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1、INTERNATIONAL STANDARD IS0 9391 First edition 1993-l O-l 5 Water quality - Sampling in deep waters for macro-invertebrates - Guidance on the use of colonization, qualitative and quantitative samplers large version typically 61 cm x 20 cm of mass about 15 kg) supporting a collecting net of about 35 c
2、m in length. The mesh size of the net may be altered to suit the purpose of the study (see annex B). b) The pole-operated Birge-Ekman grab (see figure31 is an open-ended box (typically 15 cm x 15 cm x 15 cm, giving a sampling area of 225 cm ) two spring-loaded jaws that are activated by a manually-o
3、perated release mechanism. Two hinged plates at the top of the box reduce the shock wave as the sampler approaches the bed of the river, by allowing a free flow of water through the box and also by reducing the loss of material as the sampler is raised. The pole- operated version allows greater cont
4、rol and pene- tration than one suspended from a rope, but it can only by used in water of depth less than 3 m. The shape of the sample taken is approximately cubic from mud and approximately hemicylindrical from gravel, and therefore the sampler is particularly suitable for collecting surface-dwelli
5、ng organisms in gravel see also c): Ponar grab. c) The weighted Ponar grab (typically of sampling area 560 cm2 and mass about 23 kg) has two large jaws that are closed via a scissor action with a series of lever arms (see figure4). A cross-bar holds the arms and jaws apart and is automatically relea
6、sed when the grab settles on the bed of the river. As the grab is raised, the jaws close. The shape of the sample taken is hemicylindrical from mud and saucer-shaped from gravel; the sampler is therefore suitable for collecting surface-dwelling organisms in gravel. d) The FBA air-lift sampler (typic
7、ally of sampling area 415 cm2 and mass about 14 kg) has a sampling pipe or riser of typically 10 cm diameter whose length can be altered by inserting lengths op pipe (see figure5). Air from compressed air bottles is fed through hosing to the base of the riser. An in- clined pipe at the top of the ri
8、ser directs the water and sample into a net whilst air is vented at its other end. The sampling area is enclosed by an open-ended stainless stee! cylinder which allows continuous replacement of water during pumping. The sampling cylinder and riser can be raised above the base of the outer cylinder i
9、n which they are supported, where they can be held by catches that are released by a handle near the top of the sampler. An air-driven vibrator is attached to the cylinder and air is supplied through pressure hos- ing. The passage of this air through the cylinder helps to dislodge material within th
10、e cylinder, in- creases the uptake of material for a given air flow and can also increase the penetration of the cylin- der into the substratum. Exhaust air from the vi- brator is returned to the surface to supplement the supply to the riser. An air-flow gauge is usually in- serted in the final sect
11、ion of air-line to the riser so that it measures the total flow to the riser. The gauge is essential for making efficient use of air and of differing conditions of water-depth and type of substratum. (See 5.3.4.) Figure 2 - Naturalist s dredge Copyright International Organization for Standardization
12、 Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 9391:1993(E) Figure 3 - Birge - Ekman grab Figure 4 - Ponar grab 6 Copyright International Organiza
13、tion for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted without license from IHS -,-,- 1s0 9391:1993(E) Lever 7 Steel cable - Riser - Air supply B e P Steel i Catches
14、 Collecting cylinder L Air inlet Figure 5 - Fp BA air-lift samoier -r. 7 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted witho
15、ut license from IHS -,-,- IS0 9391:1993(E) 5.2.2 Collecting nets for all samplers The mesh size of the collecting nets of the dredge and air-lift samplers and of the sieve used when decanting all samples is determined by the sampling purpose. Fine nets clog quickly and this can be re- duced by incre
16、asing the size of the mesh. Rec- ommended mesh sizes are given in annex B. A large net is especially necessary for the air-lift sampler, which pumps large volumes of water. 5.3 Procedure 5.3.1 Naturalist s dredge This is suitable for obtaining qualitative samples from gravel and stone substrata (par
17、ticle size greater than 2 mm) but not from mud. The large dredge collects about I,4 to 2 times as much material as the medium size dredge. The size chosen depends on the purpose of the sampling. The dredge should preferably be op- erated from a boat but it can also be thrown from the bank of a river
18、. When using a boat for dredging, the haul distance should first be determined and then the boat securely anchored upstream of the dredge pos- ition. The dredge should then be pulled up to the boat. This procedure is easier than towing the dredge di- rectly, because of the resistance of the dredge o
19、n the bed of the river. The dredge, when full of stones, can be a more effective brake than most anchors sold for small boats. The distance of the haul may be stand- ardized by letting out a known length of rope. The haul distance is subject to the nature of the river bed, for example on fine gravel
20、 the net may fill after 1 m whereas on larger stones, over which the dredge tends to bounce, it should be hauled over a distance of greater than 5 m before a representative sample is obtained. To prevent the dredge lifting off the river bed as it is hauled along, the angle of the rope to the river b
21、ed should preferably be maintained below about 25”. The sample should be emptied into a large container, taking care to transfer any aninals retained in the net to the container. Excess water should then be decanted from the sample before the sample is preserved and stored. 5.3.2 Birge-Ekman grab Th
22、e pole-operated Birge-Ekman grab is suitable for obtaining qualitative and quantitative samples from bottoms of mud and fine gravel. The grab is set by drawing back the jaws and fixing them to the release mechanism. The sampler should then be lowered gently to the river bed to prevent disturbance of
23、 the substrate, after which the grab should be pushed firmly into place. To actuate the sampler, the release mechanism is triggered and the jaws close automat- ically. The sampler should then be immediately re- trieved. The sample should be treated in the same way as for the dredge (5.3.1). Part of
24、the catch is sometines lost when small stones are caught be- tween the jaws or when fine particles lodge between the side of the box and the jaws, resulting in a partial loss of sample. When this occurs, the complete sample should be discarded and a further sample taken. If the bottom is too stony t
25、o allow satisfactory use (for example when stones greater than 16 mm long are present) another type of sampler should be used. 5.3.3 Ponar grab The weighted Ponar grab is suitable for qualitative and quantitative sampling on mud and fine gravel bottoms with small stones not greater than 16 mm long.
