No abstract

Problems caused by cyanobacteria are common around the world and also in raw water sources of drinking water treatment plants. Strains belonging to genera Microcystis, Anabaena and Planktothrix produce potent hepatotoxins, the microcystins. Laboratory and pilot scale studies have shown that microcystins dissolved in water may pass the conventional surface water treatment processes. In 1998 the World Health Organization proposed a guide value of 1 microgram/L for microcystin-LR (MC-LR) in drinking water. The purpose of this research was to study the occurrence of microcystins in raw water sources of surface waterworks and in bank filtration plants and to evaluate the removal of microcystins in operating waterworks. Four bank filtration plants and nine surface waterworks using different processes for water treatment were monitored. Phytoplankton was identified and quantified, and microcystins analysed with sensitive immunoassay. Microcystin occurrence in selected water samples was verified with HPLC and a protein phosphatase inhibition method. Microcystins were detected sporadically in raw water sources of most of the waterworks. In two raw water supplies toxins were detected for several months. The highest microcystin concentrations in incoming raw water were approximately 10 micrograms/L MC-LR equivalents. In treated drinking water microcystins were detected occasionally but the concentrations were always below the guide value proposed by WHO.

Abstract.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 (δ 18 O, 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.

Abstract:The microbiological and chemical drinking water quality of 20 vulnerable Finnish small groundwater supplies was studied in relation to environmental risk factors associated with potential sources of contamination. The microbiological parameters analyzed included the following enteric pathogens: Giardia and Cryptosporidium, Campylobacter species, noroviruses, as well as indicator microbes (Escherichia coli, intestinal enterococci, coliform bacteria, Clostridium perfringens, Aeromonas spp. and heterotrophic bacteria). Chemical analyses included the determination of pH, conductivity, TOC, color, turbidity, and phosphorus, nitrate and nitrite nitrogen, iron, and manganese concentrations. Giardia intestinalis was detected from four of the water supplies, all of which had wastewater treatment activities in the neighborhood. Mesophilic Aeromonas salmonicida, coliform bacteria and E. coli were also detected. None of the samples were positive for both coliforms and Giardia. Low pH and high iron and manganese concentrations in some OPEN ACCESSResources 2015, 4 638 samples compromised the water quality. Giardia intestinalis was isolated for the first time in Finland in groundwater wells of public water works. In Europe, small water supplies are of great importance since they serve a significant sector of the population. In our study, the presence of fecal indicator bacteria, Aeromonas and Giardia revealed surface water access to the wells and health risks associated with small water supplies.