Loading sedimentary

The most stable minerals are often physically eroded before they have a chance to chemically decompose. Minerals that decompose contribute to the dissolved load in rivers, and their solid chemical-weathering products contribute to the secondary minerals in the solid load. The secondary minerals and the more stable primary minerals are the most important constituents of clastic sedimentary rocks. Consequently, the secondary minerals of one cycle of erosion are... 

Data on sediment transport in the Ebro basin is very scarce. Besides some historical studies in the lowermost reaches of the catchment (e.g. [21]), almost at the delta plain, and few others undertaken during the 1990s (see Table 1), only the work undertaken by the Fluvial Dynamics group of the University of Lleida (hereafter UdL) between 2002 and 2008 in the lower part of the river supply reliable data on the total sediment load and changes in sediment transport and channel morpho-sedimentary characteristics upstream and downstream from large dams. 

Nelson CH (1990) Post Messinian deposition rates and estimated river loads in the Ebro sedimentary system. In Nelson CH, Maldonado A (eds) Marine geology of the Ebro continental margin. Geology 95 395 -18... 

As shown in Table 11.3, the concentrations of trace elements in the water column is - despite anthropogenic pollution - extremely small (10 11 - 10 7 M) illustrating the remarkable efficiency of the continuous "conveyor belt" of the settling adsorbing and scavenging particles. The sedimentary record reflects the accumulation of trace elements in sediments and a profile of concentration vs sediment-depth (or age) gives a "memory record" on the loading in the past (Fig. 11.9). 

In the last step (Part 3), the sedimentary compartment (the surface mixed sediment layer , SMSL) was treated as an independent box (Table 23.7). The steady-state solution of the combined sediment/water system explained another characteristic of the observed concentrations, which, as mentioned above, could not be resolved by the one-box model. As shown in Table 23.8, for both congeners the concentration measured on particles suspended in the lake is larger than on sediment particles. The two-box model explained this difference in terms of the different relative organic carbon content of epilimnetic and sedimentary particles. This model also gave a more realistic value for the response time of the combined lake/sediment system with respect to changes in external loading of PCBs. However, major differences between modeled and observed concentrations remained unexplained. 

It can be seen in Table 9.7 that the particulate load constitutes by far the most important contribution (88%) of total river discharge of materials to the ocean. The amount carried as solids should be increased by bed load transport, which usually is considered to be about 10% of the total suspended load (Blatt et al 1980). The mean chemical composition of river suspended matter closely approximates that of average shale (Table 9.8). This resemblance is expected because suspended solids in rivers are derived mainly from shales. Sedimentary rocks constitute about 66% of the rocks exposed at the Earth s surface fine-grained rocks, like shales, comprise at least 65% of the sedimentary rock mass. Thus, roughly 50% of surface erosion products come from shaly rocks. 

Manned space flight in Earth orbit is inefficient, and somewhat dangerous, but not overwhelmingly expensive. Mars space flight is another story. The cost of getting people there and back would be one trillion dollars Biology is the reason to go there. If we were to find a live bacterium in the sedimentary rock of Mars, that would be a monumental discovery. But humans are loaded inside and outside with bacteria that would surely contaminate the Martian environment and defeat the scientific purpose of the mission. Furthermore, the remote-controlled Mars rovers have successfully discovered tan-... 

All these conclusions have been made on the assumption that the sedimentary load of the rivers is constant through the whole period of accumulation of manganese in the deep sea. WedepohF believes that the weathering of the earth surface is stronger at present than it has been in the past, due to the pollution and the higher acidity of rain-water caused by pollution. 

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