Different responses to artificial ventilation in two stratified coastal basins

We studied the effects of pumping surface water down through pycnocline (i.e. artificial ventilation) on hydrodynamics, oxygen concentrations, hydrogen sulfide, and nutrients in two anoxic coastal basins (Lännerstasundet Sandöfjärden). In addition, a corresponding laboratory aquarium experiment, less saline entrained dense bottom with mixing ratio 6.8 illustrated dispersal below pycnocline. Oxygen saturation increased from 0 to 20%; penetrated poorly into sediment aquarium. salinity-stratified Lännerstasundet basin, ventilation also oxidized water. The removed sulfide decreased sub-pycnocline pools phosphorus ammonium, which was not observed neighboring reference basin. summertime warmed made saline. autumn, inflows cooled surroundings equal or higher salinity promoted its sinking relatively warm ventilated maintained concentrations between 4 8 mg L?1 for months after ended. contrast Lännerstasundet, did prevent formation anoxia release temperature-stratified Sandöfjärden. Here, capacity than that expanded sub-thermocline area, sediments, probably displaced oxic experimental area. promote density conditions no marked inflow-induced oxidation midsummer. conclude significant amount ascending plume reduced content experiment. Additionally, may improve status further oxidation. improvement occurs due autumn cooling favorable basin topography, larger thereby, renewal pumped semi-enclosed cannot form such thus is efficient.