26、It may perform better than the Birge-Ekman grab on stony substrata, but the sample size is considerably larger (3 to 10 times) and therefore the sorting time is greatly increased. The jaws should be opened and kept apart by a cross-bar while the grab is suspended from its rope. The grab should then
27、be lowered slowly to the river bed and the tension released on the rope. This action allows the cross-bar to fall and the jaws to close when the grab starts to be hauled up. As the digging action of the grab depends upon its own mass, it is essential that the grab should be hauled up slowly whilst t
28、he jaws are closing. The sample should be treated as before, taking care to collect any animals from inside the jaws when the grab is emp- tied. Samples should be discarded when the jaws are jammed open by stones or twigs, and a further sam- ple should be taken. The unweighted Ponar grab is suitable
29、 for mud substrata and is easier to handle, but the weighted version is superior for other substrata. 5.3.4 Air-lift sampler The FBA air-lift sampler can be used to obtain quanti- tative samples on substrata ranging from fine gravel to stones up to about 13 cm long, but it is not rec- ommended for u
30、se on mud. Although the sampler will operate on a substratum that contains very large stones (I3 cm long, see annex A), it will not lift such stones nor remove the animals firmly attached to them. The sampler should be lowered to the river bed with the length of the riser adjusted so that its top is
31、 no higher than 30 cm above the water level. Whilst it is being lowered, the riser should be held in the raised position by the catches, The cylinder should then be pushed into the river bed until the stop flange is reached, by pressing down on the top of the sampler and rotating it back and forth b
32、y a few centimetres. The catches should then be released, allowing the riser to slide freely, although it will not drop because it is now level with the river bed. A net should be placed over the outlet of the riser and the air turned on. The duration and amount of air used depends upon the depth of
33、 water and the type of substratum; recommended values can be estimated from figures 6 and 7. It is essential that the sampler be kept vertical during operation, The sample should be treated as Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NA
34、SA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 9391:1993(E) described previously. The sampler digs a vertically- sided hole with a saucer-shaped base and therefore it only poorly samples animals at
35、 depths greater than about 10 cm. If it is impracticable to push the sampler into the substratum from the boat, it can be used quantitatively in the following less effective, but nev- ertheless adequate, mode on stones of up to 2 cm long. An extension should be fitted to the lower end of the riser.
36、The sampler should then be lowered to the bottom and the catches released without pushing the sampler into the river bed. The net should be positioned and the air turned on as before. The cylin- der will slowly vibrate itself into the bottom mud but, because the sample is not totally enclosed, mater
37、ial is drawn into the sample area under the descending cylinder. The profile of the hole is more conical than before, and the sampler becomes less effective as the stone size increases. On fine sandy gravels, whichever mode is used, the riser sinks to its full depth very rapidly and it is es- sentia
38、l that the vibrator should not be used, because it compacts the sediment which restricts the flow of water to the riser. Under these conditions, the sam- pling area is excavated more rapidly if the operator prevents the riser sinking into the fine substratum and becoming blocked. Copyright Internati
39、onal Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 9391:1993(E) I I I I I I 200 400 _ 600 Air flow (lamin- ) L 0
40、Figure 6 - Minimum air-flow requirements to lift stones less than or equal to 18 mm long IO Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or network
41、ing permitted without license from IHS -,-,- IS0 9391:1993(E) Figure 7 - Minimum air-flow requirements to lift stones greater than 18 mm long Air flow (bmin-1) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/99725450
42、01 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 9391:1993(E) Annex A (normative) Summary of the qualitative and quantitative samplers that are suitable for different types of substrata in deep rivers Fine gravel Substratum Mud Fine
43、 gravel and small Small Large stones Very large stones stones stones Modal particle size (mm) 128 Qualitative samplers Weighted Ponar grab + + + Birge-Ekmann grab (pole- operated) t tF Large naturalist s dredge t t t + +F Medium naturalist s dredge -I- + + + +F Quantitative samplers Weighted Ponar g
44、rab t + t Birge-Ekman grab (pole- operated) t +F FBA air-lift ) + + + + + +: indicates that a sampler can be used on a particular substratum. F: indicates that samplers sometimes fail for various reasons, e.g. grabs not closing properly, dredges being inefficient. I) The air-lift sampler is used at
45、an air-flow rate of 200 I/min. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 9391:1993(E)
46、 Annex B (normative) Recommended net mesh sizes Survey objective Maximum aperture size mm Comments General/routine biological surveillance: Data for surveys using biotic index For routine surveillance with more complete records 0,5 or 0,75 0,5 May not capture first instar stages of some insects More
47、 likely to capture first instar stages For special surveys requiring data in complete detail 0,25 Ensures capture of insects at first in- star stages and very small organisms which may prove of value in water quality determination. Copyright International Organization for Standardization Provided by
48、 IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:21:49 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 9391:1993(E) UDC 614.777:556.115:543.3.053:592 Descriptors: water, rivers, deep water, quality, invertebrates, Sampling, sampling equipment, samplers. Price based on 13 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Stan