Origin riverine

In a continual biocoenosis test (Riverine biocoenosis model) for LAS the biocoenotic NOEC value of >0.65 mg/L has been determined. The test was carried out with a starting concentration of 1.1 mg/L LAS/L over a period of 5 weeks. The NOEC value represents the effect caused by the original detergent and the effects caused by the catabolites as well [297]. The NOEC value shows that biocoenosis reacts more sensitively to compounds than the most sensitive laboratory species, which according to general opinion should not be generalized. 

Background absorbance by dissolved organics of riverine origin. 

The abyssal clays are composed primarily of clay-sized clay minerals, quartz, and feldspar transported to the siuface ocean by aeolian transport. Since the winds that pick up these terrigenous particles travel in latitudinal bands (i.e., the Trades, Westerlies, and Polar Easterlies), the clays can be transported out over the ocean. When the winds weaken, the particles fell to the sea siufece and eventually settle to the seafloor. Since the particles are small, they can take thousands of years to reach the seafloor. A minor fraction of the abyssal clays are of riverine origin, carried seaward by geostrophic currents. Despite slow sedimentation rates (millimeters per thousand years), clay minerals, feldspar, and quartz are the dominant particles composing the surface sediments of the abyssal plains that lie below the CCD. Since a sediment must contain at least 70% by mass lithogenous particles to be classified as an abyssal clay, lithogenous particles can still be the major particle type in a biogenous ooze. 

The mixture of organic constituents in the marine environment is extremely complex. Their origin is partly terrigenuous many compounds are produced in the marine environment itself. The different sources and their relative importance for the complexation of trace metals in estuaries, coastal seas and open ocean are riverine input, runoff from the coastal zone, resuspension, import of water mases, atmospheric input and in situ biological production. 

Wetzel, R. G. 2002. Origins, fates, and ramifications of natural organic compounds of wetlands. In Proceedings of a conference on sustainability of wetlands and water resources How well can riverine wetlands continue to support society into the 21st century (M. M. Holland, M. L. Warren, and J. A. Stanturf, Eds.), pp. 183-189. Gen. Tech. Rep. SRS-50, U.S. Dept, of Agriculture, Forest Service, Asheville, NC. 

The bulk chemical composition of seawater DOM (Table 8.8), however, is not consistent with a predominant riverine origin. In particular, seawater DOM is depleted in C and enriched in C and compared with most DOM discharged by rivers (with the Amazon being taken here as an example). Seawater DOM is also depleted in aromatic carbon (as measured by C NMR) and lignin phenol structural units (as determined by CuO oxidation), possibly as a consequence both of the low phenol content of marine plankton, and of selective alteration of aromatic carbon by photodegradation. Thus all evidence to date, including elevated total concentrations in surface marine waters (Fig. 8.19), indicates that seawater DOM is largely... 

The chemical character of dissolved humic substances in estuaries also reflects its mixed origin, with a number of parameters exhibiting values intermediate between the riverine and oceanic endmembers. These properties include UV-visible absorptivities, C/N ratios, total acidity, molecular weight (Preston, 1979), amino acid content (Fox, 1981), and perhaps C/ C... 

Aggregation of dissolved humic substances can also occur with particulate materials in the estuarine water column. Preston and Riley (1982) showed that the adsorption of riverine humic substances onto kaolinite, montmorillonite, and illite increased with increasing salinity and dissolved humic substance concentration. Adsorption increased in the order kaolinite < illite < montmorillonite, which they ascribed to increasing cation-exchange capacity of the clays. They found considerable quantitative differences between the extent of adsorption of riverine versus extracted sedimentary humic substances, indicating the importance of using materials of proper origin in experiments of this type. 

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