Amino acids (AA), including the bacterial D-enantiomers (D-AA), and bacterial muramic acid were quantified in bulk particulate and dissolved organic matter (POM and DOM) from the St. Lawrence system (Canada). These tools were used to reveal the origin of POM and DOM and their mechanisms of formation and transformation across the sediment-water interface. Results show that pore waters were much more enriched in DOM and AA (6 to 25 times) than deep waters. Pore waters are thus a source of DOM and AA (e.g., in proteins, peptides) to the sediment-water interface. AA represented 1.4 to 6.6% of bulk DOC in pore waters and thus most of the DOM compounds diffusing out of the sediments do not contain AA. Estimated AA pore water fluxes were between 32 and 141 μmol C m⁻²d⁻¹ with lower values at the downstream locations. The correlations measured between AA concentrations in pore waters and deep waters, the compositional similarities between pore water DOM and deep-water DOM and their relatively altered state (measured with different diagenetic markers) suggest that a large fraction of the DOM released from the pore waters, including some AA-containing compounds, is not rapidly mineralized in the water column. Pore water DOM and deep-water DOM were the two sample types having the most similar composition when 31 parameters were considered. This similarity steadily increases downstream. Local conditions, such as POM inputs, redox conditions, and sediment mineralogy, seem to control the sediment's capacity for producing pore water AA and DOM. The C-normalized yields of the specific bacterial biomarkers and the correlations with AA yields suggest that bacteria are the major contributors to AA and to changes in POM and pore water DOM composition. In addition to the direct diffusion of altered and recalcitrant DOM out of the sediment, pore waters also provide less altered compounds, such as AA-containing structures, that can survive in the water column when the conditions are unfavorable to degradation (e.g., hypoxia) or be transformed into more recalcitrant DOM. This study suggests, based on different molecular and bulk parameters, that sediments have an important impact on the concentration and composition of the DOM persisting in deep waters.

对来自圣劳伦斯系统（加拿大）的大颗粒和溶解有机物（POM和DOM）中的氨基酸（AA）（包括细菌D-对映体（D-AA）和细菌性山寨酸）进行了定量。这些工具被用来揭示POM和DOM的起源，以及它们在沉积物-水界面上的形成和转化机理。结果表明，与深水相比，孔隙水中的DOM和AA含量更高（6至25倍）。因此，孔隙水是沉积物-水界面的DOM和AA的来源（例如，蛋白质，肽类）。AA占孔隙水中总DOC的1.4％至6.6％，因此从沉积物中扩散出来的大多数DOM化合物都不含AA。估计的AA孔隙水通量在32和141μmolC m ^-2 d ^-1之间在下游位置具有较低的值。孔隙水和深水中AA浓度之间的相关性，孔隙水DOM和深水DOM之间的组成相似性以及它们相对变化的状态（用不同的成岩标记测量）之间的相关性表明，大部分DOM从孔隙水中释放出来，包括一些含AA的化合物，不会在水柱中快速矿化。当考虑31个参数时，孔隙水DOM和深水DOM是组成最相似的两种样品类型。这种相似性在下游稳步提高。当地条件，例如POM输入，氧化还原条件和沉积物矿物学似乎控制着沉积物产生孔隙水AA和DOM的能力。特定细菌生物标志物的C标准化产量以及与AA产量的相关性表明，细菌是AA以及POM和孔隙水DOM组成变化的主要贡献者。除了变化的和顽固的DOM从沉积物中直接扩散外，孔隙水还提供了变化较小的化合物，例如含AA的结构，当条件不利于降解（例如低氧）时，它们可以在水柱中生存。或转化为更顽固的DOM。这项研究表明，基于不同的分子和体积参数，沉积物对深水中持久性有机污染物的浓度和组成具有重要影响。