This study investigated the consumption of oxygen (O₂) in 11 European lakes ranging from 48 m to 372 m deep. In lakes less than ~ 100 m deep, the main pathways for O₂ consumption were organic matter (OM) mineralization at the sediment surface and oxidation of reduced compounds diffusing up from the sediment. In deeper lakes, mineralization of OM transported through the water column to the sediment represented a greater proportion of O₂ consumption. This process predominated in the most productive lakes but declined with decreasing total phosphorous (TP) concentrations and hence primary production, when TP concentrations fell below a threshold value of ~ 10 mg P m⁻³. Oxygen uptake by the sediment and the flux of reduced compounds from the sediment in these deep lakes were 7.9–10.6 and 0.6–3.6 mmol m⁻² d⁻¹, respectively. These parameters did not depend on the lake's trophic state but did depend on sedimentation rates for the primarily allochthonous or already degraded OM. These results indicate that in lakes deeper than ~ 100 m, mineralization of autochthonous OM is mostly complete by the time of sedimentary burial. This explains why hypolimnetic O₂ concentrations improve more rapidly following TP load reduction in deeper lakes relative to shallower lakes, where larger sediment‐based O₂ consumption by settled OM and release of reduced substances may inhibit the restoration of hypolimnetic O₂ concentrations.

中文翻译：

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湖泊深层的降政治氧耗竭率：营养状态和有机质积累的影响

这项研究调查了11个欧洲湖泊中的氧气（O ₂）消耗，深度从48 m到372 m不等。在小于约100 m的湖泊中，消耗O ₂的主要途径是沉积物表面的有机物（OM）矿化和从沉积物中扩散出来的还原性化合物的氧化。在更深的湖泊中，通过水柱传输到沉积物的OM矿化占O ₂消耗的比例更大。该过程在生产力最高的湖泊中占主导地位，但随着总磷（TP）浓度的降低而降低，从而下降，因此当TP浓度降至〜10 mg P m ^-3的阈值以下时。在这些深湖中，沉积物对氧气的吸收和沉积物中还原性化合物的通量分别为7.9–10.6和0.6–3.6 mmol m ^-2 d ^-1。这些参数不取决于湖泊的营养状态，但取决于主要为异源或已退化的OM的沉积速率。这些结果表明，在深于〜100 m的湖泊中，到土体OM的矿化到沉积埋藏时已基本完成。这就解释了为什么深层湖泊中的TP浓度降低后，低层湖泊中的O ₂浓度相对于浅层湖泊会更快地提高，因为沉降的OM消耗大量基于沉积物的O ₂以及还原物质的释放可能会抑制低层湖泊O的恢复。₂浓度。