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The Study Region
The sulphur dioxide monitors are placed in a relatively confined area
around the main sources of pollution while the HAWK model accommodates the
migration of plumes over a wider area. Clicking on the above map button
opens a map showing the location of the
monitoring stations. The Base station is situated at the Richards Bay
Civic Centre.
Sulphur Dioxide Analysers
A sulphur dioxide analyser draws a sample from the ambient air at
ground level on a continuous basis. Routine and precision checks on
each analyser are performed each week and analysers are calibrated
four times a year by a certified laboratory.
Collection of Data
The meteorological and the sulphur dioxide data are collected by data
loggers at each station and transmitted every 5 minutes via high frequency
radio-waves to the base station. This data is stored on computer and is
backed up routinely. The data is then collected for reporting purposes. |
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Data Quality
Since the data collected by the system is of critical importance as it is
an integral part of the management and emission of sulphur dioxide in the
area, it is essential that the data is acceptable. In order to ensure good
data the following steps have been taken:
- The analysers are
calibrated by an accredited organisation four times a year.
- A quality assurance
procedure has been developed to guide the management of the project.
- The meteorological
equipment is calibrated twice a year.
- Checks on the
analysers are undertaken weekly.
- Data is analysed daily
and a summary weekly report is produced.
Reporting of Data
Weekly reports detailing the sulphur dioxide levels, exceedances of
guideline values and maintenance issues, are produced and distributed to
all the members of the Association.
Monthly reports summarising the recorded levels of sulphur dioxide
during the month, the exceedances, complaints and weather information
are produced. In addition an annual report is produced to summarise the
activities of the Association and the trends in sulphur dioxide levels
during the year.
The Network
The diagram below shows the flow of data in the current system which is situated
at the Base Station. All data is sent to the central server from where
it is accessed for reporting purposes. Members of the Association can
request dial-in access to the data which will allow them to view the
data remotely (e.g. at their own offices or at home).
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Configuration of the Network
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The HAWK Model
The HAWK model, situated at the Base Station, receives weather data from
the weather stations and SO2 emission data from the major industries.
The emission data for most industries is contained in an emission
inventory database. Mondi and Foskor send emission data to the model by
means of data-telephone connections. The HAWK model uses the weather
information and the SO2 data to predict concentrations of SO2 at ground
level. Different concentrations are represented by coloured contours
(see diagram below).
By using a dispersion model, tailored to the Richards Bay region, it is
possible to determine the levels of SO2 at any point in the area and
determine the relative SO2 contributions from each industry.
In addition, the model aids in the interpretation and understanding of
conditions which lead to unacceptable pollution levels.
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Example of a prediction using HAWK |
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