A semi-empirical dynamic soil acidification model for use in spatially explicit integrated assessment models for Europe

A semi-empirical soil acidification model was developed for use in integrated assessment models on a European scale. The model simulates the time development of base saturation and aluminium concentration using an empirical relationship with pH. An accompanying data set was developed by overlaying European maps of soils, land use, climate and altitude followed by a procedure that aggragates the input data over soil-texture combinations in each EMEP 150 km x 150 km grid cell. Model tests show that themodel gives results comparable to the SMART model, although it overestimates initial base saturation in some areas with high acid input and simulates a faster recovery from acidification than SMART

Modelling the recovery of acid-sensitive Finnish headwater lakes under present emission reduction agreements

International audienceAbstract: Over the past two decades, substantial reductions in the deposition of acidifying substances (primarily sulphur) have occurred in most parts of Europe and, following recent agreements, this trend is likely to continue. The question arises as to how have sensitive ecosystems reacted, and will react in the future, to these reduced inputs of acidity? In this paper, the SMART dynamic acidification model predicts the possible recovery of 36 acid-sensitive Finnish headwater lakes, for which both catchment soil and water quality measurements were available. The model was calibrated to measurements by adjusting poorly known parameters; it was then used to simulate soil and water chemistry until 2030 under the ?current legislation scenario' resulting from implementing current European emission reduction agreements. Whereas most of the catchment soils show very little change in base saturation, the positive trends in lake ANC and the negative trends in lake sulphate concentrations, observed over the past decade, continue into the future, albeit at a slower pace. The model predicts that, during 2010?30, all lakes will have reached a positive ANC, a pre-requisite for the recovery of fish populations. Keywords: acidification, lake, catchment, recovery, SMART model, Finland</p

Remarks on NonHamiltonian Statistical Mechanics: Lyapunov Exponents and Phase-Space Dimensionality Loss

The dissipation associated with nonequilibrium flow processes is reflected by the formation of strange attractor distributions in phase space. The information dimension of these attractors is less than that of the equilibrium phase space, corresponding to the extreme rarity of nonequilibrium states. Here we take advantage of a simple model for heat conduction to demonstrate that the nonequilibrium dimensionality loss can definitely exceed the number of phase-space dimensions required to thermostat an otherwise Hamiltonian system.Comment: 5 pages, 2 figures, minor typos correcte

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

Network Externalities and the Dynamics of Markets

The evolution of markets on which network externalities prevail can be expected to differ from "classical markets" where no such externalities exist. We suggest a flexible formal model that describes the dynamics od types of markets. This leads to a stochastic version of the well known replicator dynamics. Based on this approach we analyze the limit behavior of different market types where consumers use stochastic decision rules. We show that market shares converge to the set of equilibria with probability one, where, even under network externalities, several technologies can coexist. On the other hand, even if no network externalities prevail it is possible that only one technology stays in the market. This paper contributes to the work on generalized urn schemes and path dependent processes going on at IIASA

Present and potential nitrogen outputs from Norwegian soft water lakes ? an assessment made by applying the steady-state First-order Acidity Balance (FAB) model

International audienceThe steady-state First-order Acidity Balance (FAB) model for calculating critical loads of sulphur (S) and nitrogen (N) is applied to 609 Norwegian soft-water lakes to assess the future nitrate (NO3?) leaching potential under present (1992-96) S and N deposition. The lakes were separated into five groups receiving increasing levels of N deposition (-2yr-1). Using long-term sustainable N sink rates presently recommended for FAB model applications, N immobilisation, net N uptake in forests, denitrification and in-lake N retention were estimated for each group of lakes. Altogether, the long-term N sinks constituted 9.9 ± 3.2 to 40.5 ± 11.4 meq m-2yr-1 in the lowest and highest N deposition categories, respectively. At most sites, the current N deposition exceeds the amount of N retained by long-term sustainable N sinks plus the NO3? loss via the lake outlets. This excess N, which is currently retained within the catchments may, according to the FAB model, leach as acidifying NO3? in the future. If these predictions are fulfilled, NO3? leaching at sites in the various N deposition categories will increase dramatically from present (1995) mean levels of 1-20 meq m-2yr-1, to mean levels of 7-70 meq m-2yr-1 at future steady state. To illustrate the significance of such an increase in NO3? leaching, the mean Acid Neutralising Capacity (ANC) at sites in the highest N deposition category may decrease from -18 ± 15 ?eq L-1 at present, to -40 ± 20 ?eq L-1. Under present S and N deposition levels, the FAB model predicts that 46% of the Norwegian lakes may experience exceedances of critical loads for acidifying deposition. In comparison, the Steady-State Water Chemistry model (SSWC), which considers only the present N leaching level, estimates critical load exceedances in 37% of the lakes under the same deposition level. Thus far, there are great uncertainties regarding both the time scales and the extent of future N leaching, and it is largely unknown whether the FAB model predictions will ever be fulfilled. Hence, long-term monitoring and further studies on N immobilisation processes under varying N deposition levels and ecosystem types seem necessary to make better predictions of future NO3? leaching. Keywords: Lakes, hydrochemistry, nitrogen, nitrate, sinks, leaching, acidification, critical loads, FAB mode

Abatement of Air Pollutants and Cogeneration: Search for an Optimal Solution

In this paper atmospheric diffusion modelling and nonlinear optimization techniques are used for the analysis of minimum cost alternatives of air pollution control strategies. Two cases are considered: a) control of air pollution from a large point source and b) reduction of existing pollution levels in an urban area utilizing the heat cogenerated by a thermal power plant for district heating. As to a) a program has been built to compute the minimum cost function for the chosen abatement techniques (including stack height) under the constraint of keeping the ground level concentration of N pollutants (gaseous or particulates) at specified values. Cost functions for stack height and abatement techniques are input to the program. As an example, results are presented for the control of two different pollutants controlled by two abatement techniques plus stack height. As to b) an interactive program has been developed to identify minimum cost network for heat conveyance necessary to supply a set of residential areas to achieve a given reduction of pollution in the urban area. Results are presented for the city of Vienna

The Rise of Complex Beliefs Dynamics

We prove that complex beliefs dynamics may emerge in linear stochastic models as the outcome of bounded rationality learning. If agents believe in a misspecified law of motion (which is correctly specified at the Rational Expectations Equilibria of the model) and update their beliefs observing the evolving economy, their beliefs can follow in the limit a beliefs cycle which is not a self-fulfilling solution of the model. The stochastic process induced by the learning rule is analyzed by means of an associated ordinary differential equation (ODE). The existence of a uniformly asymptotically stable attractor for the ODE implies the existence of a beliefs attractor, to which the learning process converges. We prove almost sure convergence by assuming that agents employ a projection facility and convergence with positive probability dropping this assumption. The rise of a limit cycle and of even more complex attractors is established in some monetary economics models assuming that agents update their beliefs with the Recursive Ordinary Least Squares and the Least Mean Squares algorithm

Sds22 regulates aurora B activity and microtubule-kinetochore interactions at mitosis

Sds22 defines protein phosphatase 1 location and function at kinetochores and subsequent activity of aurora B in mitosis