations was applied to optimize the efficiency of nitrate removal depending on bioreactor's length and flow rate. The approach was realized through the developed algorithm containing a nonlocal condition with an incorporated PI controller. This allowed to adjust flow rate for varying inflow nitrate concentrations by using PI controller. The proposed model can serve as a useful tool for bioreactor design. The main outcome of the model is a mathematical relationship intended for bioreactor length selection when nitrate concentration at the inlet and the flow rate are known. Custom software was developed to solve the system of differential equations aiming to ensure the required nitrate removal efficiency. [ABSTRACT FROM AUTHOR]

The potential effects of climate change on nutrient (total N and total P) loads in four large-scale (A=2940-6771 km2) river basins in Lithuania were analyzed. The climate impact assessment was based on an ensemble of four (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) future climate projections, representing the averaged outputs from three (GFDL-CM3, NorESM1-M and HadGEM2-ES) global climate models. For each climate projection, near-future (2016-2035) and distant-future (2081-2100) time periods were compared to the baseline period (1986-2005) to distinguish future changes. The results have shown a decreasing trend in the annual nutrient loads in most of the studied rivers under the projected climate change. Seasonal changes in nutrient loads are also predicted with an increase occurring during the winter months and a fairly high decrease occurring in the spring and early summer months. These changes are consistent with the projected changes in the seasonal stream flow. [ABSTRACT FROM AUTHOR]

Wave power is an abundant source of energy that can be utilized to produce electricity. Therefore, assessments of wave power resources are being carried out worldwide. An overview of the recent assessments is presented in this paper, revealing the global distribution of these resources. Additionally, a study, which aims to assess the spatial distribution of the Baltic Sea near-shore wave power potential along the coast of Klaipėda (Lithuania), is introduced in this paper. The impacts of the wave propagation direction and decreasing depth on wave power resources were examined using the numerical wind-wave model MIKE 21 NSW. The wave height loss of the design waves propagating to shore was modelled, and the wave power fluxes in the studied depths were calculated using the JONSWAP wave spectrum modified for the Baltic Sea. The results revealed that all waves that propagate to the shore in the Baltic Sea near-shore area along the coast of Klaipėda from 30 m depth to 5 m depth lose at least 30% of their power. Still, most common waves in this area are low, and therefore, they start to lose their power while propagating to the shore at relatively low (10-14 m) depths. To turn this into an advantage the wave power converter would have to work efficiently under low power conditions. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Research, Engineering & Management / Aplinkos Tyrimai, Inžinerija ir Vadyba is the property of Institute of Environmental Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although in Lithuania artificial land drainage is a common water management practice, there are still concerns about its downstream hydrological effects. Due to the complexity of flow driving factors, the hydrological effect of drainage is very uncertain, making it difficult to determine its relative importance. Aiming to distinguish between the influence of drainage and other factors in this study, the extent of changes of twenty hydrologic variables (flow magnitude, frequency, duration, timing and rate of change) downstream of drained areas and five explanatory factors that described different aspects of streamflow regimes in a non-redundant way were analysed. The resolution of the task involved the application of principal component and canonical correlation analyses. The results based on data collected from six tile-drained lowland river catchments (A=167-2290 km2) within the period 1940-1990 revealed that weather and catchment soil conditions were the primary factors determining the variability of most streamflow variables. The extent of the drained land area in river catchments affects only a few hydrologic variables - it tends to extend the duration of high pulses and causes later occurrence of annual peaks. The extended duration of high pulses along with the lag in occurrence of annual peaks are attributed to the "sponge effect" of drainage. The study also showed that artificial drainage results in a reduced number of low pulses by creating a more pronounced hydrological connection to groundwater. Most probably this occurs due to the greater depth of tile drains, providing a deeper outlet for shallow groundwater drainage. A larger groundwater inflow may also contribute through deepened streches of channelized streams and newly dug ditches collecting water from lateral tiles. [ABSTRACT FROM AUTHOR]

