研究Data.xlsx

土地利用在调节降雨径流过程和改变径流氮的运输途径方面起着至关重要的作用。以前关于山坡氮损失的研究大多集中在地表水上，而忽视了地下水的作用。同时，土地利用对多界面径流对氮损失的影响仍然知之甚少，尤其是在脆弱的喀斯特生态系统中。我们研究中使用的原位监测为土地利用、多界面径流和环境因素如何影响径流氮损失提供了新的视角。它可能对喀斯特地区的生态稳定和管理具有重要意义。本研究通过监测地表流 （SF）、地（SSF） 和表层岩溶渗流 （ESF） 中的流量和氮 （TN、NO3--N 和 NH4+-N） 浓度，研究了岩溶山坡径流氮的损失动态。在山坡中选择了 3 种不同的典型土地利用 （灌木丛 （SL）、牧草地 （GL） 和开垦农田 （CL））。因此，我们研究了不同土地利用对喀斯特山坡多界面径流氮损失的影响。我们还分析了控制喀斯特地区径流氮损失的土壤性质和环境因素。结果表明，CL 的年平均径流氮损失最高，其次是 SL 和 GL。与 CL 相比，SL 和 GL 均使径流系数分别降低了 48.55% 和 51.58%，导致 TN 损失分别降低了 58.83% 和 65.08%。这些表明，由牧草种植驱动的径流减少显着减少了 TN 损失。此外，地下径流在径流中的氮损失中起着关键作用。具体而言，SSF 占 CL 总径流氮损失的 50.79% 以上，而 ESF 是 SL 和 GL 的主要途径，贡献超过 53.32%。在大暴雨期间 （&gt; 100 mm/d），CL 中通过 SSF 和 ESF 的 TN 损失分别为 SF 的 3.50 和 1.80 倍 （P &lt; 0.05）。有趣的是，大型暴雨并没有产生最高浓度的 NO3-N 和 TN，但导致 NO3-N 和 TN 的损失最大，强调径流量而不是氮浓度在氮损失中起主导作用。相关性分析进一步表明，土地利用显著改变了土壤特性与径流养分损失之间的关系，尤其是在土壤淤泥含量和钙离子浓度方面。这些发现表明，填海土地加剧了氮通过地途径的损失，表明喀斯特地区的地下水污染风险升高。Land use plays a crucial role in regulating rainfall runoff processes and altering nitrogen transport pathways in runoff. Most previous studies on hillslope nitrogen loss have focused on surface water, ignoring the role of groundwater. Meanwhile, knowledge gaps remain regarding the impacts of land use on multi-interface runoff-driven nitrogen loss, particularly in fragile karst ecosystems. The in-situ monitoring employed in this study provides novel insights into how land use, multi-interface runoff, and environmental factors affect runoff nitrogen loss, which may hold significant implications for ecological stability and management in karst regions. This study investigated the dynamics of runoff nitrogen loss on karst hillslopes by monitoring flow rates and nitrogen concentrations (Total Nitrogen [TN], nitrate nitrogen [NO3--N], and ammonium nitrogen [NH4+-N]) in surface flow (SF), shallow subsurface flow (SSF), and epikarst seepage flow (ESF). Three typical land uses were selected on the hillslope: shrubland (SL), grassland (GL), and cropland (CL). We thus examined the effects of different land uses on multi-interface runoff-driven nitrogen loss in karst hillslopes. We also analyzed the soil properties and environmental factors governing runoff nitrogen loss in karst regions. The results demonstrated that cropland (CL) exhibited the highest annual average runoff nitrogen loss, followed by shrubland (SL) and grassland (GL). Compared with CL, both SL and GL reduced runoff coefficients by 48.55% and 51.58% respectively, resulting in 58.83% and 65.08% reductions in TN loss, respectively. These findings indicate that runoff reduction driven by pasture cultivation significantly mitigates TN loss. Furthermore, subsurface runoff plays a critical role in runoff nitrogen loss. Specifically, SSF accounted for more than 50.79% of the total runoff nitrogen loss in CL, while ESF served as the primary pathway for SL and GL, contributing over 53.32%. During heavy rainfall events (>100 mm/d), TN loss via SSF and ESF in CL was 3.50 and 1.80 times that of SF, respectively (P < 0.05). Notably, heavy rainfall events did not yield the highest concentrations of NO3--N and TN, but resulted in the greatest nitrogen losses, highlighting that runoff volume rather than nitrogen concentration plays a dominant role in nitrogen loss. Correlation analysis further revealed that land use significantly altered the relationships between soil properties and runoff nutrient loss, particularly with respect to soil silt content and calcium ion concentration. These findings suggest that reclaimed cropland exacerbates nitrogen loss via subsurface pathways, indicating elevated risks of groundwater pollution in karst regions.