Exam 22: Biogeochemical Cycles

Which chemical is responsible for breaking down ozone in the atmosphere?

Consider the following: on an annual basis,C exchange from photosynthesis is 120 Gt,decomposition is 60 Gt,respiration is 60 Gt,ocean uptake of CO₂ is 92 Gt of C,ocean release is 91 Gt of C,release of C to the atmosphere from anthropogenic sources (fossil fuel use and land use change)is 6 Gt,and the atmosphere is increasing by 3.2 Gt of C.If terrestrial processes are responsible for the remaining C for net balance of the C cycle,then which of the following is likely?

The major source of free oxygen that supports life on Earth is the ________.

Why are carbon dioxide fluctuations more pronounced in the Northern Hemisphere?

In the later stages of nitrogen saturation,soils tend to become more acidic,which increases the concentration of aluminum ions in the soil solution.

Nitrogen is generally available to plants in only two forms: ammonium and ________.

Atmospheric carbon dioxide concentrations in a forest are greater during the day than during the night.

In ________ biogeochemical cycles,the main reservoirs of nutrients are the atmosphere and the oceans.

The difference between the rate of carbon uptake in photosynthesis and the rate of carbon loss due to autotrophic and heterotrophic respiration is the net ________ productivity.

The major process regulating phosphorus availability for net primary production is the internal cycling of phosphorus from

Which of the following represents the largest anthropogenic source of sulfur released to the atmosphere?

Hydrogen sulfide is transformed into sulfate or elemental sulfur by

The main reservoir of plant-available phosphorus is organic matter in the soil.

Precipitation brings appreciable quantities of nutrients into ecosystems that are collectively called ________.

Oceans represent the largest natural source of sulfur gases released to the atmosphere.

Most carbon is buried in sedimentary rocks.

In ecosystems,internal cycling is dominated by

The element ________ is a basic constituent of all organic compounds and is involved in the fixation of energy by photosynthesis.

Microbial decomposition of organic matter results in NH4+ production through a process called ________.

Without the cycling of water,biogeochemical cycles would cease.