Arsenic toxicity in the water weed Wolffia arrhiza measured using Pulse Amplitude Modulation Fluorometry (PAM) measurements of photosynthesis

作者：Ritchie Raymond J^*; Mekjinda Nutsara

来源：Ecotoxicology and Environmental Safety, 2016, 132: 178-185.

DOI：10.1016/j.ecoenv.2016.06.004

• Wolffia arrhiza
• PAM fluorometry
• Gross photosynthesis
• Phosphate
• Arsenic toxicity
• Rapid light curves

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 (Pg(max)) and not maximum yield (Y-max) 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(-3) when incubated in arsenic for 24 h. Arsenite toxicity was apparent after 1 h based on Pg(max), and gradually increased over 7 h but there was no apparent effect on Ymax or photosynthetic efficiency (alpha(0)).

• 出版日期2016-10