Interactions between copper(II) and DOM in the urban stormwater runoff: modeling and characterizations

ABSTRACT

Dissolved organic matter (DOM) can strongly interact with both organic and inorganic contaminants to influence their transportation, transformation, bioavailability, toxicity and even their ultimate fate. Within this work, DOM was extracted from urban stormwater runoff samples collected from a regular sampling site of a typical residential area in Beijing, China. Copper(II) ions were selected as model to investigate the interactions between DOM and typical heavy metals. Both ultraviolet (UV) absorbance and fluorescence titration methods were introduced to determine the complex capacities (C_L) and conditional stability constants (log K_M) of bonding between DOM and copper (II) ions, which revealed that the values of C_L were 85.62 and 87.23 μmol mg⁻¹ and the log K_M values were 5.37 and 5.48, respectively. The results suggested the successful complexation between DOM and copper(II) ions. Furthermore, morphology of the DOM binding to copper(II) ions was confirmed by both energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS), which can facilitate to clarify the corresponding mechanism. The Cu 2p_3/2 peak at 933.7 eV and the characteristic shake-up peaks of Cu–O were found in the XPS spectra, implying that copper(II) ions might coordinate with hydroxyl (aliphatic or phenolic) or carboxyl groups. With these profitable results, it can be concluded that DOM in urban stormwater runoff has a strong binding affinity with copper(II) ions, which may further lead to potentially significant influence on their migration and transformation.

KEYWORDS:

• Stormwater runoff
• dissolved organic matter
• copper ions
• titration
• interaction mechanism

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Chong-Chen Wang http://orcid.org/0000-0001-6033-7076

Additional information

Funding

We thank the financial support from the Beijing Municipal Natural Science Foundation [grant number 8152013], the Importation & Development of High-Caliber Talents Project of Beijing Municipal Institutions [CIT&CD201404076], and National Natural Science Foundation of China [No. 51478026].