University of Ljubljana, Faculty of Civil and Geodetic Engineering, Chair of Hydrology and Hydraulic Engineering, Jamova 2, SI-1000 Ljubljana, Slovenia.
University of Ljubljana, Faculty of Civil and Geodetic Engineering, Chair of Hydrology and Hydraulic Engineering, Jamova 2, SI-1000 Ljubljana, Slovenia.
Sci Total Environ. 2017 Jan 1;575:1109-1118. doi: 10.1016/j.scitotenv.2016.09.178. Epub 2016 Sep 28.
During two consecutive years the monitoring of rainfall nitrate (NO) and ammonium (NH) concentrations, combined with high-frequency measurements of streamwater NO concentrations, provided insight into the mechanisms controlling the dissolved inorganic nitrogen (DIN) budgets of the forested Padež stream catchment in SW Slovenia. During both years, the catchment's annual wet atmospheric DIN deposition (12.6 and 13.8kg-N/ha) exceeded the annual DIN export (10.7kg-N/ha and 8.8kg-N/ha). The analysis of the monthly DIN budgets discloses seasonal patterns. In winter and early spring, the catchment behaves as a net source of DIN, whereas during late spring, summer, and early fall the catchment generally behaves as a net sink of the atmospheric DIN. Due to large evapotranspiration in the growth period, most of the DIN remains in the catchment and is flushed during the dormant season. Despite high evapotranspiration and consequently low runoff coefficients characteristic for the Mediterranean climate, large rainfall events in the growth period can cause intensive washout of DIN from the catchment. At a monthly basis, the DIN flushing might exceed the catchment's DIN retention capacity and the catchment might behave as a net source of DIN. Therefore, the hydrological conditions have the ability to shift the catchment's role in regulating the DIN budgets. The high responsiveness of the streamwater NO concentration in the growth period indicates a large pool of DIN in the forest soils which can become mobile by runoff formation. Wet atmospheric DIN deposition at the Padež catchment is considerable; highest DIN inputs can be expected when air masses approach the catchment from the southwest to southeast where there are extensive urban areas along the Italian, Slovenian and Croatian coast. However, the Padež catchment does not appear to be approaching N saturation, presumably due to strong internal N cycle in the forest soils.
在连续两年的时间里，对降雨硝酸盐（NO）和铵（NH）浓度的监测，以及对溪流水中 NO 浓度的高频测量，深入了解了控制斯洛文尼亚西南部 Padež 流域森林区溶解性无机氮（DIN）预算的机制。在这两年中，集水区的年湿大气 DIN 沉积（12.6 和 13.8kg-N/ha）超过了年 DIN 输出（10.7kg-N/ha 和 8.8kg-N/ha）。DIN 月预算分析揭示了季节性模式。在冬季和早春，集水区表现为 DIN 的净源，而在晚春、夏季和初秋，集水区通常表现为大气 DIN 的净汇。由于生长期间的大量蒸散，大部分 DIN 留在集水区内，并在休眠期被冲刷掉。尽管地中海气候的蒸散量高，因此径流量系数低，但生长期间的大雨事件仍可能导致 DIN 从集水区大量冲刷。基于每月的 DIN 冲刷量可能超过集水区的 DIN 保留能力，集水区可能表现为 DIN 的净源。因此，水文条件有能力改变集水区在调节 DIN 预算方面的作用。生长期间溪流水中 NO 浓度的高响应性表明森林土壤中 DIN 储量很大，径流形成时 DIN 可能变得活跃。Padež 集水区的湿大气 DIN 沉积量相当可观；当空气团从西南向东南接近集水区时，DIN 输入量最大，因为意大利、斯洛文尼亚和克罗地亚沿海地区有广泛的城市地区。然而，Padež 集水区似乎没有接近 N 饱和，大概是因为森林土壤中氮的内部循环很强。
