DISTRIBUTION OF CHEMICAL CONSTITUENTS OF SEA WATER IN THE 



GULF OF MEXICO ' 



By ROBERT H. WILLIAMS, Marine Laboratory, University of Miami 



Earliest records of chemical analyses of Gulf of 

 Mexico waters were published by biologists and 

 biochemists who studied the sea water composi- 

 tion as one ecological factor in the complex envi- 

 ronment of the marine organisms with which they 

 were concerned. Much of this early work was 

 centered at the Carnegie Institution laboratory at 

 the Dry Tortugas near the western end of the 

 Florida Keys. First oceanographical studies of 

 the chemistry of the water were confined to the 

 system of currents flowing across the southeastern 

 corner of the Gulf from the Yucatdn Channel to 

 the Straits of Florida. Practically all analyses of 

 offshore and subsurface waters of the Gulf were 

 made in 1914, 1922, 1932, 1934-39, 1942, and 

 since 1947. 



The chemical data are summarized here in order 

 of the decreasing amount of published informa- 

 tion: salinit}', oxygen, phosphorus, nitrate, nitrite, 

 pH, alkalinity and carbon dioxide components, 

 copper, and miscellaneous chemical constituents. 



SALINITY 



Salinity is defined as the total amount of dis- 

 solved solid material in grams contained in 1 

 kilogram of sea water when all the carbonate has 

 been converted to oxide, the bromine and iodine 

 replaced by chlorine, and all organic matter com- 

 pletely oxidized. In practice, it is calculated 

 from the chlorinity which is determined by titra- 

 tion with silver nitrate solution. Less accurate 

 salinity values are calculated from densities 

 determined with hydrometers. Both salinity and 

 chlorinity are reported as parts per thousand by 

 weight, using the symbol, "/co- 

 in the shallow waters of the Dry Tortugas, in 

 the years 1910 to 1913, Dole (1914) reported 

 salinities ranging from 35.41°/oo to 36.11°/oo- 

 Diurnal and tidal changes in salinity in the same 



' Contribution No. 101, from the Marine Laboratory, University of 

 Miami. 



area in 1919 indicated a wider range, 34.61 °/oo 

 to 36.29°/oo (Wells 1922). 



In the bays along the coast of Texas the wide 

 salinity variations cause recurring mass mortality 

 of marine animals. This situation was reported 

 by Johnson (1882), Rathbun (1895), and Higgins 

 and Lord (1926). Results of detailed surveys of 

 the salinity distribution in the Texas bays in 

 1926-27 were reported by Galtsoff (1931). Addi- 

 tional studies of salinity along the Texas, Louisi- 

 ana, and Mississippi coasts were published by 

 Higgins (1931), Riley (1937), Lindner (1939, 

 1941), Gunter (1945, 1947, 1950), Wise, Winston, 

 and Culli (1945), Price (1947), Geyer (1950), and 

 Collier and Hedgpeth (1950). Alternating floods 

 and droughts cause salinity changes from nearly 

 fresh to 100°/oo, three times that of normal sea 

 water. 



In connection with studies of the red tide along 

 the west coast of Florida, salinity data were pub- 

 lished by Galtsoff (1948), Gunter, WiUiams, Davis, 

 and Smith (1948), and Ketchum and Keen (1948). 

 In the open Gulf salinities ranged from 30.6°/oo 

 to 37.0°/oo; in Estero Bay, 21.4°/oo; and near the 

 mouth of the Caloosahatchee River, 12.2°/oo. 



In connection with plankton studies in 28 man- 

 grove-bordered inland bodies of brackish water 

 on the west and south coasts of Florida in 1947- 

 48, Davis and Williams (1950) reported salinities 

 ranging from 0.6l7oo to 29.09°/oo. 



The present center of Florida's oyster industry, 

 Apalachicola Bay in northwest Florida, was the 

 subject of an 18-month survey of salinity (Ingle 

 1951; Ingle and Dawson 1951). Annual varia- 

 tions ranged from fresh water to 42.5°/oo Daily, 

 weekly, and tidal variations were considerable. 



Apparently the first published salinity records 

 for offshore and subsurface Gulf of Mexico waters 

 are those of Vaughan (1918) who reported salinity 

 values for samples collected at five stations be- 

 tween Havana and Key West from the surface to 



143 



