Ruangsomboon, Suneerat

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Bioaccumulation of cadmium in an experimental aquatic food chain involving phytoplankton (Chlorella vulgaris), zooplankton (Moina macrocopa), and the predatory catfish Clarias macrocephalus × C. gariepinus
(2006-06-10)
Ruangsomboon, Suneerat
;
Wongrat, Ladda
The accumulation of cadmium (Cd) was studied in an experimental aquatic food chain involving the phytoplankton Chlorella vulgaris as the primary producer, the zooplankton Moina macrocopa as the primary consumer, and the catfish Clarias macrocephalus × Clarias gariepinus as the secondary consumer. C. vulgaris was first exposed to Cd solutions at 0.00, 0.35, and 3.50 mg l-1, referred to as control group and experimental groups 1 and 2, respectively. Subsequently, each group was fed to three corresponding groups of M. macrocopa. Finally, three groups of catfish were fed these corresponding groups of M. macrocopa. After C. vulgaris was exposed to 3.50 mg l-1 Cd (experimental group 2), the residual Cd in solution was only 4.01 μg l-1, lower than the maximum allowable limit of Cd in natural water sources (5 μg l-1). Cd concentrations in C. vulgaris were 0.01 ± 0.00 μg g-1 (dry wt) in the control group, 194 ± 1.80 μg g-1 (dry wt) in experimental group 1, and 1140 ± 20.06 μg g-1 (dry wt) in experimental group 2. The Cd concentrations in M. macrocopa were 0.01 ± 0.00 μg g-1 (dry wt) in the control group, 16.48 ± 2.23 μg g-1 (dry wt) in experimental group 1, and 56.6 ± 3.23 μg g-1 (dry wt) in experimental group 2. The Cd concentrations in catfish muscle increased with increasing Cd concentrations in the food. After 60 days of fish culture, the mean concentrations of Cd in fish muscle were 0.01 ± 0.00 μg g-1 (dry wt) in the control group, 0.61 ± 0.02 μg g-1 (dry wt) in experimental group 1 and 1.04 ± 0.06 μg g-1 (dry wt) in experimental group 2. Cd concentration in fish muscle of experimental group 2 was equal to the permissible limit. Cd accumulation affected fish growth: at the end of the study, the mean fresh weight (12.81 g) of catfish in the control group, was significantly higher than those experimental group 1 (10.43 g) and experimental group 2 (10.00 g). The results showed that the measurement of Cd concentration in water does not necessarily give a measure of the safety of aquatic organisms as human food. Hence, heavy metal contamination is a matter for concern when organisms are harvested, for fish and human consumption, from natural water sources. © 2006 Elsevier B.V. All rights reserved.
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Effects of low pH and Pb2+ stress on living cyanobacterium, Phormidium angustissimum West & G.S.West: A test of its feasibility as a living biosorbent
(2013-06-01)
Ruangsomboon, Suneerat
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Wongrat, Ladda
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Choochote, Sakchai
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Ganmanee, Monthon
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Saparnklang, Atiya
Pb2+ adsorption by the living cyanobacterium, Phormidium angustissimum followed the Langmuir adsorption model, with the maximum adsorption capacity (q <inf>max</inf>) of 295.4 ± 13.8 mg g-1. This result suggests that P. angustissimum is a promising living biosorbent to remove Pb2+ from wastewaters. Living biosorbents are better able to remove Pb2+ from wastewater than dead biosorbents, however there are practical limitations for their use are encountered in extreme conditions such as low pH and high Pb2+ concentration. The feasibility of using cyanobacterium, P. angustissimum, as a living biosorbent for the extraction of Pb2+ from wastewater was studied by investigating its photosynthestic performance and tolerance under Pb2+ (0-5 mg L-1) contamination and low pH (pH 3-7). Decreased photosynthetic performance caused by Pb2+ contamination and low pH stress was detected in this study by means of a reduction of the maximum photochemical efficiency of PSII (F<inf>v</inf>/F<inf>m</inf>). Detoxification mechanisms of P. angustissimum on Pb2+ appeared to increase its intracellular polysaccharides (IPS), exocellular polysaccharides (EPS), and protein. Living P. angustissimum could increase the pH of the solution which resulted in Pb2+ precipitation. The unique ability of P. angustissimum to remove Pb2+ and to grow under toxic conditions, demonstrated herein, indicates that it is a promising living biosorbent for mildly acidic water contaminated with Pb2+ in bioremoval systems in the which pH is not lower than 5 and Pb2+ is not higher than 5 mg L-1. © 2013 Springer Science+Business Media Dordrecht.

Ruangsomboon, Suneerat

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