Seasonal variation in dissolved organic and inorganic materials in Coral Creek, Hinchinbrook Island, north Queensland

The concentration of dissolved organic and inorganic material was measured in water samples collected near the mouth of Coral Creek, Hinchinbrook Island between December 1982 and July 1984. Sampling was conducted for 16 tidal cycles at 1 to 2 monthly intervals during this period. For each 12 hour tidal cycle, water was sampled at various depths or locations across the channel each half hour. In July 1984, sampling was carried out over 2 consecutive tidal cycles. Water samples were immediately filtered and frozen and analysed within 1 to 2 weeks of collection.Dissolved organic carbon (DOC) analyses were carried out using a thin-film UV oxidation method. Analyses of inorganic nutrients (ammonium, nitrate, nitrite and phosphate) were carried out using an autoanalyser. Dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) analyses were carried by first digesting samples for 12 hours in a photodigestion apparatus and then analysing the samples for nitrate and nitrite, or phosphate. The concentrations of these nutrients found in samples analysed for inorganic nutrients only, were then subtracted to derive concentrations of organic N and P.A Microdata weather station was erected above the mangrove canopy, near the channel edge, close to the sampling station, for the duration of the study. Rainfall, humidity, solar radiation, air temperature, mud temperature (30cm below the mud surface), wind speed and wind direction were measured at 30 minute intervals. This research was initiated to:1. determine whether mangroves act as a source of carbon, nitrogen and phosphorus for adjacent coastal waters and benthic habitats or function as a sink for carbon and nutrients.2. determine if there are seasonal variations in flux rates and directions3. determine whether seasonal variations could be related to climatic factors

1982年12月至1984年7月期间，研究人员在欣钦布鲁克岛（Hinchinbrook Island）珊瑚溪（Coral Creek）河口附近采集水样，测量其中溶解有机和无机物质的浓度。在此期间，采样工作以1-2个月为间隔，共覆盖16个潮汐周期。对于每个12小时的潮汐周期，研究人员每半小时在河道内不同深度或位置采集水样。1984年7月，采样工作在连续两个潮汐周期内进行。水样采集后立即过滤、冷冻，并在1-2周内完成分析。溶解有机碳（Dissolved Organic Carbon, DOC）分析采用薄膜紫外氧化法；无机营养物（铵、硝酸盐、亚硝酸盐和磷酸盐）分析采用自动分析仪。溶解有机氮（Dissolved Organic Nitrogen, DON）和溶解有机磷（Dissolved Organic Phosphorus, DOP）分析的步骤为：先将样品在光消化装置中消化12小时，再分析其中的硝酸盐、亚硝酸盐或磷酸盐；随后减去仅针对无机营养物分析时测得的浓度，从而得到有机氮和有机磷的浓度。研究期间，在采样站附近的河道边缘、红树林冠层上方架设了一台Microdata气象站，每30分钟测量一次降雨量、湿度、太阳辐射、空气温度、泥温（泥面以下30厘米）、风速和风向。本研究的目的在于：1. 确定红树林是邻近沿海水域和底栖生境中碳、氮、磷的来源，还是碳和营养物的汇；2. 探究通量率和方向是否存在季节变化；3. 验证上述季节变化是否与气候因素相关。