Removal of Zinc from Tidal Water by Sediments of a Mangrove Ecosystem: A Radiotracer Study

• Published in: Water, air, and soil pollution Vol. 192; no. 1-4; pp. 77 - 83
• Main Authors: Machado, E. C, Machado, W, Bellido, L. F, Patchineelam, S. R, Bellido, A. V. B
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.07.2008; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: Applied sciences; Atmospheric Protection/Air Quality Control/Air Pollution; Biological and physicochemical properties of pollutants. Interaction in the soil; Brackish; Climate Change/Climate Change Impacts; Collisions; Cores; Creeks; Earth and Environmental Science; Earth sciences; Earth, ocean, space; Ecosystems; Engineering and environment geology. Geothermics; Environment; Environmental monitoring; estuarine sediments; Exact sciences and technology; Experiments; extraction; Floods; Heavy metals; Hydrogeology; Laboratories; mangrove forests; Mangrove swamps; Mangroves; Metals; Natural water pollution; Oxidation; Pollution; Pollution, environment geology; Radioactive tracers; radiolabeling; Seawaters, estuaries; Sediment transport; Sediment-water interface; Sediments; Soil and sediments pollution; Soil Science & Conservation; Studies; Tidewater; Trace metals; water pollution; Water Quality/Water Pollution; Water treatment and pollution; Zinc; Brazil; South America; America; ASW, Brazil, Rio de Janeiro, Sepetiba Bay; Flux; Kinetics; Zn; Radiotracer; Mangrove sediments; Zinc; Sediment water interaction; Zinc 65; Pollutant behavior; Radioactive tracers; 65Zn; Coastal zone; Heavy metal; Trace element; Mangrove; Water pollution
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-008-9636-9

The removal of ⁶⁵Zn from tidal water by underlaying sediment cores collected in a mangrove forest and a tidal creek that drains this forest in Sepetiba Bay (SE Brazil) was investigated. After 30-h experiments in laboratory microcosms, the ⁶⁵Zn half-removal times from tidal creek and mangrove forest sediments were 8.7 ± 1.8 and 9.2 ± 0.9 h respectively. Depth penetration of ⁶⁵Zn was mainly restricted to the upper 3 cm in mangrove forest cores, while detectable ⁶⁵Zn activities were found in all layers (0-7 cm depth) of tidal creek cores. An unexpected ⁶⁵Zn release back to the overlaying water was observed for one of the tidal creek experiments in the 12-18 h interval (corresponding to a return of 17% of the initial ⁶⁵Zn activity in overlaying water), suggesting a reversibility of the ⁶⁵Zn removal process (e.g., by adsorption) in tidal creek sediments. The results indicate that mangrove-vegetated sediments allowed a lower vertical mobility of Zn than observed in creek sediments and mangrove sediments appear to be less susceptible to a reversion in the process of zinc removal from overlaying water, suggesting a greater capacity to retain this metal near the water-sediment interface. This first radiotracer approach on the mangrove sediments removal of Zn from tidal waters supports earlier experimental studies employing stable Zn, contributing for a better understanding of the metal uptake kinetics by such sediments and suggesting that these sediments act as active sinks for trace metals.