Laserfiche WebLink
72 <br />• 10. <br />The <br />11.. <br />12. <br />13. <br />water <br />10 ml graduated cylinder. <br />following items are optional: <br />pH test paper <br />pH meter with two reference buffer solutions <br />Field filter unit with air pump or Nz tank for <br />pressurized filtering. <br />First, it is suggested that the analyst check this list <br />of items with other such lists and complete his own list of <br />items for collection (13, 14). Second, comments are needed <br />about the optionality of a pH meter and field filter unit. <br />With regard to a pH meter, this electrochemical measurement <br />is -technically .dif_ficult and_ the instrument_ is easily sub_ <br />ject to environmental influences. It is best to leave the <br />• pH meter set and take the samples to the meter as rapidly <br />as possible. The measurement of pH is discussed in a later <br />section. <br />Filtering Samples <br />Whether to filter the water or not has to be carefully <br />considered because this operation can bias the analytical <br />results. If the samples are filtered, a 0.45 pm membrane <br />filter should be used in a field filter unit. Such field <br />filter systems are now available from most scientific supply <br />companies. For mine drainage waters, most water is in a <br />low energy flow situation and the load of suspended solids <br />is minimal. In our studies, we have operated on the premise <br />0