Stormwater wet ponds (SWPs) are engineered structures used to collect and retain stormwater runoff from developed areas. SWPs are generally regarded as important nitrogen (N) sinks, but seasonal variation in SWP N cycling that influences pond nitrogen removal has not been characterized. To inform SWP function across seasons, we sampled the sediments and water columns of three stormwater ponds in the southeastern US coastal plain and measured gas and nutrient fluxes from the sediment-water interface during ambient conditions and nitrate (NO₃)-enriched “simulated storm” conditions. Dissolved organic nitrogen (DON) was the dominant form of dissolved N in the water column, while nitrate + nitrite (NO_x) was typically below detection. SWP sediment organic matter properties varied by study site but had minimal impact on sediment N processes or estimated NO₃ fate. SWP sediments generally functioned as TN sinks during NO₃-enriched conditions, but the estimated fate of NO₃ varied based on water temperature, DON concentrations, and sediment O₂ uptake. These results suggest that permanent N removal (denitrification) by SWPs varies seasonally, with retention of NO_x becoming more important during hotter conditions when NO_x uptake is largest. Low ambient NO_x concentrations and rapid NO₃ uptake suggest that coastal stormwater ponds can host reduced conditions that may promote NO₃ retention over denitrification. Additional research is needed to determine the fate of retained NO₃ in SWP sediments and how variation in NO₃ fate might impact downstream water quality.

中文翻译：

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沿海雨水池硝酸盐去除机制的季节性变化

雨水湿池 (SWP) 是用于收集和保留来自发达地区的雨水径流的工程结构。SWPs 通常被认为是重要的氮 (N) 汇，但影响池塘氮去除的 SWP N 循环的季节性变化尚未表征。为了告知跨季节的 SWP 功能，我们对美国东南部沿海平原的三个雨水池的沉积物和水柱进行了采样，并测量了环境条件下沉积物 - 水界面的气体和养分通量以及富含硝酸盐 (NO ₃ ) 的“模拟风暴” “ 状况。溶解有机氮 (DON) 是水体中溶解 N 的主要形式，而硝酸盐 + 亚硝酸盐 (NO _x) 通常低于检测。SWP 沉积物有机质特性因研究地点而异，但对沉积物 N 过程或估计的 NO ₃命运影响最小。NO期间SWP沉积物通常充当TN水槽₃富集的条件下，但NO的估计的命运₃向变基于水的温度，DON浓度，和沉积物Ò ₂摄取。这些结果表明，永久N的去除（脱硝）通过SWPS季节而异，没有保留_X在炎热的条件变得越来越重要时，NO _X吸收是最大的。低环境 NO _x浓度和快速 NO ₃吸收表明沿海雨水池可以容纳可能促进NO ₃保留而不是反硝化作用的减少条件。需要进一步研究以确定SWP 沉积物中保留的 NO ₃的归宿以及 NO ₃归宿的变化如何影响下游水质。