Development of the U-50 Series Multi-parameter Water Quality ...

Turbidity(NTU)50454035302520151055 月2824/172917/143014/123123/13TurbidityDO6 月121/17216/1505/28 5/30 6/1 6/3Date6/5 6/7 6/9322/14Fig.4 Continuous Test Data of Turbidity and DO in424/17Lake ImbaFigure 5 shows the measurement results for pHand ORP. On sunny days during the continuoustesting period, the pH values shifted to alkaline.This result suggests that photosynthesis of plantscaused the carbon dioxide gas and organic matterin the lake to drop. On the other hand, the ORPshifted to the reducing side, suggesting that theeffects of water purification induced byphotosynthesis.10.05 月2824/172917/143014/123123/136 月121/17216/15322/14424/17523/15523/15625/18625/18726/19726/19822/19822/19922/20922/20876543210500DO(mg/L)immersion direction changed over a range of 0.0NTU to 1.0 NTU. Measuring in the retractiondirection from 20 m to 10 m showed a significantchange from 0.0 NTU to 5.0 NTU, revealing adiscrepancy with the measurement in theimmersion direction. This suggests that airbubbles occurred on the measuring unit due todecompression and temperature rise. On theother hand, the U-53 turbidity meter, equippedwith a wiper, showed consistent results between0.3 NTU and 0.8 NTU, in both immersion andretraction directions. This result indicates thatthe wiper on the new turbidity meter effectivelycancels the effects of air bubbles.Turbidity(NTU)6543210Turbidity of U-53(Lower)Turbidity of U-20(Lower)Turbidity of U-53 (raised)Turbidity of U-20 (raised)0 10 20 30Water Depth(m)Fig.6 Turbidity immersion test in Lake MotosupH9.59.08.58.07.5pHORP450400350300250200150ORP(mg/l)5. ConclusionThe newly developed U-50 features EPAMethod 180.1 compliant turbidity sensor,expanded measurement ranges and greaterease of handling. These features can expandthe scope of an existing multi-parameter waterquality checker.7.05/28 5/30 6/1 6/3 6/5 6/7 6/9Date100Fig.5 Continuous Test Data of pH and ORP in LakeImbaFigure 6 shows the results of measurements inMotosu Lake, Yamanashi prefecture. In thismeasurement, the same test was performed usingthe turbidity meter on the former model U-20(30-degree transmission scattering method),which does not have a wiper. On the U-20turbidity meter, the measurement in the