Publication: Arsenic toxicity in the water weed Wolffia arrhiza measured using Pulse Amplitude Modulation Fluorometry (PAM) measurements of photosynthesis
Issued Date
2016-10-01
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ISSN
10902414
01476513
01476513
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2-s2.0-84974777811
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Mahidol University
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SCOPUS
Bibliographic Citation
Ecotoxicology and Environmental Safety. Vol.132, (2016), 178-185
Suggested Citation
Raymond J. Ritchie, Nutsara Mekjinda Arsenic toxicity in the water weed Wolffia arrhiza measured using Pulse Amplitude Modulation Fluorometry (PAM) measurements of photosynthesis. Ecotoxicology and Environmental Safety. Vol.132, (2016), 178-185. doi:10.1016/j.ecoenv.2016.06.004 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/40650
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Title
Arsenic toxicity in the water weed Wolffia arrhiza measured using Pulse Amplitude Modulation Fluorometry (PAM) measurements of photosynthesis
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Abstract
© 2016 Elsevier Inc. Accumulation of arsenic in plants is a serious South-east Asian environmental problem. Photosynthesis in the small aquatic angiosperm Wolffia arrhiza is very sensitive to arsenic toxicity, particularly in water below pH 7 where arsenite (As (OH)3) (AsIII) is the dominant form; at pH >7 AsO42-(As(V) predominates). A blue-diode PAM (Pulse Amplitude Fluorometer) machine was used to monitor photosynthesis in Wolffia. Maximum gross photosynthesis (Pgmax) and not maximum yield (Ymax) is the most reliable indicator of arsenic toxicity. The toxicity of arsenite As(III) and arsenate (H2AsO42-) As(V) vary with pH. As(V) was less toxic than As(III) at both pH 5 and pH 8 but both forms of arsenic were toxic (>90% inhibition) at below 0.1 mol m-3when incubated in arsenic for 24 h. Arsenite toxicity was apparent after 1 h based on Pgmaxand gradually increased over 7 h but there was no apparent effect on Ymaxor photosynthetic efficiency (α0).