托福听力

🎧 听力原文

Listen to part of a lecture in an environmental science class. The professor is discussing the role of wetlands in flood control. "Now, many people think of wetlands as just swamps or marshes—places that are muddy and full of mosquitoes. But these ecosystems provide crucial services, especially when it comes to managing floodwaters. Wetlands act like natural sponges. During heavy rainfall, they absorb and slowly release water, which reduces the peak flow of rivers downstream. This can significantly lower the risk of flooding in nearby towns and cities. Moreover, wetlands also filter pollutants from the water. As water moves through the dense vegetation and soil, nutrients like nitrogen and phosphorus are taken up by plants, and sediment settles out. This improves water quality before it reaches lakes or oceans. However, over the past century, many wetlands have been drained for agriculture or urban development. Scientists estimate that we have lost more than half of the world's wetlands. This loss has increased flood severity and degraded water quality. So, preserving and restoring wetlands is not just about protecting wildlife—it's a smart investment in flood prevention and clean water."