ADAM HART-DAVIS / SCIENCE PHOTO LIBRARY ADAM HART-DAVIS / SCIENCE PHOTO LIBRARY
Pollution monitoring. A scientist setting up equipment to investigate the effect of air pollution on the rate of photosynthesis in trees. Here, he places needles from a sapling scots pine, Pinus sylvestris, into the leaf chamber of a gas-exchange monitoring system. Instruments connected to the chamber measure the amount of incident light, the temperature of both the leaf & the air, and the rates of carbon dioxide uptake and water vapour loss. Later, the chosen bunch of needles is snipped off and its surface area is measured, allowing calculation of the rate of photosynthesis over a standard area.
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