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 km2) 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< 0.05; two-sided test) using the partial Mann–Kendall test with stream discharge as an explanatory variable. The results show a large variation in concentrations and losses of total phosphorus (TP) among the 34 studied catchments, where the long-term mean annual losses varied from 0.09 to 7.5 kg TP ha−1. In addition, a large interannual variability in losses within catchments was found with up to a factor of 23 between years within the same catchment. Six catchments showed downward temporal trends in the TP loss time series. One upward trend in TP losses was detected in a catchment in south-west Sweden. Eight downward trends were detected in the TP concentration time series. Overall, our results show (1) a huge variability in mean P losses and concentrations among catchments, (2) a huge temporal variability in losses within catchments and (3) few detectable changes in P losses and concentrations over the study period. The results showcase the need for implementation of mitigation strategies towards reduced P losses from agricultural landscapes in the Nordic/Baltic Sea region in order to improve P water quality and ecology in surface waters. [ABSTRACT FROM PUBLISHER]

In Lithuania, artificial drainage is a common agricultural practice. The country remains one of the most extensively drained in the world. The total drained land area occupies 47% of the country's land area and 86% of the agricultural land area, of which 87% is tile-drained. Although the introduction of drainage has improved the quality of agricultural land, the benefits of drainage are associated with many changes in the local environment. Therefore, a review is presented of the results from various investigations and research studies conducted in Lithuania which have reported the historical and economic aspects of the development of agricultural drainage as well as its environmental effects on landscape structure, local hydrology and nutrient losses in the soil. Temporal changes in drainage run-off since the 1970s are also discussed. Furthermore, positive bidirectional effects of natural processes in and around open drain ditches on both environment and practice are highlighted which show the possibility of fostering them intentionally. [ABSTRACT FROM AUTHOR]

A study of precipitation, runoff and total annual nitrogen concentrations in streamflow was performed in three small stream catchments ( A = 1.66 ÷ 14.2 km 2 ) located in western, middle and southeastern parts of Lithuania during 1996–2010. The studied catchments belong to different geographic districts of Lithuania in which climate, soil, land use and farming conditions differ. The main objective was to present and analyse long-term data collected from three water-quality monitoring sites and to investigate the impact of various factors that may affect nitrogen losses. The results revealed the complex and dynamic nature of the various factors affecting nitrogen losses. The nitrogen contribution from wet deposition varied from 6.3 to 56.7 kg ha −1 per year and it was found to be significant factor controlling nitrogen export from the catchments. However, the proportions of arable land and pasture within the catchment, as well as the soil conditions were also found to be important. The annual runoff varied from 54 to 403 mm and exhibited strong spatial patterns among the catchments. The highest runoff was observed in the stream in southeast Lithuania, where sandy soils and a larger groundwater supply prevail. High runoff was also found typical in the stream in western Lithuania, the catchment of which received greater precipitation, exhibited hilly topography and a large drained area. The smallest runoff and highest instream nitrogen concentration (flow-weighted annual average was 7.0 mg l −1 compared with 3.3 and 2.8 mg l −1 in the other streams) was observed in the stream in the middle Lithuanian lowland, where more intensive agricultural activity occurs. The average annual load of total nitrogen in the stream in mid-Lithuania was 15.3 kg ha −1 , compared with 11.8 and 7.0 kg ha −1 for the streams in the southeast and west, respectively. The 15-year data did not show any statistically significant trend either in the dynamics of the annual nitrogen concentration or in the annual nitrogen load of the streams. [ABSTRACT FROM AUTHOR]

In this study the main processes influencing water quality of the Lithuanian rivers have been identified. Factor analysis was tested on river hydrochemical data from 108 sites for the period of 1999-2004. It enabled the identification of main factors determining water quality each season. As a result, monitoring stations were grouped into clusters each representing the influence of relevant factor. The tested multivariate statistical procedures can be applied in practice when the reasons for water quality impairments are to be investigated. The findings reveal that Wastewater factor is prominent in small rivers downstream larger towns; Agro-geological factor — in Northern Lithuania's rivers of heavy carbonated soils and intensive agriculture lands as well as in South eastern Lithuania's rivers of more acidic soils; Hardly degradable organics factor — in Northern and Middle Lithuania's rivers of heavy-textured and fertile agricultural soils. The photosynthesis-vegetation and Aeration factors are predominant in major rivers. [ABSTRACT FROM AUTHOR]

