Assays were carried out to evaluate the dissolved oxygen uptake resulting from mineralization of humic substances (fulvic acid (FA) and humic acid (HA)) from different sources: sediment, dissolved organic matter (DOM) of 120-day decomposed aquatic macrophyte (Scirpus cubensis and Cabomba piauhyensis), and lagoon DOM. The experiments were also aimed at estimating the oxygen uptake coefficient of...

Bahía Concepción (Gulf of California) was studied to describe some extremely low dissolved-oxygen values at the bottom of the bay. Surveys included measurements of vertical distribution of temperature, dissolved oxygen, nitrate, nitrite, phosphates and hydrogen sulfide. Thermal stratification from early spring to autumn and a well-mixed water column during the winter were present. Dissolved-oxy...

Paleotemperature reconstructions rely on knowledge of the equilibrium separation of oxygen isotopes between aqueous solution and calcium carbonate. Although oxygen isotope separation is expected on theoretical grounds, the temperature-dependence remains uncertain because other factors, such as slow exchange of isotopes between dissolved CO2-species and water, can obscure the temperature signal....

Citation: Gagne-Maynard WC, Ward ND, Keil RG, Sawakuchi HO, Da Cunha AC, Neu V, Brito DC, Da Silva Less DF, Diniz JEM, De Matos Valerio A, Kampel M, Krusche AV and Richey JE (2017) Evaluation of Primary Production in the Lower Amazon River Based on a Dissolved Oxygen Stable Isotopic Mass Balance. Front. Mar. Sci. 4:26. doi: 10.3389/fmars.2017.00026 Evaluation of Primary Production in the Lower ...

Figure 2.7. The percentage of backwater sampling sites where dissolved oxygen concentrations during winter, at the surface or just below ice cover, were >5 mg/L (1994–2002) for fi ve study reaches of the Figure 2.8. Percent of backwaters that contained suitable habitat for sunfi shes during winter from 1994 and 2002 based on a combination of temperature, dissolved oxygen, and depth in study rea...

Accelerated eutrophication of lakes is usually associated with excessive inflows of nutrients such as phosphates, nitrates and ammonium. The flow of nutrients into the lake can allow for rapid increase in algae. The alga is relatively short-lived, and the lake soon exhibits high concentration of dead organic matter which starts to decay. The decay process consumes dissolved oxygen in the lower ...