The demand for fresh water rises continuously as the world’s population grows. From 1940 to 1990 withdrawals of fresh water from rivers, lakes, reservoirs, and other sources increased fourfold. Sewage, industrial wastes, and agricultural chemicals such as fertilizers and pesticides are the main causes of water pollution. Erosion, the wearing away of topsoil by wind and rain, also contributes to water pollution. Soil and silt washed from logged hillsides, plowed fields, or construction sites, can clog waterways and kill aquatic vegetation. Even small amounts of silt can eliminate desirable fish species.
- withdrawal [wiðˈdrɔ:əl] n. & v. 提取，收回
- reservoir [ˈrezəvwɑ:] n. 贮水池，水库
- fourfold [fɔ: - fəuld] n. 四倍
- fertilizer [ˈfə:tilaizə] n.肥料
- pesticide [ˈpestisaid] n.杀虫剂
- erosion [iˈrəuʒən] n. 腐蚀，侵蚀(作用)
- silt [silt] n. 沙，淤泥
- logged [lɔɡd] adj. 低湿的，浸透的(土地)
- plow [plau] v. 犁；耕
- construction site [kənˈstrʌkʃən - sait] n. 建筑工地
- clog [klɔɡ] v. 阻塞，塞满
- aquatic [əˈkwætik] adj. 水生的，水栖的
- eliminate [iˈlimineit] v. 除去，消灭
