10% Hydrochloric acid (HCl) and 30% Hydrogen peroxide (H2O2) were added to the sample and heated in order to remove the calcareous and organic matters. After the complete digestion, the mixture was carefully stirred with distilled water and kept 24 h for settling the particles. Subsequently, the supernatant was removed by syphon, and the washing process was repeated four times to remove the redundant HCl and H2O2, as well as the reaction solution. The remaining sample was diluted to 20 ml and then added
2 ml of gelatin solution to accelerate the following settlement process. The well mixed sample solution was gently decanted into a petri dish, in which two 24 mm 24 mm cover slips were fixed beforehand. After 24 h settling time, the supernatant in the dish was removed by a strip of absorptive paper. When the material was completely dried, the cover slips were transferred onto a labeled slide, mounted with Naphrax (dn ¼ 1.72). A Motic BA400 phase contrast microscope was used for diatom counting and identification under a 1000 magni- fication. Diatom fluxes were then calculated by following formula:
10% Hydrochloric acid (HCl) and 30% Hydrogen peroxide (H2O2) were added to the sample and heated in order to remove the calcareous and organic matters. After the complete digestion, the mixture was carefully stirred with distilled water and kept 24 h for settling the particles. Subsequently, the supernatant was removed by syphon, and the washing process was repeated four times to remove the redundant HCl and H2O2, as well as the reaction solution. The remaining sample was diluted to 20 ml and then added2 ml of gelatin solution to accelerate the following settlement process. The well mixed sample solution was gently decanted into a petri dish, in which two 24 mm 24 mm cover slips were fixed beforehand. After 24 h settling time, the supernatant in the dish was removed by a strip of absorptive paper. When the material was completely dried, the cover slips were transferred onto a labeled slide, mounted with Naphrax (dn ¼ 1.72). A Motic BA400 phase contrast microscope was used for diatom counting and identification under a 1000 magni- fication. Diatom fluxes were then calculated by following formula:
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