7 Heavy Metal Toxicity to Algae
The heavy metal concentration beyond a threshold limit causes direct toxicity to the
algae moreover algae are highly sensitive to environmental changes or fluctuation as
a result changes take place in their metabolism (Kaplan 2013). Toxic effects of heavy
metals on algae caused by many ways such as the displacement or removing of
essential metal ions from biomolecules, functional cellular units, inhibiting functional groups of biologically useful molecules, induction of cellular generation of
reactive oxygen species, and inactivation of enzymes as well as disruption the
integrity of cellular and organelle membrane (Fig. 13.3) (Naorbe and Serrano
2018). Also, found that some heavy metals blocking or inhibiting cell division,
inhibit or block the DNA repair mechanisms, attack nucleic acid molecules, promote
free radical chain reaction, disturbing thylakoid membrane, inhibit or block pigments
synthesis reduction in photosynthetic electron transport, inhibit CO 2 fixation,
blocking of respiratory oxygen consumption, inhibition of enzyme activity, blocking
of protein synthesis, abnormal morphological development, impairment of motility
in certain microalgae and an irreversible increase in plasmalemma permeability,
leading to the loss of cell and changes in cell volume (Liu et al. 2016; Shilpi et al.
2014; Szivák et al. 2009).
Table 13.1 Algal biomass used for removal of heavy metals
Microalgae
Heavy
metals
Removal
(%)
References
Scenedesmus obliquus
Cd
100
Chen et al. (2012)
Botryococcus sp.
Cr
94
Onalo et al. (2014)
As
9
Lyngbya
Pb
80
Pseudopediastrum boryanum Cr
70
Sutkowy and Kłosowski (2018)
Desmodesmus multivariabilis Tl
94.04
Birungi and Chirwa (2018)
Macroalgae
Ulva lactuca
Cd
99.2
Ghoneim et al. (2014)
Pb, Cd
85
Ibrahim et al. (2018)
Ulva lactuca
Cd, Pb & Cr 83
Ibrahim et al. (2016)
Jania rubens
Hg
54–71
Anastopoulos and Kyzas (2015)
Sphaerococcus
coronopifolius
Hg
70–90
Jania rubens
Pb, Cd & Ni 91
Ibrahim et al. (2018)
Palmaria palmate
Pb
100
Prasher et al. (2004)
Pelvetia canaliculata
Cr
100
Hackbarth et al. (2016)
Sargassum myriocystum
Pb
86.67
Anastopoulos and Kyzas (2015)
Azolla filiculoides
Cr
83.34
274
A. Ayele et al.
The heavy metal concentration beyond a threshold limit causes direct toxicity to the
algae moreover algae are highly sensitive to environmental changes or fluctuation as
a result changes take place in their metabolism (Kaplan 2013). Toxic effects of heavy
metals on algae caused by many ways such as the displacement or removing of
essential metal ions from biomolecules, functional cellular units, inhibiting functional groups of biologically useful molecules, induction of cellular generation of
reactive oxygen species, and inactivation of enzymes as well as disruption the
integrity of cellular and organelle membrane (Fig. 13.3) (Naorbe and Serrano
2018). Also, found that some heavy metals blocking or inhibiting cell division,
inhibit or block the DNA repair mechanisms, attack nucleic acid molecules, promote
free radical chain reaction, disturbing thylakoid membrane, inhibit or block pigments
synthesis reduction in photosynthetic electron transport, inhibit CO 2 fixation,
blocking of respiratory oxygen consumption, inhibition of enzyme activity, blocking
of protein synthesis, abnormal morphological development, impairment of motility
in certain microalgae and an irreversible increase in plasmalemma permeability,
leading to the loss of cell and changes in cell volume (Liu et al. 2016; Shilpi et al.
2014; Szivák et al. 2009).
Table 13.1 Algal biomass used for removal of heavy metals
Microalgae
Heavy
metals
Removal
(%)
References
Scenedesmus obliquus
Cd
100
Chen et al. (2012)
Botryococcus sp.
Cr
94
Onalo et al. (2014)
As
9
Lyngbya
Pb
80
Pseudopediastrum boryanum Cr
70
Sutkowy and Kłosowski (2018)
Desmodesmus multivariabilis Tl
94.04
Birungi and Chirwa (2018)
Macroalgae
Ulva lactuca
Cd
99.2
Ghoneim et al. (2014)
Pb, Cd
85
Ibrahim et al. (2018)
Ulva lactuca
Cd, Pb & Cr 83
Ibrahim et al. (2016)
Jania rubens
Hg
54–71
Anastopoulos and Kyzas (2015)
Sphaerococcus
coronopifolius
Hg
70–90
Jania rubens
Pb, Cd & Ni 91
Ibrahim et al. (2018)
Palmaria palmate
Pb
100
Prasher et al. (2004)
Pelvetia canaliculata
Cr
100
Hackbarth et al. (2016)
Sargassum myriocystum
Pb
86.67
Anastopoulos and Kyzas (2015)
Azolla filiculoides
Cr
83.34
274
A. Ayele et al.