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Black-odor water body is a collective term for water bodies that exhibit unpleasant colors and/or emit unpleasant odors. Generally, the evaluation indicators for black-odor water bodies mainly include four items: transparency, dissolved oxygen (DO), oxidation reduction potential (ORP) and ammonia nitrogen (NH3-N).
The grading standards and the related index measurement methods
Grading standards for the degree of pollution of black-odor water bodies Characteristic indicators (unit) Light black-odor Heavy black-odor Transparency (cm) 25~10*<10*,
Dissolved oxygen (mg/L) 0.2~2.0<0.2
ORP Oxidation reduction potential (ORP) (mV) -200~50< -200
Ammonia nitrogen (mg/L) 8.0~15>15
Note:*
When the water depth is less than 25 cm, the index is taken as 40% of the water depth.
Determination method of water quality indicators
1. Transparency black and white disk method or lead method on-site in-situ determination
2. Dissolved oxygen electrochemical method on-site in-situ determination
3. Redox potential electrode method on-site in-situ determination
4. Ammonia nitrogen Nano reagent photometry or salicylic acid - hypochlorite photometry Water samples should be filtered through a 0.45 μm filter membrane