1,139 research outputs found
Acidification of Forest Soils: A Model for Analyzing Impacts of Acidic Deposition in Europe - Version II
Acidification is an unfavorable process in forest soils. Timber logging, natural accumulation of biomass in the ecosystem, and acidic deposition are sources of acidification. Acidification causes a risk of damage to plant roots and a subsequent risk of a decline in ecosystem productivity.
A dynamic model is introduced for describing the acidification of forest soils. In one-year time steps the model calculates the soil pH as function of acid stress and the buffer mechanisms of the soil. Acid stress is defined as the hydrogen ion input into the top soil. The buffer mechanisms counteract acidification by providing a sink for hydrogen ions. The concepts buffer rate and buffer capacity are used to quantify the buffer mechanisms. The model compares (i) the rate of the acid stress (annual amount) to the buffer rate, and (ii) the accumulated acid stress (over several years) to the buffer capacity. The comparisons produce an estimate of the soil acidity as the output.
Since the first version in May 1984 several changes have been implemented following the advice of the experts. For aluminum and iron buffer ranges an equilibrium approach has been introduced. The pH of the silicate, cation exchange and upper aluminum buffer ranges is now a function of base saturation. In the current version of the model forests are assumed to absorb sulfur compounds more effectively than agricultural lands and, moreover, forests are assumed to grow on poor soil types rather than on the average soil type of a grid.
The model system as a whole is now available for analyzing the impact of different emission scenarios. The soil acidification model assumes sulfur deposition estimates from the other submodels as input, and as output it computes the total area of forests in Europe with the estimated soil pH lower than any selected threshold value. Additionally it produces estimates of the acidity of European forest soils in a map format
A Model for Analyzing Lake Water Acidification on a Large Region Scale - Part 1: Model Structure
The International Institute for Applied Systems Analysis is developing a computer model which can be used by decision makers to evaluate policies for controlling the impact of acid rain in Europe. As part of this task, a simple dynamic model has been developed for describing the processes leading to acidification of surface waters. The simulation model is constructed of several modules, each of them providing an overview of a particular aspect of lake acidification. The meteorologic module calculates the amount of water and deposition entering the soil or the lake directly each month. The IIASA soil acidity submodel accounts for the soil solution chemistry. A simple hydrologic method is applied for simulating the routing of internal flows so that the convective flow of ions can be estimated. The lake response is calculated according to the equilibrium reactions of inorganic carbon species. These modules are described in this paper. In part 2 the application of the model on a large regional scale will be described. Monte Carlo techniques will be used to determine those ranges and combinations of input values that produce an acceptable present day lake acidity distribution, when the model is driven by a specified deposition
Seasonal population dynamics of the invasive polychaete genus Marenzelleria spp. in contrasting soft-sediment habitats
Three species of the invasive polychaete genus Marenzelleria are among the dominant benthic taxa in many, especially deeper, areas in the Baltic Sea. The population dynamics of the polychaetes in the Baltic are, however, still largely unknown. We conducted monthly samplings of the benthic communities and environmental parameters at five sites with differing depths and sediment characteristics in the northern Baltic Sea (59 degrees 50.896', 23 degrees 15.092') to study the population dynamics, productivity and growth of Marenzelleria spp. from April 2013 to June 2014. The species of Marenzelleria occurring at the study sites were identified by genetic analyses. At the deepest site (33 m) only M. arctia was present, while all three species were found at the shallower, muddy sites (up to 20 m depth). At the shallow (6 m) sandy site only M. viridis and M. neglecta occurred. The sites differed in the seasonal dynamics of the Marenzelleria spp. population, reflecting the different species identities. The muddy sites up to 20 m depth showed clear seasonal dynamics, with the population practically disappearing by winter, whereas more stable populations occurred at the deepest site and at the sandy site. The highest density, biomass and production were observed at the 20 m deep, organic-rich muddy site where all three species recruited. The seasonally very high densities are likely to have important consequences for organic matter processing, and species interactions at these sites. The observed high productivity of the populations has possibly facilitated their establishment, and considerably increased secondary production in especially the deeper areas.Peer reviewe
Acidification in Europe : A Simulation Model for Evaluating Control Strategies
