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首页> 外文期刊>Marine Chemistry >Temporal variability in the composition and abundance of terrestrially-derived dissolved organic matter in the lower Mississippi and Pearl Rivers
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Temporal variability in the composition and abundance of terrestrially-derived dissolved organic matter in the lower Mississippi and Pearl Rivers

机译：密西西比河下游和珠江三角洲陆源性溶解有机物的组成和丰度随时间变化

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摘要

Here we report on temporal changes in the concentration and composition of lignin phenols in high molecular weight ( < 0.2 μm, > 1 kDa) dissolved organic matter (HMW DOM) collected from the lower Mississippi and Pearl Rivers (MR and PR) (USA). Monthly water samples were collected at a station in the lower reach in each river from August 2001 to August 2003. Significantly higher concentrations of lignin and Λ_8 values (mg lignin phenols in 100 mg organic carbon) in the Pearl River than in the Mississippi River, reflected sporadic inputs of terrestrial DOM during rainstorm events from wetlands and forest soils. Larger seasonal variations in lignin concentration and composition in the Pearl River, compared to the Mississippi River, were attributed to shifts in organic matter sources from topsoil inputs during rainstorm events to groundwater inputs and in situ production during base flow in this small river. Conversely, lower Λ_8 and vanillic acid to vanillin ratios [(Ad/Al)v] in the HMW DOM of the lower Mississippi River may be a result of a lower export rate of lignin from agricultural soils due to lower carbon storage in the expansive agricultural systems of the Mississippi River watershed, as well as dilution of phytoplankton DOM inputs. Large seasonal changes in lignin concentration and Λ_8 (linked at times with river discharge), and minimal variability in the composition of lignin phenols, likely represented an integrated signal of soil-derived vascular inputs from the upstream drainage basin. If we are to better understand the controls of organic matter delivery to the coastal zone from both small and large rivers, sampling strategies need to be adjusted to account for the different scales of hydrologic response time and in situ processing associated with different residence times.
机译：在这里，我们报告了从密西西比河下游和珠江三角洲（MR和PR）（美国）收集的高分子量（<0.2μm，> 1 kDa）溶解性有机物（HMW DOM）中木质素酚的浓度和组成的时间变化。 。从2001年8月至2003年8月，在每条河的下游的一个站点每月采集水样本。与密西西比河相比，珠江的木质素和Λ_8值（100毫克有机碳中的木质素酚毫克）浓度明显更高，反映了湿地和森林土壤在暴雨期间陆地DOM的零星输入。与密西西比河相比，珠江中木质素浓度和组成的季节性变化更大，这归因于有机物质源从暴雨事件中的表土输入到地下水输入以及在这条小河基流期间的原位生产的变化。相反，密西西比河下游HMW DOM中较低的Λ_8和香草酸与香兰素之比[（Ad / Al）v]较低，可能是由于扩张性农业中碳储量较低，导致了农业土壤中木质素的出口率降低。密西西比河流域的系统，以及浮游植物DOM输入的稀释。木质素浓度和Λ_8的季节性大变化（有时与河流流量相关），木质素酚的组成变化最小，可能代表了来自上游流域的土壤源性血管输入的综合信号。如果我们要更好地理解从小河流和大河流向沿海地区输送有机物的控制方法，则需要调整采样策略，以考虑到水文响应时间的不同规模以及与不同停留时间相关的原位处理。

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