Sediments collected within freshwater, estuarine and marine habitats were used to trial various chemical and physical pre-treatments to develop a systematic protocol for grain-size analysis using laser diffraction. Application of this protocol mitigates the influence of bio-physical processes that may transform grain-size distributions, enabling the characterisation and quantification of ‘primary’ mineral sediments across the complex freshwater-marine continuum to be more reliably assessed. Application of the protocol to two Great Barrier Reef (Australia) river catchments and their estuaries reveals the ecologically relevant <20 μm fraction comprises a larger component of exported sediment than existing methods indicate. These findings are highly relevant when comparing measured data to grain-size-specific modelled sediment loads and water-quality targets. Finally, adoption of the protocol also improves the environmental interpretation of the influence of ‘terrigenous sediment’ in marine settings, including quantification of newly-delivered flood plume sediment.

淡水，河口和海洋生境中收集的沉积物被用于试验各种化学和物理预处理方法，以开发使用激光衍射进行粒度分析的系统协议。该协议的应用减轻了可能改变晶粒尺寸分布的生物物理过程的影响，从而能够更可靠地评估整个复杂的淡水-海洋连续体中“主要”矿物沉积物的表征和定量。该方案在两个大堡礁（澳大利亚）河流流域及其河口的应用表明，与生态相关的<20μm分数包括比现有方法所表明的更大的出口沉积物成分。在将测量数据与特定于粒度的模拟沉积物负荷和水质目标进行比较时，这些发现具有高度相关性。最后，该协议的采用还改善了对“陆源沉积物”在海洋环境中影响的环境解释，包括对新交付的洪水羽状沉积物的量化。