162 Marine Microbiology 



tion will exist except as the ocean current is in the opposite direc- 

 tion, the polarity of the charge will be reversed, and the negative 

 charge will be observed near the surface. Thus along the surface 

 of the ocean just north and south of the equator a significant po- 

 tential difference should occur and give rise to electron flow from 

 south to north. Likewise near the ocean bottom along the equator 

 there should be a similar region of opposite polarity which will 

 give rise to an electron flow in the opposite direction. 



In the polar region the horizontal component of the earth's 

 field is essentially zero, but the vertical component is maximum. 

 The polar ocean currents, however, are not as well defined as 

 they are in the equatorial zone, and one cannot anticipate the 

 result with any degree of confidence. It will suffice to say that the 

 resultant force will be such as to cause a lateral rather than a ver- 

 tical potential gradient such as discussed by Chapman and Bar- 

 tels ( 3 ) . In any region between the polar and equatorial latitudes, 

 the resultant force will reflect both components of the earth's mag- 

 netic field. 



The above hypothesis, while physically sound in principle, 

 must be investigated in terms of the known parameters. The 

 horizontal component of the earth's field will be considered to be 

 nominally at 0.5 gauss. The velocity of surface ocean currents in 

 the middle latitudes range from zero to about 4 km per hour (9). 

 The other important parameter is the ratio of total charge to mass 

 of the carrier. 



In considering equation ( 1 ) it is obvious that the radius of 

 curvature of the path of the charge carrier will be largely de- 

 pendent on the ratio e/m. The earners range in size from simple 

 ions to macromolecules and particles up to the size of microor- 

 ganisms (1 m)- For small ionic carriers, e/m is large and the 

 radius of curvature is small, say of the order of one meter. Ex- 

 cluding local convection cuiTcnts, etc., such charge carriers will 

 have a relatively constant velocity and hence will simply cir- 

 culate in circles as they move along with the current. For larger 

 carriers the e/m ratio is smaller and the radius of curvature is 

 larger. The vertical velocity gradient, however, is steep and thus 

 while the radius of curvature of the path for high currents is large 



