Everything about Blackwater River totally explained
» This article is about a classification of rivers. For rivers officially named Blackwater
, see Blackwater River.
Blackwater rivers are rivers with
waters colored like black
tea to
coffee. Most major blackwater rivers are in the
Amazon River system and the
Southern United States.
A blackwater river is one with a deep, slow-moving channel that flows through
forested
swamps and
wetlands. The color results from the leaching of
tannins from the decaying
leaves of adjoining vegetation. Blackwaters are usually transparent, acidic, and oligotrophic (with very low nutrient content).
Comparison between white and black waters
Black and white waters differ significantly in their ionic composition, as shown in Table 1 below. Black waters have ionic concentrations not much greater than that of
rainwater. They are, however, much more
acidic and this results in black waters having an
aluminium concentration greater than that of the more neutral white waters. The major difference is the concentrations of
sodium,
magnesium,
calcium and
potassium; these are very low in black waters. This has considerable ecological implications. Some animal groups, such as
snails, need a lot of calcium with which to build their shells and so are not abundant in black waters. The lack of dissolved ions in black waters results in a low
conductivity, similar to that of rainwater.
Black and white waters also differ in their
planktonic fauna and
flora. Tables 2 and 3 below compare the number of planktonic animals caught in black and white water localities only a few meters apart. In fact, the black water wasn't even as extreme an example as can be found in the
Rio Negro system. However, it can be seen that the black water held far greater numbers of
rotifers but fewer
crustaceans and
mites. These crustaceans are important foods for
larval fish. The zones where the two waters mix are particularly attractive to
ostracods and young fish. These mixing zones tend to have high numbers of animals. The high abundance of animals is shown clearly in Table 3 which compares the numbers of animals present in 10 litres of water in each habitat sampled.
| Table 1: Mean ionic composition, specific conductivity (μS/cm), and pH in Amazon waters. Data from Ribeiro and Darwich (1993). |
| |
Solimoes or Amazon River – whitewater. |
Rio Negro – blackwater. |
| Na (mg/L) |
2.3 ± 0.8 |
0.380 ± 0.124 |
| K (mg/L) |
0.9 ± 0.2 |
0.327 ± 0.107 |
| Mg (mg/L) |
1.1 ± 0.2 |
0.114 ± 0.035 |
| Ca (mg/L) |
7.2 ± 1.6 |
0.212 ± 0.066 |
| Cl (mg/L) |
3.1 ± 2.1 |
1.7 ± 0.7 |
| Si (mg/L) |
4.0 ± 0.9 |
2.0 ± 0.5 |
| Sr (μg/L) |
37.8 ± 8.8 |
3.6 ± 1.0 |
| Ba (μg/L) |
22.7 ± 5.9 |
8.1 ± 2.1 |
| Al (μg/L) |
44 ± 37 |
112 ± 29 |
| Fe (μg/L) |
109 ± 76 |
178 ± 58 |
| Mn (μg/L) |
5.9 ± 5.1 |
9.0 ± 2.4 |
| Cu (μg/L) |
2.4 ± 0.6 |
1.8 ± 0.5 |
| Zn (μg/L) |
3.2 ± 1.5 |
4.1 ± 1.8 |
| Conductivity |
57 ± 8 |
9 ± 2 |
| pH |
6.9 ± 0.4 |
5.1±0.6 |
| Total P (μg/L) |
105 ± 58 |
25 ± 17 |
| Total C (mg/L) |
13.5 ± 3.1 |
10.5 ± 1.3 |
| HCO3-C (mg/L) |
6.7 ± 0.8 |
1.7 ± 0.5 |
Blackwater rivers of the world:
Amazonia
Orinoco basin
Atabapo: from the Guiana Highlands of Venezuela west into the Orinoco
Caroní River: from the Guiana Highlands of Venezuela west into the Orinoco
Inírida: from Colombia northeast into the Guaviare River which flows into the Orinoco
Ventuari: from eastern Venezuela southwest into the Orinoco
Vichada: from Colombia east into the Orinoco
Tomo: from Colombia east into the Orinoco
Tuparro: from Colombia east into the Orinoco
Southern United States
.
Blackwater River: a tributary of the Chowan River in Virginia.
Blackwater River: a major river in the western Florida panhandle.
Black River: a tributary of the Pee Dee River in North and South Carolina.
Cape Fear River, North Carolina: flows into the Atlantic Ocean.
Cashie River, North Carolina: flows into Albemarle Sound.
Caloosahatchee River, Florida: flows west from Lake Okeechobee to the Gulf of Mexico.
Chowan River, North Carolina: flows into Albemarle Sound.
Edisto River, South Carolina: flows into the Atlantic Ocean; the longest undammed, unleveed blackwater river in North America.
Econlockhatchee River, a tributary of the St. Johns River in Central Florida.
Great Coharie Creek, North Carolina: flows into the Black River.
Little Pee Dee River, South Carolina: flows into the Pee Dee River.
Lumber/Drowning Creek: located in North and South Carolina. Part of Lumber River State Park
Pithlachascotee River: A small river in central Florida.
Scuppernong River: A small river in Washington and Tyrrell Counties in eastern North Carolina at Pettigrew State Park.
Suwannee River: A large river in southern Georgia and northern Florida flowing into the Gulf of Mexico.
Upper Little River, North Carolina: flows into the Cape Fear River.
Blackwater River, West Virginia: Located in the Blackwater Canyon in Tucker County. Blackwater Falls a five-story waterfall is located along this river with rapids ranging from Class III-V+
Waccamaw River, North and South Carolina: flows into the Atlantic Ocean.
White Oak River, North Carolina: flows into the Atlantic Ocean.
Northern United States
Black River, New York: A river starting in the western Adirondacks that flows into Lake Ontario.
Tahquamenon River, Michigan: A river in the Upper Peninsula that flows into Lake Superior.Further Information
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