Anna-Kaisa Ronkanen

• D. Sc. (Tech.)
• Senior Scientist at Finnish Environment Institute

The drainage of peatlands increases peat decomposition, promoting the release of phosphorus (P) to soil pore water and the eventual leaching to water bodies. The P retention capacity in the soil layers affects the likelihood of subsequent P leaching to the drainage network. We aimed to study the retention patterns of P and to assess the risk of P l...

The report is in accordance with Article 10 of Council Directive concerning the protection of waters against pollution caused by nitrates from agricultural sources, and it concerns the implementation of the Directive in Mainland Finland in 2020–2023. Besides the period 2020–2023, this seventh report analyses the observed changes compared to the pre...

To achieve a good ecological status of water resources, we are exploring new frontiers by envisioning river basin planning through the newly promoted digital twin perspective. In river basin management, a digital twin is an innovative virtual paradigm – a holistic living replica of the river basin achieved by seamless integration of real-time monit...

Water covers most of the Earth's surface and is nowhere near a good ecological or recreational state in many areas of the world. Moreover, only a small fraction of the water is potable. As climate change-induced extreme weather events become ever more prevalent, more and more issues arise, such as worsening water quality problems. Therefore, protec...

Microplastics (MPs) are an anthropogenic pollutant of emerging concern prominent in both raw and treated municipal wastewater as well as urban and agricultural run-off. There is a critical need for the mitigation of both point- and diffuse sources, with treatment wetlands a possible sustainable nature-based solution. In this study, the possible ret...

After drainage for forestry and agriculture, peat extraction is one of the most important causes of peatland degradation. When peat extraction is ceased, multiple after-use options exist, including abandonment, restoration, and replacement (e.g., forestry and agricultural use). However, there is a lack of a global synthesis of after-use research. T...

In wastewater treatment, wetlands are regarded as cost-efficient and sustainable purification systems. Currently, different types of wetland are used for year-round treatment of municipal wastewater (the polishing step after the secondary or tertiary units) in cold climate regions. However, there is a lack of understanding regarding the effect of f...

In Northern Finland, the most significant land use challenges are related to bioenergy production from peat extraction and forest biomass. Increasing societal demand for bioenergy may increase production rates. However, environmental impacts of peat extraction are of increasing concern, which has led to a decline in production, thereby freeing up t...

Anaerobic digestion (AD) and composting are commonly utilized sludge management methods however, the influence of different coagulant types on these biological processes and their stabilized biomass characteristics have not been fully explained. In this study, the effect of the coagulant used in municipal wastewater treatment on the biological stab...

In northern peatlands, near‐saturated surface conditions promote valuable ecosystem services such as carbon storage and drinking water provision. Peat saturated hydraulic conductivity (Ksat) plays an important role in maintaining wet surface conditions by moderating drainage and evapotranspiration. Peat Ksat can exhibit intense spatial variability...

The HYDRUS wetland module is widely used together with the biokinetic model CWM1 to simulate reactive transport of contaminants in constructed wetlands. However, this approach has not been used previously to simulate processes in peat-based wetlands operating in cold climates and treating mining-influenced water. In this study, the goal was to clar...

Peatland restoration aims to achieve pristine water pathway conditions to recover dispersed wetness, water quality, biodiversity and carbon sequestration. Restoration monitoring needs new methods for understanding the spatial effects of restoration in peatlands. We introduce an approach using high-resolution data produced with an unmanned aircraft...

The 21st century has brought new challenges and opportunities and has also increased demands on the Nordic hydrological community. Our hydrological science focus and approaches need rethinking and adaptation to the changing requirements of society in response to climate change and human interventions, in search of more comprehensive and cross-disci...

To remove nitrogen in cold conditions, we studied new nature-based treatment solutions using six pilot-scale reactors. The pilots were woodchip bioreactor (WBR), aquatic floating hook-moss (Warnstorfia fluitans) (MBR), and a combined woodchip and floating hook-moss hybrid unit (HBR) with an improved hydraulic design. The experiment was run in a cli...

Iron (Fe) is an important element in aquatic ecosystems worldwide because it is intimately tied with multiple abiotic and biotic phenomena. Here, we give a survey of manifold influences of Fe, and the key factors affecting it in the boreal catchments and their waters. It includes the perspectives of biogeochemistry, hydrology, ecology, and river ba...

