Variability in the benthic Mn flux in coastal marine ecosystems resulting from temperature and primary production1

Abstract

The flux of Mn2+ from estuarine sediments contained in large cylinders was studied over a 14-month period by periodically capping the entire 2.5-m2 sediment surface with a benthic chamber. The seasonal magnitude in the Mn 2+ flux could be described by an exponential function of the temperature.IIowcver, the flux at a given temperature varied by a factor of 6-10. During summer (June-September), Mn flux was strongly correlated not to temperature but to the average primary productivity during the month preceding the flux determination. Significant correlations between Mn flux and primary productivity were also obtained for discrete 15-day intervals up to 68 days before the flux measurement.Postflux correlations were not significant except for a 2-week interval immediately following the measurement when annual data were considered. The results suggest that the input of new organic matter to the sediments exerts a major control over the production of Mn"+ in anoxic sediments and that temperature relationships alone do not predict the magnitude nor variability in benthic Mn flux.

Benthic-pelagic coupling and nutrient cycling across an experimental eutrophication gradient

“…Temporal variability in fluxes can be caused by the activity of macrofauna (Henricksen et al 1980, McCaffrey et al 1980, Aller 1982, Kelly 1983, and by shortterm variability in pelagic production (Hunt 1983), even when temperatures are relatively constant. While some such temporal variability undoubtedly occurred, we could not reliably address this issue because a good deal of variability was attributable to the measurement itself.…”

“…Three benthic flux measurements were made ( Table 2). The MERL in situ benthic respirometer, developed by the senior author and described by Oviatt et al (1982Oviatt et al ( , 1984 and Hunt (1983), was lowered into each tank to cover the entire sediment community. Flux methodology was similar to that used in situ in Narragansett Bay (Nixon et al 1976(Nixon et al , 1980b and in laboratory sediment microcosms (Kelly 1983, Kelly & Nixon 1984.…”

Redox cycling of iron and manganese in sediments of the Kalix River estuary, Northern Sweden

“…This balance to a large extent is controlled by the flux of organic carbon to the sediment, which influences the availability of oxygen and the thickness of the oxic surface layer. In addition, the upward fluxes of Mn 2+ and Fe 2+ into the oxic zone, adsorption of Mn 2+ / Fe 2+ onto oxide surfaces (Emerson et al, 1982;Canfield et aL, 1993), temperature (Hunt, 1983) and the kinetics of Mn 2+ and Fe 2+ oxidation are critical parameters. Microbial catalysis of Mn oxidation appears to be important in the water column of anoxic Oords (Emerson et at., 1982) as well as in sediments (Kepkay, 1985).…”

Manganese: A New Emerging Contaminant in the Environment

“…The process is initialised after the increase in temperature, the decrease in oxygen concentrations and the upward movement of the redox-cline (Balzer, 1982;Hunt, 1983). The transport of the dissolved manganese ions is governed by molecular diffusion in the water pores and it follows a manganese concentration gradient (the gradient decreases towards the oxic zone).…”