Lakes anoxic

Estuaries exhibit physical and chemical characteristics that are distinct from oceans or lakes. In estuaries, water renewal times are rapid (10 to 10 years compared to 1 to 10 years for lakes and 10 years for oceans), redox and salinity gradients are often transient, and diurnal variations in nutrient concentrations can be significant. The biological productivity of estuaries is high and this, coupled with accumulation of organic debris within estuary boundaries, often produces anoxic conditions at the sediment-water interface. Thus, in contrast to the relatively constant chemical composition of the... 

Pak K-R, R Bartha (1998) Mercury methylation and demethylation in anoxic lake sediments by strictly anaerobic bacteria. Appl Environ Microbiol 64 1013-1017. 

Depth profiles of physical and chemical properties of Pit Lake indicate that the lake is divided into two zones with a boundary at the depth at 20 m. The upper zone (mixolimnion) is characterized by variable temperature, redox and pH compared to lower zone (Figure 2). Lower zone (monimolimnion) is anoxic, and has relatively stable temperature, redox... 

The effectiveness of nitrate addition to control sulfide has been investigated in a sewer network in the Lake Balaton catchment, Hungary (Jobbagy et al., 1994). Figure 6.6 shows the effect of nitrate addition on the H2S concentration in the headspace of a manhole located downstream of the station where nitrate was added. The importance of the anoxic removal of organic matter at the inlet... 

The vertical distribution of LAS in the sediment column has been characterised in various lakes [21,22], where evidence has been found of its degradation in the top 5 cm, but not at greater depths where the conditions usually are anoxic. Amano et al. [23,24] have simulated the temporal variation of the concentration of LAS in the surface layer of sediments and have estimated the flux across the water-sediment... 

Fe(III)(hydr)oxides introduced into the lake and formed within the lake - Strong affinity (surface complex formation) for heavy metals, phosphates, silicates and oxyanions of As, Se Fe(III) oxides even if present in small proportions can exert significant removal of trace elements. - At the oxic-anoxic boundary of a lake (see Chapter 9.6) Fe(III) oxides may represent a large part of settling particles. Internal cycling of Fe by reductive dissolution and by oxidation-precipitation is coupled to the cycling of metal ions as discussed in Chapter 9. 

The freshly precipitated manganese and iron oxides which precipitate at an oxic-anoxic boundary within the lake water column or in the top layers of the sediment, form small particles with high surface area they cause an additional scavenging at... 

Conrad R, Bak F, Seitz HJ, et al. 1989. Hydrogen turnover by psychrotrophic homoacetogenic and mesophilic methanogenic bacteria in anoxic paddy soil and lake sediment. FEMS Microbiol Ecol 62 285-94. 

Phelps TJ, Zeikus JG. 1984. Influence of pH on terminal carbon metabolism in anoxic sediments from a mildly acidic lake. Appl Environ Microbiol 48 1088-95. 

In anoxic hypolimnion samples collected from Lower Mystic Lake, MA, hexachloroethane was abiotically transformed into tetrachloroethylene via reductive elimination and to pentachloro-ethane via hydrogenolysis. Tetrachloroethylene accounted for 70% of hexachloroethane in unaltered lake water and 62% in filter-sterilized water after 10 d. Trichloroethylene and pent-achloroethane accounted for <1 and 2% in unaltered lake water and filter-sterilized water, respectively. Disappearance rate constants for hexachloroethane were 0.33/d for unaltered water and 0.26/d for filter-sterilized water. At least 80% of the hexachloroethane disappearance in unaltered water was abiotic in origin due to the reactions with naturally occurring aqueous polysulfides, H2S and (Miller et al, 1998a). 

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