Particle river-borne

The first reports of plastic in the North Atlantic indicated the presence of 50-12,000 particles/km in the Sargasso Sea in 1972 (52) and from 0-14.1 particles per m in coastal waters of southern New England (42), where the main source was river-borne effluents from plastic fabrication plants (44). Plastic objects discarded from boats and from recreational activities on beaches were the main sources of debris in Narragansett Bay, being deposited at a rate of 9.6 g m of beach front per month (53). During a detailed survey off the southeast coast of the United States (43, 54), fragments of plastic were present in about 70% of the samples collected from the waters of the continental shelf, the continental slope and the Gulf Stream between Florida and Cape Cod, 50% of those from the Caribbean Sea, and 60% of those from the Antilles Current. Since unprocessed plastic was more prevalent in continental shelf waters and fabricated objects were common offshore but rare near land, the authors surmised... 

With regards to solid phase, most of the estuaries are characterized by a "turbidity maximum". The fresh water flow generates an entrainment from the bottom water, the sea water which is entrained from the lower layer by this flow being compensated by a residual landward flow along the bottom. The river-borne particles which settle in this bottom layer are taken up by the residual landward current and trapped in the middle part of the estuary. This process greatly enhances the residence time of particles, especially in tidal estuaries. 

Sedimentation FFF implies application of the centrifugal field, which is produced by placing the channel in a centrifuge basket. SdFFF instruments can be linked readily to analytical instruments to provide analysis in real time. For the first time, Beckett (1991) introduced FFF-ICP-mass spectroscopy (MS) as a powerful analytical tool for characterizing macromolecules and particles. Taylor et al. (1992) illustrated the characterization of some inorganic colloidal particles and river-borne suspended particulate matter of size range <1 pm using SdFFF and ICP-MS. 

Many environmental samples are particularly well suited for S-FFF or Gr-FFF due to their large sizes, and many successful fractionations of such samples have been reported, including silt-sized particles and river-borne particulates [377], as already discussed in the section on colloids. Another promising application is... 

Presumably river-borne pyrethroids may eventually be exported to estuaries, although few published data exist to test this theory. Indeed, prior to our recent studies, very few published data were available to allow an assessment of even the above sorption processes to be made. It is therefore the purpose of this short review to compile the results of a 5 year programme of research into the sorptive properties of pyrethroids onto minerals, soil and estuarine particles. These have been published previously as individual studies in diverse sources which may not be widely read by sedimentary geochemists. We felt, therefore, that it would be useful to compile such data. 

The distribution of sediment types in the Pacific Ocean is much different from that of the Atlantic. Except for the coastline of the northwest United States, the Pacific is ringed by deep-sea trenches and, hence, has relatively narrow continental shelves. The trenches effectively trap all the terrigenous particles carried to the sea by river runoff. The Pacific Ocean is much wider than the other oceans thus the flux of wind-borne lithogenous particles is spread over a much greater area and produces a much lower mass flux, on an areal basis, to the seafloor. This makes other particles relatively important in determining the composition of the sediments in the Pacific ocean. 

Hassett, J. P., and M. A. Anderson. 1982. Effects of dissolved organic matter on the adsorption of hydrophobic compounds by river and sewage borne particles. Water Research 16 681. 

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