Horticultural peat extraction can mobilize dissolved organic matter (DOM) and inorganic nutrients (nitrogen and phosphorous) to surface waters, harming aquatic ecosystems and water quality. However, it is uncertain how peat extraction affects solute concentration across hydrological and seasonal conditions and how biogeochemical processing in downstream drainage networks responds. Over two years, we used repeated, spatially extensive sampling in stream networks of two mixed land-use catchments (<200 km²) on the subhumid interior plains of western Canada. We used random forest models to disentangle the effects of land cover, hydrology, and temperature on water chemistry. Peatlands were the dominant source of DOM to streams, but we detected no substantial effect of peat extraction on DOM concentration or composition. Stream discharge was the most important predictor of DOM composition, with generally humic-like DOM becoming fresher during snowmelt and summer base flow. We detected no effect from peat extraction on soluble reactive phosphorous (SRP) or nitrate (NO₃⁻). However, total ammonia nitrogen (TAN) was an order of magnitude higher in subcatchments with >40% extracted peatland cover (median: 1.5 mg TAN L⁻¹) compared to catchments with similar intact peatland cover. Mass balance analysis suggested that DOM and inorganic nutrients synchronously attenuated during low flows. During high flows, DOM and inorganic nitrogen were conservatively transported, while SRP was attenuated, likely sorbing to suspended particles. Our study suggests that excess TAN mobilized by peat extraction is utilized in headwaters during low flow but propagates downstream during high flow, with implications for eutrophication that land managers should consider.

中文翻译：

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泥炭提取对下游溶解有机碳和养分浓度和衰减的影响


园艺泥炭提取可以将溶解的有机物（DOM）和无机养分（氮和磷）转移到地表水中，损害水生生态系统和水质。然而，目前尚不清楚泥炭开采如何影响水文和季节条件下的溶质浓度以及下游排水网络中的生物地球化学处理如何响应。两年多来，我们在加拿大西部半湿润内陆平原的两个混合土地利用集水区 (<200 id=0>2 ) 的河流网络中进行了重复的、空间广泛的采样。我们使用随机森林模型来阐明土地覆盖、水文和温度对水化学的影响。泥炭地是溪流中 DOM 的主要来源，但我们检测到泥炭提取对 DOM 浓度或组成没有实质性影响。河流流量是 DOM 组成最重要的预测因子，一般腐殖质类 DOM 在融雪和夏季基流期间变得更新鲜。我们检测到泥炭提取对可溶性活性磷 (SRP) 或硝酸盐 (NO ₃ ^- ) 没有影响。然而，与具有类似完整泥炭地覆盖的流域相比，在提取泥炭地覆盖率 >40% 的子流域（中位数：1.5 mg TAN L ^-1 ）中，总氨氮（TAN）要高一个数量级。质量平衡分析表明，DOM 和无机养分在低流量期间同步衰减。在高流量期间，DOM 和无机氮被保守地输送，而 SRP 被减弱，可能吸附到悬浮颗粒上。 我们的研究表明，泥炭开采产生的过量 TAN 在低流量时被利用在源头，但在高流量时会向下游传播，土地管理者应考虑对富营养化的影响。