Environmental monitoring can be essentially described as a set of continuous or frequent measurements of environmental parameters which are fundamental to assess the state of the environment, the achievement of predefined objectives, law enforcement, the detection of new environmental issues, and environmental short and medium term forecasting. Within the scope of environmental monitoring are namely the following topics:
Analytical measurement of the three main environmental media: air, water, soil, and the following materials: gases, solid and liquid waste, human, plant and animal bodies, as well as organs, and synthetic products.
Instrumental methods for the measurement of environmental noise and vibration pollution.
Development and improvement of analytical methods for measuring environmental pollutants.
Development of new analytical methods, sensors and instruments for monitoring of air, water and soil quality in residential, industrial, as well as, agricultural areas.
Development and improvement of remote sensing methods for measuring environmental pollution.
Development of new platforms (e.g. satellites and aerial configurations) and image processing techniques for detection of potential sources of contamination and monitoring of air, water and earth quality.
Development of Geographic Information Systems to perform spatial analysis of remote sensing-based and ground-based environmental assessment.
Evaluation and assessment of environmental data.
Quality assurance and quality control of environmental measurements.
Monitoring at a micro-scale is related to monitor and track one or more parameters in a small and limited geographical context, such as the control of gaseous emissions of a factory. In terms of micro-scale, environmental monitoring is generally used to control emissions of pollutants, whether gaseous or liquid. By opposition, macro-scale monitoring involves a vast geographical area, such as the control of water quality of a lake.
Vibration and particular noise are important namely in industrial/manufacturing environments because of their influence on structures safety and on workers comfort and health. Notwithstanding, soil, air and water are the more important and thus the more monitored environmental media, not only because of their direct impact on all fauna and flora and human activity, but also indirectly through the influence they have on the weather and climate.
Soil is a non-renewable resource. As interface between the earth, the air and the water, it performs vital functions such as providing the basis for food and biomass production, storing carbon and maintaining the balance of gases in the air, providing valued habitats and sustaining biodiversity, and providing raw materials. The quantities that are more pertinent to assess soil status, and thus more usually measured, are moisture, soil acidity (pH), carbon, total nitrogen and carbon to nitrogen ratio, extractable phosphorous, extractable potassium and magnesium, potentially toxic elements, microbial biomass carbon, and earthworms.
Clean air is essential to our health and to the environment. The quality of the air we breathe has deteriorated considerably mainly as a result of human activities: rising industrial and energy production, burning of fossil fuels, the rise in traffic on our cities. Carbon monoxide, nitrogen oxides, ozone, particulate matter, sulfur dioxide, hydrocarbons and volatile organic compounds, lead and heavy metals, and toxic organic micro-pollutants are the undesired air constituents most commonly monitored.
Water covers about 70% of the Earth's surface but freshwater represents only 2.5% of the Earth's water, with 98.8% of that water being ice and groundwater. This means that freshwater, which is essential for human activity, is a scarce resource in large regions of the Earth and its quality must thus be monitored and controlled. It is also important to monitor the quality of salty water of seashores and rivers because of its impact on ecosystems and on human activity. The parameters that are taken into consideration depend on the use – drinking, washing, agriculture, fishing, food processing, recreation, industrial applications, etc. – but can be organized in 5 groups: (1) biological (algae, bacteria), (2) physical (temperature, turbidity and clarity, color, salinity, suspended solids, dissolved solids (sediment); (3) chemical (pH, dissolved oxygen, biological oxygen demand, nutrients (including nitrogen and phosphorus), organic and inorganic compounds (including toxicants), (4) aesthetic (odors, taints, color, floating matter), and (5) radioactive (alpha, beta and gamma radiation emitters).
For occasional measurement of environmental pertinent quantities, the natural solution is either to use dedicated, manually operated instruments if the measurement is to be made on site, or to take a sample of the media and make the measurements in an adequate laboratory. The last solution is sometimes required because of the difficulty of measuring on site namely chemical and biological quantities.
For continuous environmental monitoring, automated measuring systems are needed. When monitoring has to be made at several locations, the system must be of the distributed type. Very often the connection of the different monitoring sites recommends or even forbids the use of wires leading to the implementation of a wireless sensor network.
This talk will address the motivation for research on environmental monitoring, highlighting the basic issues underlying the choice of solutions, reviews recent advances in the development of sensing solutions, and presents selected examples of solutions for monitoring the three main environmental media – water, air, and soil – developed and implemented by the Instrumentation and Measurement Group in the Institute for Telecommunications, Lisbon, Portugal.