Watersheds drainage

It has been shown that the main part of both soluble (53%) and particulate (> 99%) nitrogen was inputting into the Yellow sea from Northern China in spite of only 30% excess of river water discharge from the Chinese area. Totally riverine input from watershed drainage basin was equal to 52% from input values (2,581 kt/yr). Both wet and dry depositions were responsible for 20 and 22 % from input values with relatively small values of N fixation in marine waters. Denitrification is the main output items (37%) with similar values of sedimentation and water exchange with East the China Sea (7 and 8% from total input) and with negligible values of losses as N2O (< 1%). 

Watersheds, also known as drainage basins, define a natural context for the study of relationships among soils, geology, terrestrial ecosystems, and the hydrologic system because water and sediment travel downslope under the influence of gravity. This material is a continuation of some of what was presented in Chapter 6. 

Soils sampled at two sites in creek beds and drainage ditches in an agricultural area in the Point Mugu watershed near Oxnard, California, contained endosulfan at concentrations between 20 and 30 ppm. The majority of the other sites had much lower concentrations (Leung et al. 1998). 

While an exact number of site clusters has not been proposed, the authors consider from approximately 3 to 10 clusters of sites to be appropriate. These clusters should represent different ecoregions with different ecological characteristics as well as different loadings (both in amount and source) of mercury deposition. Care should be taken to monitor different types of water bodies and watersheds (e.g., seepage lakes, drainage lakes, old reservoirs, rivers, and estuaries). Areas that should be considered as potential cluster site locations include lakes in northern New England/the Adirondacks, lakes in the upper Midwest, rivers and streams in the southeastern coastal plain, lakes in south-central and southeastern Canada, western... 

Viers J, Dupre B, Polve M, Schott J, Dandurand L, Braun JJ (1997) Chemical weathering in the drainage basin of a tropical watershed (Nsimi-Zoetele site, Cameroon) comparison between organic-poor and organic-rich waters. Chem Geol 140 181-206... 

Many of the physiographic characteristics of the river Ebro can be understood from the origin and evolution of its watershed [1], The Ebro Basin underwent a long period of closed intramountain drainage as a result of tectonic topography... 

The Ebro watershed has a large surface area (85,000 km2) and a complex drainage network (a total of 347 streams). The Ebro is a relatively well known river from the point of view of the biological communities composition. Studies exist on the aquatic fauna and flora [3]. However, the functional activity of the river is largely unknown, mostly because of its complexity and associated technical difficulties. This chapter provides a state-of-the art of the who is who in the biological communities in the river, as well as considerations about the threats imposed by habitat deterioration, eutrophication, pollution and species invasions, and indicates the current gaps that still exist in the knowledge of the river. 

Stanton, M. 1973. The role of weathering in trace metal distributions in subsurface samples from the Mayday Mine Dump near Silverton, Colorado. In Church, S. E. (ed) The USGS Preliminary Release of Scientific Reports on the Acidic Drainage in the Animas River watershed San Juan County, Colorado, US Geological Survey, Denver, CO, USA, 77-85. 

The terrestrial drainage basin for each lake was digitized from 1 24,000 U. S. Geological Survey topographical maps. The reported values (which exclude lake surface area) represent the average of two estimates, one that includes and one that excludes small wetlands with internal drainage and areas where watershed boundaries were uncertain. 

Upper Colorado River Basin Colorado USA 37 streambed sediment samples (8 from nonmined areas) USA Alabama northern impacted by acid mine drainage 25 sites USA Alaska Cook Inlet Basin streams 47 sites USA Black Hills Spearfish, Whitewood, and Bear Butte creeks watersheds USA (conterminous) (541 stream bed samples)... 

Rivers and streams not only integrate the precipitation amount weighted hypsometric mean elevation of the drainage basin above the sampling site, but also the seasonal variation in the isotopic composition of the precipitation falling on that watershed. This will be most... 

Because of their position between the upland drainage and the sea, it is reasonable to suppose that estuaries have always been subjected to appreciable loadings of nutrients and other weathering products from their watersheds. However, various other features of estuaries (fisheries, commerce, etc.) have also long made them attractive for human settlement, with the result that a far larger anthropogenic input of nutrients, heavy metals and other pollutants has often been superimposed on an already rich background. 

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