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Controls on the composition of dissolved organic matter in treatment wetland source waters of South Florida, USA.

Authors :
Amaral, Joao Henrique F.
Gaddy, Jacob R.
Bianchi, Thomas S.
Osborne, Todd Z.
Newman, Susan
Dombrowski, Jacob
Morrison, Elise S.
Source :
Ecological Engineering. Sep2023, Vol. 194, pN.PAG-N.PAG. 1p.
Publication Year :
2023

Abstract

Dissolved organic matter (DOM) plays an important role in the phosphorus (P) and nitrogen (N) cycle, but the examination of coupled biogeochemical cycling in treatment wetlands, like the Everglades Stormwater Treatment Areas (STAs), has been limited. Here, we studied eight STA inflow waters to gain insights into the production and potential photo- and biolability of DOM in surface waters flowing into these treatment wetlands. A suite of optical and fluorometric indices was coupled with amino acid and bulk elemental analyses to evaluate differences in inflow water quality for particulate organic matter (POM), DOM (<0.2 μm), and high and low molecular weight DOM (HMW-DOM and LMW-DOM). A photochemical experiment was conducted with these inflow waters to assess how solar exposure alters DOM turnover and its relationship with nutrient concentrations, and to evaluate the influence of photochemistry on potential STA performance. The DOM of STA inflow water was predominantly composed of allochthonous terrestrial sources, and the LMW-DOM fraction represented 70 to 94% of the total DOM pool. Inflow waters separated along the biophysical dimension of our PCA based on their photolability and bioavailability, driven by differences in the inflow water's DOM composition. UV exposure decreased humic and aromaticity proxies with concomitant photo-production of LMW compounds and increases in bioavailability proxies. Photo-exposure significantly decreased nitrate and dissolved organic carbon (DOC) concentrations for most of the sites and dissolved organic N (DON) for three of the eight sites, but no significant changes were noted for ammonia. One site exhibited an increase in nitrate with UV exposure and had DOM primarily from terrestrial origins. Spectroscopic indices, PARAFAC components, and amino acids provided corroborating evidence that further supported the differences in photo- and biolability at each inflow site, which is likely driven by their original DOM characteristics. PARAFAC components were correlated with dissolved organic P (DOP) and suggest that there may be adsorption of DOP with humic components in the LMW fraction. This work highlights the importance of photochemistry in the STAs, the complexity of DOM turnover in STA source waters, and the potential interactions between dissolved P and other DOM components, which may further influence the treatment efficiency of the STAs. • Inflow waters were distinguished by their susceptibility to bio/photodegradation • DOM entering the STAs may contribute to the photoproduction of bioavailable LMW compounds • Lake Okeechobee outflow had unique indicators of freshly produced, autochthonous DOM • DOP was correlated with PARAFAC components, suggesting P partitioning in LMW DOM [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09258574
Volume :
194
Database :
Academic Search Index
Journal :
Ecological Engineering
Publication Type :
Academic Journal
Accession number :
170412723
Full Text :
https://doi.org/10.1016/j.ecoleng.2023.107047