Oxygen
Consumption and Organic Matter Remineralization
in Two Subtropical, Eutrophic Coastal Embayments
Hongjie Wang
Xinping Hu
Michael S. Wetz
Kenneth C. Hayes
10.1021/acs.est.8b02971.s001
https://acs.figshare.com/articles/journal_contribution/Oxygen_Consumption_and_Organic_Matter_Remineralization_in_Two_Subtropical_Eutrophic_Coastal_Embayments/7283228
There is a strong need to understand
sources of organic matter
in coastal lagoons because these systems often have long water residence
times, are susceptible to eutrophication, and display symptoms such
as low-oxygen conditions. We found that integrated dissolved oxygen
(DO) consumption in the water column accounted for 67–73% of
total DO consumption in two eutrophic coastal lagoons (Baffin Bay
and Oso Bay) in the northwestern Gulf of Mexico. The δ<sup>13</sup>C of particulate organic carbon (δ<sup>13</sup>C<sub>POC</sub>) showed temporal variations that corresponded with hydrological
condition changes in Baffin Bay but fewer temporal changes in Oso
Bay, whereas the lower δ<sup>15</sup>N<sub>PON</sub> values
in Baffin Bay indicated more agricultural influence than in Oso Bay,
where urban sewage influences dominated. Based on closed-system incubation
experiments, water-column respiration in Baffin Bay was driven by
the respiration of a combination of phytoplankton, carbon from near-shore
and benthic macrophytes, and other allochthonous organic carbon sources
depending on hydrological conditions. However, respiration of algal
carbon dominated DO consumption in Baffin Bay sediments. In comparison,
Oso Bay water-column respiration was largely attributed to the degradation
of phytoplankton, the growth of which was sustained by nutrient discharge
from wastewater treatment plants in the watershed. In contrast to
the water column, seagrass and saltmarsh carbon appeared to be the
primary organic carbon source that drove DO consumption in Oso Bay
sediments. These observations highlight the complexity of organic
carbon sources that contribute to DO consumption in estuaries affected
by human activities, especially in systems with long water residence
times that can retain both organic matter and nutrients for extended
periods of time.
2018-10-22 00:00:00
water residence times
Baffin Bay
Eutrophic Coastal Embayments
Baffin Bay sediments
hydrological condition changes
carbon sources
Organic Matter Remineralization
consumption
Oso Bay
δ 13 C
δ 15 N PON values
Oso Bay sediments
Oso Bay water-column respiration
POC
closed-system incubation experiments
wastewater treatment plants
water column