We propose here a project to study the complex phenomenon of groundwater pollution with nitrogen compounds. It is an attempt to answer the following basic questions: having found the quantity of rain or irrigation, and the quantity of fertilizer, how much will these damage the layer of drinkable water? Which is the best solution to minimize the damage? Our proposal is based on our earlier work, which treated the fluid flow through the first layer of unsaturated soil. Our main goal is to extend the model to include what happens in soil lower levels and how the influence of groundwater hydrodynamics can be taken into account. The nitrogen compound transformations take a key role in our study, which is multidisciplinary (fluid mechanics, chemistry, agriculture studies engineering). The soil pollution study implies the computation of the pollutant concentration through the soil profile. The mathematical models achieve the integration of equations describing the water movement and the pollutant concentrations. We have calibrated the hydraulic model using experimental data.
Intensified use of nitrogen based fertilizers in agriculture has resulted in a significant increases in soils and groundwater nitrate concentrations all over the world. Here we propose a new coupled model which describes the physical transport and biogeochemical dynamics of the water and nitrogen compounds in a soil-water-plant-groundwater system. Our model takes into account water infiltration into an unsaturated porous medium, the complex biogeochemical cycle of nitrogen in soils, nitrate leaching from the agricultural system toward the aquifer's water table, and the dispersion of nitrates in the groundwater. We calibrate our model and analyse the influence of soil type, precipitation or irrigation regime and fertilization schedules on leaching to groundwater as well as the temporal and spatial evolution of the nitrate pollutant plume in the aquifer. Simulations indicate that in order to achieve high crop yields while minimizing nitrogen loading to soils and groundwater we need to create an optimal balance between the amount of chemical fertilizers and water applied to crops on one hand, and the amount of nitrate and water used by plants on the other. We find that medium soils are more suitable for a sustainable corn production than coarse soils, ensuring both higher yield and less nitrate pollution of the aquifer. Regardless of soil type and irrigation schedule, a gradual fertilization throughout the plant life cycle reduces the potential for leaching and aquifer pollution. For medium soils, a more modest irrigation schedule results in more nitrate available for crops and less net leaching to the groundwater.
UE policies have played a leading role in protecting the environment by reducing emissions of greenhouse gases, and minimizing environmental impacts of energy use. Romanian National Renewable Energy Action Plan (NREAP) has promoted the use of energy from renewable sources in accordance with the Directive 2009/28/EC of the European Parliament. In this regard, renewable energy resources appear to be the one of the most efficient and effective solutions for clean and sustainable energy development in Romania. Despite the current economic downturn, electricity consumption in Romania for 2014-2020 is expected to have a growth of 2-3% per year, estimating a 4.6% gross domestic production (GDP). Romania's potentials for electricity generation from renewable resources is represented by: hydro energy with a theoretical potential estimated to 40 TWh in hydro power plant with more than 10 MW and 6 TWh in the small ones; wind energy with a theoretical potential estimated to 23 TWh and photovoltaic energy estimated to 1.2 TWh (source Romanian NREAP).From estimations and theoretical figures to reality regarding renewable energy in Romania the evolution is spectacular because in 2007 the hydro electric energy production was representative with 15.7% and renewables were no longer mentioned, and in 2013 (04.03.3013), the figures were 30.0% in hydro power and 6.5% wind (www.transelectrica.ro). According to NREAP, the expectations in the wind energy installed capacity were 1,850 MW in 2012 and the real installed capacity was 1,905 MW, with 3% growth. This paper deals with present and future prospect situation of renewable energy and the role of hydropower in Romania. This study shows that there is an important potential for renewable energy in Romania, especially concerning hydropower, and wind energy. We analyze the renewable energy sources in Romania considering the most important criteria for sustainable development.
Ground water is an important source of clean water supply throughout the world. A growing literature on the management of groundwater which takes into account the interaction of groundwater with surface water resupply sources (e.g., streams or lakes) is driven by concerns of intensified global fresh-water use coupled with increasing industrial and agricultural pollution levels. Our joint laboratory and numerical experiments simulate water withdrawals via two pumping wells from an unconfined aquifer bounded by two surface water bodies (streams or lakes). The water table position in the experimental setup was visualized by eight piezometers and numerically computed using VISUAL MODFLOW PRO, for different pumping regimes and initial hydraulic slopes. We also analyze numerically pollutant transport from the aquifer's boundaries toward the pumping wells. We show that it is possible to minimize pollution in the wells downstream of a polluted lake by managing the relative pumping rates in the two wells and the overall water table slope in the aquifer. The goal of our research is to (a) observe the physical processes involved in water and conservative tracer flow in an aquifer system surrounded by two lakes (b) develop a joint laboratorynumerical modeling teaching tool for future research and classroom use and (c) provide a simple tool that can be further developed to assist in management decisions regarding water-flow and pollution levels in aquifers.
This paper describes laboratory experiments conducted to investigate groundwater flow and solute transport within the capillary fringe (CF) and exchanges between the CF and the region below the water-table. An experimental bench was developed in order to simulate an unconfined aquifer, to observe the development of the CF and to study nitrates transfer from groundwater to CF, and also the fate of nitrates into the CF. The experimental bench has three compartments, the middle one being filled with sand and simulating an unconfined aquifer. Both sides of the middle compartment are edged by water reservoirs, which allows to develop a longitudinal flow into the sand reservoir and, as a result, a homogenous, isotropic, unconfined aquifer is obtained. The simulated water table (WT) was established at 10 cm above the bottom of the sand tank and a CF of 8 cm height have been obtained. Two soil solution extracting tube were installed in the sand tank. A continuous and diffused source of pollution has been simulated by filling the supply reservoir with water containing dissolved nitrate-ammonium with a concentration of 232.5 mg/L. The concentration values of soil extract shows a vertical upward flux of nitrates transported by capillarity from the water-table towards soil surface.
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