Bjørn Kløve

Characteristics of nitrogen and phosphorus loads in peat mining wastewater

Runoff water quality from a peat mine was studied during 1995 and 1996 in Central Finland. Water samples from three drained sub-catchments and groundwater were analysed for all the standard physio-chemical parametres including different forms of nitrogen and phosphorus. The annual leaching of phosphorus, nitrogen and suspended solids was estimated to be 16-38 kgkm(-2), 1,073-1,500 kgkm(-2), and 2-8 tkm(-2), respectively. The variation in nutrient concentrations could be best explained by the relative volumes of new water (5-day sum of rainfall), ditchwater temperature and conductivity. Heavy rainfall caused new water to infiltrate washing nitrate out of the unsaturated peat layer resulting in high concentrations in ground- and ditchwater. Ditchwater phosphorus concentrations always decreased with increased runoff and peaked, as did COD and colour, after dry spells when old groundwater dominated runoff. A large part of the suspended solids load occurred during snowmelt, whereas dissolved solids and nitrogen loads peaked during summer flows.

Long-term trends and variation of acidity, CODMn and colour in coastal rivers of Western Finland in relation to climate and hydrology

High acidity caused by geochemical processes and intensive land use of acid sulphate (AS) soils have continuously degraded the status of water bodies in Western Finland. Despite this, research on the long-term pattern and dynamics of acidification in rivers affected by acid sulphate soils is scarce. This study examined changes in alkalinity and pH value during the period 1913-2007 in nine large Finnish rivers discharging into the Gulf of Bothnia. In addition, patterns of COD(Mn) and colour were analysed during the period 1961-2007. Relationships between pH, alkalinity, COD(Mn) and colour and climate variables were also studied. In four rivers with no AS soil impact (Kokemäenjoki, Kemijoki, Iijoki and Oulujoki), critically low pH levels did not occur during the study period, whereas three rivers exposed to minor or moderate levels of runoff from AS soils (Lestijoki, Kalajoki, and Siikajoki) had all periods with critically low pH and alkalinity. The most severe acidity problems occurred in the rivers Kyrönjoki and Lapuanjoki, with extensive drainage of AS soils being the main reason for the low pH status. Maximum discharge was clearly related to the acidity status of many rivers during the autumn-winter runoff period, when a significant negative linear correlation was found between maximum discharge and minimum pH in the rivers affected by AS soils. There was also a more distinct relationship between maximum chemical oxygen demand (COD(Mn)) and minimum pH in autumn runoff than in spring. COD(Mn) levels significantly increased with increasing discharge in the rivers with no or minor AS soil impact. Climate change is predicted to increase river flow in general and winter discharge in particular, and therefore the acidity problems in affected rivers may increase in a future climate.

Erosion and sediment delivery from peat mines

Abstract Major factors affecting sediment erosion from peat mines were assessed to provide information on the peat delivery mechanism. Surface runoff and erosion from three plots of 100 m 2 were measured in the field using three different rainfall intensities varying from 0.58–4.38 mm/min. The settling of peat was studied in the laboratory using a settling column. The settling of peat increased with the wetness of the peat. Within the range of the characteristics studied, water temperature and sediment concentration did not change the settling velocity. The erosion process exhibits three different time dependent stages. First, the sediment concentration decreases rapidly from the onset of runoff due to a decrease in erosion by rainfall as more water is added to the surface. During constant surface runoff and rainfall, the erosion decreases due to a decrease in rill development. When the precipitation ceases, the decrease is more pronounced. Ditch erosion is highest in ditches where there is floating peat or the bed material consists of mineral soils. Results obtained in this study suggests that efficient sediment control procedure includes runoff detention during the early stage of a runoff event and the continuous pounding of water above the erodible bed deposits.

Hydraulics and flow modelling of water treatment wetlands constructed on peatlands in Northern Finland

In this study, we evaluated flow structure, effective flow area (A(eff)) and effective porosity (theta(eff)) in three peatlands using the stable isotope (18)O/(16)O ratio and tracer tests. We also applied the readily available groundwater modelling MODFLOW code for wetland flow modelling and simulated in one study site how the hydraulic performance of the wetland will be improved by changing the design of the distribution ditch. Preferential flow paths occurred in all three studied wetlands and A(eff) varied from 40% to 90% of total wetland area while theta(eff) was 0.75-0.99. Constructed flow models accurately simulated the hydraulic head across wetlands (r(2)=0.95-0.99). Similarities between the flow models and the stable isotope distributions observed in this study suggest possibilities in using MODFLOW to design peatlands. The improvement of the inlet ditch configuration (ditch length/wetland width>0.45) can prevent or reduce short-circuiting and dead zones in peatlands treating wastewater.

