|M.Sc Student||Marina Kovalev|
|Subject||Infrared Rays Embedded Fish Instrument as a Tool for|
Online Detection of Pollution Intrusion into
Potable Water Systems
|Department||Department of Civil and Environmental Engineering||Supervisors||Full Professor Friedler Eran|
|Dr. Ram Porat|
Biological Early Warning Systems (BEWSs) that evaluate physiological and/or behavioral responses of whole organisms to water quality have been developed in recent years. Since BEWSs measure toxicity, they provide an important complement to available physical-chemical monitoring technologies. BEWSs provide online detection of acute contamination of water systems. Biological measures can detect unexpected materials and evaluate the toxic action of mixtures of multiple chemicals. Fish were the sentinel organisms originally selected for BEWS, and continue to be a popular choice. Their behavior is relatively easy to record and quantify: quite stable under normal conditions and erratic when the environmental conditions change.
ToxProtect 64 (bbe Moldaenke GmbH, Germany), is a fish-based biomonitoring early warning system for the detecting contaminantion of drinking water supply. This work describes the adaptation of the ToxProtect system to the local conditions and the determination of optimal operation sensitivity for this device.
The main goal of the study was to define for the test fish an optimal operation sensitivity of the ToxProtect 64 device. This sensitivity should enable the generation of alarms within an hour of intrusion of relatively low concentration of selected toxicants to the monitored water (high sensitivity), while minimizing the number of false alarms (high specificity). The test fish studied were Striped Bass (Morone saxatilis) fingerlings of 1 g.
In order to find optimal operating sensitivity of the ToxProtect device, the fingerlings were exposed to un-chlorinated water and toxicity tests were performed concurrently, with various doses of pesticides representing three different chemical groups, namely: organo-phosphates, chloro-organics and carbamates. In order to simulate acute short-term contamination events in the water supply system, the fish were exposed in each experiment for one hour. The detection ability of the ToxProtrct 64 was very good in events with full and partial fish mortality, but was rather poor in detecting events with no mortality at all.
While working on system calibration, two new parameters that can be useful in triggering the alarm algorithm, were signaled out. These may improve the sensitivity of the warning program particularly during weak response events (events with very low toxicant concentration and no mortality of fish) and may reduce the response time without compromising the system’s specificity.
Based on the experimental results, short-term bioaccumulation factors (BCF) were calculated. These increased with an increase of the chemicals’ log Kow?’s . Further, possible positive correlation between the chemical’s BCF and its toxicity to the test-fish was established.