Runoff and nutrient losses during winter periods in cold climates--requirements to nutrient simulation models.

Large areas in Europe may experience frozen soils during winter periods which pose special challenges to modelling. Extensive data are collected in small agricultural catchments in Nordic and Baltic countries. An analysis on measurements, carried out in four small agricultural catchments has shown that a considerable amount of the yearly nutrient loss occurs during the freezing period.

Temporal and spatial variation of nutrient levels in the Nemunas River (Lithuania and Belarus).

There are discordant results on trends in nutrient river water quality from the economical transition countries in Europe. The present study assessed the impact of these economical changes on the load and concentration at 17 monitoring stations along the Nemunas River and its major tributaries (Lithuania and Belarus). Three time periods were evaluated: the Soviet rule command system period 1986-1991, the transfer to market economy period 1992-1996 and the post reform period 1997-2002.

Factors affecting N and P losses from small catchments (Lithuania).

Most of the important factors causing differences in nutrient losses and their interaction were analysed in three small catchments that are located in partially different geographic and climatic conditions in Lithuania. The investigation revealed that climatic factors change the amount and pattern of water discharge over year (larger water discharge during winter in the catchment located closer to the sea), but nutrient leaching is more dependent on land use. Agricultural factors, such as larger cultivated area and excessive fertilisation in one catchment cause larger nitrogen losses (15 kg N ha(-1) year(-1)).

Phosphate run-off in the Nevezis River (Lithuania).

The long-term (40 yr) observation results of phosphates-phosphorus concentration and its runoff in the Lithuanian fourth largest river Nevezis are analysed. Amounts and peculiarities of background runoff, agricultural runoff, and point source pollution from towns were studied for various periods. It has been determined that phosphates enter into the river Nevezis mainly from towns (76.