To evaluate and predict environmental health in terms of systemic homeostasis and resource balance, a comprehensive understanding of these factors requires an approach based on the "exposome paradigm", namely the totality of exposure to all substances. The environment, from microbial ecosystems to recycled resources, fluctuates dynamically due to many physical, chemical and biological factors, the profile of which reflects changes in overall state, such as environmental illness caused by a collapse of homeostasis. Additionally, lake eutrophication is increasing due to warming temperatures and this data set yields detailed molecular information about DOM composition and processing in such lakes. This work has implications for climate change as DOM photooxidation in lakes represents an understudied flux of CO2 to the atmosphere.
However, DOM composition varies more temporally than by location within the water column.
Our results show DOM composition varies with depth with more highly oxidized formulas identified deeper in the water column. In the hypolimnion, redox conditions and interactions with sediments likely influence temporal compositional change. At the surface, correlations between DOM formulas and both chlorophyll concentrations and light intensity show that photochemical reactions contribute to DOM oxidation. Temporally, increases in more oxidized formulas are observed in both the epilimnion and hypolimnion. A subset of samples is analyzed by Fourier transform‐ion cyclotron resonance mass spectrometry (FT‐ICR MS) to investigate DOM composition at the molecular level. Dissolved organic carbon concentrations and optical properties are presented for 73 samples collected at a single location at varying depths within the water column from June to November.
Here, we evaluate DOM composition as a function of time and depth in Lake Mendota, a highly productive eutrophic lake that stratifies in warm months and is located in Madison, Wisconsin, USA. Its composition influences the routes of mineralization. Dissolved organic matter (DOM) is an intermediate between organic carbon formed by primary producers and carbon dioxide (CO2) produced through respiration, making it a key component of the carbon cycle in aquatic ecosystems.
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