Mika A. Kähkönen

Analysing heavy metal concentrations in the different parts of Elodea canadensis and surface sediment with PCA in two boreal lakes in southern Finland

The concentrations of six heavy metals (Fe, Mn, Cu, Zn, Ni, Cr) were studied in the roots, shoots and leaves of Elodea canadensis and in the surface sediment collected in four different parts in the eutrophic L. Vesijarvi and in the oligotrophic L. Paajarvi in Southern Finland. Principal component analysis was performed on the data set. The heavy metal concentrations of Elodea canadensis depend on the part of the plant and do not indicate the heavy metal concentrations in the growing place. Elodea canadensis accumulates Fe and Cu in the roots and Ni, Mn and Cr in the leaves. The concentrations of these five metals were lowest in the shoots, indicating the uptake route and transport of these metals in the macrophyte. Zn is mobile in Elodea canadensis, since its concentration was nearly as high in the roots, shoots and leaves. The order of Cr, Ni, Cu, Zn and Fe concentrations in the sediment were the same between different sampling places. Only Mn differed slightly from this order.

The uptake of nickel and chromium from water by Elodea canadensis at different nickel and chromium exposure levels

The uptake of Ni and Cr from water was studied at three Ni and Cr exposure levels in a laboratory by cosmopolitan submerged macrophyte, Elodea canadensis Mixch. The uptake late of Ni and Cr diminished, when the exposure time came longer and the initial concentration was lower. The uptake of Ni by Elodea canadensis was 25 to 40 times higher than the uptake of Cr in the same initial concentration. After 24 hours Elodea canadensis accumulated rather high content of Ni (310 – 2150) μg/DWg and a much lower amount of Cr (8 – 84) μg/DWg.

Integrative assessment of sediment quality history in pulp mill recipient area in Finland

Sediments were dated and the quality assessed by polyphasic approach in an area of Lake Saimaa, which has received waste water from bleached kraft pulp production since 1954. The chosen nonrecipient forest Lake Pyylampi was situated in the same area. The activities of the enzymes butyrate-esterase and aminopeptidase were depressed at the depth of 2 to 8 cm in the recipient but not in the forst lake sediment. In the same layers the contents of EOX-C1 and toxicity to Vibrio fischeri were very high compared to those above or below. Toxicity to microbial community in the 2 to 8 cm layer was also indicated by a gap in the ATP content and a drop in diatom species richness from the 70 species to < 50 reflecting decreased water quality of the pelagic area. All these changes dated to the period of heavy organic halogen discharges, from 1960 to late 1980s, which led to sediment accumulation of solvent soluble halogen at a depth of 2 to 8 cm, to 6.4 g m−2 (cm)−1. In the most polluted sediment layers heavy metal accumulation was too little to be related to the toxicity of these layers. Almost complete recovery of both the sediment microbial ecosystems and of the pelagic diatoms occurred after elemental chlorine was completely substituted by chlorine dioxide and biological treatment adopted for wastewaters. Butyrate-esterase and aminopeptidase, but not phosphatase, activities correlated positively with the ATP content of the sediment. Butyrate-esterase may be used as a tool to estimate microbial biomass.

Hydrolytic and ligninolytic enzyme activities in the Pb contaminated soil inoculated with litter-decomposing fungi

