Question

question 11
2 pts
what is a primary sources for arsenic in water supply systems, including the source of arsenic in bangladesh that was responsible for the \largest mass poisoning of a population in history?\
oil spills
sewage waste
rainfall and flooding events
natural weathering of arsenic - rich minerals in aquifer material

question 12
2 pts
in the u.s., more than 40,000 water bodies are considered to be \impaired\. what does this mean? select all that apply.
they are blocked by dams
they are subject to alcohol poisoning
they do not meet water quality standards
they cannot support a healthy ecosystem

Explanation:

For Question 11:

• Oil spills mainly introduce hydrocarbons and other petroleum - related contaminants, not arsenic.
• Sewage waste contains organic matter, pathogens, and nutrients like nitrogen and phosphorus, not arsenic as a primary contaminant.
• Rainfall and flooding events can mobilize contaminants, but they are not the primary source of arsenic in aquifers.
• Natural weathering of arsenic - rich minerals in aquifer material is a well - known source of arsenic in water supplies, and this was the case in the Bangladesh arsenic crisis.

For Question 12:

• "Impaired" water bodies in the context of water quality do not refer to being blocked by dams. Dams are a structural feature, not a water - quality - based impairment.
• Alcohol poisoning is not a standard term for water - body impairment.
• Water bodies are considered impaired when they do not meet water quality standards (e.g., for drinking water, aquatic life support, etc.).
• If a water body does not meet water quality standards, it often cannot support a healthy ecosystem (e.g., due to excessive pollution, low oxygen levels from nutrient over - enrichment).

Answer:

Question 11: natural weathering of arsenic - rich minerals in aquifer material
Question 12: they do not meet water quality standards, they cannot support a healthy ecosystem