Solid-Phase Extraction of Aquatic Organic Matter: Loading-Dependent Chemical Fractionation and Self-Assembly

Abstract

Dissolved organic matter (DOM) is an important component in marine and freshwater environments and plays a fundamental role in global biogeochemical cycles. In the past, optical and molecular-level analytical techniques evolved and improved our mechanistic understanding about DOM fluxes. For most molecular chemical techniques, sample desalting and enrichment is a prerequisite. Solid-phase extraction has been widely applied for concentrating and desalting DOM. The major aim of this study was to constrain the influence of sorbent loading on the composition of DOM extracts. Here, we show that increased loading resulted in reduced extraction efficiencies of dissolved organic carbon (DOC), fluorescence and absorbance, and polar organic substances. Loading-dependent optical and chemical fractionation induced by the altered adsorption characteristics of the sorbent surface (styrene divinylbenzene polymer) and increased multilayer adsorption (DOM self-assembly) can fundamentally affect biogeochemical interpretations, such as the source of organic matter. Online fluorescence monitoring of the permeate flow allowed to empirically model the extraction process and to assess the degree of variability introduced by changing the sorbent loading in the extraction procedure. Our study emphasizes that it is crucial for sample comparison to keep the relative DOC loading (DOC load [wt %]) on the sorbent always similar to avoid chemical fractionation.

Revised microbial and photochemical triple-oxygen isotope effects improve marine gross oxygen production estimates

“…This recovery is ∼15% lower than reported for Brazilian coastal waters ( 57 ). This discrepancy was expected provided the 10× higher C-loading rate used in this study compared to Dittmar et al (0.4 vs. 0.04 mmol-C g −1 PPL resin), and the well documented decline in DOC recovery with increased C-loading rates ( 59 ). Martha’s Vineyard Sound DOC SPE eluent was subsequently used to create concentrated solutions of coastal DOC (14.6 ± 0.2 mg-C L −1 ; n = 3).…”

Triplet Photochemistry of Effluent Organic Matter in Degradation of Extracellular Antibiotic Resistance Genes

“…It should be noted that EfOM extracts used in this study were obtained after solid-phase extraction using PPL sorbents, which prefer to retain moderately polar to nonpolar DOM. 63 The EfOM composition could have some difference from the whole wastewater effluent. 29 In addition, the ions commonly existing in wastewater effluents, such as NO 3 − and NO 2 − , can lead to high • OH concentration in the receiving waters upon solar irradiation.…”

“…The percentage of effluent discharge in the receiving waters is expected to greatly affect the photodegradation efficiency. , For instance, in the various mixtures of EfOM and SRNOM (Text S15), significant increases in the quantum yield coefficients of photodegradation of eArGs ( f blaTEM‑1 and f tet‑A ) (from 72 to 309 M –1 for EfOM1 and from 105 to 466 M –1 for EfOM2) were predicted with increasing EfOM percentage from 25% to 75% when the total DOC remained at 5 mg C L –1 (Figure S16). It should be noted that EfOM extracts used in this study were obtained after solid-phase extraction using PPL sorbents, which prefer to retain moderately polar to nonpolar DOM . The EfOM composition could have some difference from the whole wastewater effluent .…”

Dissolved organic matter thiol concentrations determine methylmercury bioavailability across the terrestrial-marine aquatic continuum

“…This solid-phase extraction method (based on a styrene divinyl benzene polymer, so-called PPL-SPE) is the most common approach for DOM enrichment and desalting, which is a prerequisite for most types of molecular characterizations 27 , including the ones in this study. In general, PPL-SPE captures a broad range of compounds and retains overall differences in the molecular composition of the DOM between samples 28 – 31 . However, since external factors such as sample salinity impact the carbon yield of the extraction, we normalized relevant parameters to DOC concentrations to avoid quantitative biases.…”