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149 records – page 1 of 15.

Afforestation effects on SOC in former cropland: oak and spruce chronosequences resampled after 13 years.

https://arctichealth.org/en/permalink/ahliterature261397
Source
Glob Chang Biol. 2014 Sep;20(9):2938-52
Publication Type
Article
Date
Sep-2014
Author
Teresa G Bárcena
Per Gundersen
Lars Vesterdal
Source
Glob Chang Biol. 2014 Sep;20(9):2938-52
Date
Sep-2014
Language
English
Publication Type
Article
Keywords
Carbon - analysis
Carbon Sequestration - physiology
Denmark
Forests
Linear Models
Picea - growth & development
Quercus - growth & development
Soil - chemistry
Species Specificity
Time Factors
Abstract
Chronosequences are commonly used to assess soil organic carbon (SOC) sequestration after land-use change, but SOC dynamics predicted by this space-for-time substitution approach have rarely been validated by resampling. We conducted a combined chronosequence/resampling study in a former cropland area (Vestskoven) afforested with oak (Quercus robur) and Norway spruce (Picea abies) over the past 40 years. The aims of this study were (i) to compare present and previous chronosequence trends in forest floor and top mineral soil (0-25 cm) C stocks; (ii) to compare chronosequence estimates with current rates of C stock change based on resampling at the stand level; (iii) to estimate SOC changes in the subsoil (25-50 cm); and (iv) to assess the influence of two tree species on SOC dynamics. The two chronosequence trajectories for forest floor C stocks revealed consistently higher rates of C sequestration in spruce than oak. The chronosequence trajectory was validated by resampling and current rates of forest floor C sequestration decreased with stand age. Chronosequence trends in topsoil SOC in 2011 did not differ significantly from those reported in 1998, however, there was a shift from a negative rate (1998: -0.3 Mg C ha(-1) yr(-1) ) to no change in 2011. In contrast SOC stocks in the subsoil increased with stand age, however, not significantly (P = 0.1), suggesting different C dynamics in and below the former plough layer. Current rates of C change estimated by repeated sampling decreased with stand age in forest floors but increased in the topsoil. The contrasting temporal change in forest floor and mineral soil C sequestration rates indicate a shift in C source-sink strength after approximately 40 years. We conclude that afforestation of former cropland within the temperate region may induce soil C loss during the first decades followed by a recovery phase of yet unknown duration.
PubMed ID
24753073 View in PubMed
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Almost 50 years of monitoring shows that climate, not forestry, controls long-term organic carbon fluxes in a large boreal watershed.

https://arctichealth.org/en/permalink/ahliterature262840
Source
Glob Chang Biol. 2014 Apr;20(4):1225-37
Publication Type
Article
Date
Apr-2014
Author
Ahti Lepistö
Martyn N Futter
Pirkko Kortelainen
Source
Glob Chang Biol. 2014 Apr;20(4):1225-37
Date
Apr-2014
Language
English
Publication Type
Article
Keywords
Calibration
Carbon - analysis
Carbon Cycle
Climate
Droughts
Environmental monitoring
Finland
Floods
Forestry
Models, Theoretical
Seasons
Temperature
Abstract
Here, we use a unique long-term data set on total organic carbon (TOC) fluxes, its climatic drivers and effects of land management from a large boreal watershed in northern Finland. TOC and runoff have been monitored at several sites in the Simojoki watershed (3160 km(2) ) since the early 1960s. Annual TOC fluxes have increased significantly together with increased inter-annual variability. Acid deposition in the area has been low and has not significantly influenced losses of TOC. Forest management, including ditching and clear felling, had a minor influence on TOC fluxes - seasonal and long-term patterns in TOC were controlled primarily by changes in soil frost, seasonal precipitation, drought, and runoff. Deeper soil frost led to lower spring TOC concentrations in the river. Summer TOC concentrations were positively correlated with precipitation and soil moisture not temperature. There is some indication that drought conditions led to elevated TOC concentrations and fluxes in subsequent years (1998-2000). A sensitivity analysis of the INCA-C model results showed the importance of landscape position, land-use type, and soil temperature as controls of modeled TOC concentrations. Model predictions were not sensitive to forest management. Our results are contradictory to some earlier plot-scale and small catchment studies that have shown more profound forest management impacts on TOC fluxes. This shows the importance of scale when assessing the mechanisms controlling TOC fluxes and concentrations. The results highlight the value of long-term multiple data sets to better understand ecosystem response to land management, climate change and extremes in northern ecosystems.
PubMed ID
24501106 View in PubMed
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Anaerobic microbial Fe(II) oxidation and Fe(III) reduction in coastal marine sediments controlled by organic carbon content.

