Preferential Removal of Dissolved Carbohydrates During Estuarine Mixing in the Bay of Saint Louis in the Northern Gulf of Mexico
Preferential Removal of Dissolved Carbohydrates During Estuarine Mixing in the Bay of Saint Louis in the Northern Gulf of Mexico
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DOI：
10.1016/j.marchem.2010.01.006
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发表时间：
2010-04
期刊：
影响因子：
3
通讯作者：
Xuri Wang;Yihua Cai;Laodong Guo
中科院分区：
文献类型：
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作者：
Xuri Wang;Yihua Cai;Laodong Guo
从墨西哥湾北部的圣路易斯湾 (BSL) 河口采集水样，以研究溶解有机碳 (DOC) 和总溶解碳水化合物 (TCHO) 的丰度、分布和混合行为。还进行了实验室实验来研究河口混合过程中 DOC 和 TCHO 的去除机制。 DOC 和 TCHO 浓度都随着盐度的增加而降低，在 BSL 中表现出非保守行为，DOC (43%) 和 TCHO (63%) 被大量去除。 TCHO 与 DOC 的比率从河水中的 0.31 到沿海水域的 0.10 不等，随着河口内盐度的增加而降低。与胶体分数为 40-63% 的散装 DOC 相比，>1kDa 胶体分数中的 TCHO 较高，范围为 53% 至 73%（使用超滤渗透模型定量）。沿海水域的胶体相中 CHO/DOC 比率也略有升高，表明 CHO 是原位生产的。实验室实验的结果表明，物理混合导致 5-10% TCHO 的去除，而在孵化实验期间，微生物过程导致 25-30% TCHO 的去除，这表明微生物降解是 BSL 中 CHO 去除的主要机制。然而，物理去除与微生物降解相结合仅占 BSL 中 DOC 和 TCHO 去除量的 30-40%，表明去除量可能被高估和/或其他过程对于河口环境中 DOC 和 CHO 的去除也很重要。现场观察和实验室实验都表明，与散装 DOC 相比，CHO 的去除率始终更高，这支持了我们的假设，即碳水化合物是一种更活跃的有机成分，可以在河口混合过程中优先去除。
Water samples were collected from the Bay of Saint Louis (BSL) estuary in the northern Gulf of Mexico to investigate the abundance, distribution, and mixing behavior of dissolved organic carbon (DOC) and total dissolved carbohydrates (TCHO). Laboratory experiments were also conducted to examine the removal mechanisms of DOC and TCHO during estuarine mixing. Both DOC and TCHO concentrations decreased with increasing salinity, showing a non-conservative behavior in the BSL with considerable removal of DOC (43%) and TCHO (63%). The ratio of TCHO to DOC varied from 0.31 in riverwater to ∼0.10 in coastal waters, decreasing with increasing salinity within the estuary. The TCHO was higher in the >1kDa colloidal fraction, ranging from 53% to 73% as quantified using an ultrafiltration permeation model compared to the bulk DOC that had a colloidal fraction of 40–63%. Coastal waters also had a slightly elevated CHO/DOC ratio in the colloidal phase, suggesting in situ production of CHO. Results from laboratory experiments showed that physical mixing resulted in a removal of 5–10% TCHO, while microbial processes accounted for a removal of up to 25–30% of TCHO during incubation experiments, suggesting that microbial degradation was the primary mechanism responsible for the removal of CHO in the BSL. However, physical removal combined with microbial degradation accounted for only 30–40% of the removal of DOC and TCHO in the BSL, indicating that the removal might be overestimated and/or other processes are also important in the removal of DOC and CHO in the estuarine environment. Both field observations and laboratory experiments demonstrated consistently greater removal of CHO compared to bulk DOC, supporting our hypothesis that carbohydrates are a more active organic component and could be preferentially removed during estuarine mixing.