Nitrogen fixation in a mangrove system, Hinchinbrook Island, north Queensland

Nitrogen fixation was studied in the mangrove forests adjacent to Missionary Bay and in a salt flat near Double Creek, Missionary Bay, Hinchinbrook Island in the summer, winter and spring of 1989.The rate of reduction of acetylene during incubation of samples in airtight chambers was used to estimate nitrogen fixation rates. Acetylene and ethylene in the incubation mixtures were analysed simultaneously by gas-liquid chromatography. Acetylene reduction rates were converted to nitrogen fixation rates using the theoretical factor of three acetylene molecules equivalent to one nitrogen molecule.Three or more replicate samples of the following sample types were analysed:- forest sediments from low, mid and high intertidal sites- salt pan sediments- salt pan sediments covered with blue-green algal mats- prop roots with thick growths of mixed species turf algae from low, mid and high intertidal sites- decomposing logs containing varying amounts of teredinid molluscs.Some samples were discarded due to faulty equipment. This study was initiated to investigate the relative importance of various sources of nitrogen fixation and the seasonal variation in nitrogen fixation in mangrove forests and salt flats. From these data estimates of nitrogen fixation for the whole forest were made.

1989年夏、冬、春三季，研究人员于欣钦布鲁克岛（Hinchinbrook Island）传教士湾（Missionary Bay）附近的红树林，以及传教士湾双溪（Double Creek）旁的盐沼开展了固氮作用（nitrogen fixation）研究。

通过密闭培养室中样品培养期间的乙炔还原速率（acetylene reduction rate）估算固氮速率。培养混合物中的乙炔与乙烯通过气液色谱法（gas-liquid chromatography）同步分析。基于3个乙炔分子等价于1个氮分子的理论系数，将乙炔还原速率转换为固氮速率。

对以下类型的样本各进行了3份或更多重复分析：
- 低潮、中潮及高潮间带的森林沉积物
- 盐沼沉积物
- 覆盖有蓝藻藻垫的盐沼沉积物
- 低潮、中潮及高潮间带中，附生有茂密混合种草皮藻（turf algae）的支柱根
- 含有不同数量船蛆（teredinid molluscs）的腐烂木材

部分样本因设备故障被弃用。

本研究旨在探究红树林与盐沼中不同固氮来源的相对重要性，以及固氮作用的季节变化规律。基于所得数据，研究人员对整个森林的固氮量进行了估算。