Scientists study bubbles trapped in ancient glacial ice to determine how concent

Question

Scientists study bubbles trapped in ancient glacial ice to determine how concentrations of nitrogen and car- bon dioxide gas have changed over time. However, bubbles in glacial ice cannot provide information about changes in phosphorus. Explain why air samples are not useful for this purpose and propose an alternative method to study how the amount of phosphorus in a region has changed over time. Nitrogen-fixing bacteria live throughout the ocean, from its sunlit upper waters to 200 meters (650 feet) beneath its surface. Recall that nitro gen is a limiting factor in many habi- tats. What effect would an increase in populations of marine nitrogen- fixers have on carbon uptake and pri- mary productivity in those waters?

Explanation / Answer

Air sample is not used for this purpose because ice has a unique ability of capture and store air. Since carbon-dioxide and nitrogen is present mostly in atmosphere, so air bubble is not used. Since, phosphorus is present in soil, we are not able to measure the concentration of it using bubbles in glacial ice.

Methods available for measuring phosphorus content are Olsen phosphorus method that measure the ortho-phosphate available in the soil by extraction with the help of alkaline sodium bicarbonate.

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