Numerous ponds were constructed along streams for local water supply in agricultural areas of south-western France. Although the water quality of streams and ponds has been surveyed for nitrate (NO₃⁻), the role of ponds in NO₃⁻ mitigation at a catchment scale has rarely been investigated. Since denitrification in sediments is a key NO₃⁻ pathway, the denitrification variability in stream and pond sediments and its controlling factors, particularly the pond position and characteristics are important aspects to investigate. Potential denitrification rate (PDR), physico-chemical factors, and denitrification functional genes were quantified in sediments from nine ponds located in three adjacent agricultural catchments in spring period. PDR showed a great spatial variation (both horizontal and vertical) and was mainly driven by the availability of water NO₃⁻ and sediment organic carbon. Stream discharge and pond hydraulic retention time can also affect PDR in stream and pond sediments, respectively. Although high PDR was observed in stream sediments, stream discharge diluted NO₃⁻ and can indirectly lower PDR downstream. The function of denitrifiers was revealed by the abundance ratio of nirK/16S rRNA, but no significant relationship was found between PDR and abundance of functional genes. N₂O emission rate was positively related to PDR, which should be aware of in the upstream PDR hotspot ponds. Simple empirical models based on pond and sediment characteristics were good predictors of PDR, which could also help a better management of ponds by policy makers with the aim to improve NO₃⁻ mitigation and water quality.

在法国西南部的农业区，沿着溪流建造了许多池塘，用于当地供水。尽管已经对溪流和池塘的水质进行了硝酸盐 (NO ₃ ^- )调查，但很少研究池塘在流域规模的NO ₃ ^-减缓中的作用。由于沉积物中的反硝化作用是关键的 NO ₃ ^-路径、河流和池塘沉积物的反硝化变异性及其控制因素，特别是池塘位置和特征是研究的重要方面。在春季期间，对位于三个相邻农业集水区的 9 个池塘的沉积物中的潜在反硝化率 (PDR)、物理化学因素和反硝化功能基因进行了量化。PDR 显示出很大的空间变化（水平和垂直），主要受水NO ₃ ^-和沉积物有机碳的可用性驱动。河流排放和池塘水力停留时间也会分别影响河流和池塘沉积物中的 PDR。虽然在河流沉积物中观察到高 PDR，但河流排放稀释了 NO ₃ ^-并且可以间接降低下游的 PDR。通过nirK/16S rRNA的丰度比揭示反硝化菌的功能，但未发现PDR与功能基因丰度之间存在显着关系。N ₂ O 排放率与PDR 呈正相关，在上游PDR 热点池中应注意这一点。基于池塘和沉积物特征的简单经验模型是 PDR 的良好预测指标，这也有助于政策制定者更好地管理池塘，以改善 NO ₃ ^-减排和水质。