The onset of anthracene phototoxicity to Lemna gibba and the protective effects of humic acid

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:37500

Gensemer, R W ^[1]; Dixon, D G; Greenberg, B M ^[2]

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1. Univ. of Guelph, Ontario (Canada)
2. Univ. of Waterloo, Ontario (Canada)

The toxicity of anthracene to the freshwater duckweed Lemna gibba is strongly photo-induced in the presence of light containing natural levels of ultraviolet (UV) radiation. This was demonstrated using 8-day static renewal bioassays at an anthracene concentration of 2 mg-L{sup {minus}1}. Plants were incubated under simulated solar radiation (SSR) which mimics UV levels found in natural sunlight at a visible:UV-A:UV-B ratio of 100:10:1. Anthracene phototoxicity was expressed as inhibition of population growth and fluorescence induction decreases in chlorophyll content, and changes in low-temperature chlorophyll fluorescence emission scans. Furthermore, adding 6.2 mg-L-1 of an artificial humic acid ameliorated anthracene phototoxicity even though HA is also photo modified by UV light. However, anthracene inhibited photosynthesis days before the endpoint assays were performed. Therefore, the authors repeated these experiments at short time intervals following exposure to both light and chemical. Anthracene phototoxicity occurred after only 1 hour as detected by chlorophyll fluorescence induction, whereas chlorophyll contents and low-temperature fluorescence emission scans were not affected until 24--48 hours, respectively. Humic acid again ameliorated anthracene toxicity by delaying the negative physiological events by approximately 24 hours.

• OSTI ID: 37500
• Report Number(s): CONF-9410273--
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
ANTHRACENE
AQUATIC ORGANISMS
BIOLOGICAL EFFECTS
HUMIC ACIDS
PHOTOCHEMICAL REACTIONS
PLANTS
SENSITIVITY
TOXICITY