『Abstract
　Dissolved methane (CH4) was measured in the waters of the Changjian (Yangtze River) Estuary an its adjacent marine area during five surveys from 2002 to 2006. Dissolved CH4 concentrations ranged from 2.71 to 89.2 nM and had seasonal variation with the highest values occurring in summer and lowest in autumn. The horizontal distribution of dissolved CH4 decreased along the freshwater plume from the river mouth to the open sea. Dissolved CH4 in surface waters of the Changjiang was observed monthly at the most downstream main channel station Xuliujing (121゜2'E, 31゜46'N), which ranged from 16.2 to 126.2 nM with an average of 71.6±36.3 nM. The average annual input of CH4 from the Changjiang to the Estuary and its adjacent area was estimated to be 2.24 mol s^-1 equal to 70.6×10⁶ mol year^-1. Mean CH4 emission rate from the sediments of the Changjiang Estuary in spring was 1.97μmol m^-2 day^-1, but it may be higher in summer due to hypoxia in the bottom waters and higher temperatures. The annual sea to air CH4 fluxes from the Changjiang Estuary and its adjacent marine area were estimated to be 61.4±22.6 and 16.0±6.1μmol m^-2 day^-1, respectively, using three different gas exchange models. Hence the Changjiang Estuary and its adjacent marine area are net sources of atmospheric CH4.

Keywords: Methane; Changjiang (Yangtze River) Estuary; Sea-to-air fluxes; Riverine input; Sediment release』

Introduction
Methods and materials
　Sample collections
　CH4 analysis
　Measurements of CH4 emissions from the sediments
　Computation of sea-to-air fluxes
Results and discussion
　Distributions of CH4 in the Changjiang Estuary and its adjacent area
　Riverine input of CH4
　Sediment release of CH4 in the Changjiang Estuary
　Air-sea fluxes of CH4
Conclusions
Acknowledgments
References