title: Latitudinal distribution of nitrogen isotopic composition in suspended particulate organic matter in tropical/subtropical seas.
abstract: Natural nitrogen isotopic composition (δ(15)N) of suspended particulate organic matter (POM) and nitrogen fixation rates via (15)N(2) assay were measured in surface waters along 120° E from 30° N to 30° S in the Asian marginal seas (the East/South China Seas and the Sulu/Celebes/Java Seas) and the northeastern Indian Ocean in November-December 2005 and March 2006. The POM δ(15)N values ranged from-1.8 to 12.2‰ with an average of 3.6‰ and showed a decreasing trend towards the equator in both hemispheres. In parallel, the measured N(2) fixation rates showed an increase from the subtropical to the tropical seas. This implies that a higher contribution of (15)N-depleted POM was derived from enhanced N(2) fixation. Water temperature and the stability of water column were partly responsible for the observed variations in nitrogen fixation. The large-scale spatial variations in suspended POM δ(15)N and N(2) fixation rates suggest that the suspended POM δ(15)N may be a potential indicator of nitrogen fixation in surface waters in tropical/subtropical seas.
authors: Department of Oceanography, Xiamen University, People's Republic of China.
authors: Run
authors: R
authors: Zhang
authors: Min
authors: M
authors: Chen
authors: Qiang
authors: Q
authors: Ma
authors: Jianping
authors: J
authors: Cao
authors: Yusheng
authors: Y
authors: Qiu
mesh_terms: D019156:Indian Ocean; D009586:Nitrogen Fixation; D009587:Nitrogen Isotopes / Q000032:analysis*; D009792:Oceans and Seas; D012623:Seawater / Q000032:analysis*; D014329:Tropical Climate
chemical_list: D009587:Nitrogen Isotopes