Comparison of molecular characteristics between commercialized and regional natural organic matters

Natural organic matter (NOM) is a ubiquitous substance in natural aquatic ecosystems that is a significant component in any experiment involving water. However, experimentally simulating the aquatic conditions using NOMs from natural sources remains difficult. As a result, previous experimental studies have predominantly relied on commercialized NOMs. This study aimed to comprehensively compare the characteristics of two commercialized NOMs (Suwannee River NOM: SRNOM, Mississippi River NOM: MRNOM) and two regional NOMs (Nakdong River NOM: NDNOM, effluent organic matter: EfOM) using various analytical methods during water dissolution. Both commercialized NOMs showed low conductivity (SRNOM: 28.6 μS/cm, MRNOM: 35.4 μS/cm) and were highly humidified (SRNOM: HIX 14.22, MRNOM: HIX 11.44), whereas NOMs from natural water had relatively higher conductivity (NDNOM: 365.7 μS/cm, EfOM: 398.8 μS/cm) and lower humification (NDNOM: HIX 2.47, EfOM: HIX 2.50). The SRNOM and MRNOM contained large amounts of tannin-like substances (SRNOM: 43.5%, MRNOM: 43.1%). The NDNOM had a humidification state similar to that of the EfOM, except for the portion of protein-like biopolymer, which was smaller. The different characteristics of the samples can be critical in selecting appropriate NOMs for use in future studies because they can significantly influence the experimental chemical reaction.