Envirionmental math issues

Question

If you could solve any of these problems that would be great

1. During the green revolution in Mexico, the annual amount of wheat produced per hectare increased from approximately 700kg annually in 1920 to 2400 kg per hectare in 1965. Calculate the percent increase in annual wheat production during the green revolution.

2. A water sample was analyzed and found to contain .00005 ppm of DDT. Plankton living in the same water sample were found to contain 800 times the concentration of DDT. In ppm, what was the concentration of DDT in the plankton.

3. The Food and Agriculture Organization of the United Nations estimates that world consumption of herbicides was 543,776 metric tons in 1977 and 201,182 metric tons in 2001. What was the average annual percent change in consumption ?

4. According to the U.S Geological Survey it is estimated that nearly 150 million pounds of pesticides are applied to crops in the Central Valley of California each year. Total land area of California is 163,707 square miles. Approximately how many pounds of pesticides per square mile are applies to California lands per year ?

5. Reproductive controls of pests are often used as alternative to pesticides. The sterile male technique, often used to control medfly population, is currently being employed in California. Aerial drops of 1.5 million sterile male medflies are scheduled to take place twice a week over 12.2 mile area from mid September 2007 until the end of July 2008. Calculate how many total medflies will be released and approximately how many medflies are to be applied per square mile throughout the duration of this project.

6. The united states imports nearly 1.2 million shipments of food annually from other countries. The FDA monitors toxic residues on incoming fruits and vegetables, but only inspects about 1% of the food shipments that enter each year. Assuming the U.S imports 50 million metric tons of fruit and vegetables a year, calculate how many pounds of produce is not being inspected for traces of pesticides and herbicides

Answer 1

(1) Increase in wheat yield=2400/700=24/7=343% or an increase of 243%.

(2) Concentration changes to 800×0.00005=0.04ppm.

(3) If the reduction rate is r% per year then over 2001-1977=24 years, we have 543.776(1-r/100)²⁴=201.182, (1-r/100)²⁴=201.182/543.776=0.37 approx.

1-r/100=0.9594, r/100=0.0406, so percentage decrease per year on average is 4.06% approx.

(4) 150,000,000 lb over 163,707 sq miles=150000000/163707=916.27lb/sq mile.

(5) Assume 12.2 miles is intended to be 12.2 square miles. Between 2007 and 2008, 104 batches of medflies were released=156,000,000 medflies in all.

156000000/12.2=12.79M medflies/sq mile.

(6) 1.2M shipments is equivalent to 50M tonnes.

One shipment is equivalent to 50/1.2 tonnes=41.67 tonnes approx.

1 tonne=1000kg=2202.64lb approx.

Only 1% of each shipment is tested=0.4167 tonne=917.77lb.

41.67 tonnes=91776.74. Therefore 91776.74-917.77=90,859 lb (approx) pollutants not inspected per shipment.