Anoxic factor

Keywords Climate change impacts, Anoxia, Anoxic Factor, ENSO, Streamflow, Sau Reservoir... 

Fig. 4 Predicted versus observed summer Anoxic Factor (AF) in (a, b) Foix Reservoir (Spain), (c, d) San Reservoir (Spain), (e, f) Brownlee Reservoir (USA), and (g, h) Pueblo Reservoir (USA). The results have been arranged to place the systems along a gradient of relative human impact (Foix Reservoir at the top, Pueblo Reservoir at the bottom). Predictions are based on linear models using different independent variables (in brackets) Inflow = streamflow entering the reservoir during the period DOCjjiflow = mean summer river DOC concentration measured upstream the reservoir CljjjAow = mean summer river CU concentration measured upstream the reservoir and Chlepi = mean summer chlorophyll-a concentration measured in the epilimnion of the reservoir. The symbol after a variable denotes a nonsignificant effect at the 95% level. Solid lines represent the perfect fit, and were added for reference. Modified from Marce et al. [48]...

Reduction by Fe(ll) results in an increase in the amount of iron oxides, which favor further reaction. Such autocatalytic behavior characterizes the oxidation of Fe(II) by and explains C Cl NO reduction by Fe(ll) in the absence of an iron mineral phase. Generalizing this behavior, it can be assumed that Fe(III) colloids derived from Fe(ll) oxidation in subsurface anoxic systems, together with other colloids, affect the environmental persistence of nitroaromatic contaminants. Colon et al. (2006), for example, elucidate factors controlling the transformation of nitrosobenzenes and N-hydroxylanilines, which are the two intermediate... 

Sensitization of anoxic cells is also brought about by non-toxic concentrations of transition metal ions (< some 10-4 mol dm-3) such as Cu(I). A dose-modifying factor of 1.5 (at 6.6 x 10-5 mol dm-3 Cu(I)) has been observed for mammalian cells (Hesslewood et al. 1978), but no sensitizing effects were observed for oxygenated cells. Under anoxic conditions, reduction of Cu(II) to Cu(I) occurs within the cells without an added reductant (see also Cramp 1967). It would be premature to come up with detailled mechanistic concepts, but some aspects of the actions of transition-metal ions have been discussed in Chapter 2.5. 

Recently, workers (2) have been examining the equilibrium and kinetic factors that are important at the oxic-anoxic interface. The kinetic behavior is difficult to characterize completely due to varying rates of oxidation and absomtion above the interface and varying rates of reduction, precipitation and dissolution below the interface (2.51. Bacterial catalysis may also complicate the system (1). Although one can question the importance of abiotic thermodynamic and kinetic processes at this interface, we feel it is useful to use simple inorganic models to approximate the real system. Recently, the thermodynamics and kinetics of the H2S system in natural waters has been reviewed (0. From this review it became apparent that large discrepancies existed in rates of oxidation of H2S and the thermodynamic data was limited to dilute solution. In the last few years we have made a number of thermodynamic (7.81 and kinetic (9 101 measurements on the H2S system in natural waters. In the present paper we will review these recent studies. The results will be summarized by equations valid for most natural waters. 

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