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Pertti J. Martikainen

Bio: Pertti J. Martikainen is an academic researcher from University of Eastern Finland. The author has contributed to research in topics: Peat & Soil water. The author has an hindex of 77, co-authored 295 publications receiving 19111 citations. Previous affiliations of Pertti J. Martikainen include Finnish Forest Research Institute.


Papers
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TL;DR: CO2 fluxes in boreal peatlands were measured during two seasons on various mire site types representing different nutrient statuses and water tables, and peat carbon stores and the carbon balance in changing climate are discussed.
Abstract: 1 Co2 emissions in boreal peatlands were measured during two seasons on various mire site types representing different nutrient statuses and water tables. In order to examine the long term effects of water table draw-down on the CO2 fluxes, the sites also included 25-50-year-old drainages. 2 On virgin sites the lowest CO2 fluxes were measured at ombrotrophic sites dominated by Sphagnum fuscum (78-127mg CO2 m-2 h-' at 12 ?C, 60-200 g CO2-C m-2 year') and the highest CO2 fluxes were at ombrotrophic sites with abundant understorey vegetation (183-259mg CO2 m-2 h-' at 12 ?C, 290-340g C02-C m-2 year-'). 3 Lowering of the water table by 1 cm increased CO2 fluxes by an average of 7.1 mg COM2 h-' at 12 ?C and 9.5 g C02-C m-2 year-'. In some cases the effect of ditches on the water table, and correspondingly on CO2 fluxes, was small. However, effective draining caused 100% increase in CO2 fluxes. Drainages had higher CO2 fluxes compared with virgin subsites at the same temperature and water table. 4 The effect of temperature on CO2 fluxes depended on the water table, the average QIo value being 2.9 with water tables of 0-20cm and 2.0 with water tables below 20cm. 5 CO2 fluxes are compared with primary production figures, and peat carbon stores and the carbon balance in changing climate are discussed.

482 citations

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TL;DR: It seems that autochth onous and allochthonous carbon sources, which contribute to the CH(4) and CO(2) production in lakes, also have importance in the greenhouse gas emissions from reservoirs.

373 citations

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TL;DR: In this paper, the authors present a dataset on CH4 flux rates totaling 12 measurement years at sites from Greenland, Iceland, Scandinavia and Siberia, and find that temperature and microbial substrate availability (expressed as the organic acid concentration in peat water) combined explain almost 100% of the variations in mean annual CH4 emissions.
Abstract: [1] Global wetlands are, at estimate ranging 115-237 Tg CH4/yr, the largest single atmospheric source of the greenhouse gas methane (CH4). We present a dataset on CH4 flux rates totaling 12 measurement years at sites from Greenland, Iceland, Scandinavia and Siberia. We find that temperature and microbial substrate availability (expressed as the organic acid concentration in peat water) combined explain almost 100% of the variations in mean annual CH4 emissions. The temperature sensitivity of the CH4 emissions shown suggests a feedback mechanism on climate change that could validate incorporation in further developments of global circulation models.

372 citations

Journal ArticleDOI
TL;DR: In this article, the authors address the emissions and possible control of the three greenhouse gases by different managements of organic soils, and present the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes.
Abstract: . The large boreal peatland ecosystems sequester carbon and nitrogen from the atmosphere due to a low oxygen pressure in waterlogged peat. Consequently they are sinks for CO2 and strong emitters of CH4. Drainage and cultivation of peatlands allows oxygen to enter the soil, which initiates decomposition of the stored organic material, and in turn CO2 and N2O emissions increase while CH4 emissions decrease. Compared to undrained peat, draining of organic soils for agricultural purposes increases the emissions of greenhouse gases (CO2, CH4, and N2O) by roughly 1t CO2 equivalents/ha per year. Although farmed organic soils in most European countries represent a minor part of the total agricultural area, these soils contribute significantly to national greenhouse gas budgets. Consequently, farmed organic soils are potential targets for policy makers in search of socially acceptable and economically cost-efficient measures to mitigate climate gas emissions from agriculture. Despite a scarcity of knowledge about greenhouse gas emissions from these soils, this paper addresses the emissions and possible control of the three greenhouse gases by different managements of organic soils. More precise information is needed regarding the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes, before any definite policies can be devised.

