Response of the Cu(II) Ion Selective Electrode to Cu Titration in Artificial and Natural Shore Seawater and in the Measurement of the Cu Complexation Capacity

• Published in: Environmental science & technology 2004-06, Vol.38 (11), p.3139-3147
• Main Authors: Rivera-Duarte, Ignacio, Zirino, Alberto
• Format: Article
• Language: English
• Subjects: Analysis methods; Animals; Applied sciences; Biological Assay; Bivalvia; Copper; Copper - analysis; Copper - chemistry; Copper - toxicity; Earth sciences; Earth, ocean, space; Electrochemistry; Electrodes; Engineering and environment geology. Geothermics; Environmental Monitoring - methods; Environmental science; Exact sciences and technology; Ions - chemistry; Natural water pollution; Pollution; Pollution, environment geology; Seawater; Seawater - chemistry; Water Pollutants - analysis; Water Pollutants - toxicity; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es030118q

The Orion 94-29 Cu(II) jalpaite ion selective electrode (Cu−ISE) was used to measure both the concentration of the aqueous free Cu(II) ion ([Cu(II)aq]) and its changes due to additions of Cu, in artificial seawater (ASW) and in seawater from San Diego Bay, CA. The range of free copper ion (i.e., pCu, −log [Cu(II)aq]) determined in seawater samples from the San Diego Bay area (11.3−12.6, 11.9 ± 0.4, average ± SD) is consistent with that previously reported for estuarine and coastal areas (10.9−14.1). The changes in [Cu(II)aq] as a result of the additions of Cu were used to determine the Cu complexation capacity (Cu−CC), which has a measured range (2.7 × 10-8−2.0 × 10-7 M; 7.6 × 10-8 ± 4.8 × 10-8 M) comparable to the range of values previously reported for estuarine and coastal zones (i.e., L1+L2, 1.1 × 10-8−2.0 × 10-7 M). The narrow range of pCu at the Cu−CC (pCuCu - CC, 11.1−11.9, 11.5 ± 0.2) indicates the predominant role of the Cu−CC in regulating the concentration of ambient Cu(II)aq to a level ≤1 × 10-11 M Cu(II) aq. These results attest to the capability of the Cu−ISE to measure pCu and Cu−CC in aquatic coastal environments with relatively high total Cu concentrations and organic loads, such as those from heavily used coasts and bays.