Kirsi Kuoppamäki

Urban snow indicates pollution originating from road traffic

Traffic is a major source of pollutants in cities. In this well-replicated study we analysed a broad array of contaminants in snowpacks along roads of different traffic intensities. The majority of pollutants showed a similar pattern with respect to traffic intensity: pH and conductivity as well as concentrations of PAHs, total suspended solids, phosphorus and most heavy metals were higher next to high intensity roads compared to low intensity roads. These pollutant levels also decreased considerably up to 5 m distance from the roads. Furthermore, apart from nitrogen, these variables increased in concentration from control sites in urban forest patches to road bank sites next to roads of low, intermediate and high traffic intensities. The deposition pattern of various traffic-derived pollutants--whether gaseous or particle-bound--was the same. Such information can be useful for the purposes of managing pollutants in urban areas.

Responses of phyto- and zooplankton to liming in a small acidified humic lake

Liming resulted in an immediate and transitory decrease of plankton biomass and phytoplankton primary production in the limed part of an acidified humic lake. In the longer term liming has changed species composition and dominance of phyto- and zooplankton. Due to increased transparency and improved oxygen conditions plankton biomass peaked deeper in the water column after liming. During the three years post-liming period phyto- and zooplankton communities have changed less than reported in several other studies. This is largely because liming was carried out well before the collapse of perch population, which has controlled zooplankton both in the pre- and post-treatment period.

Effects of Liming on the Chemistry and Biology of a Small Acid Humic Lake

A small humic lake was limed on ice in winter. The treatment elevated the water pH after ice melt from ca. 5 to ca. 6.5. Compared with a similar reference lake, the only other noticeable chemical changes were in calcium concentration and alkalinity. Due to the short retention time of the lake, the chemical effects of liming persisted for only 1 year. The most remarkable biological change was an increase in bacterioplankton by ca. 50% after liming. In the phytoplankton, the relative biomass of dinophytes, chlorophytes and cryptophytes increased and an acidophilic diatom, Asterionella ralfsii, decreased, but the changes were only moderate. After liming, the abundance of algal species increased, but decreased again 1 year later. A cladoceran, Daphnia longispina, increased markedly, followed by other changes in the zooplankton community. In small headwater lakes the catchment area, rather than the lake itself, should be limed in order to produce a more persistent increase in water pH.

Spatio-temporal patterns of major ions in urban stormwater under cold climate

Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland Department of Built Environment, Aalto University, Espoo, Finland Department of Environmental Sciences, University of Helsinki, Helsinki, Finland Correspondence Maija Taka, Department of Geosciences and Geography, University of Helsinki, P.O. Box 64, FI‐00014 Helsinki, Finland. Email: maija.taka@helsinki.fi Funding information European Union Life + programthe Academy of Finland, Grant/Award Number: 263335. 263320. 263308.