Which chemical compound is most commonly responsible for causing algal blooms and cultural eutrophication in streams?

• A. ammonium sulfate ((NH_4)_2SO_4)
• B. phosphate (PO_4^{3-})
• C. calcium carbonate (CaCO_3)
• D. sodium chloride (NaCl)

Answer: (B)

Verified step by step guidance

1. Understand that algal blooms and cultural eutrophication are primarily caused by an excess of nutrients in water bodies, which stimulate rapid algae growth.
2. Identify the key nutrients involved in eutrophication, which are mainly nitrogen and phosphorus compounds.
3. Recognize that while nitrogen compounds like ammonium sulfate can contribute, phosphorus, especially in the form of phosphate ions (\(PO_4^{3-}\)), is typically the limiting nutrient that most commonly triggers algal blooms in freshwater systems.
4. Note that compounds like calcium carbonate (\(CaCO_3\)) and sodium chloride (\(NaCl\)) do not provide nutrients that promote algal growth and thus are not responsible for eutrophication.
5. Conclude that phosphate (\(PO_4^{3-}\)) is the chemical compound most commonly responsible for causing algal blooms and cultural eutrophication in streams.