Peatlands worldwide are being threatened by intensive land use and drainage, which leads to soil subsidence. This has consequences for farming, especially on low-gradient cultivated peat-dominated lowlands with high flood risk. In this study, we combined historical soil elevation data and new lidar data to improve the estimation of subsidence and i...

Tämän selvityksen tarkoituksena on tuottaa kirjallisuuskatsaus ja siihen pohjautuvia johtopäätöksiä soiden ennallistamisen ilmasto-, vesistö- ja suoluontovaikutuksista. Selvitys pyrkii erityisesti kasaamaan yhteen uusimpia tutkimustuloksia ja aineistoja ennallistamisen vaikutuksiin liittyen ja toisaalta muodostamaan kokonaiskuvan laaja-alaisempaa s...

Undisturbed peatlands are effective carbon sinks and provide a variety of ecosystem services. However, anthropogenic disturbances, especially land drainage, strongly alter peat soil properties and jeopardize the benefits of peatlands. The effects of disturbances should therefore be assessed and predicted. To support accurate modeling, this study de...

The influence of seasonally frozen ground (SFG) on water, energy, and solute fluxes is important in cold climate regions. The hydrological role of permafrost is now being actively researched, but the influence of SFG has received less attention. Intuitively, SFG restricts (snowmelt) infiltration, thereby enhancing surface runoff and decreasing soil...

Recirculating aquaculture systems (RAS) discharge management limits the development of the aquaculture sector, because RAS do not automatically result in low nutrient emissions. Research has helped develop discharge management systems such as wetlands and woodchip bioreactors that have been adopted by Danish commercial model trout farms. To further...

Geomembranes are used worldwide as basin liners in tailings ponds to decrease the permeability of the foundation and prevent further transportation of harmful contaminants and contaminated water. However, leakage into the environment and damage to the geomembrane have been reported. This paper reviews available literature and recommendations on geo...

Fully integrated physically based hydrological modeling is an essential method for increasing hydrological understanding of groundwater‐surface water (GW‐SW) interactions in peatlands and for predicting anthropogenic impacts on these unique ecosystems. Modeling studies represent peat soil in a simplistic manner, as a homogeneous layer of uniform th...

Impacts of mining on water quality are a great concern in the Arctic region. This study evaluated the impact of pre-treated mine effluent on river water quality. The study was conducted along the Seurujoki River in sub-Arctic Finland, which is impacted by Kittilä gold mine. The study analyzed water quality and hydrological data upstream and downstr...

Coagulants are widely used for solids (uneaten food, faeces, etc.) management in recirculating aquaculture systems (RAS), but no recent research has been performed on the effectiveness of different coagulants in treatment of aquaculture sludge. This study examined the effectivity of selected inorganic (polyaluminium chloride, PAC) and organic produ...

Peatland ecosystems are complex mosaics and located often in low-lying transitional zones between terrestrial and aquatic ecosystems. Peatlands in its pristine state play a significant role in regulating the hydrological, biogeochemical and ecological functions and act as long-term storage for carbon. However, up to 20% of the global peatland resou...

Aquaculture needs practical solutions for nutrient removal to achieve sustainable fish production. Passive denitrifying bioreactors may provide an ecological, low-cost and low-maintenance approach for wastewater nitrogen removal. However, innovative organic materials are needed to enhance nitrate removal from the low carbon effluents in intensive r...

Antimony (Sb) is a common contaminant in natural peatlands used as treatment wetlands for water influenced by metal mining in cold-climate regions. However, while other metalloids such as arsenic have been well studied, little is known about removal and retention of Sb in northern wetlands under challenging environmental conditions. In this study w...

Due to the complexity of soil freeze/thaw processes and a variety of factors affecting pollutant removal in treatment wetlands, laboratory pilot systems are powerful tools offering a rare opportunity to observe processes that have a significant impact on year-round purification. This paper describes the design, construction, monitoring and operatio...

Detailed, accurate information on soil temperature is crucial for understanding processes leading to solute leaching and greenhouse gas (GHG) emissions from managed peat soils, but few studies have attempted to study these processes in detail. Drained peat soils have different characteristics from pristine peat. Cultivated peat soils, in particular...

