Particular features of the chemical composition of the interstitial waters of the White Sea.

Abstract

This paper presents results of studies of major element concentrations, nutrient concentrations, and pH and Eh values in 84 samples of interstitial and bottom waters from the White Sea collected at 32 stations. In bottom sediments pH and Eh varied from 6.8 to 7.8 and from -324 to +523 mV, respectively. In glacial clays and moraines Eh values were less than -300 mV and total mineralization (M) of interstitial waters was increased. As compared to near-bottom water, M values in the southern and central parts of the White Sea were slightly decreased, while in the northern part of the sea they were somewhat greater. Total mineralization in interstitial and near-bottom waters was 27.4-34.5 (up to 33.9 g/kg) and 25.6-35.4 g/l (up to 34.5 g/kg), respectively. Decreased M values in interstitial waters were found in late glacial and early Holocene deposits. The Holocene transgression was accompanied by upward increasing of M, and Cl**- , Na**+ and Mg**2+ concentrations in interstitial waters. Sulfate reduction and nutrient accumulation (up to 20, 3.5, 2 mg/l, and 30 µg/l of N-NH4**+, P, Si, and N-NO2, respectively) were observed at the Solovetskie Islands and in the Kandalaksha Bay. Good correlation of all major ions excluding Alk with Cl**- was noted, which represents effect of the first (sedimentogenic) factor. The biogenic factor and the factor of vertical variability of N-NH4**+, Alk, and SO4**2- were also notable. It is supposed that increase in MgCl2 relative concentration in Holocene interstitial waters was caused by development of a cryogenic process and by jet-wise gravitational sinking of frozen-out brines.