ANDRZEJ KOSTRZEWSKI: The scientific output of Professor Bogumil Krygowski on the 100th anniversary of his birth (1905-1977) ROBERT BOGDANOWICZ: Analysis of temporal changes in nitrogen transport of the Vistula River in relation to seasonal and long-term variations in river discharge MlCHAL FARYŚ: Influence of soil salinity on soil bidirectional reflectance observed in Central Mexico MARIA GÓRSKA: Sediments of the Odra Lobe in the light of selected textural and mineral analyses ALFRED KANIECKI: Methodological problems pertaining to the study of transformations of water relations in urban areas MAŁGORZATA NITA, KRZYSZTOF WÓJCICKl: Record of Holocene vegetation changes against a background of environmental conditions in the Kłodnica valley (southern Poland) RENATA PALUSZKIEWICZ, RYSZARD PALUSZKIEWICZ: Lithofacies differences in proglacial lake sediments: an example of the Pyrzyce and Zlocieniec proglacial lakes (West Pomerania) ALOJZY WOŚ: Outline of features of the climate of Poznan in the second half of the 20th century in the light of average annual values of selected weather elements DARIUSZ WRZESINSKI: Changes of the hydrological regime of rivers of Northern and Central Europe in various periods of the North Atlantic Oscillation