Treatment peatlands are water purification systems located on existing mires. They are commonly used to treat different types of waters, ranging from municipal wastewaters to mine effluent. This study evaluated the capacity of unmanned aerial vehicle (UAV)-based thermal infrared (TIR) imaging, color infrared imaging, and stable water isotopes as a...

Hydrological connections between aquifers and boreal mires need to be better understood for protection of this type of wetland. Three-dimensional (3D) models have so far been sparsely used for such systems. This study investigated the effect of parameterisation with global sensitivity analysis on groundwater-surface water (GW-SW) interactions in a...

Ecosystem protection requires a better definition of groundwater (GW) dependence and tools to measure this dependence. In this study, a classification method for the GW dependence of headwater streams was devised based on the fact that GW affects discharge, thermal regime, and water quality. The method was tested in three boreal headwater streams d...

Nitrogen (N) loads from municipal and mine wastewater discharges typically increase N concentrations in recipient water bodies which should get more attention especially in cold-climate regions. This study compared N removal efficiency of six constructed wetlands (CWs) treating mine waters and three CWs polishing municipal wastewater. There were cl...

Managed aquifer recharge (MAR) structure is widely used to expand groundwater resources. In arid regions with flash flooding, MAR can also be used as a flood control structure to decrease peak discharge of rivers. In this paper, we present a method for quantifying the role of MAR in head water systems and assess its impact on the total water balanc...

The Min-North (Development, Evaluation and Optimization of Measures to Reduce the Environment Impact of Mining Activities in Northern Regions) project was a trans-national cooperative project, with participants from the Geological Survey of Finland (GTK), University of Oulu (UO), UiT The Arctic University of Norway (UiT), Luleå University of Techno...

Nutrient export from drained peatland has significant impacts on aquatic environments in Nordic catchments. Spatial information on variations in nutrient concentrations across different landscapes and land uses is needed to design measures for achieving the good ecological status of the EU Water Framework Directive. In this study we determined back...

Increased metal mining in the Arctic region has caused elevated loads of arsenic (As), antimony (Sb), nickel (Ni), and sulfate (SO4²⁻) to recipient surface or groundwater systems. The need for cost-effective active and passive mine water treatment methods has also increased. Natural peatlands are commonly used as a final step for treatment of minin...

Peatlands are used for the purification of mining-affected waters in Northern Finland. In Northern climate, microorganisms in treatment peatlands (TPs) are affected by long and cold winters, but studies about those microorganisms are scarce. Thus, the bacterial, archaeal and fungal communities along gradients of mine water influence in two TPs were...

The effect of cold climate conditions on nitrogen removal in treatment wetlands is not entirely clear, especially in regards to the effect of freeze-thaw conditions on purification processes. Effective monitoring of treatment wetlands in harsh climate regions is difficult. Thus, pilot wetland systems were designed to simulate real freeze-thawing co...

Using data from 22 catchments in Northern Finland, this study demonstrates how runoff prediction in ungauged high-latitude catchments can be improved using simplified conceptual models tailored to readily available data in the region. The newly developed current precipitation index (CPIsnow) model provides a parsimonious tool to predict streamflow...

Potential benefits of peatland restoration by rewetting include carbon sequestration, restored biodiversity, and improved hydrological functions. There is great uncertainty about how catchment hydrological processes change after restoration, with a particular lack of well‐documented catchment runoff data. This study compared five formerly Disturbed...

Northern peatlands in their natural state are sinks of carbon dioxide (CO2) but sources of methane (CH4). They are often nitrogen limited and can act as sinks for greenhouse gas (GHG) nitrous oxide (N2O). Peatlands have been used to treat wastewaters from different point sources. Continuous nutrient and pollutant load to a nutrient limited peatland...

In cold climate regions, ice roads are engineered as temporary winter transportation routes on frozen lakes, rivers and seas. The ice road season start, end and duration principally depend upon ice thickness, which is controlled by surface air temperature (SAT) in terms of freezing and thawing degree-days (FDD and TDD, respectively). Both FDD and T...

