Compositions and constituents of freshwater dissolved organic matter isolated by reverse osmosis

Abstract

a b s t r a c tDissolved organic matter (DOM) from riverine and lacustrine water was isolated using a reverse osmosis (RO) system. Solid-state 13 C nuclear magnetic resonance ( 13 C NMR) was used to quantitatively evaluate the compositions and constituents of DOM, which are compared with previous investigations on marine DOM. Results indicated that concentration factor (CF) was a key metric controlling yield and sorption of DOM on the RO system. The sorption was likely non-selective, based on the 13 C NMR and d 13 C analyses. Carbohydrates and lipids accounted for 25.0-41.5% and 30.2-46.3% of the identifiable DOM, followed by proteins (18.2-19.8%) and lignin (7.17-12.8%). The freshwater DOM contained much higher alkyl and aromatic C but lower alkoxyl and carboxyl C than marine DOM. The structural difference was not completely accounted for by using structure of high molecular weight (HMW) DOM, suggesting a size change involved in transformations of DOM during the transport from rivers to oceans.

Advanced solid-state NMR spectroscopy of natural organic matter

“…One-dimensional solid-state 13 C NMR provides information on the average functional group distribution of carbon in aquatic OM. Solid-state NMR has been used to study spatial and temporal (seasonal) variations of DOM composition [205,[207][208][209][210][211][212][213][214][215][216][217][218], to compare the structure of DOM and its potential sources (diatom extracellular material, algae precursor, and plant/soil leachate) [157,219,220], to characterize specific fractions of DOM [221][222][223][224][225], as well as to examine photochemically induced changes in DOM composition [226][227][228][229][230]. Study of aquatic POM by solid-state NMR is much less common than that of DOM.…”

Seasonal variation and partitioning of endocrine disrupting chemicals in waters and sediments of the Pearl River system, South China

“…Several factors may be responsible for this observation. Firstly the riverine DOC and POC are mainly derived from fresh organic matters such as soil organic matter and plankton (Zhang et al, 2014a;2014b), while SOC contains considerable old OC, which is aged condensed OC such as nonhydrolyzable carbon (NHC) in the Pearl River (Ran et al, 2007a). The different sources of OC lead to different association behaviors and distribution of EDCs in multiple phases.…”