Enn Karro

Exposure to high fluoride drinking water and risk of dental fluorosis in Estonia.

The purpose of this study was to assess exposure to drinking water fluoride and evaluate the risk of dental fluorosis among the Estonian population. The study covered all 15 counties in Estonia and 93.7% of population that has access to public water supplies. In Estonia groundwater is the main source for public water supply systems in most towns and rural settlements. The content of natural fluoride in water ranges from 0.01 to 7.20 mg/L. The exposure to different fluoride levels was assessed by linking data from previous studies on drinking water quality with databases of the Health Protection Inspectorate on water suppliers and the number of water consumers in water supply systems. Exposure assessment showed that 4% of the study population had excessive exposure to fluoride, mainly in small public water supplies in western and central Estonia, where the Silurian-Ordovician aquifer system is the only source of drinking water. There is a strong correlation between natural fluoride levels and the prevalence of dental fluorosis. Risk of dental fluorosis was calculated to different fluoride exposure levels over 1.5 mg/L.

Stormwater infiltration and accumulation of heavy metals in roadside green areas in Göteborg, Sweden

Abstract To avoid the negative effects of the traditional stormwater treatment by drainage into separate or combined sewers, various methods for local stormwater treatment have been introduced, often referred to as ecologically adapted solutions. Stormwater infiltration in urban green areas is a frequently used method. With infiltration, the pollutants contained in the stormwater are, to a great extent, accumulated in the soil profile. Theaccumulation of heavy metals in the topsoil of urban green areas with infiltration of stormwater runoff from roads is compared with that in adjacent green areas with no stormwater infiltration. The topsoil layers of urban roadside areas in Goteborg, Sweden, are polluted by heavy metals. The concentrations of Zn, Pb and Cu are about 2 to 8 times higher than in natural rural areas in Sweden. Concentrations of metals in infiltration areas were, on average, 200% higher than in reference areas.

Simulation of the hydrogeologic effects of oil-shale mining on the neighbouring wetland water balance: case study in north-eastern Estonia

The water balance of wetlands plays an integral role in their function. Developments adjacent to wetlands can affect their water balance through impacts on groundwater flow and increased discharge in the area, and they can cause lowering of the wetland water table. A 430 km2 area was selected for groundwater modelling to asses the effect of underground mining on the water balance of wetlands in north-eastern Estonia. A nature conservation area (encompassing Selisoo bog) is within 3 km of an underground oil-shale mine. Two future mining scenarios with different areal extents of mining were modeled and compared to the present situation. Results show that the vertical hydraulic conductivity of the subsurface is of critical importance to potential wetland dewatering as a result of mining. Significant impact on the Selisoo bog water balance will be caused by the approaching mine but there will be only minor additional impacts from mining directly below the bog. The major impact will arise before that stage, when the underground mine extension reaches the border of the nature conservation area; since the restriction of activities in this area relates to the ground surface, the conservation area’s border is not sufficiently protective in relation to underground development.RésuméLe bilan hydrique joue un rôle fondamental dans le fonctionnement des milieux humides. Des activités contigües peuvent impacter l’écoulement de la nappe, causer une décharge accrue et un abaissement de son niveau. Une zone de 430 km2 a été sélectionnée pour modélisation de nappe et évaluation de l’effet de l’exploitation souterraine sur le bilan hydrique d’une zone humide du Nord-Est de l’Estonie. Un périmètre naturel protégé (incluant la tourbière de Selisoo) se trouve à 3 km d’une exploitation d’huile de roche mère. Deux scénarios correspondant à différentes emprises de la future exploitation ont été simulés et comparés à l’état actuel. Les résultats montrent que la conductivité hydraulique verticale de sub-surface est critique vis à vis de l’assèchement potentiel de la zone humide conséquente à l’exploitation. Un impact significatif sur le bilan hydrique de la tourbière de Selisoo sera causé par l’approche de l’exploitation mais l’impact additionnel de l’exploitation sous la tourbière elle même sera mineur. L’impact majeur surgira avant ce stade, quand la mine souterraine atteindra la limite de la zone de protection naturelle ; comme la restriction des activités dans cette zone concerne la surface du sol, la conservation de sa bordure n’est pas une protection suffisante vis à vis du développement souterrain des travaux.ResumenEl balance de agua de los humedales juega un rol integral en su función. Los desarrollos adyacentes a humedales pueden afectar su balance de agua a través de impactos sobre el flujo de agua subterránea y el incremento de la descarga en el área, y ello puede causar el descenso del nivel freático del humedal. Un área de 430 km2 fue seleccionada para modelar del agua subterránea y evaluar el efecto de la explotación subterránea sobre el balance de agua de un humedal en el noreste de Estonia. Un área de conservación natural (que abarca el pantano de Selisoo) está dentro de un radio de 3 km de una mina subterránea de esquistos bituminosos. Se modelaron dos escenarios futuros de explotación con diferentes extensiones areales y se compararon con la situación actual. Los resultados muestran que la conductividad hidráulica vertical del subsuelo es de importancia crítica para el drenaje potencial del humedal como resultado de la explotación. Un impacto significativo sobre el balance de agua del pantano de Selisoo será causado por la aproximación a la mina, pero serán solo un impacto menor adicional proveniente de la explotación directamente debajo del pantano. El mayor impacto surgirá antes de esa etapa, cuando la extensión de la mina en el subsuelo alcance el límite del área de conservación natural; puesto que la restricción de actividades en este área se relaciona a la superficie del terreno, el límite del área de conservación no es lo suficientemente protectora en relación al desarrollo subterráneo.摘要湿地水平衡在其功能上页页着整体作用。比页湿地的页页通页页地 下 水流的影响和增加的页页可影响水平衡,可降低湿地水位。页页一个 430平方公里的区域页行地下水模页,页价地下页采页页沙尼页页北部湿 地水平衡的影响。自然保页区就页于地下油页岩页3公里之内。页不同区 域范页的两个未来页采方案页行了模页并与页在的情况页行了页比。页 果页示地下的垂直水力页水系数页页采中潜在的湿地排水至页重要。接近 页山就会页Selisoo沼页水平衡页生重要影响,但直接在沼页之下的页采只 有很小的页外影响。主要影响出页在页个页期前,即地下页山延伸到自然 保页区的页界。因页本地区的活页限制与地表有页,因此,保页区的页界 不能足页防页地下的页页。ResumoO balanço hídrico das zonas húmidas desempenha um papel fundamental na sua função. Desenvolvimentos adjacentes às zonas húmidas podem afetar o seu balanço hídrico através de impactes sobre o fluxo de água subterrânea e o aumento da descarga na área, podendo causar o rebaixamento do nível da água subterrânea na zona húmida. Foi selecionada uma área de 430 km2 para modelação das águas subterrâneas, a fim de avaliar o efeito da exploração mineira subterrânea no balanço hídrico da zona húmida, no nordeste da Estónia. A área de conservação da natureza (englobando o pântano Selisoo) fica a 3 km de uma mina subterrânea de xisto betuminoso. Dois cenários futuros de exploração mineira, com diferentes extensões de área de exploração, foram modelados e comparados com a situação atual. Os resultados mostram que a condutividade hidráulica vertical do subsolo é de importância crítica para a potencial secagem das zonas húmidas, como resultado da mineração. A aproximação dos trabalhos mineiros causará um impacte significativo sobre o balanço hídrico no pântano Selisoo, mas apenas existirão impactes adicionais menores da mineração diretamente por baixo do pântano. O maior impacte vai surgir antes dessa fase, quando a extensão subterrânea da mina atingir a fronteira da área de conservação da natureza; uma vez que a restrição de atividades nesta área se relaciona com a superfície do solo, a conservação da fronteira da área não é suficientemente protetora em relação ao desenvolvimento dos trabalhos subterrâneos.

