The Surface Charge of Particulate Matter in Seawater

Abstract

The surface charge of particulate matter in seawater from estuarine and coastal sources was investigated by microelectrophoresis. Seston consisting mostly of bacteria, small algae, and detritus exhibited a considerable range of mobilities but all were negatively charged; the mean mobility and the range of mobilities increased when the salinity of the media was reduced.The surface charge of model particles of glass, anion exchange resin, bentonite, calcium carbonate, wax, and a polysaccharide were also studied after equilibration in both natural seawater (freed of natural particulates) and an artificial seawater containing only major ions. The considerable range of mean mobilitics for these particles in artificial seawater, -1.5 to +1.2 (,um/sec) (V/cm)-l, converged to -1.1 to -0.1 (,um/sec) ( V/cm ) -' in seawater.The surface adsorption of minor constituents in seawater is the most likely cause of these changes. Dialysis experiments indicated that both high and low molecular weight materials were responsible. The macromolecular component could be removed from limited amounts of seawater by a column of porous glass. Adsorbable constituents of seawater which might produce the observed surface effects are considered.

The removal of uranium from mining waste water using algal/microbial biomass

“…cellulose, xylan, and mannans (Lobban and Wynne, 1981;Myers et al, 1975;Neihof and Loeb, 1972), with a negative charge on their surfaces. The negatively charged groups attract cations such as Zn, Cu, Al and U (Barker et al, 1998;Marques et al, 1990).…”

Particle flux and trace metal residence time in natural waters1,1

“…The sources of data for particle fluxes (s), residence times of Th (TP), and mean depth (h in m) are given in Table 2. Li et al 1980Li et al 1980Knauss et al 1978Brewer et al 1980Brewer et al 1980Li et al 1980Anderson 198 1 Moore et al 198 1 Minagawa and Tsunogai 1980Minagawa and Tsunogai 1980Minagawa and Tsunogai 19 80 Santschi et al 1980Santschi et al 1980Santschi et al 1980Li et al 1979, 1981Anderson et al 1983Anderson et al 1983 (Krishnaswami et al 1976;Brewer et al 1980;Li et al 1980 comes from observations (Neihof and Loeb 1972;Hunter and Liss 1979;Lion et al 1982) that natural particles are coated with organic or Fe-Mn-hydroxide films which give them relatively uniform outer surfaces for adsorbing trace metals.…”

The microclimate inhabited by macroalgal propagules

“…Most surfaces in marine environments (and many in freshwater) are negatively charged and, therefore, attract positively charged ions (Pravdi6, 1970;Neihof & Loeb, 1972, 1974. Surfaces have been shown to concentrate several nutrients which stimulate kelp spore chemotaxis or settlement (Amsler & Neushul, 1989a including phosphate (Paerl, 1980;Paerl & Merkel, 1982), iron (Davies, 1970;Stumm & Morgan, 1981), and nitrogenous organic compounds (Neihof & Loeb, 1972, 1974Marshall, 1976).…”