LCZO -- Stream Suspended Sediment, Streamflow / Discharge, Precipitation -- riverine particulate organic matter export -- Rio Mameyes and Rio Icacos -- (1991-2015)

Erosion, transport and deposition of riverine suspended load are pivotal processes in the terrestrial carbon cycle and function of the critical zone. In order to better understand the response of these drivers to changes in land cover and climate, it is critical to characterize these drivers. In montane rivers, such as the Luquillo Mountains, Puerto Rico, extreme storm events erode and transport clastic and organic material from mountain slopes to rivers, dominating annual export. Riverine particulate organic carbon (POC) and particulate nitrogen (PN) exports are not as well understood, especially at high runoff rates. Over 25 years, river POC export was 75±20 tC km-2 yr-1 for Rio Icacos and 22±8 tC km-2 yr-1 for the Mameyes. Caribbean river POC yields were higher in relation to their SS yields, suggesting that these rivers have greater terrestrial OM supply on the landscape to be eroded and transported into rivers, than what is expected based on data for world rivers. Additionally, we determined that 50% of the suspended load flux occurred during extreme rainfall events, spanning just over 2 days a year, but only exporting < 10% of the annual runoff and rainfall. These results emphasize the important role of extreme rainfall events as drivers of POM export from the Luquillo Mountains.

河流侵蚀、悬浮物质的运输与沉积是陆地碳循环及临界带功能中的关键过程。为了更深入地理解这些驱动因素对土地利用变化和气候变化的响应，对其特征进行描述至关重要。在山地河流中，如波多黎各的卢基洛山脉，极端风暴事件会侵蚀和运输来自山坡的碎屑和有机物质进入河流，从而主导年度输出。河流悬浮颗粒有机碳（POC）和悬浮颗粒氮（PN）的输出并不十分明确，尤其是在高径流速率下。在超过25年的时间里，里奥伊卡科斯河的河流POC输出为75±20吨碳公里-2年-1，而马梅耶斯河为22±8吨碳公里-2年-1。与他们的悬浮物（SS）产量相比，加勒比海河流的POC产量更高，这表明这些河流在景观上具有更大的陆地有机质（OM）供应，能够被侵蚀并运输到河流中，这一供应量超过了基于世界河流数据预期的水平。此外，我们确定50%的悬浮负荷通量发生在极端降雨事件中，这些事件每年仅持续超过2天，但仅输出年度径流和降雨的不到10%。这些结果强调了极端降雨事件作为卢基洛山脉POM输出驱动因素的重要作用。