Introduction: Instrumentation
is used in almost every activity and generating system, where consistent and
reliable operations are required. Instrumentation provides the means of
monitoring, recording and controlling a process to maintain it at a desired
state. A typical environmental activity yields many process variables that have
to be measured and manipulated. Variables such as boiler level, temperature and
pressure, turbine speed, generator output and many others have to be controlled
prudently to ensure a safe and efficient station operation. Instrumentation is
often referred to as the power behind scientific investigations.
This assignment also explains the
general aspect of Quadrat Survey; its purpose and approach for ecological
study.
Ecology is the scientific study of the distribution and abundance of
life and the interactions between organisms and their natural environment. The
Environment is a complete ecological units that function as natural systems
without massive human intervention, including all vegetation, animals, microorganisms,
rocks, atmosphere and natural phenomena that occur within their boundaries.
Therefore an ecological investigation is that which is concerned with study of
all the biotic (living) and abiotic (non living organisms) in an environment.
But because the total land environment cannot be studied, for obvious reasons
like population and time, samples have to be taken. An acceptable way of doing
this is to conduct a Quadrat survey.
Instrumentation
definition:
The meaning of instrumentation cannot be positioned to a particular
discipline. It is not rigid, depending on whom or what is defining it. It is
generally described as the study, development and manufacture of scientific
instruments and equipment. In other words, instrumentation is simply defined as
instruments and procedures used in collecting and analyzing data in a
study.
Types of
Instrumentation for Environmental Studies
Different types of data are required for different categories of
environmental studies; hence different instruments and procedures for their
data collection and analyses exist too. But for the sake of explanation, the
different methods of data acquisition are described below:
a. Instrumentation for field observations:
Instrumentation for these includes land survey equipment, both analogue and
digital. Instruments for analogue approach to field survey include tape, arrow,
Gunter chain, etc. Digital instruments include Total Stations, Global
Positioning Systems (GPS), geographic information systems (GIS).
There are also some indirect methods of extracting information,
especially from aerial photographs and satellite imageries.
Other categories of instrument for field surveys include samplers, which
are of various types depending on the parameter to sample; air, water, sediment
and soil samplers. We also have testers or field equipment for direct
observation, including pH and electrical conductivity meters, quadrats; for
vegetation sampling, tape, ball of string, scissors, clipboard, pens and
paper.
b. Instrumentation
for laboratory analyses: In a particular application the selection of a technique will be based
on the particular requirements:
1. What species (parameters) are to be measured;
2. Is the simultaneous determination of several parameters necessary;
and
3. What are the required accuracy, time resolution, and spatial
resolution?
4. Logistic requirements like power consumption, mounting of light
sources or retro-reflectors or accommodation of the instrument on mobile
platforms.
Classification of
laboratory equipment:
Laboratory techniques are both specialized and universal techniques. Specialized
techniques allow only one parameter (specie) to be detected by an instrument,
e.g. UV absorption detection. On the other hand universal techniques allow one
to measure many species with one instrument.
Another fundamental property of instruments is the spatial range of the
measurements, usually expressed in terms of in situ or remote sensing
measurements. While in situ measurements come close to the ideal to determine
specie concentrations in a ‘spot’ in space that is usually very close to the
instrument, remote sensing techniques allow one to make measurements from a
large distance, perhaps as far as from a satellite instrument in the earth’s
orbit. It thus usually gives averages of the concentration over a relatively
large area.
Remote sensing techniques always rely on the sensing of electromagnetic
radiation. Examples of laboratory instruments belonging to either category
include
(i) Gas chromatographic (universal technique, in situ), (ii) optical
spectroscopy (universal technique, in situ and remote sensing), (iii) mass
spectrometry (MS), (iv) any other (in situ) technique, where the most commonly
employed principles include chemiluminescence (e.g. for the detection of NO or
O), photo acoustic detection, electrochemical techniques, matrix isolation), and
chromatography (IC).
It is important that you note that field surveys equipment such as total
stations, GPS and aerial and satellite sensors are also remote sensing devise.
This is because they are a devise that obtain information from the real world
surface without being in physical contact with the object from which
information is being obtained. You will learn more in the subsequent unit.
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