**Author details**

*Biosensors for Environmental Monitoring*

but also time-consuming because they usually need sample pretreatment; the equipment is expensive and requires qualified personnel to perform the analysis. The biggest drawback of the abovementioned methods is the fact that due to long analytical procedures, their application for operative in situ measurements in cases when timely information is crucial is not possible. For example, pollutant concentrations in watercourses are dynamic and change in water flows. With weekly or even monthly sampling and analyzing, it is extremely unlikely that the maximum or the real concentration levels for a certain period can be determined. As a result, we see elevated levels of pesticides or nitrates in areas of intensive farming, even in groundwater, or increased lead levels in areas where it has been used in plumbing. In addition, thin-layer chromatography (TLC) has been often used for testing soils and groundwater for pollutants like pesticides, herbicides or fungicides. It is an effective and low-cost method and many samples can be analyzed simultaneously. However, TLC is applicable only for nonvolatile compounds; there are limitations in

resolution capability and the absence of fully automated system [6].

The gold standard for the detection of microbiological pollutants is cultivation; however, DNA-based molecular diagnostics nowadays is becoming more and more popular. Microbiological cultivation is simple and inexpensive. However, there are some disadvantages: these methods rely on the growth of the target microorganisms in one or more nutrient media, the detection of growth is carried out by visual assessment and the confirmation of the presence of a particular pathogen usually involves a combination of biochemical and serological tests [7, 8]. In addition, the interpretation of the results can be subjective, and for some bacteria, the total test time can be as long as several days [8, 9]. For example, there is a drastic increase in pathogen concentrations, and the infection risks due to late results of potentially contaminated drinking water are very high [10]. With DNA-based molecular diagnostic methods like polymerase chain reaction (PCR), it is possible to identify specific bacterial strains, but this method still require several hours to obtain results and sometimes it fails to discriminate between related species and intragenomic

Therefore, development of rapid real-time and reliable detection methods is essential. Biosensors are an alternative to traditional methods. Biosensors can act as pressure sensors, microphones, optical sensors, microfluidics, temperature and gas sensors [12]. In recent years, biosensors have also been developed to detect and recognize genetically modified microorganisms (GMOs) [13], which have generated heated debates, especially in the European countries (EU), about the safety of food and the potential impact to the environment [14]. Furthermore, biosensors can offer a strong potential for better understanding and investigating of the environment, including the fate and transport of contaminants. The number of opportunities to join science and new technology into biosensing systems is almost overwhelming. One of the first environmental biosensors was initially developed for nerve gas detection for the military in the late 1970s and modified for the detection of pesticides (organophosphorus and carbamate) in the environment and was based on the inhibition of the enzyme acetylcholinesterase [15]. Over the years, new biosensors have been developed for environmental monitoring. For example, biosensors for the detection of heavy metals like zinc, cobalt, cadmium, lead, etc. [16–22] have been developed. In addition, biosensors for the detection of phenolic compounds [23–26], pesticides [27–30], pathogens [9, 31–35] and drug residues

**2**

[36, 37] have been developed.

heterogeneity [11].

**3. Biosensing in environmental monitoring**

Kairi Kivirand1,2\* and Toonika Rinken1

1 Institute of Chemistry, University of Tartu, Tartu, Estonia

2 Thomas Johann Seebeck Department of Electronics, Tallinn Technical University, Tallinn, Estonia

\*Address all correspondence to: kairi.kivirand@ut.ee

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
