HA8 On-line Water Toxicity Monitoring
A105 & A106
8:00 AM - 12:00 PM, Thursday
() Implementation and operation of the Algae- and Daphnia-toximeter at monitoring station Keizersveer, the Netherlands.
de Hoogh, C.J.1, Wagenvoort, A.J.2, 1 Kiwa Water Research, Nieuwegein, The Netherlands2 Evides, Rotterdam, The Netherlands
ABSTRACT- Two biomonitors were chosen to monitor water quality at Keizersveer, for the continuous registration of acute toxicity of the water from the river Meuse before it is pumped into the Biesbosch reservoirs of Water company Brabantse Biesbosch. The Daphnia-toximeter at Keizersveer was implemented and currently has an operationality of over 90%. Spike-tests with diazinon were performed to determine the response of the Daphnia to cholinesterase inhibitors. A regular control sample of 5 g/l NaCl is used to check the operationality of the system. Standardisation of the organisms (clone and age) has led to the reduction of noise in the signal, but also to the detection of natural events such as molting of the organisms at approximately the same time. For a number of behavioural characteristics the normal range of values was determined for different size classes of organisms. Since the implementation of the double loop system in the Algae-toximeter the noise in the system has significantly been reduced. The algae-toximeter has a current operationality of over 85%. Spike tests were performed with diuron and atrazin, and a regular control sample of 2 
g/l diuron is used to check the operationality of the system. The noise of the measurements was determined with reference water and from these results the report limit of 4% inhibition could be calculated. Any measurement resulting in an inhibition of more than 4% can be interpreted as a significant deviation from the normal value. In spring 2004 the Daphnia-toximeter generated an alarm due to changes in water quality. Additional chemcial analyses were performed to gain insight in the cause of the alarms.
Key words: Daphnia-toximeter, continuous biomonitoring, Algae-toximeter, implementation