The Supramolecular Nature of Organic Matter from Lake Dredged Material By Humeomics: A Spectroscopic Approach

In the last decades, the Western Lake Erie Basin (WLEB), USA, has been experiencing harmful algae bloom (HABs) events attributed to the large export of phosphate (PO4-3) and nitrate (NO3-) loads into waterways from farmland. There is current concern about exacerbating the HABs at the WLEB by discarding dredged materials (DM) in open lake waters. The State of Ohio has prohibited open lake water disposal, and it is requesting beneficial uses for the DM, and this study is exploring amending farm soil with DM. Previous research has demonstrated benefits on soil health when Hoytville soil was amended with DM from Toledo Harbor, OH, as the DM contains adequate soil organic matter (SOM) and calcium content. This study aimed to characterize the SOM in the DM by conducting a gentle chemical sequential extraction named Humeomics. Total organic carbon, total phosphorous, total nitrogen, and organic moieties associated with the SOM organo-soluble and hydro-soluble extracted fractions were characterized. Emission and excitation matrices were collected and paired with Parallel Factor analysis (PARAFAC) to characterize SOM fluorophores. The organo-soluble fractions exhibited terrestrial humic-like, terrestrial fulvic-like, and microbial tryptophan-like components. The hydro-soluble fractions showed microbial and humic-like and terrestrial or freshwater humic-like components. TOC concentrations in the organo-soluble and hydro-soluble fractions ranged from 594,022 to 483,723 mg kg-1 and 299,777 to 60,830 mg kg-1, respectively. Total phosphorus in the organo-soluble and hydro-soluble fractions ranged from 920.32 to 509.94 mg kg-1 and 31,389 to 182 mg kg-1, respectively. And total nitrogen in the organo-soluble and hydro-soluble fractions ranged from 11,614.47 to 2,879.86 mg kg-1 and 16,505.86 to 4,087.97 mg kg-1, respectively.