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Title: Arsenic toxicity in the water weed Wolffia arrhiza measured using Pulse Amplitude Modulation Fluorometry (PAM) measurements of photosynthesis
Authors: Raymond J. Ritchie
Nutsara Mekjinda
Prince of Songkla University
Mahidol University
Keywords: Environmental Science;Medicine
Issue Date: 1-Oct-2016
Citation: Ecotoxicology and Environmental Safety. Vol.132, (2016), 178-185
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).
ISSN: 10902414
Appears in Collections:Scopus 2016-2017

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