RAINS (Regional Acidification Information and Simulation) is an integrated model of acidification in Europe designed as a tool for evaluating control strategies. It is currently sulfur-based, but is being expanded to include nitrogen species. Emphasis of the model is on the transboundary aspects of the acidification problem. Model computations are performed on a personal computer. Linked submodels are available for SO2 emissions, cost of control strategies, atmospheric transport of sulfur, forest soil and groundwater acidity, lake acidification, and the direct impact of SO2 on forests. The model can be used for scenario analysis, where the user prescribes a control strategy and then examines the cost and environmental consequences of this strategy, or for optimization analysis, in which the user sets cost and deposition goals, and identifies an "optimal" sulfur-reduction strategy. Preliminary use of the model has pointed to 1. the importance of examining long-term environmental consequences of control strategies, and 2. the cost advantages of a cooperative European sulfur-reduction program
Sulfur deposition onto European forests: throughfall data and model estimates
The assessment of atmospheric sulfur deposition to forest is difficult because of its complex aerodynamic structure. Therefore, atmospheric deposition of sulfur to forest is often estimated by means of measuring throughfall fluxes onto the forest floor. In this paper, reported measurements of throughfall fluxes in European forests are analyzed. These fluxes are compared to deposition to bulk collectors located in nearby open land, to get an idea of the filtering efficiency of forests. In addition, fluxes are compared with deposition estimates from a long‐range transport model of air pollutants, linked to an emission generation model. According to reported measurements from 52 European conifer stands, we found that the sulfur flux was 3.8 ± 2.3 times greater onto the forest floor than onto precipitation collectors. In a similar data set of 13 deciduous stands this ratio was 2.3 ± 0.9. The ratio of throughfall flux to model estimate was 1.8 ± 0.9 in coniferous stands and 0.9 ± 0.3 in deciduous stands. For sites that are located in moderately to highly sulfur polluted areas, it is assumed that throughfall fluxes give a good estimation of the atmospheric sulfur deposition. We conclude that (1) sulfur deposition to forests is 1.5 to 6 times higher than deposition to smooth receptor surfaces due to an efficient filtering by the forest canopy, (2) average annual sulfur deposition at a given location is 50–100% greater on conifers than on deciduous trees, (3) the existing European scale model that links sulfur deposition to the pollution generation processes is quite accurate as far as deciduous forests are concerned, and (4) the model underestimates deposition to coniferous forest
Atmospheric Deposition of Sulfur, Nitrogen and basic Cations onto European Forests : Observations and Model Calculations
Measurements of sulfur and nitrogen deposition by means of the throughfall method are compared with model estimates. The sulfur model appears to estimate deposition to deciduous forests very well, but underestimates deposition to conifers by 30 to 40%. The NH4-N deposition to forest is underestimated by the applied model. The model predictions of NO3-N deposition do not show any bias against observations, but are not better correlated with observations than NH4 calculations. Reduced nitrogen compounds are the dominant nitrogen form in throughfall in ammonia polluted areas and contribute up to 50% of the total nitrogen deposition in other areas. Deposition of alkaline material to forests is estimated by applying different methods. Basic cation deposition neutralizes about 31% of the acid sulfur deposition to forest, on the average. Because of the large spatial variability of base cation deposition, it is recommended to develop a model for atmospheric transport and deposition of calcium- and magnesium-bearing particles
Älyn polysemia:kieliopillistumisen käynnistyminen yhdyssanan määriteosan kautta
Tiivistelmä. Pro gradu -tutkielmani aiheena on määriteosan äly polysemia. Olen tutkinut, millaisia merkityksiä sanalla äly on yhdyssanan määriteosana toimiessaan ja voiko uusien äly-alkuisten sanojen ilmaantuminen suomen kieleen olla merkki kieliopillistumisesta. Olen myös esittänyt tutkimuksen kannalta oleellisia kuvausmalleja ilmiön havainnollistamiseen. Tutkimusaineistoni on ladattu Kotimaisten kielten keskuksen ylläpitämästä Nykysuomen sanatietokannasta, jota sanakirjatoimittajat käyttävät työssään. Kyseiseen tietokantaan kirjataan ylös suomen kielen uusia sanoja. Aineisto ei ole julkisesti saatavilla, mutta olen saanut tietokannasta ladattuja sanalippuja tutkimuskäyttöön.
Tutkimukseni voi nähdä kuuluvan osaksi suomen yhdyssanatutkimusta. Lisäksi työssäni tulee esille kieliopillistumisilmiön teoreettinen viitekehys, jota esimerkiksi Berndt Heine ja Tania Kuteva (2006) sekä Krista Ojutkangas (2001) ovat käsitelleet teoksissaan. Työssäni hyödynnän myös Geert Booijn (2010) konstruktiomorfologiaa, jonka avulla on mahdollista kuvata sanatason konstruktioita. Polysemian käsite on myös läsnä tutkimuksessani.
Tutkimusmetodinani olen käyttänyt semanttista luokittelua. Olen jakanut aineistoni sanat merkitysluokkiin yhdyssanan alkuosan merkityksen perusteella. Tutkimuksestani käy ilmi, millaisia merkityksiä määriteosalla äly on nykysuomen uudismuodosteissa. Lisäksi tutkimuksessani tulee ilmi, millaisia ovat prototyyppiset yhdyssanat kussakin merkitysluokassa. Aineistostani löytyy myös sanoja, joiden määriteosat eivät selvästi edusta yhtä merkitysluokkaa, joten olen sijoittanut tällaiset tapaukset marginaalisiin merkitysluokkiin. Olen myös esittänyt työssäni oman skenaarioni siitä, miten älyn merkityksen laajentuminen on edennyt viime vuosikymmeninä.
