Litter type affects the activity of aerobic decomposers in a boreal peatland more than site nutrient and water level regimes

The discussion paper published in Biogeosciences Discuss.: Straková, P., Niemi, R. M., Freeman, C., Peltoniemi, K., Toberman, H., Heiskanen, I., Fritze, H., and Laiho, R. 2011. Litter type affects the activity of aerobic decomposers in a boreal peatland more than site nutrient and water level regimes, Biogeosciences Discuss., 8, 1879-1916. doi:10.5194/bgd-8-1879-2011Peatlands are carbon (C) storage ecosystems sustained by a high water level (WL). High WL creates anoxic conditions that suppress the activity of aerobic decomposers and provide conditions for peat accumulation. Peatland function can be dramatically affected by WL drawdown caused by land-use and/or climate change. Aerobic decomposers are directly affected by WL drawdown through environmental factors such as increased oxygenation and nutrient availability. Additionally, they are indirectly affected via changes in plant community composition and litter quality. We studied the relative importance of direct and indirect effects of WL drawdown on aerobic decomposer activity in plant litter. We did this by profiling 11 extracellular enzymes involved in the mineralization of organic C, nitrogen, phosphorus and sulphur. Our study sites represented a three-stage chronosequence from pristine (undrained) to short-term (years) and long-term (decades) WL drawdown conditions under two nutrient regimes. The litter types included reflected the prevalent vegetation, i.e., Sphagnum mosses, graminoids, shrubs and trees. WL drawdown had a direct and positive effect on microbial activity. Enzyme allocation shifted towards C acquisition, which caused an increase in the rate of decomposition. However, litter type overruled the direct effects of WL drawdown and was the main factor shaping microbial activity patterns. Our results imply that changes in plant community composition in response to persistent WL drawdown will strongly affect the C dynamics of peatlands.Peer reviewe

Metabolism and cytotoxicity of diphenylarsinic acid, a degradation product of sea-dumped chemical warfare agents, in a rainbow trout liver cell line

Recent studies have found primary degradation products of phenylarsenic chemical warfare agents (CWAs) accumulating in fish tissues, while the potential effects of these dumped phenylarsenic CWAs, such as Clark I and II, in the Baltic Sea biota are poorly understood. In this study, the metabolism and cytotoxicity of diphenylarsinic acid (DPA), a primary degradation product of phenylarsenic CWA, was studied by incubating rainbow trout cell line RTL-W1 cells in media with 100 mg/L DPA. Previously undescribed metabolites were identified by ultra-high performance liquid chromatography–high resolution mass spectrometry (UPHLC-HRMS). Moreover, the cytotoxicity of diphenylarsine glutathione conjugate (DPA-SG), the major metabolite of DPA, was studied. Cytotoxicity of the compounds was evaluated using the Neutral Red retention test (NRR), showing an IC50 value of 278 mg/L for DPA and 1.30 mg/L for DPA-SG, indicating that the glutathione (GSH) conjugate of DPA is more than two orders of magnitude toxic than DPA itself, suggesting that toxic properties of DPA are increased after conjugation with intracellular GSH leading enhanced toxicity after uptake. Results gained in this study give more detailed information for elucidating biological effects of dumped chemical munitions in marine environment. Moreover, the results help in assessing the environmental and health risks posed by marine munition continued presence and deterioration in the sea bottom.Peer reviewe

