Background: Diffusion of carbon dioxide and oxygen is approximately 10,000 times slower in water than in air. When soils are flooded, they quickly lose oxygen, becoming hypoxic (an environment with O2 concentration below 2 mg/liter) and eventually completely anoxic where anaerobic bacteria thrive among the roots. Water also influences the intensity and spectral composition of light as it reflects off the water surface and submerged particles. Aquatic plants exhibit a wide variety of morphological and physiological adaptations that allow them to survive, compete, and diversify in these environments. For example, their roots and stems contain large air spaces (aerenchyma) that regulate the efficient transportation of gases (for example, CO2 and O2) used in respiration and photosynthesis. Salt water plants (halophytes) have additional specialized adaptations, such as the development of special organs for shedding salt and osmoregulating their internal salt (NaCl) concentrations, to live in estuarine, brackish, or oceanic environments. Anaerobic soil microorganisms in aquatic environments use nitrate, manganese ions, ferric ions, sulfate, carbon dioxide, and some organic compounds; other microorganisms are facultative anaerobes and use oxygen during respiration when the soil becomes drier. The activity of soil microorganisms and the chemistry of the water reduces the oxidation-reduction potentials of the water. Carbon dioxide, for example, is reduced to methane (CH4) by methanogenic bacteria. The physiology of fish is also specially adapted to compensate for environmental salt levels through osmoregulation. Their gills form electrochemical gradients that mediate salt excretion in salt water and uptake in fresh water.

Situation: Bobby and Ned are two neighbors who both have medium sized gardens in their backyards. They regularly talk to each other about what they are growing and share gardening tips. Bobby is out working in his garden when Ned comes over to chat. Ned mentions that the garden at his house is currently flooded, but he's not sure why since it didn't rain. He asks Bobby if his garden experienced the same thing. Bobby replies that his garden is not currently flooded. He does mention that he did see Ned's daughter walking around near Ned's garden carrying a hose turned on to full power.

Question: Whose garden is losing oxygen more quickly?
Answer: Ned's garden

Situation: Bobby and Ned are two neighbors who both have medium sized gardens in their backyards. They regularly talk to each other about what they are growing and share gardening tips. Bobby is out working in his garden when Ned comes over to chat. Ned mentions that the garden at his house is currently flooded, but he's not sure why since it didn't rain. He asks him if Bobby's garden experienced the same thing. Bobby replies that his garden is not currently flooded. He does mention that he did see Ned's daughter walking around near Ned's garden carrying a hose turned on to full power.

Question: Whose garden is losing oxygen more slowly?
Answer: Bobby's garden

Situation: Bobby and Ned are two neighbors who both have medium sized gardens in their backyards. They regularly talk to each other about what they are growing and share gardening tips. Bobby is out working in his garden when Ned comes over to chat. Ned mentions that the garden at his house is currently flooded, but he's not sure why since it didn't rain. He asks him if Bobby's garden experienced the same thing. Bobby replies that his garden is not currently flooded. He does mention that he did see Ned's daughter walking around near Ned's garden carrying a hose turned on to full power.

Question: Is Bobby's garden at more or less risk of hypoxia than Ned's garden?
Answer: less

Situation: Bobby and Ned are two neighbors who both have medium sized gardens in their backyards. They regularly talk to each other about what they are growing and share gardening tips. Bobby is out working in his garden when Ned comes over to chat. Ned mentions that the garden at his house is currently flooded, but he's not sure why since it didn't rain. He asks him if Bobby's garden experienced the same thing. Bobby replies that his garden is not currently flooded. He does mention that he did see Ned's daughter walking around near Ned's garden carrying a hose turned on to full power.

Question: Is Ned's garden at more or less risk of hypoxia than Bobby's garden?
Answer: more

Situation: Bobby and Ned are two neighbors who both have medium sized gardens in their backyards. They regularly talk to each other about what they are growing and share gardening tips. Bobby is out working in his garden when Ned comes over to chat. Ned mentions that the garden at his house is currently flooded, but he's not sure why since it didn't rain. He asks him if Bobby's garden experienced the same thing. Bobby replies that his garden is not currently flooded. He does mention that he did see Ned's daughter walking around near Ned's garden carrying a hose turned on to full power.

Question: Who has more anaerobic bacteria in their garden's soil?
Answer: Ned

Situation: Bobby and Ned are two neighbors who both have medium sized gardens in their backyards. They regularly talk to each other about what they are growing and share gardening tips. Bobby is out working in his garden when Ned comes over to chat. Ned mentions that the garden at his house is currently flooded, but he's not sure why since it didn't rain. He asks him if Bobby's garden experienced the same thing. Bobby replies that his garden is not currently flooded. He does mention that he did see Ned's daughter walking around near Ned's garden carrying a hose turned on to full power.

Question: Who has less anaerobic bacteria in their garden's soil?
Answer: Bobby