Time filter

Source Type

Ilvesniemi H.,Finnish Forest Research Institute | Pumpanen J.,University of Helsinki | Duursma R.,University of Western Sydney | Hari P.,University of Helsinki | And 9 more authors.
Boreal Environment Research | Year: 2010

In terrestrial ecosystems, the amount and availability of water is one of the key factors affecting the net primary productivity and other biological processes of the system. At the SMEAR-II station, we have monitored the water balance of two adjacent micro-catchments since 1997. In this study, we report the long-term measurements of precipitation, throughfall, snow depth, soil water content, runoff and evapotranspiration and the annual water balances based on these measurements and discuss the uncertainties related to different measurements. The proportion of throughfall, evapotranspiration and runoff was 67%, 43% and 32% of the annual precipitation, respectively. The measured amounts of evapotranspiration and runoff were so small that the aim of closing the water balance of the studied system was not fully reached. The largest uncertainties are related to the evapotranspiration measurements and the determination of the actual surface area of the catchments used in the calculation of the runoff. © 2010.

Helema S.,Finnish Forest Research Institute | Holopainen J.,University of Helsink | Partonen T.,Finnish National Institute for Health and Welfare
Malta Medical Journal | Year: 2014

Aim: To calculate the suicide rates (for males and females) in Malta and other European countries with long series of suicide mortality as recorded in the WHO (World Health Organization) database, and compare the Maltese suicide rates with European rates.Method: Suicide rates were computed from the WHO database as rates (suicides per 100,000 persons) using the reported suicide and population counts in Malta and ten other European countries for a common period 1955-2009. Suicide rates were age standardized following the WHO recommendations. These calculations were carried out separately for both sexes.Results: Compared to other European counties, the suicide rates (both male and female) in Malta have remained at considerably low level as calculated over the full period. Maltese suicide rates have however multiplied since the 1980s. European data exhibit clear decrease in suicide rates towards the present consistently in several countries. Malta is the only European country showing its highest suicide rates during the 2000s.Conclusions: Although the suicide rates in Malta remain at considerably low level, they have exhibited a notable increase towards the present, whereas the European suicide rates are in decline. Becoming aware of this fact and the issue may help in building a suicide prevention programme to mitigate the situation. © 2014, Malta Medical Journal. All right reserved.

Seliman A.F.,Egypt Atomic Energy Authority | Helariutta K.,University of Helsink | Wiktorowicz S.J.,University of Helsinki | Tenhu H.,University of Helsinki | Harjula R.,University of Helsink
Journal of Environmental Radioactivity | Year: 2013

New dual functionality scintillating anion-exchange resins were developed for selective determination of 99TcO4 - in various natural freshwater samples. Stable scintillating particles were formed by preparing the vinyl monomer 2-[4-(4'-vinylbiphenylyl)]-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (vPBD), starting with the commercial organic flour TBut-PBD and its subsequent copolymerization with styrene, divinylbenzene, and p-chloromethylstyrene mixture. To integrate the radiochemical separation and radiometric detection steps within the same bead, the chloromethyl groups of the scintillating resins were subjected to amination reactions with dioctylamine (DOA) and trioctylamine (TOA). On-line quantification of 99TcO4 - was achieved by packing the scintillating anion-exchange resin into Teflon tubing for quantification by a flow scintillation analyzer (FSA). The two functionalized resins were selective for pertechnetate over the common anions in natural freshwaters, especially Cl- and SO4 2- with up to 1000ppm and with up to 10ppm I- and Cr2O7 2-. The uptake efficiency of the TOA sensor decreased from 97.88% to 85.08% in well water and river water, respectively, while the counting efficiency was almost constant (69.50%). The DOA performance showed lower efficiency in the two water types relative to TOA. On the other hand, the DOA sensor could be regenerated by 5M HNO3 for reuse at least four times without losing its chemical or optical performance. The detection limit was 1.45Bq which could be achieved by loading 45mL from well and tap water containing the maximum contaminant level (MCL) of 99Tc (33Bq/L). © 2013 Elsevier Ltd.

Loading University of Helsink collaborators
Loading University of Helsink collaborators