Groundwater Pollution and Quality Monitoring Approaches at the European Level

The authors investigate the sources and processes of groundwater contamination and their assessment within the Drivers-Pressures-State-Impact-Response (DPSIR) framework. Naturally occurring substances, trace elements, radionuclides, nutrients, and salt (sodium chloride) are reviewed with emphasis on the assessment of the natural background load. Some synthetic substances are also considered, these being petroleum hydrocarbons, chlorinated aliphatics, pesticides and organic-waste contaminants. Newly emerging contaminants cannot be described within the DPSIR; therefore monitoring approaches and indicators of contamination are discussed in order to propose improved monitoring plans that combine physical, chemical and biological indicators and combine science with policy.

Effect of soil properties on peat erosion and suspended sediment delivery in drained peatlands

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

Human health risk assessment of dissolved metals in groundwater and surface waters in the Melen watershed, Turkey

Determination of metal risk levels in potable water and their effects on human health are vital in assessment of water resources. Risk assessment of metals to human health in a watershed, which has not been studied before, is the main objective of the present study. Surface and groundwater sampling was carried out between September 2010 and August 2011 in the Melen Watershed, Turkey, an important drinking water resource for millions of people. Metals were analyzed in the laboratory using inductively coupled plasma. Of the 26 different metals monitored, Al, B, Ba, Cr, Cu, Fe, Mn, Mo and V were found in surface water and As, B, Ba, Cr, Cu, Mn, Mo, V and Zn in groundwater. In groundwater, unitless hazard quotient (HQ) values were 6 for As, 2.7 for Mn and 1 for Zn, while in surface water all metals were below the risk level (HQ < 1). The ingestion risk was found to be higher than the dermal uptake risk. Arsenic mean concentration was observed to be 0.044 mg/L in groundwater. The As carcinogenic risk (CR) value was higher than the internationally accepted risk level (10−4) and with maximum ingestion of groundwater the carcinogenic risk was found to be higher in adults than children. These results show that even unpolluted watersheds can pose a risk to human health and that potential carcinogenic impacts should receive more attention.

Runoff generation in a plough-drained cutover fen in Central Finland

The hydrology of a cutover fen was studied from May to October in 1995 and 1996. Rainfall equivalent depths were measured every 15 min and stream runoff was continuously monitored. Water table depths were measured bi-weekly during 1995 and continuously during 1996. Storm runoff was separated into different components; rain falling directly into channels and rapid groundwater response based on a contributing area method and on different electrical conductivities of rain-, ground- and streamwater. The results show three sources of storm runoff from cutover fens. Frequent small runoff peaks were caused by rain falling directly into channels. The amount of quick runoff increased when rain fell on wet soil, resulting in intermediate sized runoff peaks generated by rapid groundwater response. The largest runoff values were observed after prolonged rainfall when water from the upper part of the catchment flooded the fen

Water‐table‐dependent hydrological changes following peatland forestry drainage and restoration: Analysis of restoration success

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 sites. Different approaches were developed and used to analyze WT changes (mean WT position, WT fluctuation, WT hydrograph, recession, and storage characteristics). Restoration increased WT in most cases but particularly in spruce mires, followed by pine mires and fens. Before restoration, the WT fluctuation (WTF) was large, indicating peat temporary storage gain (SG). After restoration, the WT hydrograph recession limb slopes and SG coefficients (Rc) declined significantly. Drainage or restoration did not significantly affect mean diurnal WT fluctuations, used here as a proxy for evapotranspiration. Overall, the changes in WT characteristics following restoration indicated creation of favorable hydrological conditions for recovery of functional peatland ecosystems in previously degraded peatland sites. This was supported by calculation of bryophyte species abundance thresholds for WT. These results can be used to optimize restoration efforts in different peatland systems and as a qualitative conceptual basis for future restoration operations.

Impact of peatland drainage and restoration on esker groundwater resources: modeling future scenarios for management

