title: Carbon and nitrogen cycling in the Zhubi coral reef lagoon of the South China Sea as revealed by 210Po and 210Pb.
abstract: The radionuclides (210)Po and (210)Pb were examined to trace the cycling of particulate organic carbon (POC) and particulate organic nitrogen (PON) in the Zhubi coral reef lagoon. The net export flux of POC to the open sea is 14 mg Cm(-2) d(-1). However, the net exchange of PON has not yet been observed. On average, the vertical export fluxes in the lagoon of POC and PON, as derived from (210)Po/(210)Pb disequilibria, are 43 mg Cm(-2) d(-1) and 13.8 mg Nm(-2) d(-1), respectively. The deficit of (210)Po relative to (210)Pb in particulate matter provides evidence for the degradation of particulate organic matter. According to the mass balance budgets, 310 mg Cm(-2) d(-1) and 121 mg Nm(-2) d(-1) were recycled into dissolved fractions. Based on a first-order kinetics model, the degradation rate constants of POC and PON are 0.28 and 0.30 m(-1), respectively. Thus, (210)Po and (210)Pb can quantify the cycling of carbon and nitrogen in this coral lagoon.
authors: Department of Oceanography, Xiamen University, Xiamen 361005, China.
authors: W F
authors: WF
authors: Yang
authors: Y P
authors: YP
authors: Huang
authors: M
authors: M
authors: Chen
authors: Y S
authors: YS
authors: Qiu
authors: H B
authors: HB
authors: Li
authors: L
authors: L
authors: Zhang
mesh_terms: D002244:Carbon / Q000032:analysis*; D057486:Carbon Cycle; D002681:China; D057894:Coral Reefs; D004784:Environmental Monitoring / Q000379:methods*; D007856:Lead Radioisotopes / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D058458:Nitrogen Cycle; D009792:Oceans and Seas; D011059:Polonium / Q000032:analysis*; D011849:Radioactive Tracers; D012623:Seawater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D007856:Lead Radioisotopes; D011849:Radioactive Tracers; D014874:Water Pollutants, Chemical; D002244:Carbon; D011059:Polonium; D009584:Nitrogen