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a b s t r a c tThe early Holocene cooling, which occurred around 8200 calendar years before present, was a prominent abrupt event around the north Atlantic region. Here, we investigate the timing, duration, magnitude and regional coherence of the event as expressed in carbonate oxygen-isotope records from three lakes on northwest Europe's Atlantic margin in western Ireland, namely Loch Avolla, Loch Geal ain and Lough Corrib. An abrupt negative oxygen-isotope excursion lasted about 200 years. Comparison of records from three sites suggests that the excursion was primarily the result of a reduction of the oxygen-isotope values of precipitation, which was likely caused by lowered air temperatures, possibly coupled with a change in atmospheric circulation. Comparison of records from two of the lakes (Loch Avolla and Loch Geal ain), which have differing bathymetries, further suggests a reduction in evaporative loss of lake water during the cooling episode. Comparison of climate model experiments with lake-sediment isotope data indicates that effective moisture may have increased along this part of the northeast Atlantic seaboard during the 8200-year climatic event, as lower evaporation compensated for reduced precipitation.

The delta polymorph of sulfanilamide (or 4-aminobenzenesulfonamide), C(6)H(8)N(2)O(2)S, displays an overall three-dimensional hydrogen-bonded network that is dominated by a two-dimensional substructure with R(2)(2)(8) rings; these result from dimeric N-H...O interactions between adjacent sulfonamide groups. This study shows how the polymorphism of sulfanilamide is linked to its versatile hydrogen-bonding capabilities.

Polymorph VI of 4-amino-N-(2-pyridyl)benzenesulfonamide, C(11)H(11)N(3)O(2)S, is monoclinic (space group P2(1)/n). The asymmetric unit contains two different tautomeric forms. The structure displays N-H...N and N-H...O hydrogen bonding. The two independent molecules form two separate two- and three-dimensional hydrogen-bonded networks which interpenetrate. The observed patterns of hydrogen bonding are analogous to those in polymorph I of sulfathiazole.