In order to implement a monitoring programme for surface water quality indicators in watersheds, the selection of appropriate measuring instruments and adherence to appropriate testing standards are key to ensuring the accuracy and reliability of the data.Below are the recommended measuring instruments for different water quality indicators and the corresponding national or international standards.
1. physical indicator
- turbidity
- Measuring instrument: turbidimeter (e.g. HACH 2100Q)
- Standard: "Water quality Determination of turbidity Turbidimeter method" (GB/T 13200-91)
2. Chemical indicators
- pH value
- Measuring instrument: pH meter
- Standard: "Determination of pH value of water quality Glass electrode method" (GB 6920-86)
- Dissolved Oxygen (DO)
- Measuring Instrument: Dissolved Oxygen Meter
- Standard: "Water quality Dissolved oxygen determination Electrochemical probe method" (GB/T 11913-89)
- Chemical Oxygen Demand (COD)
- Measuring Instrument: COD Rapid Measuring Instrument
- Standard: "Water quality Chemical Oxygen Demand Determination Dichromate Method" (GB 11914-89)
- Biochemical Oxygen Demand (BOD)
- Measuring instrument: BOD tester
- Standard: "Water quality Five-day Biochemical Oxygen Demand (BOD₅) Determination Dilution and Inoculation Method" (GB 7488-87)
- total nitrogen（TN）
- Measuring instrument: Total Nitrogen Analyser
- Standard: Determination of Total Nitrogen in Water Quality Alkaline Potassium Persulfate Elimination Ultraviolet Spectrophotometric Method (GB 11894-89)
- Total phosphorus (TP)
- Measuring instrument: Total phosphorus analyser
- Standard: "Determination of total phosphorus in water quality Ammonium molybdate spectrophotometric method" (GB 11893-89)
- Ammonia (NH₃-N)
- Measuring instrument: ammonia analyser
- Standard: "Water quality Ammoniacal nitrogen determination Nano reagent spectrophotometric method" (GB 7479-87)
- Heavy metals (e.g. lead, mercury, cadmium, etc.)
- Measuring instrument: Atomic absorption spectrometer, inductively coupled plasma mass spectrometer
- Pesticides and other organic pollutants
- Measuring instrument: gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS)
3. bioindicator
- Chlorophyll a
- Measuring Instrument: Water Chlorophyll Tester
- Microbial communities (e.g. E. coli, faecal coliforms)
- Measuring instrument: Multi-tube fermentation method, enzyme substrate method
- International standards:
- ISO 5667 Series: Water Quality - Sample Collection and Preservation
- ISO 6107 series: Water quality - Terms and definitions
- ISO 10648 series: Water quality - Biological monitoring methods
Through the above programme, the scientific and standardised monitoring of water quality of surface sources in the basin can be ensured, providing solid data support for environmental protection and water resources management.The selection of each monitoring point, the setting of the sampling frequency and the determination of specific indicators should be flexibly adjusted according to the actual situation in order to achieve the best monitoring effect.
