Brackish water
Brackish water(less commonlybrack water) issalt waterand fresh water mixed together. It issaltierthanfresh water,but not as salty asseawater.It may result from mi xing of seawater with fresh water, as inestuaries,or it may occur in brackishfossilaquifers.
Somehumanactivities can produce brackish water, mostly certaincivil engineeringprojects such asdikesand the flooding ofcoastalmarshland to produce brackish pools for freshwaterprawns.
Technically, brackish water contains between 0.5 and 30 grams ofsaltperlitre—more often expressed as 0.5 to 30 parts per thousand (ppt or ‰). Thus,brackishcovers a range ofsalinity regimesand is not considered a precisely defined condition. It is characteristic of many brackish surface waters that theirsalinitycan vary considerably over space and/or time.
| Water salinity based on dissolved salts in parts per thousand (ppt) | |||
|---|---|---|---|
| Fresh water | Brackish water | Salinewater | Brine |
| < 0.5 | 0.5—35 | 35—50 | > 50 |
Etymology
[change|change source]The term brackish water comes from theLow GermanwordBrack,which is a small lake made when astorm tidebreaks adikeand floods land behind the dike.
Brackish water habitats
[change|change source]Estuaries
[change|change source]
The most important brackish water habitats areestuaries,where a river meets the sea, mi xing salt and fresh water. The RiverThamesflowing throughLondonis one of the most familiar of river estuaries.
Mangroves
[change|change source]Another important brackish water habitat is themangroveswampormangal.
Brackish seas and lakes
[change|change source]Some seas and lakes are brackish. TheBaltic Seais a brackish sea adjoining theNorth Sea.
TheCaspian Seais the world's largest lake and contains brackish water with a salinity about one-third that of normal seawater. The Caspian is famous for its peculiar animal fauna, including one of the few non-marine seals (the Caspian seal) and the greatsturgeons,the source ofcaviar.
Important brackish bodies of water
[change|change source]Brackish seas
- Baltic Sea(the world’s largest pool of brackish water)
- Black Sea
- Caspian Sea(world’s largest lake)
Brackish water lakes
- Lake CharlesinLake Charles, Louisiana,USA
- Chilika Lake,Odisha,India
- Pangong Tso (Lake)inLadakh,Jammu and Kashmir,India
- Lake Van,Turkey
Coastal lagoons, marshes, and deltas
- TheBurgas Lakesnear theBulgarianBlack SeaCoast
- Kaliveli Lake,nearPondichery,India
- Kerala Backwaters,Series of lagoons and lakes inKerala
- Lagos LagooninLagos,Nigeria
- LakePontchartrain,north ofNew Orleans,Louisiana,USA
- Pulicat Lake,north ofChennai,India
- TheRann of Kutch,on the border ofIndiaandPakistan
- Parts of theRhôneDelta,France:An area known as theCamargue
Estuaries
- Amazon River,empties so much freshwater into theAtlantic Oceanthat it reduces the salinity of the sea for hundreds of miles
- Chesapeake Bay,inMaryland,USA
- TheFleetlagoon,Dorset,England
- Hampton Roads,Virginia,USA
- LowerHudson River,inNew YorkandNew Jersey,USA
- Lingding Yang,Guangdong,thePeople's Republic of China
- Port Royal Soundpart of Beaufort County,South Carolina,USA[1]Archived2015-07-10 at theWayback Machine
- Saint LawrenceandSaguenayRivers, the part downstream fromQuébecandSaguenayrespectively
- TheThamesEstuary in South EastEngland