Deep-Sea Research, 1974, Vol. 21, pp. 161 to 162. Pergamon Press. Printed in Great Britain.

I N S T R U M E N T S A N D M E T H O D S

The boron/elflorinity ratio of deep-sea water from the Pacific Ocean

LEIF R . UPPSTR6M*

(Received 17 August 1973; accepted 21 September 1973)

PREVIOUS investigations of the boron/chlorinity ratio in the Pacific show values in the range 0-238-0"241 B(mg kg-1)/C1 (%0) as can be seen in the summary of CULrIN (1965). Other water masses from different parts of the world show a broader variation of the ratio: 0.222-0.255. Most of tbese samples have been taken from the upper layers, where contributions from land run-off, atmospheric precipitation and differences in the biota might cause some changes of the ratio. It is therefore of great interest to compare these results with measurements on the deep-sea water masses.

G~ENHALGH and RILEY (1962) published a determination on a water sample from the Indian Ocean collected at a depth of 3958 m. The boron/chlorinity ratio found was 0.02304-0.001. This value has been taken as a reference e.g. by K~MLING (1970, 1972) and by DYRSSEN and UPPSTR6M (1973) in separate investigations of the boron content in the Baltic.

E X P E R I M E N T A L

The samples from the Pacific Ocean were collected by Almgren, Dyrssen and Strand- berg during the 9th cruise of R.V. Dmitry Mendeleev, January 20-May 10, 1973, and stored in boron-free glass tubes and later analysed at our department. Previousinvestiga- tions have shown that storage of boron samples for half a year or more at room tempera- ture can be maintained without any detectable changes of the boron concentration. The determination of the total boron content has been made as described by UPPSTR~M (1968). The corresponding chlorinity values were determined directly on board.

R E S U L T S

The results can be seen in Table 1. The mean value of all the samples analysed was found to be 0,2324-0.005 B(mg kg-1)/Cl(Voo).

D I S C U S S I O N

The mean value of the boron/chlorinity ratio found in this investigation is quite close to that for the deep-sea water in the Indian Ocean by Greenhalgh and Riley, but somewhat lower than previous values for the Pacific and the value of 0.239 used by ALMGREN, DYRSSEN and STRANDBERG (1974) for the calculation of carbonate species.

*Department of Analytical Chemistry, University of Gothenburg, Fack S-402, 20 G6tcborg 5, Sweden.

161

162 LEIF R. UPPSTROM

Table 1. Values of boron concentrations and chlorinities for three Pacific sites in February and April 1973.

Sta. no. Sample Depth Number of de- B CI B/CI no. (m) terminations (mg kg -1) (%0)

Sta. 615 1 152 3 4.43 19.364 0.229 20°06'N, 2 303 3 4.40 19.003 0-231 165°47'W 3 505 3 4.35 18.916 0.230 1973-02-O2 4 1010 3 4-46 19.107 0.233

Sta. 618 5 1880 3 4.37 19.177 0.228 20°12'N, 6 2710 3 4.35 19.185 0.227 165°54'W 7 3530 3 4.52 19.142 0.236 1973-02-03 8 4390 3 4.60 19-192 0.240

Sta. 645 9 88 2 4.69 19.380 0.243 18°22'N, 10 260 2 4.60 19.119 0.240 141°15'W 11 435 2 4.52 19.110 0.236 1973-02-24 12 865 2 4.52 19.151 0.236

13 1740 2 4-43 19.162 0.232 14 3000 2 4.37 19.262 0.228 15 3980 2 4.49 19-258 0.233

Sta. 715 16 4 2 4.38 19-451 0-225 14°50'S, 17 97 2 4.49 20.065 0.224 177°2YE 18 191 2 4.44 19-844 0-224 1973-04-16 19 1000 2 4.51 19.154 0.236

20 1430 2 4.44 19.195 0.231 Total mean value 0.2324-0.005

If a 95% confidence interval is chosen, no significant difference can be found between

the different stations or depths. The coefficient of variat ion of the determinat ion method is + 1%.

It is interesting to compare these results with those found by DVRSSEN and UPPSTR6M (1973)in the investigation of the boron content in the Baltic. The spread of the values of the boron/chlor ini ty ratio, as well as the mean, differ significantly from the results found for the Pacific deep-sea water, and show a posit ion anomaly. This has been discussed in another paper by DYRSSEN and UPPS~6M (in press).

REFERENCES

ALMGREN T., D. DYRSSEN and M. STRANDBERG (1974) Some carbonate system experiments on board Dmitry Mendeleev, submitted to Deep-Sea Research.

CULKIN F. (1965) The major constituents of sea water. In: Chemical oceanography, J. P. RILEY and G. SKIRROW, editors, Academic Press, pp. 121-161.

DYRSSEN O. and L. UPPSTR(3M (1973) Investigation of the boron content in the Baltic sea water. Report on the chemistry of sea water IX, Univ. of Gothenburg, pp. 1-6.

DYRSSEN n . and L. UPPSTR~M (in press) The boron/chlorinity ratio in Baltic sea water. Ambio. GREENHALGH R. and J. P. RILEY (1962) The development of a reproducible spectrophotometric

curcumin method for determining boron, and its application to sea water. The Analyst, 87, 970-976.

KREMLING K. (1970) Untersuchungen tiber die chemische Zusammensetzung des Meerwassers aus der Ostsee II. Kieler Meeresforschungen, 26, 1-20.

KREMLING K. (1972) Untersuchungen tiber die chemische Zusammensetzung des Meerwassers aus der Ostsee III. Kieler Meeresforschungen, 28, 99-118.

UPPSTROM L. (1968) A modified method for the determination of boron with curcumin and a simplified water elimination procedure. Analytica Chimica Acta, 43, 475-486.