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Monitoring Station

Development of a common intraregional monitoring system for the environmental protection and preservation of the Black Sea ECO-Satellite “Continuous water quality monitoring through telemetric stations” Agamemnon Andrianopoulos Environmentalist, MSc Training Seminar and Technical Meeting

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Monitoring Station

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  1. Development of a common intraregional monitoring system for the environmental protection and preservation of the Black Sea ECO-Satellite “Continuous water quality monitoring through telemetric stations” Agamemnon Andrianopoulos Environmentalist, MSc Training Seminar and Technical Meeting June 5-6, 2013 Varna, Bulgaria

  2. Continuous monitoring: repeated measurements (at specific points) with a time interval between measurements that is sufficiently small to result in a water-quality record that can be considered continuous. IN SITU monitoring represents parameter values at specific “time-moments”. Continuous monitoring produces data that describetemporal trends (time-series of data), i.e. changes of parameter values over time.

  3. Monitoring stations: stations set up at specific locations that are equipped with sensors for the measurement of selected parameters. After installation the stations operate automatically without the need for permanent human presence

  4. Telemetry: all recorded data can be distributed “in real-time” through telemetry over long distances and therefore can be used to sound an alarm, in case of an emergency, or even to initiate action by automatic control mechanisms. Monitoring Station Data Transmission Telemetry Office

  5. The set up and operation of a continuous water quality monitoring network is focused around the following main axes: • Selection of site, • Selection of the parameters to be monitored and corresponding sensors, • Developing the telemetric system for the transmission of data, • Maintenance/operation of the system.

  6. Selection of site • Basic factors to take under consideration: • Quality of measurements • Must be representative of the water body being monitored. • Range of stream stage (from low flow to flood) that can be ex­pected. • Water velocity. • Presence of turbulence that will affect water-quality measurements. • Conditions that may enhance the rate of fouling, such as excessive fine sediments, algae, or invertebrates. • Need for protection from vandalism.

  7. Selection of site • Quality of measurements • Representative location: the optimal site is the one that permits sensors to be located at a point that best represents the section of interest for the aquatic environment being monitored. • Sufficient measurement surveys of field parameters must be made to provide adequate confidence that the magnitude and spatial distribution of variability are understood: • Horizontal variability (lakes, bays, estuaries, coastal waters) • Vertical-profile surveys (lakes, deep rivers, or estuaries) • Different seasons and hydrographic flow conditions

  8. Selection of site • Basic factors to take under consideration: • Technical issues (installation and maintenance) • Type of state or local permits required before installation can begin. • Safety hazards relevant to monitor construction and installation. • Accessibility of site, including parking or boat access. • Safe and adequate space in which to perform maintenance. • Availability of electrical power or telephone service. • Costs of installation.

  9. Selection of parameters/sensors • Involves e following major interrelated elements : • the objectives of the data collection, • the types of stations to be installed, • The accuracy and precision requirements of the data-quality objectives – in relation to the budget available

  10. Selection of parameters/sensors Sensors are available as individual instruments or as a single combined multi-instrument that has several different sensors in various combinations (sonde). AP7000 Aquaprobe A sonde typically has a recording unit or electronic data logger to record the output of multiple sensors. The most widely used water-quality sensors in monitoring installations are temperature, conductivity, DO, pH, and turbidity.

  11. Selection of parameters/sensors • Temperature: affects the density of water, the solubility of constituents (such as oxygen), pH, specific conductance, the rate of chemical reactions, and biological activity in water • Measured with a thermistor, which is a semiconductor having resistance that changes with temperature. • Thermistors are reliable, accurate, and durable and require little maintenance and are relatively inexpensive. • The preferred water-temperature scale for most scientific work is the Celsius scale.

  12. Selection of parameters/sensors • Electrical conductivity: is a measure of the capacity of water to conduct an electrical current and is a function of the types and quantities of dissolved substances in water. As concentrations of dissolved ions increase, conductivity of the water increases. • Conductivity sensors generally are of two types—contact sensors with electrodes and sensors without electrodes • Conductivity sensors are reliable, accurate, and durable but are susceptible to fouling from aquatic organisms and sediment.

  13. Selection of parameters/sensors Salinity : not measured directly, some sondes include the capability of calculating and recording salinity based on conductivity measurements. Conductivity has long been a tool for estimating the amount of chloride, a principal component of salinity, in water. pH: is a measure of the effective hydrogen-ion concentration. It is measured with the electrometric method, using a hydrogen-ion electrode. A correctly calibrated pH sensor can accurately measure pH to + 0.2 pH unit; however, the sensor can be scratched, broken, or fouled easily

  14. Selection of parameters/sensors Dissolved Oxygen: in surface waters are primarily atmospheric reaeration and photosynthetic activity of aquatic plants. DO is important for chemical reactions in water and for the survival of aquatic organisms. DO saturation decreases as water temperature increases, and DO saturation increases with increased atmospheric pressure. The technology most commonly used for continuous water-quality sensors is the amperometric method. Although DO sensors generally provide accurate results, they are sensitive to temperature and water velocity and are prone to fouling from algal growth and sedimentation.

