Estimation of vertical groundwater fluxes into a streambed through continuous temperature profile monitoring and the relationship of groundwater fluxes to coaster brook trout spawning habitat

We hypothesized that the spatial distribution of groundwater inflows through river bottom sediments is a critical factor associated with the selection of coaster brook trout (a life history variant of Salvelinus fontinalis,) spawning sites. An 80-m reach of the Salmon Trout River, in the Huron Mountains of the upper peninsula of Michigan, was selected to test the hypothesis based on long-term documentation of coaster brook trout spawning at this site. Throughout this site, the river is relatively similar along its length with regard to stream channel and substrate features. A monitoring well system consisting of an array of 27 wells was installed to measure subsurface temperatures underneath the riverbed over a 13-month period. The monitoring well locations were separated into areas where spawning has and has not been observed. Over 200,000 total temperature measurements were collected from 5 depths within each of the 27 monitoring wells. Temperatures within the substrate at the spawning area were generally cooler and less variable than river temperatures. Substrate temperatures in the non-spawning area were generally warmer, more variable, and closely tracked temporal variations in river temperatures. Temperature data were inverted to obtain subsurface groundwater velocities using a numerical approximation of the heat transfer equation. Approximately 45,000 estimates of groundwater velocities were obtained. Estimated velocities in the spawning and non-spawning areas confirmed that groundwater velocities in the spawning area were primarily in the upward direction, and were generally greater in magnitude than velocities in the non-spawning area. In the non-spawning area there was a greater occurrence of velocities in the downward direction, and velocity estimates were generally lesser in magnitude than in the spawning area. Both the temperature and velocity results confirm the hypothesis that spawning sites correspond to areas of significant groundwater influx to the river bed

Impact of acid atmospheric deposition on soils : quantification of chemical and hydrologic processes

Atmospheric deposition of SO x , NOx and NHx will cause major changes in the chemical composition of solutions in acid soils, which may affect the biological functions of the soil. This thesis deals with quantification of soil acidification by means of chemical budgets, kinetics of mineral weathering of aluminum and base cations, and simulation of soil acidification. Most results apply to an acid forest soil on the Hackfort estate, for which monitoring data were available from 1981 to 1987.Spatial variability of soil solution composition was found to be the dominant source of uncertainty in determining chemical budgets. Uncertainty in annual chemical budgets due to simulation of unsaturated soil water fluxes generally does not exceed 10%. A new method was developed for in situ measurement of unsaturated soil water fluxes at a similar accuracy as obtained by numerical simulation.Weathering of Al is the dominant process for proton buffering in acid soils. In dutch acid soils, the most reactive pool for Al is present in hydrated oxides, often in association with organic matter. On average the weathering rate of Al increases nearly proportional with (H +), and decrease strongly with increasing depletion of reactive Al. Total exhaustion of the reactive pool of hydrated oxides may become a problem in the coming century.A new column percolation technique was developed to measure weathering rates at controlled pH in absence of mechanical disturbance. In all cases base cation weathering rates from laboratory experiments were considerably higher than estimated ' from field mass balance studies. A yet unconsidered effect for explanation of this discrepancy, is the increase of weathering rate with (by approximation the square root of) the percolation rate. Moreover, evidence was found that assumed patchy coatings of secondary Al may be protective against weathering of Ca from plagioclases.The ILWAS model was adapted for simulation of soil acidification. The model proved to be appropriate to simulate annual budgets and seasonal variation of concentrations for all major components. Concentration peaks near the end of summer appeared to be overestimated, but also scarce field observations may be biased. The model seemed somewhat too crude to predict N-dynamics. The model was used to analyze the response of the soil system to 50% reduction of deposition, fertilization, and removal of forest vegetation. Scenario analyses, demonstrated that pH is not a sensitive indicator for changes in soil chemistry. Simple models, using large time steps, may be adequate to evaluate average annual changes of soil solution characteristics over periods of several decades

Top Level Negotiations in the European Union: The European Council

The European Council, the meeting of the Heads of State and Government of the member states of the European Union, has evolved into EU's most influential and powerful decision-making institution. However, the process of deepening (expansion of policy areas) and widening (enlargement) of European integration have forced the European Council to tackle the potential threat of a crisis in European top-level decision making before actual enlargement with ten new members in May 2004. If the current generation of political leaders is not able to reach agreement on necessary reforms, future decision-making in the European Council could eventually turn out to be a mission impossible. Despite a successful record, the European Council seemed to have lost its grip on the integration process, still based on an unchanged negotiation structure since its creation in the 1970's, are needed if the European Council wants to continue its important and guiding role in European integration. Two parallel processes of European Council reform have been initiated or intensified and are to be finalized before actual enlargement next year. The first process deals with the operational settings of the European Council summits. The second process deals with the institutional structure and the balance of power between the EU institutions. The main purpose of this paper is twofold. The first is to present information on the evolution and current functioning of the European Council since the summits are still surrounded by a lot of secrecy and informal decision-making. Secondly, an overview and analysis will be presented on these current reform processes that need to prepare the European Council for the upcoming enlargement. It is argued that the European Council has accurately overcome many of its problems and critics by ensuring a stronger institutional position in the future EU. The European Council will be in the driving seat more than ever before

Costs and benefits of nitrogen in the environment

Single issue policies have been an effective means of reducing reactive nitrogen (N_r) emissions in the EU, but to make further reductions more-integrated approaches are required