The volume of sample to be collected will depend on the number ofanalyses that will be carried out. If a comprehensive analysis of the wateris to be carried out, 2 L of sample should be collected. If one or fewanalytes are to be determined, smaller volumes may be satisfactorydepending on the volume required for the test. Plastic or glass bottlescan be used, depending on the analyte. In some instances it may benecessary to collect samples in several different bottles. Analysis ofdissolved oxygen requires separate bottles.You should remember that the sample you collect is only representativeof the place and time of sampling. A detailed survey of a water bodymay require an investigation of spatial and temporal variability. Thecomposition of the sample may also change during transport andstorage, mainly due to biochemical and surface reactions. Be sure tofollow the recommended procedure for each analyte.Surface water samples are the easiest to collect. Collecting samples atdepth requires special collectors, of which there are several types(Ruttner, Kemmerer, Dussart, Valas, Watt, etc.). The most commonsampler is the Van Dorn sampler, shown in Figure 4.1. The samplerconsists of a hollow cylinder of PVC and two rubber valves at the openends. The two valves are interconnected by a rubber tube and also have astring attached to them. Prior to immersion in water the two valves arepulled out and the strings are attached to a lock fitted outside theXi lanh. Xi-lanh, mở ở cả hai đầu, hạ xuống đến độ sâu mong muốnbằng dây thừng tốt nghiệp. Một messenger bằng kim loại được phát hành cùng cácsợi dây thừng. Messenger cuộc đình công khóa và phát hành các van hai cao suđể đóng hình trụ.
đang được dịch, vui lòng đợi..