naa a22 4500 510752012 CHVBK 20180411083108.0 cr unu---uuuuu 180411e20130501xx s 000 0 eng 10.1007/s11270-013-1551-z doi (NATIONALLICENCE)springer-10.1007/s11270-013-1551-z Factors Affecting Nutrient Concentration and Stable Carbon and Nitrogen Isotope Ratio of Particulate Organic Matter in the Ishikari River System, Japan [Elektronische Daten] [Pawan Jha, Minagawa Masao] Water and particulate organic matter samples were analyzed for dissolved nutrients and stable carbon and nitrogen isotope ratio, respectively, in the Ishikari River system, from August 2009 to July 2010. Dissolved nutrient concentration showed significant spatial and seasonal variations within the river system. Mean concentration and standard deviation of ammonium, nitrite, nitrate, phosphate, silica, and dissolved organic carbon were 0.17 ± 0.17, 0.01 ± 0.01, 0.93 ± 0.59, 0.03 ± 0.01, 9.07 ± 2.40, and 3.7 ± 0.93 (mgl−1), respectively. The δ 13C, δ 15N, and molar C/N ratio of particulate organic matter samples ranged from −34.6 to −24.6‰, −4.8 to 15.8‰, and 5.3 to 17.8, respectively, in the Ishikari River system. Nutrient concentration showed increasing trend during the past 50years owing to increased urban growth and development taking place in the river basin. The molar ratio of dissolved inorganic nitrogen (DIN)/dissolved inorganic phosphate (DIP) was higher than the Redfield ratio (16:1), which implies phosphorus limitation of phytoplankton growth in the river water. The negative value of the indicator of coastal eutrophication potential for nitrogen for the Ishikari River system indicated the absence of eutrophication problem in its coastal areas. Annual nutrient fluxes from Ishikari River for dissolved inorganic nitrogen (DIN-N), phosphate (PO4-P), dissolved silica (SiO2-Si), and dissolved organic carbon (DOC-C) were 1.6 × 104, 379, 13.2 × 104, and 5.4 × 104tyear−1, respectively. Springer Science+Business Media Dordrecht, 2013 Ishikari River nationallicence Nitrogen nationallicence Phosphate nationallicence Carbon isotope nationallicence Nitrogen isotope nationallicence Nutrient molar ratios nationallicence Jha Pawan Graduate School of Environmental Science, Hokkaido University, 060-0810, Hokkaido, Sapporo, Japan aut Masao Minagawa Graduate School of Environmental Science, Hokkaido University, 060-0810, Hokkaido, Sapporo, Japan aut Water, Air, & Soil Pollution Springer Netherlands 224/5(2013-05-01), 1-23 0049-6979 224:5<1 2013 224 11270 https://doi.org/10.1007/s11270-013-1551-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11270-013-1551-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jha Pawan Graduate School of Environmental Science, Hokkaido University, 060-0810, Hokkaido, Sapporo, Japan aut NATIONALLICENCE 700 1- Masao Minagawa Graduate School of Environmental Science, Hokkaido University, 060-0810, Hokkaido, Sapporo, Japan aut NATIONALLICENCE 773 0- Water, Air, & Soil Pollution Springer Netherlands 224/5(2013-05-01), 1-23 0049-6979 224:5<1 2013 224 11270 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer