Watershed The

The nature of human impacts on the Great Lakes relates closely to historical development and land use in the basin which, in turn, relate closely to the geology and physiography of the watershed. The southern part of the basin consists largely of Palaeozoic sedimentary rocks. Land use consists primarily of intense... 

Fig. 2 Time-series of annual mean water temperature in the San Reservoir (Spain) and air temperature in the Ter River watershed. The series start in 1964, after the first filling of the reservoir. Annual means are based on monthly measures of the volume weighted mean temperature. Only years with at least 10 temperature profiles were included in the figure. The air temperatures are annual means for the whole Ter River watershed, calculated from data collected in several meteorological stations in the basin, and weighted according to their area of influence...

The role of radionuclides as tracer of the chemical transport in river is also reinforced by the fact that each of the U-Th-Ra elements has several isotopes of very different half-lives belonging to the U-Th radioactive series. Thus, these series permit comparison of the behavior of isotopes of the same element which are supposed to have the same chemical properties, but very different lifetimes. These comparisons should be very helpful in constraining time scales of transport in rivers. This was illustrated by Porcelli et al. (2001) who compared ( " Th/ U) and ( °Th/ U) ratios in Kalix river waters and estimated a transit time for Th of 15 10 days in this watershed. The development of such studies in the future should lead to an important progress in understanding and quantifying of transport parameters in surface waters. This information could be crucial for a correct use of U-series radioactive disequilibria measured in river waters to establish weathering budgets at the scale of a watershed. 

Soil compartment chemical fate modeling has been traditionally performed for three distinct subcompartments the land surface (or watershed) the unsaturated soil (or soil) zone and the saturated (or groundwater) zone of a region. In general, the mathematical simulation is structured around two major cycles the hydrologic cycle and the pollutant cycle, each cycle being associated with a number of physicochemical processes. Watershed models account for a third cycle sedimentation. 

The Centro de Estudios Hidrograficos del Centro de Estudios y Experimentacion de Obras Publicas (CEH-CEDEX, http //hercules.cedex.es) provides the daily discharges for 275 gauging stations in the Ebro watershed. The CHEBRO website... 

The 210Pb input from the atmosphere must have been constant over the past 150 years due to the relative constancy in the maritime climate (temperature and soil moisture influences the radon emanation rate) and the resulting constancy in the input source for 210Pb. Therefore, the deviations from a single log-linear relationship of the unsupported 210Pb activity with the dry mass of sediment accumulation must be due to some property of the watershed. The three different relationships shown in... 

In 1995, the Somerset County Conservation District in Somerset County, Pennsylvania, constructed wetland treatment systems and limestone drains at four separate locations in the Oven Run/Pokeytown Run watershed. The estimated cost of the Oven Rnn/Pokeytown Rnn Project was 5.2 million (D204284, p. 34). 

Historically, less attention has been paid to atmospheric deposition to connecting channels and tributary rivers of the Great Lakes, mainly because of the smaller surface areas presented by rivers for direct atmospheric deposition, compared with deposition and transport to rivers from their watersheds. The atmospheric deposition of chlordanes and HCHs to the St. Lawrence River ranged from < 1 kg/yr for a-chlordane to 5 kg/yr for a- and y-HCHs these loadings represented < 1 to 14% of the atmospheric deposition to the watershed [58]. 

French Water Agency of the Rhin-Meuse Watershed, the French Agency for Environment and Energy Ressources. 

Many factors control whether a given water body will become acidified as a result of a given deposition regime. In addition to the deposition rate and the lake residence or turnover time, these include the ratio of water surface area to watershed area, the composition of the lake bottom, the residence time of incident precipitation en route through the watershed, and the buffering capacity of the watershed. The presence of organic material can also be important. 

Usually, for pristine watersheds, biologic and exchange reactions are assumed to be at steady state and the weathering flux is the difference between the watershed output and the precipitation input. In perturbed watersheds, the calculations become more complex due to agricultural inputs or changes in the exchangeable ions due to watershed acidification. 

A 50,000 GPD slow sand filtration water treatment plant supplies a community of 500 people with drinking water from a reservoir in a protected watershed. The raw water supply has the following characteristics (a) turbidity = 5-10 NTU (b) total estimated Giardia cyst level = less than 1 per 100 mL (c) pH = 6.5-7.5 (d) temperature = 5-15°C. 

The Tuscaloosa formation contributed significant amounts of very soft water to the Upper Three Runs Creek watershed. The remaining watersheds received significant water input from the McBean formation. The yield and calcareous nature of the McBean formation groundwater increased with its distance southeast-wards (12) consequently, the systems receiving groundwater from this formation displayed increased Ca and alkalinity in a seaward direction. 

The calculations (Howarth, 1996) showed that for the North Atlantic Ocean watershed the percentage of sewage and wastewaters to total nitrogen input varies among the regions, from a high of 34% in the North Sea region to virtually none in the Amazon basin (Table 6). 

Regional biogeochemical mass balance of nitrogen in the North Atlantic watershed The overall nitrogen fluxes within and between the terrestrial, groundwater and river systems of the North Atlantic watershed are summarized graphically in Figure 9. 

Most experiments on chemical weathering have been performed on pure minerals under carefully controlled laboratory conditions. However, under natural conditions in the field, mixtures of minerals of different abundances are reacting simultaneously, together with amorphous material and organic material subject to ion exchange in soils and sediments. It is instructive to conduct experiments on natural soils in the laboratory and then to compare these results with small plot experiments in the field and the prototype watershed. The site of Bear Brook Watershed at Lead Mountain, Maine (latitude 44 51 75", longitude 68 6 25") is shown in Figure 8. It contains two almost... 

Kumar V, Bennett M. 1981. The biology of marrow dependent cells in mice. In Watershed. The handbook of cancer immunology. New York, NY Garland STPM Press, Vol. 6, 145-160. 

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