Explain how coastal upwelling and riverine inputs interact to shape biogeochemical cycles, focusing on nutrient spiraling.

• A. Upwelling supplies inorganic nutrients; rivers deliver organic matter and nutrients; along the flow, phytoplankton uptake, bacterial remineralization, and denitrification create nutrient spirals; these processes enhance productivity in coastal systems.
• B. Upwelling and rivers cancel each other's effects on nutrients
• C. Nutrient spiraling occurs only in freshwater systems
• D. Rivers remove nutrients from coastal waters

Answer: (A)