https://arctichealth.org/en/permalink/ahliterature285578
Source
Environ Microbiol. 2016 Sep;18(9):3159-74
Publication Type
Article
Date
Sep-2016
Author
Katja Laufer
James M Byrne
Clemens Glombitza
Caroline Schmidt
Bo Barker Jørgensen
Andreas Kappler
Source
Environ Microbiol. 2016 Sep;18(9):3159-74
Date
Sep-2016
Language
English
Publication Type
Article
Keywords
Anaerobiosis
Bacteria - classification - genetics - isolation & purification - metabolism
Carbon - analysis - metabolism
Denmark
Ferric Compounds - metabolism
Ferrous Compounds - metabolism
Geologic Sediments - chemistry - microbiology
Nitrates - metabolism
Oxidation-Reduction
Abstract
Coastal marine sediments contain varying concentrations of iron, oxygen, nitrate and organic carbon. It is unknown how organic carbon content influences the activity of nitrate-reducing and phototrophic Fe(II)-oxidizers and microbial Fe-redox cycling in such sediments. Therefore, microcosms were prepared with two coastal marine sediments (Kalø Vig and Norsminde Fjord at Aarhus Bay, Denmark) varying in TOC from 0.4 to 3.0 wt%. The microcosms were incubated under light/dark conditions with/without addition of nitrate and/or Fe(II). Although most probable number (MPN) counts of phototrophic Fe(II)-oxidizers were five times lower in the low-TOC sediment, phototrophic Fe(II) oxidation rates were higher compared with the high-TOC sediment. Fe(III)-amended microcosms showed that this lower net Fe(II) oxidation in the high-TOC sediment is caused by concurrent bacterial Fe(III) reduction. In contrast, MPN counts of nitrate-reducing Fe(II)-oxidizers and net rates of nitrate-reducing Fe(II) oxidation were comparable in low- and high-TOC sediments. However, the ratio of nitratereduced :iron(II)oxidized was higher in the high-TOC sediment, suggesting that a part of the nitrate was reduced by mixotrophic nitrate-reducing Fe(II)-oxidizers and chemoorganoheterotrophic nitrate-reducers. Our results demonstrate that dynamic microbial Fe cycling occurs in these sediments and that the extent of Fe cycling is dependent on organic carbon content.
PubMed ID
27234371 View in PubMed
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An almost completed pollution-recovery cycle reflected by sediment geochemistry and benthic foraminiferal assemblages in a Swedish-Norwegian Skagerrak fjord.