  15. Selection of parameters/sensors • Turbidity: is an expression of the optical properties of a sample that cause light rays to be scattered and absorbed, rather than transmitted in straight lines through a sample. It is an expression of the water’s “clarity”. • Turbidity sensors direct a light beam from a light-emitting diode into the water sample and measure the light that scatters or is absorbed by the suspended particles in the water. • Sensors that are maintained and calibrated routinely should be relatively error free. Most commercially available sensors report data in nephelometric turbidity units (NTU).

  16. Development of data transmission system • Two components: • Telemetry stations with built-in data logger and a GPRS type of data communication • Base station with GPRS gateway and all the necessary equipment for the data storage (servers, ups, etc) GPRS technology provides the means for real time bidirectional communication between telemetry stations and the base station

  17. Development of data transmission system • 1) Telemetric station: • Sensors – carry out measurements • Data logger – store data (autonomy for at least one month in order to avoid data loss due to loss of communications. • Supply of energy (usually solar panels) • Antenna/modem (and provider of mobile phone services) – transmission of data • Protection cage

  18. Development of data transmission system • 2) Base station: • Gateway responsible for the data retrieval from all the telemetry stations and also for the remote programming and parameter changes • Server that stores in real time the data from the gateway into the database • Network attached storage device for backup purposes in a daily, weekly and monthly bases • PC for the monitoring the telemetry network by the administrator

  19. Maintenance/operation of the system The main axes for the maintenance/operation of a telemetric monitoring system involve: a) the maintenance procedure of the monitoring station and equipment, b) the periodic sensor calibration, c) the detailed and systematic record keeping.

  20. Maintenance/operation of the system • Standard protocol • similar for the operation of continuous water-quality monitors in nearly all aquatic environments and site characteristics (extend of fouling and calibration drift vary) • a series of steps that must be performed every time, in a routine basis, at all continuous water-quality stations.

  21. Maintenance/operation of the system The frequency of the maintenance of a water quality monitoring station is mostly dependent on the fouling rate of the sensors. The fouling rate in turn is governed by the type of the sensor (DO, pH, and turbidity are more affected), the hydrologic and environmental conditions (nutrient-enriched waters), and by the season (high temperatures). Other hardware or software errors include sedimentation, electrical disruption, debris, ice, pump failure or vandalism.

  22. Maintenance/operation of the system • Frequency is dependent on the specific maintenance requirements that derive from site configuration and specific equipment used • Daily maintenance functions (through telemetry): • Review of sensor function and data download • Battery (or power) check • Deletion of false data, if necessary

  23. Maintenance/operation of the system • Maintenance during field visits: • Inspection of the site for signs of physical disruption • Inspection and cleaning of sensor(s) for fouling, corrosion, or damage • Battery (or power) check • Time check • Calibration of the field meter(s) • Calibration check (and recalibration, if necessary) • Downloading of data

  24. Maintenance/operation of the system • Routine sensor inspection: • recording of the initial sensor readings in the environment, • removing and cleaning the sensors, • recording the cleaned-sensor readings in the environ­ment, • performing a calibration check of sensors by using appropriate calibration standards, and • recalibrating the sensors if the readings are outside the ranges of acceptable differences

  25. Maintenance/operation of the system • The difference between the initial sensor reading and the cleaned-sensor reading is the sensor error caused by fouling. • The difference between the cleaned-sensor readings and the readingsin calibration standard solutions of known quality represents sensor error caused by calibration drift. • This routine inspection ensures that the sensor is working properly and provides: • The end of the water-quality recording period since the last maintenance visit • The start of the water-quality recording period until the next maintenance visit

  26. Maintenance/operation of the system Data processing a) Initial data evaluation: immediately upon completion of the field trip to ensure that all necessary information is available and to check for possible instrument malfunctions b) Data correction: Application of data corrections and debugging within a few weeks or more frequently if the data are being served to the public over the Internet. c) Final data evaluation: A review of the record and final evaluation of the data computed prior to any publication.

  27. Advantages and Limitations of water quality monitoring from telemetric stations • data from telemetric stations represent measurements that are either continuous or at fixed intervals, allowing very cost-effective studies of temporal trends • provide real-time information and a constant “view” of a site’s state that can also serve as a trigger and an alarm in unexpected pollution incidents or other sudden events (flooding etc).

  28. Advantages and Limitations of water quality monitoring from telemetric stations • technical restrictions of the automated sensors, meaning that one can only measure those parameters for which the relevant sensors already exist (no sensors for biological parameters/living organisms except chlorophyll) • need for energy source (electric current, solar panels etc) and requirements of the transmitter-receiver system (distance limit, mobile network availability, obstacles etc). • installation and maintenance costs

  29. Thank you for your attention !

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