Absorbance and fluorescence properties of dissolved organic matter (DOM) were measured in the upper and lower polar mixed layer (UPML and LPML, respectively) over an 11‐year period (2007–2017) to assess for yearly changes in the quality and quantity of colored and fluorescent DOM (CDOM and FDOM, respectively) in relation with sea ice concentration in central Canada Basin waters. The LPML waters were enriched in CDOM, total dissolved lignin phenols, terrestrial humic‐like C1, and in microbial humic‐like C2 and C7 relative to the UPML waters (p > 0.05). The low ice years (i.e., 2012, 2016–2017) were characterized by lower humic‐like fluorescence intensity (C4 only) and abundances relative to high ice years (i.e., 2007–2011, 2013–2015), likely the result of the preferential photoalteration of humic material when sea ice concentration was reduced. Significant time increases were found in tryptophan‐like C3 in UPML and terrestrially derived humic‐like C4 in LPML, suggesting an increase in the proteinaceous and terrigenous character of FDOM in UPML and LPML during the 11‐year period, respectively. No interannual variation in dissolved organic carbon concentration was found in LPML and UPML. Weak but positive Spearman correlations were found between the humic‐like intensities and abundances, and sea ice concentration in UPML waters, a consequence of reduced photodegradation in ice covered waters. This 11‐year survey provides the first insight into the influence of summer sea ice concentration and river runoff on the quality and quantity of CDOM and FDOM.

中文翻译：

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北冰洋加拿大盆地中溶解有机物组成的长期趋势及其与海冰的关系（2007–2017）

在过去11年（2007-2017年）内，在上极性混合层和下极性混合层（分别为UPML和LPML）中测量了溶解有机物（DOM）的吸光度和荧光性质，以评估其质量和数量的年度变化彩色和荧光DOM（分别为CDOM和FDOM）与加拿大盆地中部海域海冰浓度的关系。相对于UPML水，LPML水富含CDOM，总溶解的木质素酚，陆地腐殖质C1以及微生物腐殖质C2和C7（p > 0.05）。低冰期（即2012、2016–2017）的特征是腐殖质样荧光强度较低（仅C4），相对于高冰期（即2007–2011、2013–2015），丰度较高。降低海冰浓度时，腐殖质的优先光交换作用。在UPML中色氨酸样C3和在LPML中陆地衍生的腐殖质样C4中，时间显着增加，这表明UPML和LPML中FDOM的蛋白质和陆源特性分别在11年期间增加。在LPML和UPML中未发现溶解有机碳浓度的年际变化。发现在腐殖质样强度和丰度与UPML水域中海冰浓度之间存在弱但正的Spearman相关性，冰覆盖水域中光降解减少的结果。这项为期11年的调查首次了解了夏季海冰浓度和河流径流对CDOM和FDOM的质量和数量的影响。