Fiber-optics remote biosensor systems for continuous biological monitoring of the state of surface water and bottom sediments in real time Печать

KHOLODKEVICH S.V. Saint-Petersburg Scientific Research Center for Environmental Safety RAS, Russia

The development, spoil and transport of oil and gas are sources of potential danger for ecosystems in regions of industrial active zones.

The level of ecological danger and economical losses due to natural hydrocarbons spills highly depends on how fast governing decision directed to its liquidation could be made. That is why the problem of developing and improving methods and tools for early elicitation and express assessment of an emergency pollution level being dangerous for the environment and humans is of great importance for oil and gas companies. Taking into account the total product of such enterprises it becomes obvious that any delay in accidental conditions could dramatically increase the impact on the environment.

Any anthropogenic impact on the environment should be considered from the point of view of its ecological danger for species (including man) inhabiting that territories (or water areas). The world practice shows that monitoring of the environmental components (air, surface water, bottom sediments etc) based on automatic on-line registration stations is the most reliable and economically effective method to obtain object and necessary information for working out governing decisions directed on minimization of ecological risks in the case of environmental or technogenic emergency situations including terrorism {Kholodkevich..., 2001; Kholodkevich..., 1999).

Modern technical devices and automatic stations for monitoring physical-chemical parameters of environmental components do not allow to determine what impact on the living beings could be possessed by their changes.

The only opportunity to reveal pollutions and their toxicity for the environmental components is use of monitoring based on biological methods which take into account the multifactor synergetic effects to reveal negative to biota changes in the quality of their environment (Depledge..., 1990; Depledge..., 1995; Basics..., 2004; Kholodkevich..., 2006). It is to be mentioned that it is highly important to use aboriginal animals as bioindicators for each specified region.

So the development, creation and improvement of information systems (IS) which may estimate in the real time the functional state of aboriginal biota in the oil and gas active zone is the necessary condition for the development of automatic systems for enterprises based on principles of ecological safety. In particular it should include information supplement for governing decisions aimed to minimize ecological risks in the case of environmental and technogenic emergency situations.

In spite of the actuality of the problem there are no such serially produced information systems in the world nowadays. Nevertheless during last ten years in Russia and abroad there was increased the number of fundamental and applied investigations targeted on development of methods and technical devices for automatic control of accidental or other pollutions of environmental components in real time, including analytic and bioanalytic (based on monitoring of aboriginal animals functional state) assessments of their quantitative characteristics (Depledge..., 1990; Depledge..., 1995; Basics..., 2004; Kholodkevich..., 1999; Fedotov..., 2000; Kholodkevich..., 2006). As it was shown (Depledge..., 1990; Depledge..., 1995; Kholodkevich..., 2006) the most perspective ones in this direction are the methods based on measuring physiological and behavioral biomarker reactions.

Today the most developed methods are those which based on registration of cardioactivity of animals with solid external skeleton, i.e. crustacean, crabs, sea and freshwater and terrestrial mollusks. The presence of external skeleton or cover in numerous species as well as their tolerance to the individual cage-keeping make them convenient for using in automatic monitoring systems as bioindicators.

In 1999 in the framework of this approach in the laboratory of experimental ecology of water systems SRCES RAS there was developed an original fiber-optic method for recording cardioactivity of the invertebrates with external skeleton, such as: Crustacean (Decapoda) and Mollusca. The method allows to carry out remote (up to hundreds meters) non-invasive control of functional state of test-organisms in real time. The assessment of functional state of animals-targets is conducted with use of adapted to invertebrate method of variational pulsometry which was worked out in space medicine for monitoring of cosmonauts' health during selection, preflight choice and working on orbit. After adaptation this physiological method was assumed as a basis of the bioanalytic block of a new IS for permanent biological monitoring of environmental components quality (PBMECQ) based on permanent analysis of cardioactivity of animals with hard external skeleton.

Small fiber-optic sensor (weight less than 2g) is attached to external carapace over the heart placement. It does not limit the animal locomotion activity and other functions and therefore does not lead to animal stress reactions. In automatic biomonitoring systems based on registration and analysis of crayfish cardioactivity the animals (without substitution) were used during one year period without essential changes in functional state. The presence of sensor with a fiber has no effect on such complex process as molting (after which the sensor was glued again upon new carapace). Therefore such biosensor systems can be applied for long-term (no less than one year) biomonitoring of investigated environmental component. This system might be used, for example, as automatic early-warning system for the control of environmental quality (Kholodkevich..., 2006; Kholodkevich..., 2005).