351 citations

Journal ArticleDOI
01 Nov 1993-Nature
TL;DR: In this article, a comparison of present-day N2O fluxes from virgin peatlands in Finland with those from sites in the same regions that were drained by ditching 30 and 50 years ago is presented.
Abstract: NORTHERN peatlands contain 20–30% of the total organic nitrogen and carbon in the world's soils1,2, and thus they apparently have the potential to exert a significant influence on the global atmospheric budget of the greenhouse gases carbon dioxide, methane and nitrous oxide (N2O). In the drier, warmer summer conditions predicted at high latitudes by some climate models3,4 as a result of greenhouse-gas forcing, northern peatlands would become drier, increasing the rate of mineralization of organic matter1,5 and of the microbial processes that produce N2O. These regions might therefore be expected to exert a strong feedback on climate. But whereas methane emissions have been well studied6,7, little is known about the effect on N2O fluxes of changes in the level of peatland water tables. Here we present a comparison of present-day N2O fluxes from virgin peatlands in Finland with those from sites in the same regions that were drained by ditching 30 and 50 years ago. The lowered water table had no effect on N2O emissions from nutrient-poor peat but enhanced those from nutrient-rich peat. We estimate that equivalent drying caused by climate change would increase the total emissions of N2O from northern peatlands by 0.03–0.1 teragrams of nitrogen per year, which is just 0.3–1% of the present global annual emissions. Thus northern peatlands are unlikely to exert a significant climate feedback from N2O emissions.

348 citations


Cited by
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6,278 citations

Journal Article
TL;DR: In this article, the authors present a document, redatto, voted and pubblicato by the Ipcc -Comitato intergovernativo sui cambiamenti climatici - illustra la sintesi delle ricerche svolte su questo tema rilevante.
Abstract: Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

4,187 citations

Journal ArticleDOI
TL;DR: In this paper, the role of inland water ecosystems in the global carbon cycle has been investigated and it is shown that roughly twice as much C enters inland aquatic systems from land as is exported from land to the sea, roughly equally as inorganic and organic carbon.
Abstract: Because freshwater covers such a small fraction of the Earth’s surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking published estimates of gas exchange, sediment accumulation, and carbon transport for a variety of aquatic systems, we have constructed a budget for the role of inland water ecosystems in the global carbon cycle. Our analysis conservatively estimates that inland waters annually receive, from a combination of background and anthropogenically altered sources, on the order of 1.9 Pg C y−1 from the terrestrial landscape, of which about 0.2 is buried in aquatic sediments, at least 0.8 (possibly much more) is returned to the atmosphere as gas exchange while the remaining 0.9 Pg y−1 is delivered to the oceans, roughly equally as inorganic and organic carbon. Thus, roughly twice as much C enters inland aquatic systems from land as is exported from land to the sea. Over prolonged time net carbon fluxes in aquatic systems tend to be greater per unit area than in much of the surrounding land. Although their area is small, these freshwater aquatic systems can affect regional C balances. Further, the inclusion of inland, freshwater ecosystems provides useful insight about the storage, oxidation and transport of terrestrial C, and may warrant a revision of how the modern net C sink on land is described.

3,179 citations

Journal ArticleDOI
TL;DR: The data suggest that amoA represents a very powerful molecular tool for analyzing indigenous ammonia-oxidizing communities due to (i) its specificity, (ii) its fine-scale resolution of closely related populations, and (iii) the fact that a functional trait rather than a phylogenetic trait is detected.
Abstract: The naturally occurring genetic heterogeneity of autotrophic ammonia-oxidizing populations belonging to the beta subclass of the Proteobacteria was studied by using a newly developed PCR-based assay targeting a partial stretch of the gene which encodes the active-site polypeptide of ammonia monooxygenase (amoA). The PCR yielded a specific 491-bp fragment with all of the nitrifiers tested, but not with the homologous stretch of the particulate methane monooxygenase, a key enzyme of methane-oxidizing bacteria. The assay also specifically detected amoA in DNA extracted from various aquatic and terrestrial environments. The resulting PCR products retrieved from rice roots, activated sludge, a freshwater sample, and an enrichment culture were used for the generation of amoA gene libraries. No false positives were detected in a set of 47 randomly selected clone sequences that were analyzed further. The majority of the environmental sequences retrieved from rice roots and activated sludge grouped within the phylogenetic radiation defined by cultured strains of the genera Nitrosomonas and Nitrosospira. The comparative analysis identified members of both of these genera in activated sludge; however, only Nitrosospira-like sequences with very similar amino acid patterns were found on rice roots. Further differentiation of these molecular isolates was clearly possible on the nucleic acid level due to the accumulation of synonymous mutations, suggesting that several closely related but distinct Nitrosospira-like populations are the main colonizers of the rhizosphere of rice. Each of the amoA gene libraries obtained from the freshwater sample and the enrichment culture was dominated by a novel lineage that shared a branch with the Nitrosospira cluster but could not be assigned to any of the known pure cultures. Our data suggest that amoA represents a very powerful molecular tool for analyzing indigenous ammonia-oxidizing communities due to (i) its specificity, (ii) its fine-scale resolution of closely related populations, and (iii) the fact that a functional trait rather than a phylogenetic trait is detected.

2,576 citations