Karst wetland is a special, complex and fragile type of wetland. With increasing economic and agricultural activities, the negative impacts of human activities on water quality particularly on karst wetland is also increasing. In this paper multiple datasets and methods including hydrological, hydrochemical and stable isotope data were used to elucidate the distribution and transport of nitrate pollution in Huixian karst wetland under the influence of seasonal hydrodynamic changes and human activities. Hydrodynamic conditions around the wetland during both wet and dry seasons show large differences due to the complex exchange between surface water and groundwater. The northern recharge area receives rainfall recharge with rapid responses in groundwater level, temperature and electrical conductivity, while those responses are relatively stable in the central area where the surface water interacts with groundwater frequently. However, their diurnal variations are significant. In the western drainage area where groundwater always discharges to rivers, the groundwater levels show sharp responses after rainfall, but their temperatures are stable. In addition, δ¹⁵N and δ¹⁸O of nitrate suggest that the nitrate pollution mainly comes from NH₄⁺ in fertilizer and rainfall, soil nitrogen, animal feces and livestock manure. The nitrate concentrations of most surface waters are lower during the wet season, affected by the dilution and mixing effect of heavy rainfall and agricultural activities. Nitrate distributions show considerable spatial variability during the dry season, especially in the wells located in residential areas which are mainly polluted by nearby residents. This study highlights the vulnerability of karst wetlands and presents methods that are significant for ecological restoration as well as development of karst water resources in karst areas.

喀斯特湿地是一种特殊，复杂和脆弱的湿地。随着经济和农业活动的增加，人类活动对水质特别是对喀斯特湿地的负面影响也在增加。本文利用水文，水化学和稳定同位素数据等多种数据集和方法阐明了辉县喀斯特湿地中季节性水动力变化和人类活动的影响下硝酸盐污染的分布和迁移。由于地表水和地下水之间的复杂交换，在湿季和干季期间湿地周围的水动力条件显示出很大的差异。北部补给区接受降雨补给，对地下水位，温度和电导率具有快速响应，而在地表水与地下水频繁相互作用的中部地区，这些响应相对稳定。但是，它们的日变化很大。在地下水总是流向河流的西部流域，降雨后地下水位显示出尖锐的响应，但它们的温度是稳定的。另外，δ¹⁵ N和δ ¹⁸硝酸盐的O-表明硝酸盐污染主要来自NH ₄ ⁺化肥和降雨量，土壤氮，动物粪便和牲畜粪便。在雨季，大多数地表水的硝酸盐浓度较低，这受暴雨和农业活动的稀释和混合作用的影响。硝酸盐分布在干旱季节表现出相当大的空间变化，特别是在居住区的水井中，这些井主要受到附近居民的污染。这项研究突出了喀斯特湿地的脆弱性，并提出了对喀斯特地区的生态恢复以及喀斯特水资源开发具有重要意义的方法。