The statistical model MESAW was applied to simultaneously estimate export coefficients and retention of nutrients in four Lithuanian and three Estonian river basins (range 946-8,388 km²). This modelling approach uses non-linear regression to yield the export coefficients for total nitrogen and total phosphorus losses to surface waters, considering different land-use classes and retention of nutrients in the river network. The model was applied to data from 40 water quality monitoring sites and corresponding sub-basin data on land use, point sources and atmospheric deposition. The results showed that the studied river basins had a high nutrient retention capacity: 67-78 and 24-63% of total nitrogen and total phosphorus inputs remained in surface waters. The estimated retention was large in lakes: 27-59% for nitrogen and 11-31% for phosphorus. In-stream retention was apparently much lower, in the range 11-15% for total N and 3-12% for total P. Retention in lakes was lower in Estonia than in Lithuania due to the locations and smaller areas of the lakes in the Estonian basins. In Estonia, the highest relative retention in lakes was 46% for nitrogen and 35% for phosphorus. In-stream retention was also somewhat lower than in Lithuania, possibly because of the lower temperature in Estonian rivers in summer. [ABSTRACT FROM AUTHOR]

The statistical model MESAW was applied to simultaneously estimate export coefficients and retention of nutrients in four Lithuanian river basins (area range: 2,634-6,140 km²). The estimated results revealed substantial capabilities to retain nitrogen and phosphorus in river basins: from 67 to 78% of total nitrogen and from 24 to 63% of total phosphorus relative to the input is retained in surface waters. Estimation of retention was found to be larger in lakes: 27-59% for nitrogen and 11-31% for phosphorus. In-stream retention appeared to be much lower and varied from 11 to 15% for total N and from 3 to 12% for total P. [ABSTRACT FROM AUTHOR]

Copyright of Ekologija is the property of Lithuanian Academy of Sciences Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ekologija is the property of Lithuanian Academy of Sciences Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biochar has received increased attention in environmental applications in recent years. Therefore, three pilot-scale denitrifying bioreactors, one filled with woodchips only and the other two enriched with 10% and 20% by volume of biochar from deciduous wood, were tested under field conditions for the removal of nitrate (NO3-N) and phosphate (PO4-P) from tile drainage water in Lithuania over a 3-year period. The experiment showed the possibility to improve NO3-N removal by incorporating 20% biochar into woodchips. Compared to the woodchips only and woodchips amended with 10% biochar, the NO3-N removal effect was particularly higher at temperatures below 10.0 °C. The results also revealed that woodchips alone can be a suitable medium for PO4-P removal, while the amendment of biochar to woodchips (regardless of 10% or 20%) can lead to large releases of PO4-P and other elements. Due to the potential adverse effects, the use of biochar in woodchip bioreactors has proven to be very limited and complicated. The experiment highlighted the need to determine the retention capacity of biochar for relevant substances depending on the feedstock and its physical and chemical properties before using it in denitrifying bioreactors. [ABSTRACT FROM AUTHOR]

Excess nutrient inflow from tile-drained agricultural fields significantly contributes to the pollution of surface waters in Lithuania. Therefore, two parallel experiments, each using three pilot-scale woodchip-denitrifying bioreactors, were conducted for 2.5- and 1.5-year periods to test whether activated carbon (C) and flaxseed cake (both 10% v /v) and biochar (10% v/v and 20% v/v made of deciduous wood) additives, respectively, can enhance the removal of nitrate-nitrogen (NO 3 -N) and phosphate-phosphorus (PO 4 -P) from tile drainage water and reduce C losses from bioreactors. Higher NO 3 -N removal efficiencies and rates were achieved in bioreactors amended with activated C (10% v /v) and biochar (20% v /v) than in those amended with woodchips alone. Bioreactors amended with 10% v /v flaxseed cake and 10% v/v biochar showed no significant differences from those amended with woodchips alone. The ability to enhance NO 3 -N removal by the addition of activated C and biochar was particularly evident at lower temperatures (≤10.0 °C). Moreover, activated C has proven to be an effective additive capable of substantially reducing C losses and supporting the lowest C/N (i.e., carbon loss to N removal) ratios. To a lesser extent, these capabilities were also characteristic of biochar-amended woodchips, whereas the addition of flaxseed cake resulted in the highest C/N removal ratios. These experiments also revealed that woodchips, alone or amended with flaxseed cake or activated C, are a suitable media that can allow PO 4 -P removal. However, the addition of biochar demonstrated large releases of PO 4 -P and other inorganic elements. Biochar itself was found to be a potential PO 4 -P source that poses a risk of large startup and over time releases. Although the addition of activated C under non-N-limiting conditions resulted in undesirable sulfate-sulfur (SO 4 -S) reduction (this occurred in all study bioreactors), the experiments demonstrated that the addition of activated C can be used to design a more efficient bioreactor with prolonged longevity and higher NO 3 -N and PO 4 -P removal capacities. Owing to the risk of adverse environmental effects (i.e., decreased pH, large exports of inorganic elements or organic C), the application of biochar or flaxseed cake additives in woodchip-denitrifying bioreactors proved to be limited for tile water treatment. • Biochar (20% v /v) and activated carbon (10% v /v) amendments increased NO 3 -N removal in woodchip-denitrifying bioreactors. • The effect of NO 3 -N removal due to biochar and activated C amendments was more distinct at lower temperatures (≤10.0 °C). • Activated carbon substantially reduced C losses and supported the lowest C-to-N removal ratios. • Woodchips alone are a suitable media to provide PO 4 -P removal capacity. • Biochar is a potential source of PO 4 -P and other elements that poses a risk of large startup and over time releases. [ABSTRACT FROM AUTHOR]