It is expected that it will be more effective during simultaneous usage with automatic systems controlled physical-chemical characteristics of the specified environmental components. During application of such information systems at specific enterprises of gas-oil companies one needs to solve a number of problems: to determine animals-bioindicators for biotopes (where these enterprises are situated), to adapt or to develop new fiber-optic devices and software to provide possibilities for remote registration and analysis of cardioactivity in situ or in special conditions of the specific production including the climate peculiarities.

The area of application of such IS and their usage could be rather wide. In particular, as the length of fiber-optic cable 6 (Fig. 1) can be more than hundreds meters and taking in mind that the invertebrates with external cover are spread widely in different biotopes, the systems PBMECQ could have applications in the Automatic Control Systems of Industrial Process (ACSIP) in enterprises of oil-gas companies, located on the ground as well as at sea and on the sea bottom (depth up to hundreds meters) as remote automatic biological systems of early-warning control of environmental components in potentially dangerous areas of water and lands (for example in the regions of development, spoil and transport of oil and gas). One should mention that in the case when a fiber-optic cable has enough length to situate an electron-optic registration system for cardiac activity analysis in normal indoor conditions, there is no difference regarding animal-bioindicator locations. It can be settled ashore or in deep waters as well as in tropical or polar climatic zones, since a fiber-optic cable is made of inert material (quartz glass) which characteristics are independent of temperature and ambient medium (liquid or gas).

Industrial embedding for such a system started to be not long ago. In 2005 the laboratory of experimental ecology of water systems (SRCES RAS) developed a System for Industrial Biological Water Quality Monitoring (SIBWQM) as an order by the SUE "Vodokanal StPetersburg". This system is designed to provide on-line monitoring for toxicity level changes in the Neva River water intakes of St.Petersburg's drinking water supplying stations (WSS). To the present, 11 such automatic systems have already been mounted in all 11 WSS of StPetersburg and put in industrial operation for 9 months. Heart rate (HR) and a variational pulsometry characteristic of stress-index SI (Kholodkevich..., 2006; Kholodkevich..., 2005) are used as biomarkers. To measure these physiological biomarkers continuously and regularly, a special flow 6-aquarium system is used housing one adult male crayfish in each aquarium.

Crayfish are "on duty" pairwisely for three-day periods in every six days. Alarm signal is produced only if both animals react simultaneously. To prevent false alarm signaling the Neva River (as water source) toxicity, SIBWQM is also equipped with the "ASCEM-2" system for selected physical-chemical parameters control including noise and vibration sensors. It helps to reveal stress influences on bioindicators in the cases caused by not dangerous for citizenry changes of water source characteristics and industrial noise nearby the flow aquarium system. In spite of high stress level of crayfish in those occasions, an appropriate algorithm blocks alarm signal when it is not corresponding to toxicological risk occurrences.

Lack of data on ecotoxicological and ecophysiological investigations is the main reason limiting a widespread application of Continuous Biological Environmental Components Quality Monitoring (CBECQM) systems in particular in Arctic. Such investigations allow to fulfill methodologically-substantiated selection of indigenous benthic invertebrates (as test-organisms) for use in the systems of the surface water quality on-line biomonitoring based on registration of the animals cardiac activity changes. In particular it is related to necessity of knowledge of the circadian activity of the selected animals, their cardiac activity peculiarities in normal and stress states, of choosing stress stimuli for functional state express assessment and "calibrating" animals depending on their stress reactions to these stimuli. Later such "standardized influences" after overall approbation could be used as a basis for methodical guidance in environmental quality biomonitoring.

Besides in some cases there will be necessary additional development of devices and tools adapted to peculiarities in shell structure, anatomy and cardiorhythm of the selected animals for their further cardiac activity analysis in situ as well as in artificial keeping conditions at oil and gas enterprises of different profiles. The improvement and adaptation of the computer software used for analysis of cardiorhythm variability for each of selected species in normal or stress states is also of a great importance as well as development of automatic working places for information support of governing decision.

To the present time we have checked the possibility to record the cardioactivity of the invertebrate animals-bioindicators for 4 species of freshwater crayfish, 1 species of crab, 4 species of freshwater bivalves, 2 species of gastropod mollusks, 3 species of sea bivalves and 2 species of terrestrial snail.

References
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OIL AND GAS OF ARCTIC SHELF 2006 (PROCEEDINGS OF INTERNATIONAL CONFERENCE)