| Autor: |
Baumser, Lea, Potts, Lindsey, Walker, Brett D., Mahmoudi, Nagissa |
| Předmět: |
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| Zdroj: |
Geophysical Research Letters; 7/16/2024, Vol. 51 Issue 13, p1-10, 10p |
| Abstrakt: |
Dissolved organic matter (DOM) is a key component of the global carbon cycle, with rivers delivering significant amounts of DOM to oceans. Urbanization and agricultural land‐use alter the age and chemical composition of riverine DOM, which likely impact the downstream bioavailability of riverine DOM. Here, we use bioreactor incubations of a marine bacterium (Pseudoalteromonas sp. 3D05) to investigate DOM bioavailability from two distinct rivers: the Suwannee River (natural, non‐urbanized), and the Upper Mississippi River Basin (anthropogenically influenced). We measured rates of microbial CO2 production and radiocarbon ages (as Δ14C) to assess DOM remineralization. We observed nearly identical cell densities and degradation patterns for both riverine DOM incubations. Respired DOM Δ14C values were also similar and decreased over time indicative of preferential utilization of recently synthesized "modern" substrates. These findings reveal unexpected similarities in riverine DOM bioavailability, indicating similar short term biological reactivity despite large DOM compositional differences. Plain Language Summary: Our study explores the relationship between anthropogenic activity and breakdown of dissolved organic matter (DOM) from rivers, which represents a vital link between land and ocean ecosystems. The composition of DOM in rivers is linked to the characteristics of the surrounding land. Urbanization and agricultural land‐use change the age and chemical composition of the riverine DOM. Consequently, these alterations induced from human activity would be expected to impact the bioavailability of riverine DOM to microorganisms in coastal environments. We compared DOM sourced from a natural river system (Suwannee River) to DOM from a river impacted by anthropogenic activity (Upper Mississippi River Basin) to understand how the availability of DOM from these distinct rivers varies to marine microorganisms. We carried out laboratory experiments with a model marine bacterium and measured the respiration of carbon dioxide and associated isotopic signatures during the breakdown of riverine DOM. Surprisingly, we discovered striking similarities in the breakdown patterns of DOM from both rivers, despite their differing origins. This suggests that the impact of human activities on downstream transformation of DOM may not be as straightforward as previously assumed and underscore the need for a nuanced understanding of how microorganisms process DOM in coastal environments. Key Points: Riverine dissolved organic matter (DOM) from distinct rivers shows similar bioavailability to marine bacteriumRadiocarbon values of microbially respired carbon dioxide during incubations reveal preferential utilization of modern carbon compoundsThe fate of riverine DOM in coastal environments may depend on the metabolic potential of microorganisms that are present and active [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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