The coastal dune system in Lençóis Maranhenses National Park in northeastern Brazil is among the most surreal landscapes on Earth. At first glance, the park looks like a desert, but it is far from it. This place receives about 125 centimeters (50 inches) of rain per year—slightly more than Seattle and double what falls in London.
巴西东北部伦索伊斯马拉尼塞斯国家公园的沿海沙丘系统是地球上最超现实的景观之一。乍一看，公园就像一片沙漠，但又远非沙漠。这个地方每年的降雨量约为 125 厘米（50 英寸），略高于西雅图，是伦敦的两倍。
The result is a paradox: rows of sparkling white quartz dunes, some rising 30 meters (100 feet), soar over a mosaic of blue and green freshwater lagoons. The park’s name stems from the Portuguese word lençóis , meaning “bedsheets,” a reference that makes the most sense when the park is viewed from afar. From that perspective, the sweeping curves of the largest coastal dune field in South America resemble a rumpled, white bedsheet.
其结果是一个悖论：一排排闪闪发光的白色石英沙丘，有些高达 30 米（100 英尺），高耸在蓝绿色淡水泻湖的上方。该公园的名字源于葡萄牙语单词 lençóis ，意思是“床单”，当从远处观看公园时，这个参考意义最有意义。从这个角度来看，南美洲最大的沿海沙丘场的连绵曲线就像一张皱巴巴的白色床单。
These Landsat 9 images were captured in June 2026, around the time when lagoon water levels typically peak. The partially impermeable layer of bedrock and clay beneath the sand prevents the lagoons from draining during the wet season. However, as rains subside between August and November, the water table falls, and by December, most of the lagoons dry up.
这些 Landsat 9 图像于 2026 年 6 月拍摄，当时正是泻湖水位通常达到峰值的时间。沙子下面的部分不透水的基岩和粘土层可防止泻湖在雨季排水。然而，随着 8 月至 11 月期间降雨减少，地下水位下降，到 12 月，大部分泻湖干涸。
The dune field, a tan area within an expanse of green, is the centerpiece of the park. It spans about 900 square kilometers (350 square miles), roughly the size of New York City. From above, shallower lagoons appear light blue, often taking on turquoise or aquamarine hues as sunlight reflects off the sand below. Deeper lagoons are darker, a result of the deeper water absorbing more red, yellow, and green wavelengths, leaving mostly blue light to scatter back. Suspended sediment , microscopic algae, and dissolved organic matter also contribute to the array of colors, giving some lagoons greener and browner tones.
沙丘场是一大片绿色中的棕褐色区域，是公园的中心。它占地约 900 平方公里（350 平方英里），大致相当于纽约市的大小。从上方看，较浅的泻湖呈浅蓝色，当阳光从下面的沙子反射时，通常呈现绿松石色或海蓝宝石色。较深的泻湖颜色较深，这是因为较深的水吸收了更多的红色、黄色和绿色波长，而大部分蓝光被散射回来。悬浮沉积物、微小藻类和溶解的有机物也对颜色的排列做出了贡献，使一些泻湖呈现出更绿色和更棕色的色调。
Green vegetation surrounds the dune field, which sits at the intersection of three Brazilian biomes : the Amazon rainforest to the west, the tropical wooded savannas of the Cerrado to the south, and the dry shrublands and thorn forests of the Caatinga to the east. Closest to the dunes are mangroves and restinga forests , ecosystems well adapted to sandy, coastal soils.
沙丘地周围环绕着绿色植被，沙丘地处巴西三个生物群落的交汇处：西边的亚马逊雨林、南边塞拉多的热带稀树草原、以及东边卡廷加的干燥灌木丛和荆棘林。最靠近沙丘的是红树林和雷斯汀加森林，这些生态系统非常适合沙质沿海土壤。
The dune field exists because of the rare convergence of geologic and climatic conditions. Rivers, including the Mearim and Parnaíba, deliver the key ingredient—quartz sand—to this unusually flat portion of the Maranhão coastline in massive quantities. It has accumulated here over the past few hundred thousand years driven in part by fluctuating sea levels and shoreline transgression and regression . Persistent easterly trade winds have also played a critical role. During the dry season, winds often reach at least 50 kilometers per hour, fast enough to build the dunes and push them westward at a pace of roughly 4 to 25 meters per year. That is fast for sand dunes, though not the fastest in the world. Satellites have tracked small barchan dunes in Namibia’s Sperrgebiet region moving at rates exceeding 80 meters per year.
沙丘场的存在是因为地质和气候条件罕见的融合。包括米里姆河和帕尔纳伊巴河在内的河流将大量的关键成分——石英砂——输送到马拉尼昂州海岸线这片异常平坦的地区。在过去的几十万年里，它在这里积累起来，部分原因是海平面波动和海岸线海侵和退缩。持续的东风信风也发挥了关键作用。在旱季，风速通常至少达到每小时 50 公里，足以建造沙丘并将其以每年约 4 至 25 米的速度向西推。这对于沙丘来说已经是很快的速度了，尽管不是世界上最快的。卫星追踪到纳米比亚 Sperrgebiet 地区的小新月形沙丘每年移动超过 80 米。
Landsat images, meanwhile, show the dune field at Lençóis Maranhenses has extended westward by about 0.5 kilometers between 1986 and 2026 in some areas due to the conveyor belt of dunes running inland from the coastline. The nearly constant movement of sand prevents vegetation from becoming established across much of the dune field.
与此同时，陆地卫星图像显示，1986 年至 2026 年间，由于沙丘传送带从海岸线向内陆延伸，伦索伊斯马拉赫塞斯的沙丘场在某些地区向西延伸了约 0.5 公里。沙子几乎持续不断的移动阻止了大部分沙丘地植被的生长。
UNESCO declared the park a World Heritage site in 2024, citing its remarkable geology and rich biodiversity. The park is home to more than 850 documented species, including fish , birds, reptiles , mammals, and phytoplankton . Among them are four endangered species, including the neotropical otter, West Indian manatee, scarlet ibis, and oncilla (a type of wild cat). Among the lagoons’ most remarkable inhabitants are the trahira (Hoplias malabaricus) , a predatory fish species with large canine-like teeth. During the dry season, it burrows far enough under the sand to find damp mud, where it enters a dormant state, emerging after the rains to hunt insects and other fish.
联合国教科文组织以其非凡的地质和丰富的生物多样性于 2024 年宣布该公园为世界遗产。该公园拥有超过 850 种记录在案的物种，包括鱼类、鸟类、爬行动物、哺乳动物和浮游植物。其中有四种濒临灭绝的物种，包括新热带水獭、西印度海牛、朱鹮和oncilla（一种野猫）。泻湖中最引人注目的居民是特拉希拉鱼（Hoplias malabaricus），这是一种掠食性鱼类，拥有像犬科动物一样的大牙齿。在旱季，它会在沙子下挖足够远的地方，找到潮湿的泥土，在那里它进入休眠状态，雨后出现，捕食昆虫和其他鱼类。
NASA Earth Observatory images by Michala Garrison, using Landsat data from the U.S. Geological Survey . Story by Adam Voiland.
NASA 地球观测站图像，由 Michala Garrison 使用美国地质调查局的陆地卫星数据拍摄。亚当·沃伊兰的故事。