La. Warren et Ap. Zimmerman, SUSPENDED PARTICULATE OXIDES AND ORGANIC-MATTER INTERACTIONS IN TRACE-METAL SORPTION REACTIONS IN A SMALL URBAN RIVER, Biogeochemistry, 24(1), 1994, pp. 21-34
The relative scavenging abilities of suspended particulate oxides (SPO
X), and organic matter (SPOM) for Cd, Zn and Cu were evaluated in a sm
all, anthropogenically influenced river. In addition, the factor most
important in influencing the sorption density (A(d): metal concentrati
on associated with a given phase divided by the concentration of that
geochemical phase in the suspended particulate pool) of each metal to
SPOX and SPOM were identified through multiple linear regression analy
ses from the suite of: pH, temperature, dissolved metal concentration,
and the concentration of the other particulate fraction. Results indi
cate that SPOX-SPOM interactions do occur in trace metal complexation
reactions; and interactions are both phase and cation specific. Fe oxi
des are able to outcompete discrete organic binding sites for Cu and Z
n as a relative decrease in the amount of these two cations sorbed to
organic matter was observed with increasing particulate Fe oxides. SPO
M concentration was identified as being most important in influencing
Cu sorption densities associated with the SPOX fraction. Organic matte
r - oxide complexes are postulated to occur that enhance oxide sorptio
n of Cu such that relatively more Cu is sorbed to particulate oxides w
ith increasing particulate organic matter concentrations. Dissolved co
ncentrations of Cd and Zn were found to be most important in influenci
ng the sorption densities for these two metals associated with the oxi
des fraction. The sorption behaviour appears to follow Freundlich isot
herm behaviour where the amount sorbed is a function of the dissolved
concentration.