What's wrong with the environment in Florida?

When Europeans first arrived in North America, South Florida was still very prosperous, with temperate pine forests, giant trees, riverbeds, swamps, wetlands, estuaries and bays, and wetlands dominated the topography of the region.

In the past 100 years, the area has experienced great man-made changes, mainly in the development of drainage and irrigation systems, and only some natural land and water sources have been reserved at the southern tip of the peninsula. In other natural systems, drainage and irrigation systems and human development seriously affect the environment, for example, leading to large-scale landslides and soil erosion, loss of wetland function, invasion of alien species, ecological degradation of delta and coast, and so on.

1. Loss of wetland function

The development of drainage irrigation system has seriously affected the wetlands in South Florida. Half of the original everglades have disappeared, about 897,000 hectares, and the grassland vegetation has lost 24%, about146,000 hectares. Due to the change of hydrological characteristics, many surviving wetlands are negatively affected by the increase of runoff. The increase of wetland drought frequency and the expansion of spatial scope reduce the output of food chain at all levels of wetland ecology. In addition, the change of hydrological characteristics of the wetland also deprived wading birds of their nests.

The disappearance of wetlands in South Florida has seriously affected the ecological environment and the survival of animals on a large spatial scale, for example, causing scattered fragments of ecological communities and ecological losses.

According to the statistics of the US Department of Fisheries and Wildlife, due to the lack of wetlands in South Florida, 18 species are endangered, and 12 species remain to be observed. The number of wading birds decreased from 2.5 million in 1.870 to 70,000 in 1.973, mainly due to the change of hydrological conditions.

Irrigation and human development increase the chances of invasive species, which usually compete with local species for growth.

In this area, centralized drainage irrigation and related agriculture in Okeecholee Hunan caused serious loss of organic soil function, and large-scale irrigation caused serious loss of organic soil.

2. Water quality

The water quality in South Florida is seriously affected by human activities. The water in urban and rural channels usually contains high concentrations of nutrients and toxic substances, which seriously damages the ecosystems of lakes, rivers, channels, estuaries, deltas and bays.

The deterioration of water quality was only discovered in recent years. Many water quality problems in the eastern industrial zone occur in urban canals, especially in the case of low flow. At this time, many canals are covered with algae and dirt, and sometimes with aquatic plants. This situation is mainly due to the discharge of sewage and storm runoff rich in nutrients, carrying pollutants such as bacteria, viruses, oils, toxic metals and pesticides. These degraded runoff will flow into coastal areas, groundwater or public water supply systems.

Rich dissolved oxygen in water is an important sign of good water quality, especially in urban areas. Because the decomposition of organic matter in sewage consumes a lot of dissolved oxygen, the growth of aquatic plants pollutes the canal, and the dissolved oxygen content is slightly higher during the day and almost zero at night. Therefore, in many urban canals, there are no fish that are good at swimming, and only some small fish that are resistant to hypoxia, such as loach, can grow.

Chlorine-containing chemicals such as polychlorinated biphenyls are produced in cities and industrial areas, which are extremely harmful to fish, wildlife and human health. Polychlorinated biphenyls (PCBs) are mainly used in industrial applications, such as transformers, plastic production, rubber, adhesives, inks, stabilizers, leak-proof agents and so on. Although the international community has banned the use of polychlorinated biphenyls since 1970, the lasting effect of this pollutant in the environment still exists until now, and chlorine pollution is also produced by burning harmful substances, drugs and solid pollutants, chemical manufacturing, plastic production, paper making and chlorine industry.

Polychlorinated biphenyls and other organic pollutants are widely distributed in South Florida, mainly through rain and airborne dust, but the density is the highest in industrial areas and urban areas. For example, fish in the water near Miami International Airport contains 65,438+0,000 micrograms of this organic pollutant per 65,438+0,000 grams. The concentration of organic pollutants in industrial areas will pollute groundwater, and then pollute people's drinking water safety.

The rapid urbanization in Florida and the agricultural development in low-lying areas along the eastern coast have caused organic pollution, such as fertilizers and pesticides, which will pose a threat to the quality of groundwater. However, due to the dilution of rainfall, the areas where the real pollution exceeds the standard are only concentrated in a few areas.