Search

Your search keyword '"Leppänen, Matti T."' showing total 168 results
Start Over Author "Leppänen, Matti T."
168 results on '"Leppänen, Matti T."'

20. Risk Assessment of Gypsum Amendment on Agricultural Fields: Effects of Sulfate on Riverine Biota

Author

Rantamo, Krista, primary, Arola, Hanna, additional, Aroviita, Jukka, additional, Hämälainen, Heikki, additional, Hannula, Maija, additional, Laaksonen, Rami, additional, Laamanen, Tiina, additional, Leppänen, Matti T., additional, Salmelin, Johanna, additional, Syrjänen, Jukka T., additional, Taskinen, Antti, additional, Turunen, Jarno, additional, and Ekholm, Petri, additional

Published
2021
Full Text
View/download PDF

24. Rapid Quantification of Microalgae Growth with Hyperspectral Camera and Vegetation Indices

Author

Salmi, Pauliina, Eskelinen, Matti A., Leppänen, Matti T., and Pölönen, Ilkka

Subjects
klorofylli, growth, monitorointi, levät, ympäristön tila, remote sensing, strain, vegetation, viherlevät, mobile spectral camera, chlorophyll, state of the environment, biomassa (ekologia), algae, rasitus, biomass, microalgae, spektrikuvaus, fluoresenssi, Botany, kasvillisuus, mikrolevät, green algae, monitoring, transmission imaging, vegetation indices, QK1-989, kaukokartoitus
Abstract

Spectral cameras are traditionally used in remote sensing of microalgae, but increasingly also in laboratory-scale applications, to study and monitor algae biomass in cultures. Practical and cost-efficient protocols for collecting and analyzing hyperspectral data are currently needed. The purpose of this study was to test a commercial, easy-to-use hyperspectral camera to monitor the growth of different algae strains in liquid samples. Indices calculated from wavebands from transmission imaging were compared against algae abundance and wet biomass obtained from an electronic cell counter, chlorophyll a concentration, and chlorophyll fluorescence. A ratio of selected wavebands containing near-infrared and red turned out to be a powerful index because it was simple to calculate and interpret, yet it yielded strong correlations to abundances strain-specifically (0.85 &lt, r &lt, 0.96, p &lt, 0.001). When all the indices formulated as A/B, A/(A + B) or (A − B)/(A + B), where A and B were wavebands of the spectral camera, were scrutinized, good correlations were found amongst them for biomass of each strain (0.66 &lt, 0.98, p &lt, 0.001). Comparison of near-infrared/red index to chlorophyll a concentration demonstrated that small-celled strains had higher chlorophyll absorbance compared to strains with larger cells. The comparison of spectral imaging to chlorophyll fluorescence was done for one strain of green algae and yielded strong correlations (near-infrared/red, r = 0.97, p &lt, 0.001). Consequently, we described a simple imaging setup and information extraction based on vegetation indices that could be used to monitor algae cultures.

Published
2021

29. Risk Assessment of Gypsum Amendment on Agricultural Fields: Effects of Sulfate on Riverine Biota.

Author

Rantamo, Krista, Arola, Hanna, Aroviita, Jukka, Hämälainen, Heikki, Hannula, Maija, Laaksonen, Rami, Laamanen, Tiina, Leppänen, Matti T., Salmelin, Johanna, Syrjänen, Jukka T., Taskinen, Antti, Turunen, Jarno, and Ekholm, Petri

Subjects
INDUCTIVE effect, GYPSUM, SODIC soils, SULFATES, WATER quality monitoring, BIOTIC communities, BROWN trout, FOOT movements
Abstract

Gypsum (CaSO4∙2H2O) amendment is a promising way of decreasing the phosphorus loading of arable lands, and thus preventing aquatic eutrophication. However, in freshwaters with low sulfate concentrations, gypsum‐released sulfate may pose a threat to the biota. To assess such risks, we performed a series of sulfate toxicity tests in the laboratory and conducted field surveys. These field surveys were associated with a large‐scale pilot exercise involving spreading gypsum on agricultural fields covering 18% of the Savijoki River (Finland) catchment area. The gypsum amendment in such fields resulted in approximately a four‐fold increase in the mean sulfate concentration for a 2‐month period, and a transient, early peak reaching approximately 220 mg/L. The sulfate concentration gradually decreased almost to the pregypsum level after 3 years. Laboratory experiments with Unio crassus mussels and gypsum‐spiked river water showed significant effects on foot movement activity, which was more intense with the highest sulfate concentration (1100 mg/L) than with the control. Survival of the glochidia after 24 and 48 h of exposure was not significantly affected by sulfate concentrations up to 1000 mg/L, nor was the length growth of the moss Fontinalis antipyretica affected. The field studies on benthic algal biomass accrual, mussel and fish density, and Salmo trutta embryo survival did not show gypsum amendment effects. Gypsum treatment did not raise the sulfate concentrations even to a level just close to critical for the biota studied. However, because the effects of sulfate are dependent on both the spatial and the temporal contexts, we advocate water quality and biota monitoring with proper temporal and spatial control in rivers within gypsum treatment areas. Environ Toxicol Chem 2022;41:108–121. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