• The addition of activated carbon (10% v/v) substantially reduced organic C losses from denitrifying woodchip bioreactor while maintaining denitrification. • Activated carbon amended woodchips compared to woodchips only showed higher NO 3 -N removal efficiency and supported higher removal rates at low temperatures (<10 °C). • Woodchips amended with flaxseed cake (10% v/v) showed no significant difference in removing NO 3 -N compared to the use of woodchips only. • Highest NO 3 -N removal efficiency is achieved at a pH of 7.0–7.5. The performance of three (1.0 m3 volume each) pilot-scale bioreactors, with one filled with woodchips only and the other two amended (10% v/v) with activated C and flaxseed cake, respectively, was tested under field conditions for nitrate removal from tile drainage water in Lithuania. The bioreactors were monitored for a period of 1.5 y, during which the flow rate, hydraulic retention time, water T, pH, dissolved O, nitrate, nitrite, ammonium, sulfate, and chemical O demand concentrations were measured. The results showed that the average nitrate removal efficiency in the bioreactor with no additives was 40.3%, and it was 44.1% in the bioreactor with activated C additives. In the bioreactor with flaxseed cake additives, 41.2% of the N was removed. During the cold seasonal period when the inflow T varied between +1.8 °C and +10.0 °C, activated C-amended woodchips showed higher efficiency and supported higher nitrate removal rates compared to those of other fillers. The highest nitrate removal efficiency was achieved at a pH of 7.0–7.5. The experiment demonstrated the potential for the enhancement of nitrate removal through the incorporation of activated C in denitrifying bioreactors. The addition of activated C substantially reduced the organic C losses while maintaining denitrification. Woodchips amended with flaxseed cake showed no significant difference in nitrates removal compared to the woodchips only treatment. A much higher release of organic C with no added effect on nitrate removal indicated that flaxseed cake as an external C source was more biodegradable than woodchips, but the benefit of its addition to woodchips was not proved. [ABSTRACT FROM AUTHOR]

