Method For Identifying Hypoxia InWater Body:

(1) The color changes: dissolvedoxygen in water gradually decreases with the deterioration of water quality.First, the color becomes clear, then turns white, and then red, finally to theblack. Plankton in large quantities of death, after the decomposition of thebody, causing ammonia nitrogen, hydrogen sulfide, nitrite harmful substances inthe water gradually increased.

(2) Observe the activity status ofzooplankton and benthic animals in the water. During Hypoxia, Zooplanktonregular gather in the upper layer of water, and cladocerans are usually red.When severe, water earthworm, aquatic insects, crabs, snails and other wildbenthic animals reach the pool side, and not afraid of shock and death.

(3) Observe the ingestion ofaquatic animals. Mild hypoxia, reduced feeding; Severe hypoxia, death happened.

(4) Observe the bottom quality anddischarged sewage. During Hypoxia, the sediment smells bad, and dischargedsewage is back, bad smell.

(5) Determine the dissolved oxygen.Do the best , dissolved oxygen of normalaquatic animal maintained at more than 5mg/L, less than 2mg/L showed symptomsof hypoxia.