Sj. Gonsior et al., THE EFFECTS OF EDTA ON METAL SOLUBILIZATION IN RIVER SEDIMENT WATER SYSTEMS/, Journal of environmental quality, 26(4), 1997, pp. 957-966
Ethylenediaminetetraacetic acid (EDTA), widely used in chelant formula
tions for applications to sequester metal ions in solution, has been d
etected in some environmental waters. Concern has arisen that EDTA, be
cause of its high binding constants with metals, may solubilize metals
from sediments in river systems. To address this issue, the effects o
f EDTA on metal solubilization were examined in a river sediment/water
system. Microcosms prepared with authentic Rouge River, Detroit, MI,
sediment and water were amended with a range of EDTA concentrations an
d shaken in the dark at 23 degrees C for 28 d. Metal concentrations we
re determined by inductively coupled plasma-optical emission spectrosc
opy (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS
). In the presence of EDTA, 28 d were required for equilibration of di
ssolved metal species with sediments. Higher levels of trace metals we
re solubilized by EDTA under oxidizing vs. reducing conditions. Statis
tically determined (alpha = 0.05) no observed effects levels (NOELs) f
or metal solubilization by EDTA were generated for the trace metals Ni
, Co, Cu, Zn, Cd, Fe, and Pb. These NOELs were 0.4, 0.6, 1.0, 1.0, 3.0
, 3.0, and 8.0 mu M EDTA, respectively. On a stoichiometric basis, the
se NOELs were at least fivefold higher than the background level of ED
TA present in the river water sample used in this study, indicating th
at EDTA did not contribute to trace metal solubilization in this syste
m. These results suggest that environmental concentrations of EDTA typ
ically found in river systems for which the subject river is represent
ative, are unlikely to contribute to trace metal solubilization from s
ediments.