Tutkimustulokseni antavat syytä olettaa, että älyn tapauksessa on mahdollisesti käynnissä kieliopillistuminen varhaisessa vaiheessa ja että kieliopillistuminen on käynnistynyt yhdyssanan määriteosan kautta. Tutkimuksessa hyödyntämäni konstruktiomorfologian kuvausmalli soveltuu hyvin älyn kaltaisen sanan eri merkitysten kuvailuun. Tutkimuksessani nousee selvästi esille seitsemän merkitystä määriteosalle äly: ’järkeä, ymmärrystä sisältävä’, ’havainnoiva, tarkkaileva’, ’mukautuva’, ’tietokonemainen’, ’itseohjautuva’, ’tietoa sisältävä’ ja ’seurantajärjestelmään liitetty’.
Tutkimustani voi hyödyntää tulevaisuudessa suomen yhdyssanojen tutkimuksessa. Käyttämääni aineistoa ja metodia on mahdollista soveltaa myös muiden määriteosien kuin äly merkitysten tutkimiseen. Myös yhdyssanojen edusosien tutkimuksessa työstäni voi olla hyötyä
Severity of symptoms persists for decades in fibromyalgia-a 26-year follow-up study
The aim of this study is to find out the outcome of 28 patients who got the diagnosis of primary fibromyalgia (pFM) 26 years ago. In 1986, 56 patients with widespread pain were examined and filled in a base questionnaire (BQ). Of them, 42 fulfilled the Yunus criteria for pFM. Twenty-six years later, addresses of 38 patients were found, and an extensive follow-up questionnaire (FupQ) was mailed to them. Of them, 28 (74%) answered the FupQ. This included nine identical questions with the BQ and questions concerning changes in their symptoms and quality of life (Qol). Three patients (11%) had healed from fibromyalgia (FM), and 23% reported having one or several symptomless periods lasting at least 1 year. In others (n = 25), all but pain and ache showed slight deterioration. Despite the aging and FM, the level of functional ability evaluated by Stanford Health Assessment Questionnaire (HAQ) remained at the same level (BQ 0.41 vs. Fup 0.44, p = 0.82). The sum score of reported symptoms (n = 21) did not change significantly (10.8 (SD 2.9) vs. 11.1 (SD 4.1), p = 0.75). Experienced sleeplessness increased most significantly (27 vs. 65%, p = 0.0034). Exercising did not have a significant influence on the changes of the measured parameters. However, the three healed patients exercised regularly. Symptoms of FM have persisted in most patients for decades without significant deterioration of self-reported functional ability. About one fourth of patients had experienced long symptomless periods during their illness. Three patients (11%) reported that they have healed from FM.Peer reviewe
Acidification of forest soils : Model development and application for analyzing impacts of acidic deposition in Europe.
Acidification is considered to be an unfavourable process in forest soil. Timber logging, natural accumulation of biomass in the ecosystem, and acidic deposition are known sources of acidification. Acidification causes a risk of damage to plant roots and subsequent risk of a decline in ecosystem productivity.
A dynamic model is introduced for describing the acidification of forest soils. In 1-year time steps the model calculates the soil pH as a function of the acid stress and the buffer mechanisms of the soil. Acid stress is defined as the hydrogen ion input into the top soil. The buffer mechanisms counteract acidification by providing a sink for hydrogen ions. The concepts buffer rate and buffer capacity are used to quantify the buffer mechanisms. The model compares (a) the rate of acid stress (annual amount) with the buffer rate, and (b) the accumulated acid stress (over several years) with the buffer capacity. These two comparisons give an estimate of the soil acidity.
The model was incorporated into the Regional Acidification Information and Simulation (RAINS) model system of the International Institute for Applied Systems Analysis for analyzing the acidic deposition problem in Europe. This system links information on energy production, pollutant emission, pollutant transport, and pollutant deposition. The data on acid stress entering the soils was obtained from other submodels. Data on buffer rate and buffer capacity were collected from soil maps and geological maps.
The model system as a whole is now available for analyzing the impact of different emission scenarios. The soil acidification model assumes sulfur deposition estimates from the other submodels as input, and as output it produces estimates of the acidity of European forest soils in a map format. Additionally it computes the total area of forests in Europe with the estimated soil pH lower than any selected threshold value. Sources of uncertainty in the soil acidification model are listed and briefly evaluated
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