Reducing Exposure to High Fluoride Drinking Water in Estonia—A Countrywide Study

Fluoride is a naturally occurring contaminant in groundwater in Estonia. There are several regions in Estonia with fluoride contents in public water supplies as high as 7 mg/L. Long-term exposure to high-fluoride drinking water may have several adverse health effects, primarily dental fluorosis. The opportunities for exposure reduction rely highly on water treatment technologies. Since 2004 public water suppliers in Estonia have made efforts to diminish fluoride content in drinking water systems. A follow-up study on a country level was carried out in 2004–2012 to analyze the changes in population exposure to excessive (over 1.5 mg/L) fluoride in drinking water and to get information about the reduction methods applied by public water supplies (PWS) to optimize the fluoride levels in public water system. The results showed that bigger PWS have been more effective in fluoride reduction measures than small PWS. The main methods used to lower the fluoride content were reverse osmosis technology and replacement of water sources with new ones (new drilled wells). As a result of all the measures taken the overall high-fluoride exposure has been reduced substantially (82%).

Sea-Level Change and Flood Risks at Estonian Coastal Zone

This paper reviews Estonian relative sea level, land uplift and coastal floods data and provides sea-level scenarios and risk assessment of coastal flooding in urban areas for the twenty-first century. Considering the present post-glacial land uplift rates of Estonian coastal areas and the global ocean level rise projections, the long-existing trend of relative sea-level lowering may very probably be replaced by a relative sea-level rising trend during the twenty-first century. By the end of the twenty-first century we project the relative sea level to be c. 20 to 40 cm or c. 40 to 60 cm higher in the case of the International Panel for Climate Change Representative Concentration Pathways (RCP) 4.5 or RCP 8.5 scenario, respectively. The sea-level rise together with the increased storm frequency and decreased winter ice cover period will very probably increase the extent of floods during the twenty-first century. A significant coastal flooding risk affects four cities, Parnu, Kuressaare, Haapsalu and Tallinn and eight smaller towns. The largest coastal flooding in Estonia is recorded in Parnu, with the highest sea level 275 cm in 2005. Calculations show that due to the impact of predicted climate change and in the case of certain weather conditions, coastal floods in Parnu may affect areas up to 400 cm above the present sea level by the end of the twenty-first century. The scenarious of future flood limits are needed for sustainable planning of the coastal zone and for development of rescue strategies.There are already several land use and urban planning instruments and laws for climate adaptation, such as environmental impact assessment, risk assessment and restriction zones for construction in certain buffer and flood areas. Flooding risk measures consist of risk mapping and a national emergency plan. However, further integration of climate issues into existing laws, strategies and land use plans is essential to have a targeted approach in reducing the vulnerability of populated areas and strengthening the adaptive capacity of the urban system against climate change.