The impact of Pb contamination was tested to five hydrolytic (beta-glucosidase, beta-xylosidase, beta-cellobiosidase, alpha-glucosidase and sulphatase) and two ligninolytic (manganese peroxidase, MnP and laccase) enzyme activities in the humus layer in the forest soil. The ability of eight selected litter-degrading fungi to grow and produce extracellular enzymes in the heavily Pb (40 g Pb of kg ww soil(-1)) contaminated and non-contaminated soil in the non-sterile conditions was also studied. The Pb content in the test soil was close to that of the shooting range at Hälvälä (37 g Pb of kg ww soil(-1)) in Southern Finland. The fungi were Agaricus bisporus, Agrocybe praecox, Gymnopus peronatus, Gymnopilus sapineus, Mycena galericulata, Gymnopilus luteofolius, Stropharia aeruginosa and Stropharia rugosoannulata. The Pb contamination (40 g Pb of kg ww soil(-1)) was deleterious to all five studied hydrolytic enzyme activities after five weeks of incubation. All five hydrolytic enzyme activities were significantly higher in the soil than in the extract of the soil indicating that a considerable part of enzymes were particle bound in the soils. Hydrolytic enzyme activities were higher in the non-contaminated soil than in the Pb contaminated soil. Fungal inocula increased the hydrolytic enzyme activities beta-cellobiosidase and beta-glucosidase in non-contaminated soils. All five hydrolytic enzyme activities were similar with fungi and without fungi in the Pb contaminated soil. This was in line that Pb contamination (40 g Pb of kg ww soil(-1)) depressed the growth of all fungi compared to those grown without Pb in the soil. Laccase and MnP activities were low in both Pb contaminated and non-contaminated soil cultures. MnP activities were higher in soil cultures containing Pb than without Pb. Our results showed that Pb in the shooting ranges decreased fungal growth and microbial functioning in the soil.

Ecotoxicological assessment of a recipient lake sediment of bleached—kraft pulping discharges

We assessed the biological status of age—dated sediments in Lake Saimaa, a recipient lake for wastewaters from pulp and paper industry for more than 100 years that has also received kraft pulp bleaching wastewater since 1954. Adenosine triphosphate content dropped in the recipient sediment from the top 1 cm (deposited in the 1990s) to 4 to 6 cm below the sediment surface (deposited in 1980s) by a factor of 1,000 but increased again in deeper, older layers (23 cm). The dominant species in the diatom community, Aulacoseira alpigena and Cyclotella kutzingiana, disappeared and were replaced by Asterionella formosa in the 4- to 6-cm layer. This layer was three- to fivefold more toxic to Vibrio fischeri (as measured by the median effective concentration) and slightly genotoxic (as measured by the SOS—chromotest induction ratio, IC/I0 for Esherichia coli PQ37) compared with the layers above and below it. The 4- to 6-cm layer also contained up to 4,900 mg of solvent—soluble organic halogen (per kilogram of sediment dry weight). Enzyme activity (chitinase, phosphatase, α-glucosidase, and β-glucosidase) was detected at depths of 0 to 1 cm and 4 to 6 cm, and more than 90% of the enzymes were bound to the particulate matter. Ninety—seven percent of the organic halogen in the sediment was particle bound. Apparently, full ecological recovery occurred in the layer from 0 to 1 cm, which had accumulated in 1990s, after the discharging pulp mill discontinued use of Cl2 in the bleaching process and installed full—scale biological treatment for the wastewaters.

Mycoremediation of wood and soil from an old sawmill area contaminated for decades.

We investigated the potential of white-rot and litter-decomposing fungi for the treatment of soil and wood from a sawmill area contaminated with aged chlorinated phenols, dibenzo-p-dioxins and furans (PCDD/F). Eight screening assays with emphasis on application of non-sterile conditions were carried out in order to select the strains with capability to withstand indigenous microbes and contamination. Nine fungi were then selected for degrading pentachlorophenol (PCP), and 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP) and mineralizing radiolabelled pentachlorophenol ((14)C-PCP) in non-sterile soil or wood during 15 weeks of incubation. Soil indigenous microbes and fungal inoculated soil (fungal inoculum+indigenous microbes) achieved similar degradation of PCP and 2,3,4,6-TeCP and mineralization of (14)C-PCP. However, the mineralization rate of (14)C-PCP by indigenous microbes was much slower than that boosted by fungal inoculum. The litter-decomposing fungus (LDF) Stropharia rugosoannulata proved to be a suitable fungus for soil treatment. This fungus mineralized 26% of (14)C-PCP and degraded 43% of 2,3,4,6-TeCP and 73% of PCP. Furthermore, S. rugosoannulata attained 13% degradation of PCDD/F (expressed as WHO-Toxic Equivalent). In wood, white-rot fungi grew and degraded chlorophenols better than LDF. No efficient indigenous degraders were present in wood. Interestingly, production of toxic chlorinated organic metabolites (anisoles and veratroles) by LDF in wood was negligible.

