Water quality measurements from the river plumes in the central Great Barrier Reef, associated with Cyclone Sadie (1994)

On the 4th February, 1994, water samples were collected from 10 stations along an offshore transect between the Brook Islands and the Mulgrave River. Cyclone Sadie caused a large rain depression over most of the north Queensland catchment area and sampling took place two days after the main flood peak had occurred. Samples were collected hourly, while the research vessel was steaming. Surface samples were collected at six stations, using a bucket. At a further four stations, samples were collected at four depths using a series of three Niskin bottles spaced over a depth profile for subsurface samples and a bucket to collect the surface samples. In situ temperatures were recorded using digital reversing thermometers attached to the Niskin bottles.Samples were analysed for chlorophyll, suspended solids, dissolved inorganic and organic nutrients and salinity.Water transparency was measured using a secchi disk and the presence of Trichodesmium spp. noted visually. Additional data collected at each station were cloud cover, wind speed, wind direction, tide and acoustic depth. This research was undertaken to examine changes in water quality in a flood plume resulting from increased river runoff into the Great Barrier Reef lagoon.

1994年2月4日，研究团队从布鲁克群岛（Brook Islands）与马尔格雷夫河（Mulgrave River）之间的近海断面的10个采样站位采集水样。气旋萨迪（Cyclone Sadie）致使昆士兰州北部多数集水区出现强降雨，本次采样于主洪峰过境后两日开展。科研船航行期间，每小时采集一次水样，其中6个站位采用采水桶采集表层水样；剩余4个站位的表层水样通过采水桶采集，次表层水样则使用按深度剖面布设的3个尼斯金采水器（Niskin bottles）采集4个深度层级的样品。现场水温由连接于尼斯金采水器的数字颠倒温度计记录。本次采集的水样将开展叶绿素、悬浮固体、溶解态无机与有机营养盐及盐度的分析检测，水体透明度采用塞氏圆盘（Secchi disk）测量，并通过目视记录束毛藻属（Trichodesmium spp.）的存在情况。各站位还同步采集了云量、风速、风向、潮汐及声测水深等辅助数据。本研究旨在探究河流径流量增加引发的洪水羽流对大堡礁潟湖（Great Barrier Reef lagoon）水质造成的变化。