Algal blooms are primarily caused by increases in which nutrients?

Algal blooms are primarily associated with increases in nitrogen and phosphorus. These nutrients act as fertilizers for algae, promoting rapid growth and proliferation in aquatic systems. When the levels of nitrogen and phosphorus in water bodies increase, often due to agricultural runoff, wastewater discharges, and other human activities, algal populations can explode, leading to blooms.

These blooms can have negative environmental impacts, including depleting oxygen in the water, blocking sunlight for submerged aquatic plants, and producing toxins harmful to aquatic life and humans. The specific combination of nitrogen and phosphorus is particularly effective in stimulating these growths, making them the primary nutrients of concern in the context of algal blooms.

The other options do not typically contribute to algal bloom events. Potassium and magnesium, while essential for plant growth, do not play a significant role in the excessive algal growth that characterizes blooms. Calcium and sodium are also not major contributors in this context. Furthermore, while carbon and sulfur are important nutrients in various biological processes, they do not directly lead to the proliferation of algae in the same way that nitrogen and phosphorus do.