A lake has a volume of 750,000 m3 (dimensions 15 m deep, 100 m wide, and 500 m long) and behaves as two completly mixed cells. Cell 1 makes up 40% of the lake ( dimensions 15 m deep, 100 m wide, and 200 m long) cell 2 makes up 60% of the lake (dimensions 15 m deep, 100 m wide, and 300 m long). the flow into the lake is from is from a stream is 300 m3/d andthe flow into the lake from runoff averages 20 m3/d. The lake is used for fishing by the local residents but the pesticides from local farms may damage the fish population. the stream and runoffboth carry pesticides from the local farms. Assume the runoff enters the lake uniformly around the edges. The stream has a concentration of 0.2 g/m3 and the run off has a concentration of 0.5 g/m3. the pesticide decays at a rate of 0.0001/d and is known to be toxic to fish at a concentration of 0.05 g/m3. Neglecting the the width of the streams, the lake has a permieter of 1200 m (500 m + 500 m +100 m + 100 m). So the lake recieves 20 m3/day over 1200 m perimeter. Now compute the percentages of the total runoff going into cell 1 and cell 2 based on the percentages of the perimeter each recieves runoff from.
Using the completly mixed model, estimate the pesticide concetration in the lake. Is this level dangerous to the fish population?