Nutrient exchange and oxygen demand at the sediment-water interface during dry and wet seasons off the Medjerda River Delta (Tunis Gulf, Tunisia)

作者：Helali Mohamed Amine; Zaaboub Noureddine; Oueslati Walid; Added Ayed; Aleya Lotfi

来源：Environmental Earth Sciences, 2016, 75(1): 25.

DOI：10.1007/s12665-015-4820-x

• Early diagenesis
• Nutrients
• Oxygen
• Benthic flux
• Diffusive fluxes
• Sediment-water exchanges

In situ benthic flux of oxygen, alkalinity, and nutrients was assessed at the water-sediment interface using benthic chambers at three stations in the Medjerda River Delta (Tunisia) at 10, 20 and 40 m depth during March and August 2012. Simultaneously, three sediment cores were taken at the same locations to determine the diffusive flux of dissolved inorganic nitrogen (DIN = NO2-, NO3-, NH4-) and PO43- with a Technicon Autoanalyzer III to estimate diagenetic mechanisms occurring below the sediment-water interface. Oxygen consumption at the interface is about 1.7-10 mmol/m(2)/day essentially controlled by organic matter degradation and oxidation of reduced elements. Nitrate concentration is relatively high in the sediment (above 140 mu M for NO3-), and its production did not always conform to the general scheme of early diagenesis. NH4+ and PO43- were released at a rate of 96.5 and 1.27 mu mol/m(2)/day, respectively, consistent with those measured in benthic chambers, but amounting to <30 % of benthic fluxes for NH4+ and <5 % for PO43-.

• 出版日期2016-1