Esker aquifers are common groundwater bodies in Europe. Management of these aquifers should take account of the sustainability of groundwater-dependent ecosystems and land use in an integrated way. An unconfined esker aquifer in northern Finland was modelled with MODFLOW to determine how groundwater resources are impacted by the surrounding peatland drainage scheme and to simulate scenarios for possible drainage restoration. The impacts of groundwater abstraction and climate change were also simulated. A calibration-constrained Monte Carlo method was used to provide information on the uncertainties associated with model predictions. The results suggest that peatland drainage in the vicinity of eskers can have a significant role in lowering the water table, even though climate variability may mask these impacts. Drainage restoration by filling the ditches might have positive impacts on the aquifer water levels. Comparison of water-table changes caused by peatland drainage with the changes brought by water abstraction and climate variability helped to quantify impacts of different land-use scenarios and facilitated discussion with the local stakeholders. Based on this study, more attention should be devoted to peatland drainage schemes in integrated groundwater management of esker aquifers.RésuméLes aquifères au sein des eskers sont des masses d’eau souterraine communes en Europe. La gestion de ces aquifères doit tenir compte de la durabilité des écosystèmes tributaires des eaux souterraines et de l’utilisation des terres de manière intégrée. Un aquifère libre au sein d’esker dans le nord de la Finlande a été modélisé avec MODFLOW afin de déterminer comme les ressources en eau souterraine sont impactées par les modalités de drainage des tourbières environnantes et pour simuler des scénarios de restauration possible de drainage. Les impacts de prélèvement des eaux souterraines et du changement climatique ont également été simulés. La méthode de calibration Monte Carlo a été utilisée pour fournir une information sur les incertitudes associées aux prévisions du modèle. Les résultats suggèrent que le drainage des tourbières dans le voisinage des eskers peut avoir un rôle significatif sur l’abaissement du niveau phréatique, même si la variabilité climatique peut masquer ces impacts. La restauration du drainage en comblant des fossés peut avoir des impacts positifs sur les niveaux piézométriques de l’aquifère. La comparaison des modifications des niveaux piézométriques causés par le drainage des tourbières avec les modifications induites par les prélèvements en eau souterraine et la variabilité climatique a aidé à quantifier les impacts des différents scénarios d’utilisation des terres et a facilité la discussion avec les parties prenantes locales. A partir de cette étude, plus d’attention devrait être accordée aux modalités de drainage des tourbières dans la gestion intégrée des eaux souterraines des aquifères d’esker.ResumenLos acuíferos en esker son cuerpos comunes de agua subterránea en Europa. El manejo de estos acuíferos debe tener en cuenta la sostenibilidad de los ecosistemas que dependen del agua subterránea y del uso de la tierra de una forma integrada. Se modeló un acuífero esker no confinado en el norte de Finlandia con MODFLOW para determinar como los recursos de agua subterránea son impactados el esquema de drenaje de una turbera circundante y para simular escenarios para una posible restauración del drenaje. También se simularon los impactos de la extracción de agua subterránea y del cambio climático. Se utilizó el método Monte Carlo restringido por el calibrado para proveer información sobre las incertidumbres asociadas con las predicciones del modelo. Los resultados sugieren que el drenaje de turberas en la vecindad de los eskers puede tener un rol significativo en el descenso del nivel freático, aun cuando la variabilidad climática pueda enmascarar estos impactos. La restauración del drenaje mediante el relleno de las zanjas podría tener impactos positivos sobre los niveles de agua del acuífero. La comparación de los cambios en el nivel freático causado por el drenaje de las turberas con los cambios acarreados por la extracción del agua y la variabilidad del clima ayudaron para cuantificar los impactos de diferentes escenarios de uso de la tierra y facilitaron la discusión con los actores locales. Basado en este estudio, se debe dedicar más atención a los esquemas de drenaje de las turberas en un manejo integrado del agua subterránea de los acuíferos eskers.摘要蛇形丘含水层是欧洲常见的地下水体。这些含水层的管理应该综合考虑依赖地下水的生态系统的可持续性和土地利用。采用MODFLOW模拟了芬兰北部一个非承压蛇形丘含水层,以确定地下水资源是怎样受到周围泥炭地排水方案影响的,并模拟了可能排水恢复的各种方案。同时还模拟了地下水抽取和气候变化的影响。采用校准约束的蒙特卡洛法提供了与模型预测相关的不确定性方面的信息。结果表明,蛇形丘附近的泥炭地排水在降低水位中具有重要作用,尽管气候变异可能掩饰着这些影响。通过填充壕沟使排水恢复可能对含水层水位有积极影响。泥炭地排水造成的水位变化与抽水及气候变异导致的变化对比有助于定量不同土地利用方案的影响,促进与当地利益相关人之间的探讨。在本研究的基础上,应该更加注重蛇形丘含水层综合管理中的泥炭地排水。ResumoOs aquíferos esker são massas de água subterrânea comuns na Europa. A gestão destes aquíferos deve ter em conta, de forma integrada, a sustentabilidade dos ecossistemas dependentes de água subterrânea e o uso do solo. Um aquífero esker não confinado no norte da Finlândia foi modelado com o MODFLOW para determinar como os recursos hídricos subterrâneos são afetados na envolvência de um sistema de drenagem de turfeiras e para simular cenários para uma possível restauração da drenagem. Os impactes da captação de águas subterrâneas e de alterações climáticas também foram simulados. O método de Monte Carlo com restrições de calibração foi utilizado para fornecer informações sobre as incertezas associadas às previsões do modelo. Os resultados sugerem que a drenagem das turfeiras na vizinhança de eskers pode ter um papel significativo no rebaixamento do nível freático, apesar da variabilidade climática poder encobrir esses impactes. A restauração da drenagem através do preenchimento das valas pode ter impactes positivos sobre os níveis da água no aquífero. A comparação das variações do nível freático causadas por drenagem de turfeiras com as variações resultantes da captação de água e da variabilidade climática ajudou a quantificar os impactes de diferentes cenários de uso do solo e facilitou a discussão com os atores locais interessados. Com base neste estudo, conclui-se que se deve dedicar mais atenção aos sistemas de drenagem de turfeiras na gestão integrada das águas subterrâneas em aquíferos esker.