910 research outputs found

    Acidification of Forest Soils: A Model for Analyzing Impacts of Acidic Deposition in Europe - Version II

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    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

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    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

    Acidification in Europe : A Simulation Model for Evaluating Control Strategies

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    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

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    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

    Social network ties before and after retirement : a cohort study

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    Social networks are associated with individual's health and well-being. Working life offers opportunities to create and maintain social networks, while retirement may change these networks. This study examined how the number of ties in social network changes across the retirement transition. The study population consisted of 2319 participants (84% women, mean age 63.2 years) from the Finnish Retirement and Aging study. Information about social network ties, including the number of ties in the inner, middle and outer circles of the social convoy model, was gathered using annual postal surveys before and after retirement. Three repeat surveys per participant covered the retirement transition and the post-retirement periods. Mean number of network ties was 21.6 before retirement, of which 5.6 were situated in the inner, 6.9 in the middle and 9.1 in the outer circle. The number of ties in the outer circle decreased by 0.67 (95% CI - 0.92, - 0.42) during the retirement transition period, but not during the post-retirement period (0.11, 95% CI - 0.33, 0.12) (interaction period * time, p = 0.006). The pattern of change in these ties did not differ by gender, occupational status, marital status, number of chronic diseases and mental health during the retirement transition period. The number of ties in the inner and middle circles overall did not decrease during these periods. The number of peripheral relationships decreased during the retirement transition but not after that, suggesting that the observed reduction is more likely to be associated with retirement rather than aging.Peer reviewe

    Acidification of forest soils : Model development and application for analyzing impacts of acidic deposition in Europe.

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    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

    Acidification of Forest Soils: Model Development and Application for Analyzing Impacts of Acidic Deposition in Europe

    Get PDF
    Acidification is considered as an unfavorable process in forest soils. Timber logging, natural accumulation of biomass in the ecosystem, and acidic deposition are known as sources of acidification. Acidification causes the 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 one-year time steps the model calculates the soil pH as 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 (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. These two types of comparisons produce an estimate of the soil pH as the output. The model was incorporated into a model system for analyzing the acidic deposition problem in Europe. The data on acid stress, entering the soils, was obtained from other submodels which link information on energy production, pollutant emission, pollutant transport, and pollutant deposition. 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 different emission scenarios. The soil acidification model assumes sulfur deposition estimates from the other submodels as the input, and as the output it produces estimates of the pH 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 of the soil acidification model are listed and briefly evaluated

    Acidification of Forest Soils

    Get PDF
    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 oil acidity. The model was incorporated into the Regional Acidification INformation and Simulation (RAINS) model system of IIASA for analyzing the acidic deposition problem in Europe. This system links information on energy production, pollutant emission, pollutant transport, and pollution 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 are listed and briefly evaluated

    Healthcare costs and outcomes in adult patients with juvenile idiopathic arthritis : a population-based study

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    Objectives: Evidence of the economic burden and long-term outcomes of juvenile idiopathic arthritis (JIA) remains scarce. Our aim was to explore healthcare costs and long-term outcomes in adult patients with JIA. Method: We identified all adult patients (>= 18 years) with JIA who visited Jyvaskyla Central Hospital rheumatology unit between May 2007 and March 2016. We considered individual medians of time-dependent clinical variables. These data were linked to administrative data from the area from the fiscal year 2014, which include information on all public healthcare contacts. Healthcare utilization is presented as direct costs in euros (EUR). Factors affecting direct costs were assessed with a generalized linear model. Results: In 218 patients, median 28-joint Disease Activity Score with three variables (DAS28-3) was = 30 years, and median Health Assessment Questionnaire (HAQ) score was <0.5 in 85.7% and 45.4%, respectively. In the utilization data (four municipalities, 137 patients), the total annual health services-related direct costs were 432 257 EUR (mean = 3155 EUR/patient/year). Thirty-six patients (26.3%) used biological disease-modifying anti-rheumatic drugs (bDMARDs) in 2014 for a total of 355 months, and the annual cost of bDMARDs was estimated at 355 000 EUR. Those with active disease had mean costs 2.4-fold higher than those with low or no disease activity. A one-point increase in median raw HAQ incurred an average 228 EUR increase in annual costs (p = 0.03). Conclusion: Most adult patients with JIA seem to manage well with their arthritis, bearing in mind that there still is room for improvement in long-term outcomes.Peer reviewe
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