The effects of nickel on the nutrient fluxes and on the growth of Elodea canadensis

Abstract In the through-flow method was measured the effect of Ni exposure on the net uptake and/or release of phosphorus and nitrogen and on the growth of submerged macrophyte, Elodea canadensis Michx. These results showed that Ni clearly inhibited the nutrient metabolism of Elodea at all exposure levels, from 70 up to 1700 μmol dm−3. The nutrient metabolism was more sensitive and earlier response than the growth of the test plants.

Impact of Cadmium, Chromium, Cobalt, Lithium and Manganese to the Growth of Fungi and Production of Enzymes

Impact of Cadmium, Chromium, Cobalt, Lithium and Manganese to the Growth of Fungi and Production of Enzymes Impacts of metals to the growth and enzyme production of fungi were tested with Cd- (0-10 mg kg–1), Co- (0-100 mg kg–1), Cr- (0-100 mg kg–1), Li- (0-100 mg kg–1) or Mn- (0-400 mg kg–1) containing media with ABTS [2,2’-azino-bis (3-ethylbentzthiazoline-6-sulfonicacid)] as indicator of oxidative enzymes, laccase and/or peroxidases.

Newtonian boreal forest ecology: The Scots pine ecosystem as an example

Isaac Newtons approach to developing theories in his book Principia Mathematica proceeds in four steps. First, he defines various concepts, second, he formulates axioms utilising the concepts, third, he mathematically analyses the behaviour of the system defined by the concepts and axioms obtaining predictions and fourth, he tests the predictions with measurements. In this study, we formulated our theory of boreal forest ecosystems, called NewtonForest, following the four steps introduced by Newton. The forest ecosystem is a complicated entity and hence we needed altogether 27 concepts to describe the material and energy flows in the metabolism of trees, ground vegetation and microbes in the soil, and to describe the regularities in tree structure. Thirtyfour axioms described the most important features in the behaviour of the forest ecosystem. We utilised numerical simulations in the analysis of the behaviour of the system resulting in clear predictions that could be tested with field data. We collected retrospective time series of diameters and heights for test material from 6 stands in southern Finland and five stands in Estonia. The numerical simulations succeeded to predict the measured diameters and heights, providing clear corroboration with our theory.

Stratification of selected hydrolytic enzyme activities in the sediment in two lakes in Finland

Abstract To investigate the stratification of hydrolytic enzyme activities and importance of subsurface layers in depolymerization of detritus biopolymers, nine hydrolytic enzyme activities involved in the cycling of carbon, phosphorus, nitrogen and sulphur were measured in various sediment layers and their extracts at Kylaniemi in Lake Saimaa in southern Finland and in Lake Ahvenjarvi in northern Finland. The results show that for each lake all nine hydrolytic enzyme activities were higher in all sediment layers than in comparable sediment extracts indicating that the major part of enzymes was bound to the sediment particles in all layers in both lakes. Carbohydratase, β-cellobiosidase, activities did not show any gradient with sediment depth at Kylaniemi in Lake Saimaa indicating that there was rapid turnover of carbohydrates in the entire sediment column. The activities of acetate esterase, butyrate esterase, phosphomonoesterase, aminopeptidase, N-acetyl glucosaminidase, sulphatase and β-glucosidase in the deepest layers were 19–53% of those in the surface sediment indicating that depolymerization of biopolymers involved in the cycling of carbon, nitrogen, phosphorus and sulphur was substantial in subsurface sediment.