https://arctichealth.org/en/permalink/ahliterature272280
Source
Mar Pollut Bull. 2015 Jun 15;95(1):126-40
Publication Type
Article
Date
Jun-15-2015
Author
Irina Polovodova Asteman
Daniela Hanslik
Kjell Nordberg
Source
Mar Pollut Bull. 2015 Jun 15;95(1):126-40
Date
Jun-15-2015
Language
English
Publication Type
Article
Keywords
Aquatic Organisms
Carbon - analysis
Environmental Monitoring - methods
Estuaries
Foraminifera - physiology
Geologic Sediments - analysis - chemistry
Industrial Waste
Lead Radioisotopes - analysis
Metals, Heavy - analysis
Nitrogen - analysis
Norway
Sweden
Water Pollutants, Chemical - analysis
Water Pollution, Chemical - analysis
Abstract
During the 20th century Idefjord was considered one of the most polluted marine areas in Scandinavia. For decades it received high discharges from paper/pulp industry, which made it anoxic and extremely polluted by heavy metals and organic contaminants. Today the fjord is close to fulfil a complete pollution-recovery cycle, which is recorded in its sediment archives. Here we report results from five sediment cores studied for TC, C/N, heavy metals and benthic foraminifera. All of the cores have laminations deposited during 1940-1980s and indicative of long-lasting anoxia; high TC and heavy metal content, poor foraminiferal faunas and lack of macrofauna. The upper part of the cores deposited since 1980s shows a gradual pollutant decrease and partial foraminiferal recovery. The majority of foraminiferal species in Idefjord are agglutinated opportunistic and stress-tolerant taxa, which to some extent tolerate hypoxia and are early colonisers of previously disturbed environments. The current study demonstrates a value of benthic foraminiferal stratigraphy as a useful tool in understanding processes driving environmental degradation and recovery of coastal ecosystems.
PubMed ID
25931174 View in PubMed
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Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils.

https://arctichealth.org/en/permalink/ahliterature272603
Source
Glob Chang Biol. 2015 Aug;21(8):3169-80
Publication Type
Article
Date
Aug-2015
Author
Nadia I Maaroufi
Annika Nordin
Niles J Hasselquist
Lisbet H Bach
Kristin Palmqvist
Michael J Gundale
Source
Glob Chang Biol. 2015 Aug;21(8):3169-80
Date
Aug-2015
Language
English
Publication Type
Article
Keywords
Carbon - analysis
Carbon Sequestration
Ecosystem
Nitrogen - analysis
Soil - chemistry
Soil Microbiology
Sweden
Taiga
Abstract
It is proposed that carbon (C) sequestration in response to reactive nitrogen (Nr ) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO2 emissions. While studies have helped clarify the magnitude by which Nr deposition enhances C sequestration by forest vegetation, there remains a paucity of long-term experimental studies evaluating how soil C pools respond. We conducted a long-term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50 kg N ha(-1) yr(-1) ) in the boreal zone of northern Sweden to understand how atmospheric Nr deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non-significant increase in the organic horizon C pool of ~15% and a significant increase of ~30% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10 kg C kg(-1) N. We also found a concomitant decrease in total microbial and fungal biomasses and a ~11% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26 kg C kg(-1) N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region.
PubMed ID
25711504 View in PubMed
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An X-ray diffraction study of the crystalline composition of gallstones.

https://arctichealth.org/en/permalink/ahliterature238370
Source
Scand J Gastroenterol. 1985 Sep;20(7):901-6
Publication Type
Article
Date
Sep-1985
Author
A J Aho
E. Vilhonen
S. Peltola
A. Lehtonen
Source
Scand J Gastroenterol. 1985 Sep;20(7):901-6
Date
Sep-1985
Language
English
Publication Type
Article
Keywords
Adult
Aged
Calcium Carbonate - analysis
Cholelithiasis - metabolism - pathology
Crystallization
Female
Finland
Humans
Male
Middle Aged
Palmitic Acid
Palmitic Acids - analysis
X-Ray Diffraction
Abstract
The crystalline composition of gallstones removed from 30 patients from southwestern Finland was determined by the X-ray powder method. A total of eight crystalline compounds, varying from one to four per stone, were identified. Anhydrous cholesterol was by far the most abundant compound, occurring in 29 patients (97%), and calcium salts occurred in half the material studied. The stones could be classified on the basis of crystalline composition: pure cholesterol stones (40%), stones of cholesterol and calcium carbonate (37%), stones of cholesterol and sodium chloride or/and calcium palmitate (20%), and a stone of apatite and calcium carbonate (3%). The average amount of crystalline components per stone was as follows: cholesterols, 82%; calcium carbonates, 14%; and the rest, apatite, calcium palmitate, and sodium chloride. The crystalline composition of the stones related to the sex and age of the patients indicated several trends, including the occurrence of calcium carbonates in the stones of patients over 50 years of age and their simultaneous occurrence in small stones and with the cholesterols. Calcium palmitate was also more frequently present in the calculi of male patients.
PubMed ID
4048841 View in PubMed
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Application of a Finnish mutagenicity model to drinking waters in the U.S.

