In the slow-moving waters of the Rio Negro of the southern Pantanal, acids (mostly tannic acids (compounded glucose esters of gallic acid)) are leeched from decaying organic matter in flooded forests creating transparent, tea-colored water. These waters have an extremely low water hardness and an acidic pH of 5-6. The substrate of this black water habitat is typically leaf litter over a base of sand.The muddy brown waters of the Aquidauana river carry a heavy sediment load originating in clay rich soils.
On fazenda Barranco Alto you can see the meeting of these two waters a few days after heavy rains in the headwaters of the Aquidauana river. Then some of it comes through a side-arm into the Rio Negro and presents us with this unique nature spectacle. Both waters flow side-by-side for a distance before they mix into a cafe-au-lait colored river ...
On the photo you see left the black water, right the muddy water and in between some reflexions of the forest.
And least but not last, this is not the Rio Negro in the Amazon but it's homonym in the Pantanal ! Two very different rivers and in their own way very unique ...
