The researchers studied carbon pollution in Lake Dianchi, China, from 2003 to 2006. They looked at different types of carbon and how they impact the lake's pollution levels. By analyzing data, they found that carbon from city sewage affects the lake more than rural areas. They discovered a strong connection between carbon pollution and the growth of algae in the lake, leading to eutrophication, or excessive plant growth. This suggests that carbon pollution plays a big role in the lake becoming overly rich in nutrients and causing problems like algae blooms.