https://arctichealth.org/en/permalink/ahliterature205146
Source
Chemosphere. 1998 Aug;37(3):451-64
Publication Type
Article
Date
Aug-1998
Author
K M Schenck
L J Wymer
B W Lykins
R M Clark
Author Affiliation
U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA.
Source
Chemosphere. 1998 Aug;37(3):451-64
Date
Aug-1998
Language
English
Publication Type
Article
Keywords
Ammonia - analysis
Carbon - analysis
Chlorine - adverse effects - analysis
Environmental monitoring
Finland
Fresh Water - analysis
Humans
Models, Theoretical
Mutagenicity Tests
Mutagens - analysis
Neoplasms - chemically induced
Resins, Synthetic - chemistry
United States
Water Pollutants, Chemical - adverse effects - analysis
Water Purification
Abstract
Recent epidemiological studies conducted in Finland have reported a positive correlation between the mutagenicity of chlorinated drinking waters and certain human cancers. In these studies, past exposure to drinking water mutagenicity was assessed using a model developed by Vartiainen et al. [1] based on data collected in Finland. In this model, mutagenicity, as determined in the Ames assay, is a function of the total organic carbon (TOC) concentration of the water, chlorine dose, and to a minor extent, the concentration of ammonia. A study has been initiated to assess the applicability of this model to source waters and water treatment practices in the United States. Water samples were collected from three full-scale treatment plants and one pilot-scale plant. All the plants used chlorine exclusively for disinfection. One full-scale plant used ground water. Surface water sources were used by the other plants. TOC and ammonia concentrations were determined analytically and chlorine doses were obtained from the treatment plants. The water samples were concentrated by XAD resin adsorption for testing in the Ames assay. The observed levels of mutagenicity in the finished waters were 1.5 to 2-fold higher than those predicted using the model as specified in Vartiainen et al. [1]. Consequently, further validation is needed prior to widespread use of the Finnish model to assess exposure to mutagenicity in chlorinated drinking waters in the United States.
PubMed ID
9661275 View in PubMed
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Arctic hydrology during global warming at the Palaeocene/Eocene thermal maximum.

