. Removal of nitrate by an algal system. Water; Nitrates; Water; Algae. The water for the previous study was collected in early September when sump flows were characteristic of sum- mer irrigation practices, especially rice flooding. Another series of samples from the same tile systems was collected in October when field irrigation had been discontinued. The plots of nitrate meter reading versus time for cultures grown in the three tile drainages are snown in Figure l8. Complete nitrate assimilation in all the sumps required about 12 days or about the same length of time required by cultures i
. Removal of nitrate by an algal system. Water; Nitrates; Water; Algae. The water for the previous study was collected in early September when sump flows were characteristic of sum- mer irrigation practices, especially rice flooding. Another series of samples from the same tile systems was collected in October when field irrigation had been discontinued. The plots of nitrate meter reading versus time for cultures grown in the three tile drainages are snown in Figure l8. Complete nitrate assimilation in all the sumps required about 12 days or about the same length of time required by cultures in DPS 1367, HMH 7016, and BVS 7^02 water in the previous study. Results using water from GSY O855 were similar to those from the other sumps. Algae grown in a composite sample from the four systems to which iron and phosphorus had been added but which contained only about 30 mgN/l, assimilated essentially all of the nitrogen by day 7. The difference in time needed to reach zero nitrate between the composite and the individual sumps undoubtedly was caused by the original difference in nitrogen content of the samples. The individual drainage samples were all brought up to about 55 mgN/l as nitrate. More studies of this type are needed for confirma- tion; however, seasonal variation in the algal growth poten- tial of individual tile systems does occur, at least in labo- ratory cultures. The water used in this investigation appears typical of other systems, and the nutrient additions re- quired for growth of Scenedesmus probably will be required in a combined system. Miscel- laneous Lightbox Studies. Addi- tional lightbox studies were de- signed to answer specific questions about occurrences in the outdoor growth units. The results of these studies will be presented in later discussions, DAYS AFTER INOCULATION FIGURE 18-COMPARISON OF NITROGEN ASSIMILATION IN VARIOUS TILE DRAINAGE SYSTEMS-OCTOBER SAMPLE NOTE: 5% COj 2mg/l PO4-P 3nig/l Fe CONTINUOUS LIGHT. -he-. Please note that thes
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Keywords: ., bookcentury1900, booksubje, booksubjectalgae, booksubjectnitrates
