Selenium Flashcards
Facts on Selenium and water quality
What is an example of natural source of selenium?
Common in rocks and soil. Includes cretaceous marine sedimentary rocks, coal and other fossil fuel deposits.
Examples of anthropogenic sources causes of selenium in surface waters?
- Coal ash from coal-fired power plants
- Irrigation waters from seleniferous soils
- Wastewater from some industrial processes
What are some of the toxic effects of selenium on aquatic biota?
- Mortality
- Deformities
- Reproductive failure
- Reduced growth
- Gill damage
Where can selenium accumulate in surface water?
In sediments and lower trophic levels (e.g., algae and invertebrates) which in turn are consumed by organisms at higher trophic levels (e.g., fish).
How do fish uptake selenium?
Directly from the water across the gills and across the gut from their diet.
How does selenium taken up across the gills different from gut?
Selenium taken up across the gills is thought to be inorganic, either as selenite or selenate. Uptake from the diet is most likely in an organic form, where selenium has substituted for sulfur in the sulfur containing amino acids, such as seleno-methionine.
Which form of selenium has the higher bioaccumulation factor>
The organic form, seleno-methionine
Not a question just a review:
What is the British Columbia guideline for fish-egg-ovary for selenium?
11 ug/g dry weight (2014)
When does toxicity to fish occur with selenium?
Only slightly above the essential requirement.
When are fish most susceptible to selenium toxicity?
Egg and larval stage
What wildlife is the most sensitive to selenium and is often used as an indicator species?
Fish tissue.
How does exposure to selenium in fish during the larval stage occur?
Through maternal transfer to the eggs and yolk sac absorption.
What are the most common effects observed in early life stages of fish?
- Reduced hatching
- Teratogenicity (deformities)
- Edema
