Phytoremediation of heavy metals by calcifying macro-algae (Nitella pseudoflabellata): Implications of redox insensitive end products

• Published in: Chemosphere (Oxford) Vol. 92; no. 10; pp. 1328 - 1334
• Main Authors: Gomes, Pattiyage I.A., Asaeda, Takashi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-08-2013; Elsevier
• Subjects: Applied sciences; bioaccumulation; Biodegradation, Environmental; Cadmium; Cadmium - isolation & purification; Cadmium - metabolism; calcification; Carbonate bound; Charophyceae - metabolism; Charophytes; Chromium; Chromium - isolation & purification; Chromium - metabolism; Continental surface waters; Exact sciences and technology; heavy metals; Metals, Heavy - isolation & purification; Metals, Heavy - metabolism; Natural water pollution; Nitella; Oxidation-Reduction; Phytoremediation; Pollution; sediments; senescence; Water Pollutants, Chemical - isolation & purification; Water Pollutants, Chemical - metabolism; Water treatment and pollution; Chromium; Cadmium; Charophytes; Carbonate bound; Phytoremediation; Algae; Reaction product; Transition metal; Time variation; Heavy metal; Freshwater environment; Trace element; Decontamination; Charophyta; Calcification; Carbonation; Water pollution; Bioremediation; Biological accumulation
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2013.05.043

[Display omitted]
•Charophytes to form redox insensitive end products in phytoremediation was studied.•Heavy metal accumulation in alkaline to acidic areas was with a split >1:1.•This elucidate an association between calcification and heavy metal accumulation.•Validated by showing greater fraction of carbonate-bound heavy metals in sediment.
To evaluate the phytoremediation of heavy metals in water and understand the biochemistry of end products of calcifying macro algae (charophytes), an 84-wk laboratory experiment was conducted. Eighteen microcosms were maintained with and without plants. These were given different heavy metal treatments: no heavy metals, 0.2mgL−1 Cr6+ and 0.01mgL−1 Cd. Accumulation observed to be 0.06% Cr by dry weight and for Cd it was 0.02%. The bioconcentration factors were 3000 and 25000 for Cr and Cd, respectively. Ratios of heavy metal accumulation in alkaline (i.e., calcified areas) to acidic areas of plants were 6 to 4 (for Cr) and 1 to 1 (for Cd). This elucidated an association between heavy metal accumulation and calcification. This was validated by sequential extraction of sediments. It was shown that in microcosms with plants, the heavy metals were mainly in redox insensitive and less bioavailable carbonate bound form (39–47%). This was followed by organic-bound form (23–34%). Carbonate bound end products will ensure long term storage of heavy metals and after plant senescence these will not re-enter the water column.