The northern terrestrial ecosystems are important carbon sinks globally storing up to 1715.8 Pg of carbon. This carbon may be partly released as an effect of global warming. Thus, it is of high importance to understand the dynamics of carbon fluxes between atmosphere and these ecosystems in the face of changing climate. One of the governing factors...

Fully-integrated physically-based groundwater-surface water models are valued tools to study groundwater-surface water (GW-SW) interactions. Despite this fact, little applications exists of integrated physically-based modelling investigating the GW-SW interactions at large scales. Long computational times and high data requirements are generally co...

Drainage is known to affect peatland natural hydrology and water quality, but peatland restoration is considered to ameliorate peatland degradation. Using a replicated BACIPS (Before-After-Control-Impact Paired Series) design, we investigated 24 peatlands, all drained for forestry and subsequently restored, and 19 pristine control boreal peatlands...

This study evaluated variabilities and trends in annual snowfall to total precipitation (S/P) ratio at Sodankylä, Kajaani and Kaisaniemi weather stations in northern, central and southern Finland during 1909–2008. Annual S/P ratio was estimated using daily precipitation and temperature records as input to a calibrated and validated temperature-inde...

Peat is an inexpensive and biodegradable sorbent material with good capacity to sorb cationic ions such as metals and metalloids. The aim of this study was to evaluate metal removal efficiency of natural and chemically treated (HCl) peat when applied as sorbent media in small scale pilot filter systems. Based on the results obtained, purification e...

Increased N load on recipient water bodies typically deteriorate water quality, especially if N is the limiting nutrient in an aquatic ecosystem. In this study, constructed wetlands as an N removal step in mine wastewater treatment were studied with the focus of winter time purification efficiencies and hydraulic wetland designing. The results show...

Tutkimuksessa tarkasteltiin turvetuotannon valumavesiä puhdistavan pintavalutuskentän toimintaa laajan vedenlaatuaineiston perusteella. Aineisto kerättiin vuonna 2012 sisältäen lumen sulantavaiheen, kesän ja syksyn. Tutkimuksessa havaittiin roudan yhteys valumaveden laatuun. Pintavalutuskentän toiminta oli parhaimmillaan kesäaikaan, mutta se kykeni...

In dry and semi-dry climate, Artificial Ground-Water Recharge Structures (AGWRS) are used to manage aquifer recharge and control flood . These structures decrease the maximum discharge and increase the runoff duration through the wet seasons. In this study, we are going to present a framework to quantify the role of AGWRS in headwater tributaries o...

The unique biodiversity and plant composition of peatlands rely on a mix of different water sources: precipitation, runoff and groundwater (GW). Methods used to delineate areas of ecosystem groundwater dependence, such as vegetation mapping and solute tracer studies, are indirect and lack the potential to assess temporal changes in hydrology, infor...

A new precipitation index-based model, which includes a snow accumulation and melt component, has been developed to simulate hydrology in high latitude catchments. The model couples a point snowmelt model with a current precipitation index (CPI) formulation to simulate continuous daily runoff from catchments with seasonal snow cover. A new runoff c...

Restoration impact of forestry-drained peatlands on runoff water quality and dissolved organic carbon (DOC) and nutrient export was studied. Eight catchments were included: three mesotrophic (one undrained control, two treatments), two ombrotrophic (one drained control, one treatment) and three oligotrophic catchments (one undrained control, two tr...

In cold climate regions, ice roads are engineered as temporary winter transportation routes on the frozen seas, lakes and rivers. The ice road season parameters (start, end and length) are principally dependent on the thickness of ice, which is naturally controlled by temperature in terms of freezing (FDDs) and thawing (TDDs) degree-days. It has be...

In a study on northern treatment wetlands, we examined whether P adsorption capacity remained high, with maintained P retention, after almost 20 years of loading. We also examined the most important processes for the treatment wetlands as a long-term P sink and analysed peat and water quality in the peat soils of the wetland. We tested P adsorption...

Pristine peat soils are characterized by large porosity, low density and large water and organic matter contents. Drainage and management practices change peat properties by oxidation, compaction and mineral matter additions. This study examined differences in physical properties (hydraulic conductivity, water retention curve, bulk density, porosit...

