What is a major effect of nitrogen oxides on lakes?

Nitrogen oxides, particularly from vehicle emissions and industrial processes, play a significant role in acidifying lakes. When nitrogen oxides enter the atmosphere, they can combine with water vapor to form nitric acid. This acid then falls to the surface, either directly or through precipitation (acid rain), leading to a decrease in the pH of the lake water. As the acidity of the water increases, it can have detrimental effects on aquatic life, including fish and invertebrate populations, disrupting the entire ecosystem. Acidification can impair the ability of organisms to reproduce, grow, and survive, leading to a decline in biodiversity within the lake.

The other options, while related to environmental issues, do not directly correlate with the primary effects of nitrogen oxides on lakes. Increased temperature can occur due to climate change but is not a direct result of nitrogen oxides. Decreased oxygen levels may relate to various factors, particularly organic pollution, but are not primarily linked to nitrogen oxides. Algal blooms can be caused by excess nutrients like phosphorus, but nitrogen oxides primarily contribute to acidification rather than directly fostering algal growth. Thus, acidification stands out as the major effect of nitrogen oxides on lakes.