The causal relationship of changes in nitrogen and phosphorus concentrations in the Akmena-Danė River and its largest tributary, the Eketė River, was analysed for the period 1999–2014. Results showed that the annual concentrations of NH4-N and PO4-P significantly decreased in the Eketė River over the research period. NH4-N also significantly decreased in the Akmena-Danė River. This was mostly due to the shrinkage of agriculture, i.e., the reduction in agricultural land area, total farm and animal numbers and other agricultural activities. The effect of other factors such as air temperature, precipitation rate, shift of precipitation maximum from warm to cold season, drainage runoff from the large tile-drained areas, soil types and the slight increase in forested land was also examined. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study aimed at the evaluation of the change in the effectiveness of Best Management Practices (BMPs) for agricultural pollution control in terms of reduction of nutrient loads to surface water bodies in Lithuania in the context of climate change (CC). The SWAT model was used by applying two CC representative concentration pathways (RCP4.5 and RCP8.5), three time horizons (historical – 2000–2019, mid-century – 2040–2059, and end-century – 2080–2099), and five BMPs (arable land conversion to grasslands, reduced fertilization, no-till farming, catch-crops, and stubble fields throughout winter). The most effective (with the greatest nutrient reduction) BMPs include grasslands, stubble fields, and winter cover crops. No-plough farming and reduced fertilization BMPs appear to be the least effective ones. CC would increase the potential of reduced fertilization and conversion to grasslands BMPs up to 179% and 17%, respectively for total nitrogen (TN) reduction. Regarding total phosphorus (TP), the reduction potential would increase 226% for fertilization reduction, and remain approximate for grasslands (at median −4%). Due to winter reduction of loads, no-plough stubble fields, and winter cover crops would decrease by as much as − 50%, − 12% and − 26%, respectively for TN, and − 30%, − 11%, and − 17%, respectively for TP, compared to the historical period. The greatest change would be recorded for the most extreme CC scenario (RCP8.5) and the longest time horizon (end-century). The effectiveness of BMPs (except for no-plough) for TN load reduction would increase more, and on average would become greater in agriculture dominated areas (of central-northern Lithuania) than elsewhere, although the maximum reduction values would occur in western (and in some cases eastern) Lithuania (except for reduced fertilization). This suggests the importance of the application of the measures in both areas. BMPs (except for grasslands) are expected to have relatively little effect on the overall crop yield. • Climate change will alter the effectiveness of Best Management Practices. • Practices intervening surface runoff pathway is expected to lose effectiveness. • Nutrient reduction potential is predicted to increase in agricultural areas. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Many of the peatlands that used to extend over large parts of Northern Europe have been reclaimed for agriculture. Human influence continues to have a major impact on the hydrology of those that remain, affecting river flow and groundwater levels. In order to understand this hydrology it is necessary to analyze and assess the groundwater and surface water system as a whole. The SIMGRO model was developed for such situations: it simulates groundwater flow in the saturated and unsaturated zones and also surface water flow. Being physically-based, it is suitable for application to situations with changing hydrological conditions and for practical aspects of water management in peatlands. This paper describes the application of the model to different hydrological situations in the Netherlands, Poland and Lithuania. The 3 cases deal with aspects of flooding, natural flow regime and flood storage in relation to suitable conditions for agriculture and nature. The calibration of the model for the cases was limited, but the simulation results show that the estimates of the discharges and groundwater levels were satisfactory, demonstrating that the model is an adequate tool for simulating the hydrological system, and has the potential to assess the impact of different measures. The Dutch case demonstrates that lowland basins where the groundwater has been lowered by extensive land drainage can be restored by restricting the inflow of surface water from the upper parts of the basin: peak flows are significantly reduced. For the Polish case, the damming of ditches in the valley of the Biebrza River could significantly improve the water regime in the peatlands of this floodplain. For the Lithuanian case, the flow regime for the Dovine River could be made more natural if sluice gates were replaced by overflow spill weirs. Understanding the hydrological system is crucial for sustainable land development and effective soil and nature conservation. The different measures simulated in the 3 cases illustrate SIMGRO's potential to simulate hydrological measures. [ABSTRACT FROM AUTHOR]

Abstract Climate change is likely to increasingly impact estuarine fish populations. Changes in water temperature or salinity can have deleterious effects on fish growth and behaviour. A decrease in the abundance of freshwater fish in the northern areas of the Curonian Lagoon has been attributed to increased salinity of inflowing water from the Baltic Sea. Thus, this study investigated the effects of possible changes in environmental salinity and temperature on the growth and behaviour of perch (Perca fluviatilis L.). Laboratory experiments revealed that brackish water (salinity 3 and 6) has neither a negative nor a positive effect on growth rates among perch young-of-the-year, when compared to freshwater (salinity 0). In contrast, results from behavioural experiments demonstrated that perch prefer to remain in brackish water (salinity 6) when given a choice between brackish and freshwater, and in warm water (18 °C) when given a choice between warm and cold water (12 °C). For this reason, the temperature rather than the salinity of inflowing colder brackish water from the Baltic Sea will be the most likely driver of short-term changes in fish distribution in the Curonian Lagoon. Highlights • Brackish water (salinity 3 and 6) has no effect on perch YOY growth rates. • Perch prefer to remain in brackish (salinity 6) water compared to fresh (0) water. • Perch prefer to remain in warm (18 °C) water compared cold (12 °C) water. • Temperature is the driver of changes in fish distribution in the Curonian Lagoon. [ABSTRACT FROM AUTHOR]