Torjunta-aineiden vaikutukset maaperän mikrobeihin ja niiden toimintaan

Perunan viljelyssä käytetään yleisesti rikkakasvien ja perunaruton torjuntaaineita. Perunan viljely ja torjunta-aineiden käyttö perättäisinä vuosina samassa maassa vaikuttaa maaperän mikrobeihin ja niiden toimintaan. Tässä tutkimuksessa selvitettiin torjunta-aineiden vaikutuksia mikrobeihin myrkyllisyystestillä, astiakokeilla ja kenttäkokeessa Lammilla. Tutkittavat torjuntaaineet olivat metributsiini ja linuroni sekä fluatsinami. Metributsiini oli valobakteeritestin mukaan vähiten myrkyllinen, linuroni sitä myrkyllisempi ja fluatsinami erittäin myrkyllinen. Flutsinami oli myrkyllinen myös astiakokeissa ja kenttäkokeissa. Kaikkia torjunta-aineita löydettiin keväällä perunamaasta edellisen kesän jäljiltä. Fluatsinami myös säilyi maassa biosaatavana. Mikrobien aktiivinen biomassa ATP-pitoisuutena mitattuna puolestaan väheni kasvittomassa torjunta-aineilla käsitellyssä maassa. Tämä voi johtua mittauksessa käytetyn entsyymin estymisestä, sillä perunaa kasvavissa astiakokeissa vaikutusta ei havaittu. Myöskään sienten biomassa ergosterolin pitoisuutena mitattuna ei muuttunut huomattavasti torjunta-ainekäsittelyissä. Ammoniumin mikrobiologin hapettuminen eli nitrifikaatio heikkeni metributsiinin vaikutuksesta perunaa kasvavissa astiakokeissa, muttei kenttäkokeessa. Torjunta-aineet vaikuttivat kymmenen tutkitun entsyymin aktiivisuuteen eri tavoin kasvittomassa maassa ja perunaa kasvavissa astioissa. Kasvittomassa maassa etenkin rikkakasvien torjunta-aineet lisäsivät monien entsyymien aktiivisuutta, mutta perunaa kasvavissa astioissa kävi päinvastoin. Tämän katsottiin johtuvan kasvittomassa maassa siitä, että rikkakasvit ja niiden juurten aiheuttama mikrobien stimulaatio puuttui. Fluatsinami vaikutti entsyymiaktiivisuuksiin vähemmän kuin metributsiini ja linuroni. Torjunta-aineet vaikuttivat maaperän mikrobeihin vähän ja usein ohimenevästi. Mikrobirakenteessa saattoi kuitenkin tapahtua muutoksia. Niinpä näiden torjunta-aineiden, ja erityisesti fluatsinamin, vaikutuksia mikrobien, etenkin sienten, lajistoon tulee tutkia lisää.In the cultivation of potatoes, weed control and the control of potato late blight caused by Phytophthora infestans are usually carried out by the application of herbicides and fungicides. In the present study, the impacts of the herbicides metribuzin and linuron and the fungicide fluazinam on soil microbiota were investigated in microcosms, in mesocosms and in the field. The luminescent bacteria toxicity test revealed a strong inhibition by fluazinam. In microcosms the herbicides increased several enzyme activities but metribuzin temporarily appeared to decrease the ATP content and inhibited luminescence in the bacterial test. Fluazinam was highly toxic in microcosms and appeared to decrease the ATP content. Decreased activities of some of the ten measured enzymes were observed first in the surface soil and at harvesting also deeper in the soil in the mesocosm with combined use of pesticides. In the mesocosm experiment with separate use of pesticides, less impacts were observed. In the field experiment the pesticides decreased some enzyme activities. Herbicides decreased weed rhizosphere, and the decreases in some enzyme activities were interpreted to be due to the lack of the stimulating impact of weed roots. A strong inhibition in the soil toxicity test and continuing bioavailability of fluazinam were detected throughout the experiments even after winter in the field. Further studies on its impacts on soil microbial diversity, especially fungal species composition are needed.voktatMyynti MTT, Tietopalvelut 31600 JokioinenImpacts of pesticides on soil microorganisms and their activitie

Variability of soil enzyme activities and vegetation succession following boreal forest surface soil transfer to an artificial hill

A landfill site in southern Finland was converted into urban green space by covering it with a layer of fresh forest humus transferred from nearby construction sites. The aim was to develop the 70 m high artificial hill into a recreational area with high biodiversity of flora and fauna. Forest humus was used as a source of organic matter, plant roots, seeds, soil fauna and microorganisms in order to enable rapid regeneration of diverse vegetation and soil biological functions. In this study we report the results of three years of monitoring of soil enzyme activity and plant species compositional patterns. Monthly soil samples were taken each year between June and September from four sites on the hill and from two standing reference forests using three replicate plots. Activities of 10 different enzymes, soil organic matter (SOM) content, moisture, pH and temperature of the surface layer were monitored. Abundances of vascular plant species were surveyed on the same four hill sites between late May and early September, three times a season in 2004 and 2005. Although the addition of organic soil considerably increased soil enzyme activities (per dw), the activities at the covered hill sites were far lower than in the reference forests. Temporal changes and differences between sites were analysed in more detail per soil organic matter (SOM) in order to reveal differences in the quality of SOM. All the sites had a characteristic enzyme activity pattern and two hill sites showed clear temporal changes. The enzyme activities in uncovered topsoil increased, whereas the activities at the covered Middle site decreased, when compared with other sites at the same time. The different trend between Middle and North sites in enzyme activities may reflect differences in humus material transferred to these sites, but difference in the succession of vegetation affects enzyme activities strongly. Middle yielded higher β-sitosterol content in 2004, as an indication of more intense plant impact. All reclaimed sites had characteristic plant species assemblages and parallel temporal changes, reflecting vegetation succession, occurred across all the sites. Rapid growth of vegetation on the covered sites restored the rhizosphere and contributed to the persistence of microbial activity. We suggest that transferring the surface soil humus layer is a useful approach for ensuring the outcome of habitat restoration and complementary habitat creation especially in situations where the source soil areas would otherwise be lost

Microbial toxicity and impacts on soil enzyme activities of pesticides used in potato cultivation

