Complexation of copper ions in atmospheric precipitation in Croatia

Abstract

Organic complexation in atmospheric precipitation is an important control mechanism of the biogeochemistry of metal ions. We have measured complexation of copper ions in bulk precipitation by the method of differential pulse anodic stripping voltammetry (DPASV), which introduces least perturbation in the samples. The precipitation samples were collected periodically during one year in the mainland area of Croatia (Zagreb) and at the Adriatic coast The highest capacity was measured in April 2003 in rainwater sample from the Šibenik area, which could be associated to the contribution of biogenically driven organics to marine aerosol. Apparent stability constants determined were in the range of 6.1 -10. The sources of organic ligands in the samples could be multiple. The concentrations of dissolved organic carbon (DOC) as well as of surface active substances (SAS) were measured. The proportion of complexing ligands in these two organic matter fractions has also been discussed.

Physico-Chemical Characterization of an Urban Rainwater (Zagreb, Croatia)

“…CuCC was measured by using differential pulse anodic stripping voltammetry (DPASV) by direct titration of the sample with copper ions [34]. The value of CuCC, as well as the corresponding stability constant, was calculated by applying the linear transformation plot [34] (and references therein). The RSD of the mean value calculated for five independent measurements was below 10%.…”

“…The complexation of copper ions (CuCC) in rainwater obtained in 11 unfiltered samples varied between 48-370 nM (Figure S1 in Supplementary Materials) with apparent stability constants (log Kapp) in the range between 6.0 and 9.5. The complexation stability constant (log Kapp) can be used to compare the relative stability of the Cu complexes [34]. In the previous study conducted in Zagreb on other location, on the hill (northern part of Zagreb) surrounded by a forest, approximately 2 km (airline) from the city center, with low traffic, the CuCC was higher, up to 586 nM with stability constants, of up to 10 [22].…”

“…Quantification and characterization of the SAS in the atmospheric deposition are important for a better understanding of its contribution to organic carbon (OC) cycling.Complexation of OC with metal ions has a significant impact on mobility, solubility, and bioavailability of metals in precipitation and further in the aquatic environment [30][31][32][33][34][35][36].The organically complexed metals such as Cu, Co, Ni, Pb, Cd, and Zn have been observed in urban rainwater [32] (and references therein). Metal complexing capacity (MeCC) refers to the amount of OM present that can specifically bind metal ions, and it is often used as a parameter for qualitative and quantitative characterization of the OM in natural waters [32][33][34][35]. These investigations are usually focused on the complexation of Cu ligands [32][33][34][35] because the Cu ions have a strong affinity for naturally occurring organic ligands [32,33]…”

“…Complexation of OC with metal ions has a significant impact on mobility, solubility, and bioavailability of metals in precipitation and further in the aquatic environment [30][31][32][33][34][35][36].…”

“…The organically complexed metals such as Cu, Co, Ni, Pb, Cd, and Zn have been observed in urban rainwater [32] (and references therein). Metal complexing capacity (MeCC) refers to the amount of OM present that can specifically bind metal ions, and it is often used as a parameter for qualitative and quantitative characterization of the OM in natural waters [32][33][34][35]. These investigations are usually focused on the complexation of Cu ligands [32][33][34][35] because the Cu ions have a strong affinity for naturally occurring organic ligands [32,33]…”