Climatic changes will influence the possibilities for agricultural production (e.g. longer growing season), agricultural management practices (e.g. changes in tillage, fertilization, increased use of fungicides) and runoff conditions, and thereby the losses of nutrients from agricultural fields to the environment. Nitrogen (N) is of particular interest in the Baltic Sea region because of its adverse effects on water quality. This paper gives an overview of the expected climatic changes in the Nordic–Baltic region, and the possible effects of these changes on runoff and N losses. Downscaled climate scenarios are used as a basis for evaluating the potential effects of climate change on hydrology, runoff and N losses. Examples from selected catchments in Nordic–Baltic water quality monitoring programmes, including data from extreme events, are presented and used for an assessment of the required adaptations. The analysis shows that there is a strong relationship between annual precipitation and runoff, and between runoff and N loss. The seasonality of precipitation, runoff and N loss indicate high losses outside the growing season. With climate change, increased precipitation is expected to occur mainly outside the growing season – in September–March – and result in increased runoff and thereby increased N losses. Existing data show that extreme events of precipitation have occurred in all seasons during the monitoring period, and have caused high runoff and high losses of N. With the expected increases in N losses, there is an urgent need for efficient measures to reduce N losses in order to fulfil the requirements of e.g. the EU Water Framework Directive (EU-WFD) and the Nitrates Directive and reduction of greenhouse gas emissions (GHG) from agriculture. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Concerns over deteriorating water quality in both freshwater and marine waters have initiated efforts to control diffuse nitrogen (N) losses in all Nordic-Baltic countries. The national strategies for combating diffuse nitrogen losses including selection of mitigation measures, areal extent of measures and incentives for farmers to use the measures differ between the Nordic-Baltic countries. Effects of legislation and other incentives to change agricultural practices and hence to reduce N losses from agriculture are first observed by monitoring close to the source of these losses. Consequently, all Nordic-Baltic countries have set up monitoring programmes including small agriculturally dominated catchments where inputs, outputs and loss of N are followed closely at plot, field and/or catchment scale. We explore the connection between political decisions and regulations, provide an overview of measures and incentives used in the Nordic-Baltic countries, and assess the effect of the measures based on data from national monitoring programmes. [ABSTRACT FROM AUTHOR]

Long-term monitoring data from catchments with relatively uniform land use is important in order to cover management needs such as implementation of various EU Directives. This paper in a uniform fashion examines the temporal trends in nitrogen (N) concentrations and losses from agricultural catchments in the Nordic and Baltic countries. Thirty-five (35) catchments (range 0.1–33 km 2 ) in Norway (9), Denmark (5), Sweden (8), Finland (4), Estonia (3), Latvia (3) and Lithuania (3) were selected for this study. The longest time series were 23 years (1988–2010), while the shortest one was 10 years (2002–2011). The monthly nitrogen concentration and loss data series were tested for statistical trends ( p < 0.05; two-sided test) using the partial Mann–Kendall (PMK) test with stream discharge as an explanatory variable. The study results show a large variation in nitrogen concentrations and losses among the studied catchments, with a large interannual variability in all catchments. For nitrogen losses, 11 statistically significant trends were detected. Nine of these were downward (four out of five Danish catchments; four out of eight in Sweden; one out of three in Finland). Upward trends were detected in two catchments (one in Estonia and one in Latvia). For nitrogen concentrations, 13 statistically significant trends were detected. 10 of these were downward. Among the 11 catchments that showed trends in nitrogen losses, nine catchments also showed statistically significant trends in the in-stream concentration series. In addition, three more Swedish catchments showed downward trends in the concentration series, and one Estonian catchment showed an upward trend. These results indicate that targeted strategies towards reduced nitrogen losses from agricultural land (as in the case of Denmark and Sweden) may significantly improve nutrient surface water quality in small agricultural catchments [ABSTRACT FROM AUTHOR]

Concerns over deteriorating water quality in both freshwater and marine waters have initiated efforts to control diffuse nitrogen (N) losses in all Nordic-Baltic countries. The national strategies for combating diffuse nitrogen losses including selection of mitigation measures, areal extent of measures and incentives for farmers to use the measures differ between the Nordic-Baltic countries. Effects of legislation and other incentives to change agricultural practices and hence to reduce N losses from agriculture are first observed by monitoring close to the source of these losses. Consequently, all Nordic-Baltic countries have set up monitoring programmes including small agriculturally dominated catchments where inputs, outputs and loss of N are followed closely at plot, field and/or catchment scale. We explore the connection between political decisions and regulations, provide an overview of measures and incentives used in the Nordic-Baltic countries, and assess the effect of the measures based on data from national monitoring programmes. [ABSTRACT FROM AUTHOR]