title: Spatial and temporal variability of stable isotopes and biological parameters for the Danube River in Serbia.
abstract: This paper presents the results of hydrological, physicochemical, biological, and isotopic investigations of the Danube River along the stretch through Serbian territory conducted during four campaigns in September and November 2007, September 2008 and April 2009. The stable isotope values exhibited significant changes both in the Danube (-10.7 to-9.5 per thousand for delta(18)O and-73.7 to-67.1 per thousand for delta(2)H) and in its tributaries (-9.1 to-8.5 per thousand for delta(18)O and-69.4 to-59.4 per thousand for delta(2)H) depending on the time of survey, which could be partly attributed to the influences of seasonal effects. Results emphasise the dominant role of tributaries inflows from aquifers along the Danube. The very narrow range of delta(13)C(POC) (from-28.9 to-27.4 per thousand) was associated with relatively high C/N ratios (C/N>9), and together with delta(15)N(TPN) values, the date suggested that, in early spring, a major fraction of particulate organic matter was derived from allochthonous matter. An orthogonal varimax rotation of the principal components analysis identified four latent factors ('mineral related', 'biological', 'hardness', and 'soil inlets') which are responsible for the data structure covering 79% of the observed variations among the variables studied. A reliable grouping of samples with respect to the season was found.
authors.affiliation: Jaroslav Cerni Institute for Development of Water Resources, Belgrade, Serbia.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Mitrovic
authors.forename: Vesna
authors.initials: V
authors.lastname: Obradovic
authors.forename: Dusan
authors.initials: D
authors.lastname: Golobocanin
authors.forename: Nives
authors.initials: N
authors.lastname: Ogrinc
authors.forename: Nada
authors.initials: N
authors.lastname: Miljevic
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis; D007554:Isotopes / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D009930:Organic Chemicals / Q000032:analysis; D025341:Principal Component Analysis; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D055771:Serbia; D013997:Time Factors
chemical_list: D002247:Carbon Isotopes; D007554:Isotopes; D009587:Nitrogen Isotopes; D009930:Organic Chemicals