美国密西西比河三角洲湿地流失的原因及修复措施

WETLAND LOSS IN MISSISSIPPI RIVER DELTA COMPLEX:CAUSES AND REMEDIATION

密西西比河三角洲是世界上最大的三角洲，包括1．2万km。海岸湿地，是一个重要的生态区。然而，近年来密西西比河三角洲湿地不断流失，从20世纪30年代至90年代，已经流失了3950km2，流失速率达65～91km2／a，对沿岸城市的生态环境和经济发展造成了巨大的负面影响，专家预测，到2050年湿地流失面积将达到1833km2。造成湿地流失的主要原因有三角洲循环、相对海平面上升、海水入侵、地面沉降、大规模的冬季风暴和飓风袭击、啮齿类食苹动物对湿地的破坏及履带车的使用等。为减缓湿地流失速度，恢复湿地生态环境，可采取分流河道引入淡水、种植湿地植物、补充泥沙及恢复障壁岛等措施。

The Mississippi River Delta is the largest in the world. It is a significant ecological region in the US, including 12,000 km2 of coastal wetlands. However, during the period from the 1930s to 90s, the wetlands at coastal Louisiana had lost a total of 3950 square miles at a rate of 65~91 square miles per year. Some scientists forecast that the wetlands of coastal Louisiana will loss 1833 square miles more up to 2050. The reasons of wetland loss are complicated and vary from place to place, such as deltaic cycles, seawater intrusion, land subsidence, sea level rise, large scale winter storm and hur- ricane, the deterioration by rodents and use of tracklaying vehicles. A lot can be done to restore the wetland, such as building freshwater diversion system, planting superior plants and sand nourishment for rebuilding of barrier systems.