关键词：农药；硝酸盐；水质污染；湖泊；地下水
摘 要：The landscape, hydrology, and ecology of Lake Wales Ridge, central Florida, are unique in many respects. The Ridge is the highest and most prominent topographic feature in peninsular Florida and contains one of the largest collections of rare and endangered species in the United States (Dobson and others, 1997), one of the highest concentrations of endemic species in North America (Martin, 1998), and more than 200 lakes, most of which are seepage lakes with significant ground-water inflow. Lake Wales Ridge (subsequently referred to as the Ridge) is also one of the most intensely cultivated citrus regions in the world, with citrus groves covering about 25 percent (170 square miles) of the land area. Geologically, the Ridge is underlain by highly permeable marine sands forming relict Miocene-Holocene paleoislands which support some of the oldest ecologic communities in Florida. Ground water and surface water are closely linked in this region where ground-water inflow contributes more than 80 percent of the net water input to some lakes (Sacks and others, 1998). Ground water is the primary drinking-water supply in this region. The unconfined surficial aquifer supplies drinking water for some rural wells, and recharges water to the underlying Upper Floridan aquifer which is the primary municipal water supply.