Nitrogen deposition within the littoral-highlands county of Croatia between 1996 and 2008

Abstract

Temporal trends in bulk nitrogen (NH4 + + NO3-) deposition at four sites within the Littoral-highlands County of Croatia are discussed. The selected sites included: the remote island Site 1, an urban and industrial coastal Site 2 (Rijeka), Site 3 which is a settlement and Site 4 a hunting resort located in the highlands area, claimed to suffer from acidic deposition. The lowest deposition of nitrogen (N) was measured at the remote Site 1 (5.6–11.2 kg N ha-1 year-1), while higher values were obtained at the urban Site 2 (7.6–17.9 kg N ha-1 year-1) due to the local washout of the atmosphere, and at the highlands Sites, 3 (10.3–32.1 kg N ha-1 year-1) and 4 (5.6–24.9 kg N ha-1 year-1) because of higher precipitation. The bulk nitrogen (N) deposition at the highlands Sites 3 and 4 is below the critical load for the corresponding soil-vegetation type (CL = 64.4 kg N ha-1 year-1). In the period 1996–2003 NH4-N made up 66 % of the N deposition at all sites, but since 2004 this ratio has diminished to 50 %, due to the increase in NO3-N deposition. Overall there has been almost no change in N deposition at all except Site 4, where N deposition has increased, reflecting an increase in NO3-N deposition but no significant decline in NH4-N.