ABSTRACT:

Results of measuring the relative brine content (Ql) in the liquid phase of frozen sea water (SW) at temperatures between -2oC and -43oC with variable rate and direction of temperature change and with the use of various pulsed and steady-state NMR methods are presented and compared with analogous known literature data. Hysteresis loops corresponding to the crystallization range of SW salts, mainly NaCl, which partially precipitates as the crystalline hydrate NaCl.2H2O at temperatures below -23oC, are detected on the temperature dependence of Ql in brine. The main causes of hysteresis are indicated. Brine salinity in pores (S) is calculated from the results of determining Ql and agrees well with current literature data in a wide temperatures range. Empirical equations for determination mass of brine are given.

INTRODUCTION

Knowledge about brine content in sea ice pores and its brine composition under various conditions of sea water freezing are important for understanding the formation of the physicochemical properties of sea ice. The volumes of sea ice brine and ice porosity determine heat exchange processes between sea water and atmosphere via the ice surface, particularly at the polar caps. These processes to a considerable extent determine our planet" s climate. There have been many studies (e.g., Ringer, 1906; Gitterman, 1937; Nelson and Thompson, 1954; Thompson and Nelson, 1956; Assur, 1958; Blinov, 1965; Richardson and Keller, 1966; Nazintsev and Nazintseva, 1972; Doronin and Kheisin, 1975; Tzurikov, 1976; Richardson, 1976; Cox and Weeks, 1983; Franks, 1985; Bogorodskiy and Gavrilo, 1988; Cho et al., 2002; Maus, 2007), as well as many other publications. Brine properties near eutectic points have been insufficiently studied, even for binary systems (salt and water), to say nothing of such a complex natural object as sea water. The mechanical strength of sea ice depends on brine salinity and ice porosity (Assur, 1958).

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