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Wahlroos O.,University of Helsinki | Valkama P.,Water Protection Association of the River Vantaa and Helsinki Region | Makinen E.,Environment and Natural Resources | Ojala A.,University of Helsinki | And 10 more authors.
International Journal of Biodiversity Science, Ecosystems Services and Management | Year: 2015

Urbanization changes water balance, degrades water quality and disrupts habitats. Wetlands offer storm water volume and flow control, water pollution mitigation, and rich land-water interphase habitats. In the present case study, urban wetlands were designed and implemented to provide multiple functions, including water quality improvement and the establishment of critically endangered clay stream habitat, along a revived urban stream within the Baltic Sea watershed in Southern Finland. The primary water quality concern in the recipient lake is algal bloom controlling and clay particle-carried phosphorus.Wetlands were monitored for functioning over five calendar years. At a wetland monitored for 5 years, herbaceous vegetation was well self-established in the second year, and reached 102 species, of which 97% were native, in the fifth growing season. Successful breeding of amphibians and water birds occurred right after construction. Continuous water quality monitoring over the fourth year at this wetland, with 0.1% area of its watershed, revealed seasonal and event-based differences: for total phosphorus, an annual 10% average with lower removal rates outside, and up to 71% event reductions during the growing season, while highest load reductions occurred during heavy rain and snowmelt events outside the growing season. The created wetlands provided critical habitat and beneficial functions and thus compensated partly for urbanization. © 2015 Taylor & Francis.

Maunula L.,University of Helsinki | Soderberg K.,University of Helsinki | Vahtera H.,Water Protection Association of the River Vantaa and Helsinki Region | Vuorilehto V.-P.,Helsinki Region Environment Services Authority HSY | And 4 more authors.
Journal of Water and Health | Year: 2012

Norovirus (NoV) is one of the most common causative agents of waterborne gastroenteritis outbreaks. The main objective of the study was to determine the presence of human NoVs in river water and in treated wastewater (TW) released into the river. During a one-year survey in 2007/2008, NoVs were detected in 30.8% of river samples (20/65), and 40.5% of TW samples (17/45) with a realtime reverse transcription-PCR assay. NoVs were present in the river water in the winter and spring, coinciding with the NoV epidemiological peak in the community and the presence of NoVs in TW. Later in 2009, the concentration method used, pre-filtration with a Waterra filter combined with filtration through a negatively charged membrane, was evaluated against glass wool filtration and freeze-drying for the detection of adenoviruses in river water. The virus amounts measured varied greatly depending on the virus concentration method. The continued monitoring in the spring of 2009 also revealed that the average concentration of noro- and adenoviruses in TW was 2.64 × 10 3 and 1.29 × 10 4 pcr units per mL, respectively. No correlation between the presence of viruses and Escherichia coli was found. These results may be useful for risk assessment studies. © IWA Publishing 2012.

Rautio A.,University of Helsinki | Kivimaki A.-L.,Water Protection Association of the River Vantaa and Helsinki Region | Korkka-Niemi K.,University of Helsinki | Nygard M.,Pöyry | And 3 more authors.
Hydrology and Earth System Sciences | Year: 2015

A low-altitude aerial infrared (AIR) survey was conducted to identify hydraulic connections between aquifers and rivers and to map spatial surface temperature patterns along boreal rivers. In addition, the stable isotopic compositions (δ18O, δD), dissolved silica (DSi) concentrations and electrical conductivity of water in combination with AIR data were used as tracers to verify the observed groundwater discharge into the river system in a boreal catchment. Based on low temperature anomalies in the AIR survey, around 370 groundwater discharge sites were located along the main river channel and its tributaries (203 km altogether). On the basis of the AIR survey, the longitudinal temperature patterns of the studied rivers differed noticeably. The stable isotopes and DSi composition revealed major differences between the studied rivers. The groundwater discharge locations identified in the proximity of 12 municipal water intake plants during the low-flow seasons should be considered as potential risk areas for water intake plants during flood periods (groundwater quality deterioration due to bank infiltration), and should be taken under consideration in river basin management under changing climatic situations. © Author(s) 2015.

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