This study investigated the export of dissolved iron (DFe) from river catchments with emphasis on land use and land cover (LULC). The DFe concentrations were measured at 61 and 63 sites during summer and winter, respectively, in the Kitakami Mountain in northeast Japan. LULC was classified as broadleaf forest, conifer, grassland, paddy field, cropland, and urban area using GRASS GIS software. In the downstream areas, the riverine DFe concentrations ranged from 0.84 to 115 μg/L and from 1.5 to 103 μg/L in winter and summer, respectively, whereas the DFe in the upstream areas ranged from 0.16 to 7.6 μg/L and from 1.1 to 20.0 μg/L. Regression analysis was applied to the DFe and LULC data, and the unit load for DFe was estimated for each LULC type, the unit load values being 1.6, 139, and 439 g/km²/day for broadleaf forest, paddy fields, and urban area, respectively, in winter and 61.9, 564, and 727 g/km²/day for grassland, paddy fields, and urban area, respectively, in summer, reflecting the impact of distinct seasonality. A significant positive correlation was found between urban area and riverine DFe concentration in each season, emphasizing the influence of human activity on DFe export to river catchments. Overall, our investigation provides a series of quantitative evidence showing the importance of LULC to understand DFe export from river catchments.

这项研究调查了河流集水区的溶解铁（DFe）出口，重点是土地利用和土地覆盖（LULC）。在夏季和冬季，分别在日本东北的北上市山中测量了61处和63处的DFe浓度。使用GRASS GIS软件将LULC分为阔叶林，针叶树，草地，稻田，农田和市区。在下游地区，冬季和夏季的河流DFe浓度范围分别为0.84至115μg/ L和1.5至103μg/ L，而上游地区的DFe浓度范围为0.16至7.6μg/ L和1.1至20.0μg/ L。对DFe和LULC数据进行回归分析，并针对每种LULC类型估计DFe的单位负荷，单位负荷值为1.6、139和439 g / km ²冬季阔叶林，稻田和市区的日/天，夏季分别为61.9、564和727 g / km ² /天，夏季草地，稻田和市区的日/天，反映了季节性。在每个季节，市区和河流中的DFe浓度之间存在显着的正相关关系，强调了人类活动对向河流集水区出口DFe的影响。总体而言，我们的调查提供了一系列定量证据，显示了LULC对于了解河流集水区DFe出口的重要性。