The production of high-salinity brines during 9 sea-ice freezing in circum-arctic coastal polynyas is 10 thought to be part of northern deep water formation as it 11 supplies additional dense waters to the Atlantic meridional 12 overturning circulation system. To better predict the effect 13 of possible future summer ice-free conditions in the Arctic 14 Ocean on global climate, it is important to improve our 15 understanding of how climate change has affected sea-ice 16 and brine formation, and thus finally dense water formation 17 during the past. Here, we show temporal coherence 18 between sea-ice conditions in a key Arctic polynya (Stor-19 fjorden, Svalbard) and patterns of deep water convection in 20 the neighbouring Nordic Seas over the last 6500 years. A 21 period of frequent sea-ice melting and freezing between 6.5 22 and 2.8 ka BP coincided with enhanced deep water 23 renewal, while near-permanent sea-ice cover and low brine 24 rejection after 2.8 ka BP likely reduced the overflow of 25 high-salinity shelf waters, concomitant with a gradual slow 26 down of deep water convection in the Nordic Seas, which 27 occurred along with a regional expansion in sea-ice and 28 surface water freshening. The Storfjorden polynya sea-ice 29 factory restarted at *0.5 ka BP, coincident with renewed 30 deep water penetration to the Arctic and climate amelioration over Svalbard. The identified synergy between Arctic polynya sea-ice conditions and deep water convection during the present interglacial is an indication of the potential consequences for ocean ventilation during states with permanent sea-ice cover or future Arctic icefree conditions.

Efflorescence and subflorescence are frequent phenomena occurring in buildings of porous inorganic materials such as bricks, stone, and concrete. Since the above phenomena have detrimental effects, they were the subject of detailed physicochemical investigations. Efflorescence on wooden material was commonly observed on collection artefacts treated with preservatives such as inorganic salts or organic pesticides. Occurrence of efflorescence in historical wooden buildings was less studied although it could cause serious conservation concerns. This paper describes an examination of chemical and mineralogical composition of salt efflorescence in wooden buildings. In situ analysis by X-ray fluorescence spectrometry was followed by investigation of plain efflorescence by infrared spectrometry, X-ray diffraction, electron microscopy, and electron probe microanalysis. Quantitative analysis of purified efflorescence was performed by plasma atomic emission spectrometry, ion chromatography and absorption spectrophotometry. In addition, depth-profiling of characteristic ions in wood was performed. The objects of study were a series of log houses of the Sverresborg Trøndelag Folk Museum in Trondheim, Norway. It was found that the efflorescence in these buildings includes a series of metal ions, the most abundant being Al . In addition the ammonium ion is present in a large amount. The single detected anion is sulfate. Actually, the efflorescence consists of a mixture of simple and double sulfate salts of alum and Tutton's compound types. Identified Tutton's compounds are mohrite ((NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O), ammonium zinc sulfate hexahydrate ((NH 4 ) 2 Zn(SO 4 ) 2 ·6H 2 O)), and boussingaultite ((NH 4 ) 2 Mg(SO 4 ) 2 ·6H 2 O)). Among the alums, both tschermigite (NH 4 Al(SO 4 ) 2 ·12H 2 O), and potassium alum (KAl(SO 4 ) 2 ·12H 2 O)) were detected. The composition of efflorescence suggests that the wooden material was treated with a blend of sulfate salts ((NH 4 ) 2 SO 4 , Al 2 (SO 4 ) 3 ·18H 2 O, MgSO 4 ·7H 2 O, FeSO 4 ·7H 2 O, ZnSO 4 ·7H 2 O, and Na 2 SO 4 ·10H 2 O)) for protection against fire and biological degradation. The efflorescence appeared as a consequence of water leakage through the roof that led to the dissolution of the salts contained in the wood, followed by evaporation and salt crystallization at the surface in the form of double sulfate salts. Although the occurrence of efflorescence in this case was accidental, a natural and more frequent cause of efflorescence could be the deliquescence of inorganic preservatives impregnated in the wood.

Homocysteine (Hcy) and cysteine (Cys) mercury thiolate layers were prepared by anodic polarization of a mercury electrode in amino acid containing solutions and then investigated in the cathodic regime in the presence of Ni 2þ or Co 2þ ions. The sulfhydryl function in the mercury thiolate undergoes a slow disintegration resulting in surfaceattached mercury sulfide. During the cathodic scan, Hg 2þ substitution by Ni 2þ or Co 2þ yields minute amounts of the relevant metal sulfide. Such a species catalyzes hydrogen evolution at À 1.3 V vs. Ag j AgCl j KCl(3 M). Hcy experiences a faster decomposition and, consequently, displays a stronger catalytic effect. Each compound catalyzes the reduction of Ni 2þ or Co 2þ , but only Cys (bound in metal complexes) induces typical catalytic hydrogen evolution processes such as the Brdička reaction (with Co 2þ ; pH around 9), or the catalytic hydrogen prewave (CHP) (with Ni 2þ ; pH near 7). On the other hand, Hcy catalyzes the hydrogen evolution in the presence of Co 2þ at À 1.5 V in the same way than sulfur derivatives with no amine function do. Metal sulfide formation does not interfere with CHP and Brdička processes. Correlations between the physical state of the metal sulfide (adsorbed molecule or aggregate form) and its catalytic properties are discussed and possible analytical applications suggested.

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At a mercury electrode, Hcy and Cys yield similar cathodic stripping peaks connected to the reduction of the pertinent mercury thiolate. However, due the different behavior as a ligand for nickel ion, the above compounds perform very differently in the presence of this ion. Whereas the nickel ion at a high enough concentration suppresses the Cys peak, in the case of Hcy it causes the cathodic peak to shift to more negative potentials. The peculiar behavior of Hcy is due to the stabilization of the mercury thiolate surface layer by intermolecular Ni 2þ bridges within the surface layer. Conversely, in the case of Cys, the nickel ion strongly competes with the mercury ion and leads to the formation of a surface adsorbed bis-cysteinatonickelate complex, which prevents the formation of mercury cysteinate. Such a difference allows determining Hcy by cathodic stripping voltammetry in the presence of nickel ion with no Cys interference.