Introduction, Characteristics and some localities of Brackish Water on earth

Water generally can be classified into three categories that is Fresh water, Brackish Water and Marine water. Fresh water is defined as the Water Which is enclosed by the earth crust and Salinity is less then 0.5 ppt and Marine water is that Water which encloses the earth crust and salinity is more then 35ppt. While Brackish water is piquant and briny than fresh water but not as salty as marine water. Brackish water has a wide range of salinity that is 0.5 to 30ppt.It can be created by combining fresh and salt water, as in estuaries, as well as by some human activities, most notably the construction of coastal marshland. Brackish water has a salty, disagreeable taste and a higher salinity (500–17,000 mg/l) than fresh water. But it is not as salty as marine water (30,000–40,000 mg/l). Water is classified primarily based on its salinity level, TDS, and conductivity. Conductivity, TDS, salinity of fresh water and marine water is 150-500 µs/cm, 1000 mg/l, 500 mg/l and 46,000-72,000 µs/cm, 30,000-40,000 mg/l, 35,000-40,000 mg/l respectively. Conductivity, TDS, and salinity of brackish water is 1000-46,000 µs/cm, 1000-5000 mg/l, and 500-17,000 mg/l respectively.

Brackish water habitats are dynamic. The salinity is influenced by the amount of freshwater that enters from rivers or rain, the tide, and evaporation rate. As a result, many fish species in brackish water environments can tolerate fluctuations in salinity. Brackish water is another significant  source of aquatic life. Due to the tidal regime, brackish water is naturally present in estuaries, river deltas, lagoons in all over the world. Depending on the tide phase and the amount of fresh water discharged into the sea through the river, the salinity of the water in such ecosystems fluctuates dramatically, ranging from zero to 35 ppt. According to theory, brackish water has a specific gravity of 1.005 to 1.010 and contains between 0.5 and 30 grammes of salt per liter, which is more commonly expressed as 0.5 to 30 parts per thousand of salt. As a result, brackish water is a broad term that refers to a variety of salinity regimes. Estuaries, lakes, man-made pools, streams, aquifers, and underground water in different countries of the world are all places where brackish water can be found. Man-made sources of brackish water include dikes, which are walls constructed to restrict the flow of water from rivers and oceans, and the pools and streams that arise from purposefully flooding marshes for prawn farming. Lastly, deep fossil aquifers underground contain brackish groundwater. Because of ancient oceans, saltwater intrusion in coastal locations, or excessive mineral absorption when water percolates into the earth, groundwater can become brackish. 

LOCATION OF BRACKISH WATER IN THE WORLD

Salinity (PPT)	Name	Type	Countries	Reference
3.40–3.60	World Ocean	Ocean	Worldwide	Pérez and Chebude (2017)
1.00-1.20	Sea of Azov	Mediterranean Sea	Ukraine, Russia	Guinness world record
1.14	Sarygamysh Lake	Salt Lake	Turkmenistan, Uzbekistan	Aladin and Plotnikov (2004)
35.0	Garabogazköl	Lagoon	Turkmenistan	Hammer, U.T. (1986)
32.4	Lake Tuz (Tuz Gölü)	Salt Lake	Turkey	Almardini et al. (2015)
2.30	Lake Van	Salt Lake	Turkey	Susan et al 2018
3.00–4.00	Lake Natron	Salt Lake	Tanzania	UNESCO
3.80	Mediterranean Sea	Mediterranean Sea	Southern Europe, Levant, North Africa	White et al. (2014)
40.0	Lake Retba	Salt Lake	Senegal	Russian Nature Reserved
9.50	Lake Techirghiol	Salt Lake	Romania	Lacu Sarat
3.40	Lough Hyne	Marine lake	Republic of Ireland	Observation on Lacu Sarat
0.8 1.0	Baltic Sea	Marginal sea	Northern Europe	Encyclopedia Britannica Online
2.80–3.20	Beaufort Sea	Marginal sea	North of Alaska and Canada	The Canadian Encyclopedia
0.59	Issyk Kul	Salt Lake	Kyrgyzstan, Central Asia	Dotsika et al. (2004)
33.7	Dead Sea	Salt Lake	Israel, Jordan, West Bank	Schutte et al. (2020)
8.50–28.0	Lake Urmia	Salt Lake	Iran	South-central Oregon
3.17	Chilika Lake	Lagoon	India	Lacul Techirghiol
15.3	Lake Pikrolimni	Salt Lake	Greece	Willever (2016)
31.7	Great Salt Lake, North Arm	Salt Lake	Great Basin, Utah, United States	Suosaari et al. (2016)
14.2	Great Salt Lake, South Arm	Salt Lake	Great Basin, Utah, United States	The Salton Sea Authority
12.0	Lake Abert	Salt Lake	Great Basin, Oregon, United States	El-Serehy et al. (2018)
8.80	Mono Lake	Salt Lake	Great Basin, California, United States	Science Learning Hub
4.40	Salton Sea	Salt Lake	Great Basin, California, United States	Anati (1999)
43.3	Gaet’ale Pond	Salt Lake	Ethiopia	Aquatic Resource Management
3.60–4.10	Red Sea	Mediterranean Sea	Egypt, Sudan, Arabian Peninsula, Horn of Africa	Ocean Salinity
4.10–4.50	Great Bitter Lake	Salt Lake	Egypt	Floods of Lake Eyre
1.25	Caspian Sea	Salt Lake	Eastern Europe/ Western Asia	Marine Nature Reserved
34.8	Lake Assal	Salt Lake	Djibouti	Horn of Africa
1.40	Qinghai Lake	Salt Lake	China	Republic of China
18.0	Little Manitou Lake	Salt Lake	Canada	Canadian Reserved Centre
30.0	Lake Sarat	Salt Lake	Braila, Romania	Facts about Romania
2.20	Sea of Marmara	Mediterranean Sea	Between the Balkan Peninsula and the Anatolian peninsula	Sea of Marmara
1.30–2.30	Black Sea	Mediterranean Sea	Between Europe and Asia – Balkan Peninsula, Eastern Europe, Anatolia, Caucasus	Sea of Marmara
6.60	Hamelin Pool	Lagoon	Australia	Indian Journal of Marine Sciences
3.50+	Lake Eyre	Endorheic lake	Australia	Indian Journal of Marine Sciences
30.0	Lake Baskunchak	Salt Lake	Astrakhan Oblast, Russia	The Black Sea Environment
33.8	Don Juan Pond	Salt Lake	Antarctica	National Oceanographic Centre
0.00-14.6	Lake Vanda	meromictic lake	Antarctica	National Oceanographic Centre