Problem: Unfortunately, the layer of good ozone is being destroyed by air pollution. The chief culprits are chlorine and bromine gases. They are released in aerosol sprays, coolants, and other products. Loss of ozone has created an ozone hole over Antarctica. Ozone depletion results in higher levels of UV radiation reaching Earth. In humans, this increases skin cancers and eye cataracts. It also disturbs the nitrogen cycle, kills plankton, and disrupts ocean food webs. The total loss of the ozone layer would be devastating to most life. Its rate of loss has slowed with restrictions on pollutants, but it is still at risk. Two researchers studied air quality over the North Pole, and over Antarctica. Dan was more fond of the south pole, so he studied Antarctica, while Colt liked reading about the North Pole. Which researcher learned more about aerosol sprays?

A: Dan

Problem: Clouds on Earth are made of water vapor. Venus's clouds are a lot less pleasant. They are made of carbon dioxide, sulfur dioxide and large amounts of corrosive sulfuric acid! The atmosphere of Venus is so thick that the pressure on the surface of Venus is very high. In fact, it is 90 times greater than the pressure at Earth's surface! The thick atmosphere causes a strong greenhouse effect. As a result, Venus is the hottest planet. Even though it is farther from the Sun, Venus is much hotter even than Mercury. Temperatures at the surface reach 465C (860F). That's hot enough to melt lead! Two students studied the atmosphere of Earth and other planets from our solar system. Zack learned about Earth's atmosphere, while Ken learned about the atmospheric conditions on planet Venus. Which student learned less about corrosive sulfuric acid?

A: Zack

Problem: Groundwater salinization compromises buffering properties. Vegetation clearance, along with irrigation, causes serious issues. Irrigation increases the water table and mobilizes salts, and vegetation clearance allows it to come in contact with water habitats and vegetation. This stresses species not adapted to high salinity. High levels of salinity reduces water uptake in plants, by causing stomatal closure, reducing photosynthesis. Forests undergo decline in areas of high salinity and shallow groundwater depths because these conditions make them more susceptible to droughts. Forests undergo decline in areas of high salinity and shallow groundwater depths making them more susceptible to droughts. In the sixteenth century the State of Michigan had forests all over. But that has long been gone. Especially, in the state's northeast part the vegetation has been cleared in the twentieth century. Wooded areas were replaced by farm lands. All these farmlands were under heavy Irrigation. At one time, in the sixteenth century, plant species like elm and oak used to be plentiful. We still had some elms and oaks in the twentieth century, but they were not great many in number. Was the mobilized salts at increased or decreased level in northeast Michigan in the sixteenth century?

A: decreased level

Problem: Desertification is a type of land degradation in which a relatively dry area of land becomes a desert, typically losing its bodies of water as well as vegetation and wildlife.[2] It is caused by a variety of factors, such as through climate change (particularly the current global warming)[3] and through the overexploitation of soil through human activity.[4] When deserts appear automatically over the natural course of a planet's life cycle, then it can be called a natural phenomenon; however, when deserts emerge due to the rampant and unchecked depletion of nutrients in soil that are essential for it to remain arable, then a virtual "soil death" can be spoken of,[5] which traces its cause back to human overexploitation. Desertification is a significant global ecological and environmental problem with far reaching consequences on socio-economic and political conditions.[6] People in Iran used extensive grazing, fell most of their trees so they have lots of problems with desertification. Iraq took a more mindful approach to land use, they preserved native species, planted trees and didn't overgraze the land. Which country lost more vegetation and wildlife?

A:
Iran