32. Assessing ecotoxicity of biomining effluents in stream ecosystems by in situ invertebrate bioassays : A case study in Talvivaara, Finland

Author

Salmelin, Johanna, Leppänen, Matti T., Karjalainen, Anna, Vuori, Kari-Matti, Gerhardt, Almut, and Hämäläinen, Heikki

Subjects
ekosysteemit (ekologia), ecotoxicity, Talvivaara, mines, in situ invertebrate bioassays, mining
Abstract

Mining of sulfide-rich pyritic ores produces acid mine drainage waters and has induced major ecological problems in aquatic ecosystems worldwide. Biomining utilizes microbes to extract metals from the ore, and it has been suggested as a new sustainable way to produce metals. However, little is known of the potential ecotoxicological effects of biomining. In the present study, biomining impacts were assessed using survival and behavioral responses of aquatic macroinvertebrates at in situ exposures in streams. The authors used an impedance conversion technique to measure quantitatively in situ behavioral responses of larvae of the regionally common mayfly, Heptagenia dalecarlica, to discharges from the Talvivaara mine (Sotkamo, Northern Finland), which uses a biomining technique. Behavioral responses measured in 3 mine-impacted streams were compared with those measured in 3 reference streams. In addition, 3-d survival of the mayfly larvae and the oligochaete Lumbriculus variegatus was measured in the study sites. Biomining impacts on stream water quality included increased concentrations of sulfur, sulfate, and metals, especially manganese, cadmium, zinc, sodium, and calcium. Survival of the invertebrates in the short term was not affected by the mine effluents. In contrast, apparent behavioral changes in mayfly larvae were detected, but these responses were not consistent among sites, which may reflect differing natural water chemistry of the study sites. peerReviewed

Published
2017

36. Fate of polychlorinated biphenyls in a contaminated lake ecosystem: Combining equilibrium passive sampling of sediment and water with total concentration measurements of biota:Chemical equilibrium status of an aquatic ecosystem

Author

Mäenpää, Kimmo, Leppänen, Matti T., Figueiredo, Kaisa, Mayer, Philipp, Gilbert, Dorothea, Jahnke, Annika, Gil-Allué, Carmen, Akkanen, Jarkko, Nybom, Inna, Herve, Sirpa, Mäenpää, Kimmo, Leppänen, Matti T., Figueiredo, Kaisa, Mayer, Philipp, Gilbert, Dorothea, Jahnke, Annika, Gil-Allué, Carmen, Akkanen, Jarkko, Nybom, Inna, and Herve, Sirpa

Abstract

Equilibrium sampling devices can be applied to study and monitor the exposure and fate of hydrophobic organic chemicals on a thermodynamic basis. They can be used to determine freely dissolved concentrations and chemical activity ratios and to predict equilibrium partitioning concentrations of hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course using equilibrium sampling devices for measurements in sediment and water and by also analyzing biota. The authors used equilibrium sampling devices (silicone rubber and polyethylene [PE]) to determine freely dissolved concentrations and chemical activities of PCBs in the water column and sediment porewater and calculated for both phases the corresponding equilibrium concentrations and chemical activities in model lipids. Overall, the studied ecosystem appeared to be in disequilibrium for the studied phases: sediment, water, and biota. Chemical activities of PCBs were higher in sediment than in water, which implies that the sediment functioned as a partitioning source of PCBs and that net diffusion occurred from the sediment to the water column. Measured lipid-normalized PCB concentrations in biota were generally below equilibrium lipid concentrations relative to the sediment (CLip ⇌Sed ) or water (CLip ⇌W ), indicating that PCB levels in the organisms were below the maximum partitioning levels. The present study shows the application versatility of equilibrium sampling devices in the field and facilitates a thermodynamic understanding of exposure and fate of PCBs in a contaminated lake and its discharge course. Environ Toxicol Chem 2015;34:2463-2474. © 2015 SETAC.

Published
2015

37. Fate of polychlorinated biphenyls in a contaminated lake ecosystem: Combining equilibrium passive sampling of sediment and water with total concentration measurements of biota

Author

Mäenpää, Kimmo, primary, Leppänen, Matti T., additional, Figueiredo, Kaisa, additional, Mayer, Philipp, additional, Gilbert, Dorothea, additional, Jahnke, Annika, additional, Gil-Allué, Carmen, additional, Akkanen, Jarkko, additional, Nybom, Inna, additional, and Herve, Sirpa, additional

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results