Abstract: In the conventional Cultivation of potatoes, weed control and the control of potato late blight caused by Phytophthora infestans are carried out by the application of herbicides and fungicides. We investigated the impacts of the herbicides metribuzin and linuron and the fungicide fluazinam oil soil microbiota in microcosms, in mesocosms and in the field. The toxicity of each pesticide in Solution was assessed using the luminescent bacteria test and in soil by a solid phase modification. In microcosm tests, the microbial activity and biomass were estimated by measuring several soil enzyme activities together with soil ATP content. In the mesocosm tests, the separate addition of each pesticide and the Simultaneous use of all the pesticides were investigated. We monitored the impacts on ten different soil enzyme activities and Measured soil toxicity with the luminescent bacteria test separately in the 5 cm top layer and in the layer from 5 to about 20 cm below the surface. During one season, the impact of the use of pesticides was monitored in the field in plots receiving pesticides for the third consecutive year and in control plots Cultivated without the use of pesticides for the 3 preceding years. The pesticide concentrations were monitored in each experiment. The luminescent bacteria toxicity test revealed a strong inhibition by fluazinam. In microcosms the herbicides increased several enzyme activities but metribuzin inhibited luminescence in the bacterial test. Fluazinam was highly toxic in microcosms. In the mesocosm with combined use of pesticides, decreased activities of some enzymes were observed first in the surface soil and at harvesting also deeper in the soil. In the mesocosm experiment with separate use of pesticides, less impacts were observed. In the field experiment the pesticides decreased seven enzyme activities, when calculated per soil fresh weight but activities of four enzyme decreases if calculated per soil organic matter. Controlling weeds by herbicides decreased weed growth and the decreases in enzyme activities were interpreted to be due to the lack of the stimulating impact of weed roots. A strong inhibition in the soil toxicity test and continuing bioavailability of fluazinam were detected throughout the experiments even after winter in the field. (c) 2008 Elsevier B.V. All rights reserved.v2009oktat ta

A preliminary study on the ecotoxic potency of wastewater treatment plant sludge combining passive sampling and bioassays

Sewage sludge is an inevitable byproduct produced in wastewater treatment. Reusing nutrient-rich sludge will diminish the amount of waste ending in soil dumping areas and will promote circular economy. However, during sewage treatment process, several potentially harmful organic chemicals are retained in sludge, but proving the safety of processed sludge will promote its more extensive use in agriculture and landscaping. Environmental risk assessment of sludge requires new methods of characterizing its suitability for various circular economy applications. Bioavailable and bioaccessible fractions are key variables indicating leaching, transport, and bioaccumulation capacity. Also, sludge treatments have a significant effect on chemical status and resulting environmental risks. In this study, the concentrations of polyaromatic hydrocarbons (PAHs), triclosan (TCS), triclocarban (TCC), methyl triclosan (mTCS), and selected active pharmaceutical ingredients (APIs) were determined in different sludge treatmentsand fractions. Passive samplers were used to characterize the bioavailable and bioaccessible fractions, and the sampler extracts along the sludge and filtrate samples were utilized in the bioassays. The TCS and PAH concentrations did not decrease as the sludge was digested, but the contents diminished after composting. Also, mTCS concentration decreased after composting. The API concentrations were lower in digested sludge than in secondary sludge. Digested sludge was toxic for Aliivibrio fischeri, but after composting, toxicity was not observed. However, for Daphnia magna, passive sampler extracts of all sludge treatments were either acutely (immobility) or chronically (reproduction) toxic. Secondary and digested sludge sampler extracts were cytotoxic, and secondary sludge extract was also genotoxic. The measured chemical concentration levels did not explain the toxicity of the samples based on the reported toxicity thresholds. Bioassays and sampler extracts detecting bioavailable and bioaccessiblecontaminants in sludge are complementing tools for chemical analyses. Harmonization of these methods will help establish scientifically sound regulative thresholds for the use of sludge in circular economy applications.Peer reviewe

Mitochondrial DNA Polymerase W748S Mutation: A Common Cause of Autosomal Recessive Ataxia with Ancient European Origin

Mutations in the catalytic subunit of the mitochondrial DNA polymerase γ (POLG) have been found to be an important cause of neurological disease. Recently, we and collaborators reported a new neurodegenerative disorder with autosomal recessive ataxia in four patients homozygous for two amino acid changes in POLG: W748S in cis with E1143G. Here, we studied the frequency of this allele and found it to be among the most common genetic causes of inherited ataxia in Finland. We identified 27 patients with mitochondrial recessive ataxia syndrome (MIRAS) from 15 Finnish families, with a carrier frequency in the general population of 1:125. Since the mutation pair W748S+E1143G has also been described in European patients, we examined the haplotypes of 13 non-Finnish, European patients with the W748S mutation. Haplotype analysis revealed that all the chromosomes carrying these two changes, in patients from Finland, Norway, the United Kingdom, and Belgium, originate from a common ancient founder. In Finland and Norway, long, common, northern haplotypes, outside the core haplotype, could be identified. Despite having identical homozygous mutations, the Finnish patients with this adult- or juvenile-onset disease had surprisingly heterogeneous phenotypes, albeit with a characteristic set of features, including ataxia, peripheral neuropathy, dysarthria, mild cognitive impairment, involuntary movements, psychiatric symptoms, and epileptic seizures. The high carrier frequency in Finland, the high number of patients in Norway, and the ancient European founder chromosome indicate that this newly identified ataxia should be considered in the first-line differential diagnosis of progressive ataxia syndromes