Constructed wetlands (CWs) are commonly established to reduce pollution load from different sources. In environmental permits, the load remaining after CW purification is typically estimated through concentration and flow measurements. This load monitoring is often carried out using long water quality sampling intervals, which causes uncertainty in...

Recovery of hydrological conditions after restoration in previously drained peatlands is typically faster process compared to changes in runoff water quality. Often nutrient load from restored sites increase remarkably during restoration operation and reduce over time when conditions stabilize. However, in some sites nutrient load can remain high f...

Peatland hydrology and ecology can be irreversibly affected by anthropogenic actions or climate change. Especially sensitive are groundwater dependent areas which are difficult to determine. Environmental tracers such as stable isotopes of water are efficient tools to identify these dependent areas and study water flow patterns in peat-lands. In th...

The poster was presented in the Peatland hydrology session of the EGU General Assembly 2016.

A before-after-control approach was used to analyze the impact of peatland restoration on hydrology, based on high temporal resolution water-table (WT) data from 43 boreal peatlands representative of a south-boreal to north-boreal climate gradient. During the study, 24 forestry drained sites were restored and 19 pristine peatlands used as control s...

Many types of boreal peatland ecosystems such as alkaline fens, aapa mires and Fennoscandia spring fens rely on the presence of groundwater. In these ecosystems groundwater creates unique conditions for flora and fauna by providing water, nutrients and constant water temperature enriching local biodiversity. The groundwater-peatland interactions an...

Wetlands are commonly used to treat phosphorus from the effluent of municipal wastewater plants after conventional treatment and wastewater from various diffuse sources, with good results. The long term phosphorous (P) retention capacity of wetland treatment systems is a key research question. This study examined phosphorus retention in wetland (pe...

Runoff generation and fluxes of dissolved elements were studied in two drained peatlands under different land uses during spring snowmelt 2012. One site experienced soil frost, whereas the other site was frost-free due to groundwater seepage. Runoff water was sampled at 12-hour intervals during the snowmelt peak and soil and snow samples were taken...

Greenhouse gas (GHG) emissions from pristine peatlands and peatlands drained for agriculture, forestry or peat extraction have been studied intensively. However, few studies have compared GHG emissions from peatlands under different land-use type within the same peatland area. This study examined methane (CH4) and nitrous oxide (N2O) emissions and...

With climate warming, snowmelt and runoff will occur more frequently during winter months. For efficient removal of runoff loads, water pollution protection methods such as constructed wetlands must also function during winter runoff periods. This study evaluated the purification efficiency and function of constructed wetlands in treating peat extr...

Purification efficiency of a treatment wetland for a peat extraction area in Northern Finland was studied March–October 2012. The focus was on the snowmelt season, with inflow and outflow sampled twice a day. All samples were analysed for stable isotopes of water and various water quality parameters. The wetland inflow and outflow were continuously...

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Conference poster presented at International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, Vienna, 2015. http://www-pub.iaea.org/iaeameetings/46527/International-Symposium-on-Isotope-Hydrology-Revisiting-Foundations-and-Exploring-Frontiers

Peat extraction runoff water requires chemical treatment to remove organic matter and phosphorus. In Finland, ferric sulphate (FS) is normally used as coagulant agent, but significant variations in runoff water quality and the lack of optimisation of process parameters has led to increased acidity, metal and sulphate concentrations in the purified...

Peatland restorations have been actively done in Finland since the 1970s. The restoration has covered about 1300 hectares of land annually in order to meet the global target of halting the loss of biodiversity and secure ecosystem services. This is for the fact that restoration of drained peatlands is believed to restore back the lost biodiversity...

There is increasing interest to restore degraded peatland, but long term effects of restoration are poorly known. Totally 46 boreal peatland were included in a study set, including 20 fens, 13 pine mires and 13 spruce mires, with peatland types ranging from nearly ombrotrophic Sphagnum bogs to rich fens. Study sites covered spatially almost whole F...

Numerous studies have reported significant declines in snow resources in Finland and elsewhere during the 20th century. To identify the main climate factors controlling these declines in Finland, this study evaluated long-term variations and trends in wintertime climate, snowpack hydrological processes (SHPs) and continuous snow cover duration (CSC...