UPM Threshold Data - Fundamental Standards View

The Fundamental Stds tab on the UPM Threshold Data dialog allows you to inspect the thresholds for dissolved oxygen and un-ionised ammonia concentrations for three fixed standards: Sustainable Salmonid, Sustainable Cyprinid and Marginal Cyprinid. For each standard, concentrations are shown for a range of return periods and impact durations. You may also enter one set of user-defined concentrations for each UPM Threshold item.

The UPM Threshold Data dialog is displayed when you open an existing UPM threshold item by either double-clicking on the relevant UPM threshold item, or right-clicking on it and selecting Open from the context menu.

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When you select a standard from the drop-down list at the top of the dialog, the corresponding thresholds are displayed. If you choose the User Defined standard, you can enter the concentration values.

The tables show the concentrations for a range of impact durations and return periods. The impact duration is the period for which the given level of concentration can be tolerated; the return period specifies the frequency with which this level may be exceeded. For example, the top left cell of the Un-ionised Ammonia table gives the concentration for an impact duration of 1 hour and a return period of one month; this level may be exceeded for no more than 12 one-hour periods per year.

The following concentrations are specified for each standard:

Field	Description
Dissolved Oxygen Concentrations	The grid contains the minimum DO concentration that can be tolerated for each combination of Return Period and Impact Duration.
Un-ionised Ammonia Concentrations	The grid contains an the maximum un-ionised ammonia concentration that can be tolerated for each combination of Return Period and Impact Duration.