Abstract
We determined the complex stability of copper, zinc, cobalt and aluminum with humic acid (HA) and fulvic acid (FA) in pH 8 seawater. The method is based on metal competition against iron, for which the complex stability with humic substances (HS) in seawater had been calibrated previously against EDTA. The conditional stability constants, log K'(Mn+HS) values, were found to decrease in the order of Cu > Zn > Co and Fe > Al. The complex stability of the HA species was greater than the FA species, but all determined complex stabilities are sufficiently high for significant complexation of the examined metals by HS in seawater. Data modeling shows a good data fit over the entire titrations for Cu and Co and for low levels of Zn. A second site on the HS appears to bind higher levels of Zn. The Al data suggest that Fe is exchanged for Al at a ratio different from 1:1. The data suggests that HS may be an important ligand for these metals in seawater.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
