Soil oceanic deposition

The atmosphere, in turn, affects soil development by providing oxygen and by wind erosion and deposition. Sand dunes are only the most obvious example. Loess soils are deposits of silt-sized particles carried by winds from riverbeds and glacial outwash. A large fraction of the clay content of the soils along the eastern shores of the Mediterranean Sea has been carried by winds several thousand kilometers from the Sahara Desert and Atlas Mountains of North Africa. Trade winds carry Saharan clay particles several thousand kilometers out into the Atlantic Ocean. 

Am levels in surface seawater of the North Sea and North Atlantic Ocean have stayed around 10 Bq/m3 (270 pCi/m3) between 1976 and 1988 (Pattenden and McKay 1994), but may be considerably higher near discharges from nuclear facilities. 241 Am in soil resulting from cumulative deposition and ingrowth in the New York region should reach a maximum of 0.88 mCi/km2 (33 MBq/km2) in the year 2035. In the Food... 

The basement complex for the Patagonian desert and arid northeastern Brazil is formed by metamorphosed Precambrian rocks. Landscapes are characterized by level erosion surfaces of different ages. The landscape is dissected by a large number of valleys. Large depressions are filled with marine and continental beds of sedimentary rocks. Rocks in the Andean system, that stretches the entire length of the west side of the continent, vary greatly. Many depressions are filled with sediments. In addition, many active volcanoes are responsible for periodic lava flows and the deposition of volcanic ash. East of the Andes, the land surface is level and slopes towards the Atlantic Ocean. Broad depressions contain saline or sodic soils. 

Environmental distribution After 40 years of continuous application of DDT to vegetation (80%) and soil (20%), 73% of the total mass present in the environment in December 1990 are stored in soil, 24 % in the ocean, 2 % in vegetation, and less than one percent in the atmosphere (Table 3.2).The high storage in soil is caused by its strong absorptive capacity of organochlorine compounds, which is related to its organic matter content. The only source of DDT and DDE in the ocean is deposition... 

Benninger et al., [3] found values of about 1 dpm cm 2 yr for the deposition rate of 210Pb in soils and sediments near New Haven, Connecticut and Long Island. Recent measurements in Puget Sound at Sinclair Inlet by W. R. Schell (unpublished data), indicated that the deposition rate was about 0.35 dpm cnr yr. Thus, to explain the very high and variable values for the 210Pb deposition rate at the deep ocean stations, one must propose a mechanism whereby material from the topmost layers of sediments near the Atlantic Disposal Site is transported and re-deposited at these stations. 

River transport of clay minerals into the ocean is spatially and temporally variable. The global annual suspended load of river sediment into coastal waters currently averages 12.6 X 10 ton. This flux is approximately 10% less than was delivered before humans began damming rivers. (One notable exception is the Mississippi River, whose sediment load has increased due to very high rates of soil erosion. The riverine sediments deposited in the mouth of the Mississippi River form one of the world s largest deltas.)... 

Carbonate sediments deposited in shallow marine environments are often exposed to the influence of meteoric waters during their diagenetic history. Meteoric diagenesis lowers 8 0- and 8 C-values, because meteoric waters have lower 8 0-values than sea water. For example. Hays and Grossman (1991) demonstrated that oxygen isotope compositions of carbonate cements depend on the magnitude of depletion of respective meteoric waters. 5 C-values are lowered because soil bicarbonate is C-depleted relative to ocean water bicarbonate. 

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