https://arctichealth.org/en/permalink/ahliterature95711
Source
Nature. 2006 Aug 10;442(7103):671-5
Publication Type
Article
Date
Aug-10-2006
Author
Pagani Mark
Pedentchouk Nikolai
Huber Matthew
Sluijs Appy
Schouten Stefan
Brinkhuis Henk
Damsté Jaap S Sinninghe
Dickens Gerald R
Author Affiliation
Department of Geology and Geophysics, Yale University, PO Box 208109, New Haven, Connecticut 06520, USA. mark.pagani@yale.edu
Source
Nature. 2006 Aug 10;442(7103):671-5
Date
Aug-10-2006
Language
English
Publication Type
Article
Keywords
Alkanes - metabolism
Arctic Regions
Biological Markers - analysis
Calcium Carbonate - analysis - metabolism
Carbon - metabolism
Carbon Isotopes
Geologic Sediments - chemistry
Greenhouse Effect
History, Ancient
Humidity
Hydrogen - analysis - chemistry
Marine Biology
Oceans and Seas
Plants - metabolism
Rain
Seawater - analysis - chemistry
Sodium Chloride - analysis
Temperature
Time Factors
Abstract
The Palaeocene/Eocene thermal maximum represents a period of rapid, extreme global warming 55 million years ago, superimposed on an already warm world. This warming is associated with a severe shoaling of the ocean calcite compensation depth and a >2.5 per mil negative carbon isotope excursion in marine and soil carbonates. Together these observations indicate a massive release of 13C-depleted carbon and greenhouse-gas-induced warming. Recently, sediments were recovered from the central Arctic Ocean, providing the first opportunity to evaluate the environmental response at the North Pole at this time. Here we present stable hydrogen and carbon isotope measurements of terrestrial-plant- and aquatic-derived n-alkanes that record changes in hydrology, including surface water salinity and precipitation, and the global carbon cycle. Hydrogen isotope records are interpreted as documenting decreased rainout during moisture transport from lower latitudes and increased moisture delivery to the Arctic at the onset of the Palaeocene/Eocene thermal maximum, consistent with predictions of poleward storm track migrations during global warming. The terrestrial-plant carbon isotope excursion (about -4.5 to -6 per mil) is substantially larger than those of marine carbonates. Previously, this offset was explained by the physiological response of plants to increases in surface humidity. But this mechanism is not an effective explanation in this wet Arctic setting, leading us to hypothesize that the true magnitude of the excursion--and associated carbon input--was greater than originally surmised. Greater carbon release and strong hydrological cycle feedbacks may help explain the maintenance of this unprecedented warmth.
Notes
Erratum In: Nature. 2006 Oct 5;443(7111):598
PubMed ID
16906647 View in PubMed
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Arctic mosses govern below-ground environment and ecosystem processes.

https://arctichealth.org/en/permalink/ahliterature95622
Source
Oecologia. 2007 Oct;153(4):931-41
Publication Type
Article
Date
Oct-2007
Author
Gornall J L
Jónsdóttir I S
Woodin S J
Van der Wal R.
Author Affiliation
School of Biological and Biomedical Sciences, Durham University, DH1 3LE Durham, UK. J.l.gornall@durham.ac.uk
Source
Oecologia. 2007 Oct;153(4):931-41
Date
Oct-2007
Language
English
Publication Type
Article
Keywords
Bryophyta - growth & development
Carbon - analysis
Ecosystem
Nitrogen - analysis - metabolism
Soil - analysis
Soil Microbiology
Svalbard
Temperature
Water - analysis
Abstract
Mosses dominate many northern ecosystems and their presence is integral to soil thermal and hydrological regimes which, in turn, dictate important ecological processes. Drivers, such as climate change and increasing herbivore pressure, affect the moss layer thus, assessment of the functional role of mosses in determining soil characteristics is essential. Field manipulations conducted in high arctic Spitsbergen (78 degrees N), creating shallow (3 cm), intermediate (6 cm) and deep (12 cm) moss layers over the soil surface, had an immediate impact on soil temperature in terms of both average temperatures and amplitude of fluctuations. In soil under deep moss, temperature was substantially lower and organic layer thaw occurred 4 weeks later than in other treatment plots; the growing season for vascular plants was thereby reduced by 40%. Soil moisture was also reduced under deep moss, reflecting the influence of local heterogeneity in moss depth, over and above the landscape-scale topographic control of soil moisture. Data from field and laboratory experiments show that moss-mediated effects on the soil environment influenced microbial biomass and activity, resulting in warmer and wetter soil under thinner moss layers containing more plant-available nitrogen. In arctic ecosystems, which are limited by soil temperature, growing season length and nutrient availability, spatial and temporal variation in the depth of the moss layer has significant repercussions for ecosystem function. Evidence from our mesic tundra site shows that any disturbance causing reduction in the depth of the moss layer will alleviate temperature and moisture constraints and therefore profoundly influence a wide range of ecosystem processes, including nutrient cycling and energy transfer.
PubMed ID
17618466 View in PubMed
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149 records – page 1 of 15.