This study quantified the bioavailable nitrogen contribution from riverine plumes to Great Barrier Reef (GBR) coastal environments. The potential bioavailable nitrogen from two Dry Tropics riverine plumes was considerable [9 - 30% added to the end-of-catchment dissolved inorganic nitrogen (DIN) load]. Particulate inorganic nitrogen conversion to DIN was an important process in short timeframes (25% to 100% of the generated load). The remaining load was contributed by microbial mineralisation of organic nitrogen. Flood plume sediment has potential to generate nitrogen once deposited and/or resuspended. Nitrogen generation was insignificant in a few plumes where immobilisation of nitrogen in bacteria biomass occurred. The source of organic matter in the plumes and availability of nitrogen relative to organic matter were important determinants of mineralisation/immobilisation. This research demonstrates that riverine plumes have potential to be considerable sources of bioavailable nitrogen to coastal environments of the GBR and that organic matter is a key bioavailability driver.

这项研究量化了河流羽流对大堡礁 (GBR) 沿海环境的生物可利用氮的贡献。来自两个干热带河流羽流的潜在生物可利用氮相当可观 [9 - 30% 添加到流域末端溶解无机氮 (DIN) 负荷中]。将颗粒无机氮转化为 DIN 是一个在短时间内（产生负荷的 25% 到 100%）的重要过程。剩余的负荷由有机氮的微生物矿化贡献。洪水羽状沉积物一旦沉积和/或重新悬浮，就有可能产生氮。在细菌生物质中发生氮固定的一些羽流中，氮的产生是微不足道的。羽流中有机物的来源和氮相对于有机物的可用性是矿化/固定化的重要决定因素。这项研究表明，河流羽流有可能成为大堡礁沿海环境中生物可利用氮的重要来源，并且有机物质是关键的生物利用度驱动因素。