The analysis of sea water. A review

Abstract

The analysis of sea water is of fundamental importance to oceanography; the results by many of the techniques employed are often reported, however, in journals rarely consulted by many analysts in other fields of enquiry, with the consequence that there is much duplication of effort. The present review summarises some of the results, both to prevent further duplication and to draw attention to some of the analytical problems involved.THE seas cover by far the larger portion of the Earth's surface, and a knowledge of the processes taking place in and about them is of great importance to many branches of pure and applied science; no excuses need be made for a study of the oceans. At an early stage in many of these investigations a knowledge of the chemical composition of the water is wanted, and many interesting analytical problems immediately arise. These problems are of a varied character, and their solution has been attempted by marine chemists whose results are published in journals not readily accessible to, or perhaps rarely consulted by, other analysts. These results, which are often of considerable importance in other fields, have therefore frequently been neglected. The purpose of this review is twofold; first, to bring the results of analytical work in marine science to the notice of other analysts in the hope that duplication of effort-which seems to be becoming increasingly common-may be avoided and, secondly, to arouse interest in some of the problems encountered-problems which can perhaps be better elucidated in a chemical than in a marine laboratory. Some fifty elements have been detected in sea water1; additional ones have been found in marine organisms (which have presumably accumulated them from the sea) and no doubt others remain still to be discovered. The concentrations range from the large amounts of chloride (19.0 g per kg) and sodium (10.5 g per kg) ions to the minute quantities of organic 573 574 BARNES: THE ANALYSIS OF SEA WATER. A REVIEW [Vol. 80nutrients, such as the vitamins (vitamin B,,, 5 mpg per litre); in between stand the nutrient elements, such as phosphorus and nitrogen, and micro-nutrients, such as copper and manganese. It will not be possible to deal with every element ; some selection must be made, and attention will therefore be particularly directed to those elements on which it is thought that the analytical work is relatively unknown and of interest to other analysts. Nor will it be possible to quote all the relevant literature; reference will be made to the major contributions and reviews, consultation of which would lead to a fairly comprehensive bibliography. The analysis of such a complex mixture as sea water presents many analytical problems, and, except perhaps as a challenge to his skill, the analyst would hardly choose it as a medium on which to work if it were not for the importance of the knowledge to be gained thereby. The analytical problems arise from a number of circumstances; first, two of the major cations, namely, sodium and potassium, are among those elem...

Electrical conductivity of dilute solutions of ""sea water"" from 5 to 120 °C

“…Compamtive values are given in table 6. Includ ed are values of limiting equivalent condu ctances of sea salt, Aox, calculated using appropriate limi tin g ion conductances weighted in proportion to the ionic composition of the sea salt (see table 1).…”

Determination of calcium in sea water: Analytical experiment using the radionuclide Ca45

“…The reaction which takes place in the vicinity of the end point may be represented by Ca-Pur + EDTA = Ca-EDTA + Pur where Pur is the purpurate ion. The volume added from the microburet to reach the end point will be 1 We use a cell 4.5 X 3.3 X 9.3 cm made from 3/s-in. Lueite.…”

“…1.242 X 10-4 X = 1.0704 X HU6 moles Ca/g sea water 1.0704 X 10~6 X 40.08 X 106 = 429.0 ± 0.0 mg Ca/kg sea water « Surface, 30°N, 64°35'W, salinity = 36.624%0.…”

“…Challenger (1873-76), he employed a gravimetric procedure for calcium which involved a single oxalate precipitation followed by ignition to the oxide. In Barnes' 1955 review on the analysis of sea water (1) he notes that "precipitation of calcium as the oxalate is still the principal method employed." Various modifications of the oxalate procedure have included dissolution of the precipitate in acid followed by a permanganate titration (<?…”

“…), dissolution and reprecipitation {11), and in silu generation of oxalate ion from methyloxalate (7). Difficulties with the oxalate procedure have, however, persisted and been discussed for several decades (1). The application of the oxalate method to rigorous studies of the calcium content of sea water has been limited by several sources of error, among which the coprecipitation of magnesium and strontium is probably the most significant.…”