38
Oceanic uptake of anthropogenic CO 2 resulted in acidification of the ocean, with
the pH of ocean surface water decreasing by 0.1 since the beginning of the industrial
era corresponding to a 26% increase in hydrogen ion concentration.
Beneficial impact of climate change includes milder winters that would decrease
the seasonal winter-time peak in deaths that occur in temperate countries. Increase
in temperatures may reduce the disease-transmitting mosquito populations. Climate
change can result in thermal extremes and related health impacts, in winter as well
as summer. Change in climate would also result in rising sea levels, disturbance of
food-producing ecosystems, and hydro-meteorological disasters that include avalanches, coastal storm surges, drought, hailstorms, tornados, blizzards, tropical
cyclones, thunderstorms, heavy snowfall, floods, heat waves, as well as cold spells.
1.9.1.3 Nitrogen Cycle
Nitrogen cycle (Fig. 1.23) is the process in which nitrogen is converted into numerous chemical forms through chemical, physical, as well as biological processes.
Nitrogen is present in the environment in various organisms in the form of
organic nitrogen, ammonia, ammonium, nitrous oxide, nitrate, nitric oxide, nitrous
oxide, nitrite, inorganic nitrogen gas, as well as other compounds. Nitrogen in the
organic form will be present as living organisms.
The N 2 O concentrations in the atmosphere have increased by a factor of 1.2 since
pre-industrial times. Changes in the nitrogen cycle, besides interactions with CO 2
sources and sinks, affect emissions of N 2 O from the oceans and from land (Stocker
et al. 2013).
The nitrogen cycle has five steps: (1) nitrogen fixation, (2) nitrification, (3)
assimilation, (4) ammonification, and (5) denitrification.
Conversion of atmospheric nitrogen into ammonia is called nitrogen fixation.
This process is carried out by microorganisms present in the roots of leguminous plants.
Nitrogen in the atmosphere is converted into N 2 O 5 and its union with water produces HNO 3 , which is carried to the earth with rain and becomes nitrate by a series
of reactions. Anthropogenic activities such as transportation, power generation, and
manufacturing will generate oxides of nitrogen, which will contribute to acid rain
and may become nitrate by a series of reactions. Photolysis also contributes to atmospheric nitrogen, wherein high-energy ultraviolet radiation disintegrates nitrous
oxide in the atmosphere.
Biological oxidation of ammonia into ammonium and then into nitrite followed
by oxidation into nitrates is known as nitrification. Nitrate is assimilated into the
plant tissue by absorption followed by a series of biochemical reactions. Animals
eat plants and pass on nitrogen along the food chain.
The remains of plants/animals as well as their waste products are decomposed by
microorganisms into ammonia.
Nitrates are reduced into inert nitrogen gas by denitrification, which completes
the nitrogen cycle.
1 Fundamentals of Chemistry for Environmental and Medical Professionals
Oceanic uptake of anthropogenic CO 2 resulted in acidification of the ocean, with
the pH of ocean surface water decreasing by 0.1 since the beginning of the industrial
era corresponding to a 26% increase in hydrogen ion concentration.
Beneficial impact of climate change includes milder winters that would decrease
the seasonal winter-time peak in deaths that occur in temperate countries. Increase
in temperatures may reduce the disease-transmitting mosquito populations. Climate
change can result in thermal extremes and related health impacts, in winter as well
as summer. Change in climate would also result in rising sea levels, disturbance of
food-producing ecosystems, and hydro-meteorological disasters that include avalanches, coastal storm surges, drought, hailstorms, tornados, blizzards, tropical
cyclones, thunderstorms, heavy snowfall, floods, heat waves, as well as cold spells.
1.9.1.3 Nitrogen Cycle
Nitrogen cycle (Fig. 1.23) is the process in which nitrogen is converted into numerous chemical forms through chemical, physical, as well as biological processes.
Nitrogen is present in the environment in various organisms in the form of
organic nitrogen, ammonia, ammonium, nitrous oxide, nitrate, nitric oxide, nitrous
oxide, nitrite, inorganic nitrogen gas, as well as other compounds. Nitrogen in the
organic form will be present as living organisms.
The N 2 O concentrations in the atmosphere have increased by a factor of 1.2 since
pre-industrial times. Changes in the nitrogen cycle, besides interactions with CO 2
sources and sinks, affect emissions of N 2 O from the oceans and from land (Stocker
et al. 2013).
The nitrogen cycle has five steps: (1) nitrogen fixation, (2) nitrification, (3)
assimilation, (4) ammonification, and (5) denitrification.
Conversion of atmospheric nitrogen into ammonia is called nitrogen fixation.
This process is carried out by microorganisms present in the roots of leguminous plants.
Nitrogen in the atmosphere is converted into N 2 O 5 and its union with water produces HNO 3 , which is carried to the earth with rain and becomes nitrate by a series
of reactions. Anthropogenic activities such as transportation, power generation, and
manufacturing will generate oxides of nitrogen, which will contribute to acid rain
and may become nitrate by a series of reactions. Photolysis also contributes to atmospheric nitrogen, wherein high-energy ultraviolet radiation disintegrates nitrous
oxide in the atmosphere.
Biological oxidation of ammonia into ammonium and then into nitrite followed
by oxidation into nitrates is known as nitrification. Nitrate is assimilated into the
plant tissue by absorption followed by a series of biochemical reactions. Animals
eat plants and pass on nitrogen along the food chain.
The remains of plants/animals as well as their waste products are decomposed by
microorganisms into ammonia.
Nitrates are reduced into inert nitrogen gas by denitrification, which completes
the nitrogen cycle.
1 Fundamentals of Chemistry for Environmental and Medical Professionals