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Distribution and speciation of dissolved iron in Jiaozhou Bay (Yellow Sea, China)

Su, Han; Yang, Rujun; Pižeta, Ivanka; Omanović, Dario; Wang, Shirong; Li, Yan (2016) Distribution and speciation of dissolved iron in Jiaozhou Bay (Yellow Sea, China). Frontiers in Marine Science, 3 . pp. 1-17. ISSN 2296-7745

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Abstract

The distribution of total dissolved iron (DFe) and its chemical speciation were studied in vertical profiles of the shallow and semi-closed Jiaozhou Bay (JZB, China) during two contrasting periods: summer (July 19th, 2011) and spring (May 10th, 2012). Samples collected from the surface, middle and bottom layers were analyzed by competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-aCSV). The mean DFe concentration during the summer period (median 18.8 nM ; average 20.7 nM) was higher than in the spring period (median 12.4 nM ; average 16.9 nM), whereas the spatio-temporal variation in spring was larger than in summer. The DFe-values showed distinct regional and seasonal differences, ranging from 5.6 to 107 nM in spring period and 13.4 to 43.4 nM in summer period. In spring, the highest DFe-values were observed in the eastern coastal region, especially near an industrial area (up to 107 nM), whereas the DFe distribution in summer was relatively even. Due to a tide influence, the vertical variations in the DFe and Lt in both seasons were not significant. On average, the Lt concentration (one class of ligand was estimated in all samples), was higher in spring (35.2 ± 23.4 nM) than in summer (31.1 ± 10.3 nM). A statistically significant correlation was found between Lt and DFe concentrations, it was higher for the summer period than for the spring period. The conditional stability constants (logK′) of organic complexes with iron were weaker in spring (11.7 ± 0.3) than in summer (12.3 ± 0.3). The concentrations of Lt were higher in comparison to DFe in all samples: the average [Lt]/[DFe] ratio in the spring and summer samples was 2.4 and 1.5, respectively. Speciation calculations showed that the DFe in the JZB existed predominantly (over 99.99%) in the form of strong organic complexes in both seasons.

Item Type: Article
Additional Information: his work was financially supported by the National Science Foundation of China (all awarded to RY, 41140037, 41276069), the Young Scientist Award Science Foundation of Shandong, China (awarded to RY, BS2010HZ026), the Open Science Funding of the Key Lab of The First Institute of Oceanography, SOA (awarded to RY, MESE-2011-03), and the visiting scholar funding of the Key Laboratory of Physical Oceanography of Ministry of Education, China (awarded to Chunlei Fan). We acknowledge bilateral Chinese-Croatian project “Determination of trace metal speciation in coastal waters: toward developing new criteria for water quality control and risk assessment” (PI RY and IP), that enabled our collaboration. This work is also supported by the Croatian Science Foundation under the project number IP–2014–09–7530–MEBTRACE (PI DO)
Uncontrolled Keywords: dissolved iron; organic ligand; horizontal and vertical distribution; speciation, coastal water; the Jiaozhou Bay (JZB)
Subjects: NATURAL SCIENCES > Chemistry
Divisions: Division for Marine and Enviromental Research
Projects:
Project titleProject leaderProject codeProject type
Novi metodološki pristupbiogeokemijskim istraživanjima specijacije metala u tragovima u obalnim vodenim ekosustavima-MEBTRACEDario OmanovićIP-09-2014-7530HRZZ
Depositing User: Dario Omanović
Date Deposited: 19 Dec 2016 17:10
Last Modified: 19 Dec 2016 17:10
URI: http://fulir.irb.hr/id/eprint/3265
DOI: 10.3389/fmars.2016.00099

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