Water quality sampling is a fundamental link in environmental monitoring, water management, and scientific research, and its standardization directly affects the accuracy and representativeness of the test results. The following is the standardized operation process of water quality samplers, covering four core steps: preparation, sampling, preservation, and recording:

1、 Preparation before sampling

1. Equipment inspection and matching

Select the corresponding length of sampling rod according to the sampling depth requirements (telescopic rod is required in deep water areas), and check the flexibility of the sampler valve opening and closing;

Confirm the material of the sampling bottle (glass bottle is suitable for trace metal detection, polyethylene bottle is suitable for organic matter analysis), and rinse it three times with the water to be collected;

Equipped with portable pH meters, dissolved oxygen meters and other on-site measurement tools, calibrate the instrument zero point in advance.

2. Sampling point positioning

Following the principle of "three-point method": upstream background point, midstream control point, and downstream discharge outlet;

Surface water sampling should be conducted within 0.5m of the water surface, and a sampling layer should be added for every 2m increase in deep water;

Dynamic water bodies (rivers) should be sampled at uniformly mixed cross-sectional areas, while static water bodies (lakes) should be distributed in concentric circles.

2、 On site sampling operation

1. Basic sampling steps

Slowly immerse the sampler in water, and when it reaches the predetermined depth, pull the lifting rope to trigger the valve to close;

Slowly lift the sampler to avoid disturbing the sediment and causing a sudden increase in turbidity;

After the water flow stabilizes, open the exhaust valve to release excess gas, and then unscrew the drain valve to collect the water sample.

2. Special scenario handling

Plankton sampling: using a vertical dragging of the 25th plankton net, filtering water volume ≥ 50L;

Bottom sediment interface sampling: Use a gravity mud collector to obtain a 2cm sample of the upper layer of sediment;

Automatic sampling mode: Set the time interval or flow ratio to trigger the sampling program, suitable for continuous monitoring.

3、 Sample preservation and transportation

1. Packaging and labeling

Divide each sample into two identical bottles (one for testing and one for retention);

The label indicates the sampling time, location, depth, weather conditions, and sampler information;

Special testing items require the addition of fixatives.

2. Refrigerated transportation

The sample box is equipped with ice packs to maintain a low temperature of below 4 ℃ and avoid direct sunlight;

If the transportation time exceeds 6 hours, the fresh-keeping ice pack needs to be replaced, and easily degradable substances (such as BOD ₅) need to be measured on site.

4、 Data Recording Standards

The paper record book and electronic device are synchronized to register the following information:

-Basic information: latitude and longitude coordinates, water depth, water temperature, flow velocity;

-Sensory indicators: abnormal color, odor description, suspended solids status;

-Equipment parameters: sampler model, filter membrane aperture, flow meter reading.