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Monitoring the toxicity of phenolic chemicals to activated sludge using a novel optical scanning respirometer. 总被引:3,自引:0,他引:3
This paper reports the development of optical scanning respirometer for determining the toxicity of chemicals to activated sludge. The respirometer is used to measure the dissolved oxygen concentration by monitoring the luminescence intensity of ruthenium dye immobilized in a polymer film in contact with the wastewater sample. The intensity is related to the extent of oxygen quenching of luminescence. The toxicity of chemicals can be evaluated by measuring the inhibition on respiration rate of microorganism using the scanning respirometer. The IC50 values (concentration of a chemical that exhibits 50% respiration inhibition) of various phenolic chemicals in activated sludge were determined. The performance of this method is compared with other toxicity methods. The experimental results indicate that the reproducibility and sensitivity of this respirometer are reasonably good. 相似文献
867.
Individuals of the pit crabs Cryptochirus coralliodytes Heller inhabit massive corals of the family Faviidae. Their pit walls were observed to be covered by blue-green algae and
fungi. We suggest that the crabs enhance the growth of these algae and fungi with their metabolic excretions, which contain
ammonium. The endolithic algae and the fungi may facilitate the abrasion of the coral skeleton by the crabs, by perforating
it and thus weakening the skeletal structure. Computerized tomography analysis revealed dense skeletal material around the
pits. Transverse sections showed that the calcification around the pit was similar to other parts of the colony, whereas the
macro-architecture was different. Such a difference is the result of the crabs' influence on the corals' living tissue, possibly
on the calicoblast which deposits the coenosteum. Crabs, which were exposed to carbon-labeled corals for 1, 7 and 18 d, accumulated
labeled carbon, indicating transfer of carbon from the coral tissue to the crabs. Histochemical examination of the stomach
and gut of crabs revealed the presence of mucopolysaccharids in the gut, supporting the hypothesis that the crabs eat coral
products. The findings of this study provide additional evidence that C. coralliodytes are parasites and support the general hypothesis that a nutritional relationship may have served as a basis for selection.
Received: 20 October 1998 / Accepted: 29 April 1999 相似文献
868.
In this work, the heavy metals cadmium and lead in Kepez harbor were studied with regard to the determination of the environmental pollution levels. Seawater samples of the Dardanelles (Canakkale Strait) were collected from the nearest station to Kepez harbor in July 2007. Then, the concentrations of these metals were determined after simple pretreatment of samples by the proposed inductively coupled plasma?Catomic emission spectrometry (ICP-AES) method. The analysis of a given sample is completed in about 15 min by the ICP-AES method, and the concentrations of Cd and Pb were found to be 73.80 mg L???1 (relative standard deviation [RSD], 1.07%) and 9.39 mg L???1 (RSD, 0.70%), respectively. The accuracy of the applied ICP technique was checked by recovery studies, and good recoveries were obtained. The pollution levels of Cd and Pb recorded in this study were compared with those in other studies to analyze the water sample in Kepez harbor. 相似文献
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