Biochemical
cycles and
human impact
Science 1206
Outline
 BIOGEOCHEMICAL


INTRODUCTION
THE CYCLING PROCESS
 TWO


CYCLES:
CARBON CYCLE
NITROGEN CYCLE
 HUMAN


CYCLES
IMPACTS
GLOBAL WARMING
AQUATIC EUTROPHICATION
Introduction
 BIOGEOCHEMICAL

CYCLES:
The RECYCLING of MATERIALS through living
organisms and the physical environment.
 BIOCHEMIST:


Scientists who study how LIFE WORKS at
CHEMICAL level.
The work of biochemists has led to the
understanding that LIVING ORGANISMS are
composed of some of the SAME elements
that are found in air, water, and soil.
Biogeochemical cycles
 Although
there are 92 elements known to
occur naturally on Earth, fewer than 20
elements are presently known to occur in
the tissues of living things.
 For example, only 6 elements make up 99.2
% of human tissue . . . And pumpkin tissue!!!
 Look at the table on the following slide to
see a comparison between the elements in
the EARTH’s CRUST, a HUMAN, and a
PUMPKIN!
(Symbol)
'9xygen (O)
arbon (C)
!Hydrogen (H)
!Nitrogen (N)
[c alcium (Ca)
osphorus (P)
§ otassium (K)
'[
[
'I
'I
Earth
Human
Pumpkin
% weight
% weight
% weight
46.6
][
0.19
trace
[
trace
I
I
65
18
10
3
2.0
I[
1.2
'I
2.6
][
[
0.20
L
0.25
<0.05
II
0.1
0.05
[
I[
[
L
0 .0 08
'I
trace
2.8
2 .1
'[
[
trace
][
5 .0
[
trace
!copper (Cu)
'I
trace
trace
! odine (I)
11
trace
I
I
b thers
0 . 16
0.02
trace
!Magnesium (Mg)
uminum (Al)
I
I
'[
'[
[z inc (Zn)
3.3
10 .7
[
odium (Na)
ilicon ( Si)
[
3.6
'[
ron (Fe)
85
I[
ulfur (S)
hlorine (Cl)
L
'[
'[
27 .7
trace
'[
I[
8 .1
trace
0 . 15
[
trace
trace
I[
trace
[
trace
trace
][
[
[
0.05
0.34
0.00 1
0.01
<0.05
I
I
0 .000 1
I
0 .0002
L
L
L
<0.0 5
trace
trace
trace
Conclusions



So . . . .you don’t really need to dress up like a
pumpkin!!!
And when you say you feel like dirt, you kind of
are like dirt!
Oh yeah, and also . . .

THE FOUR ELEMENTS that make up the MAJORITY
of LIVING TISSUES are:
OXYGEN
 CARBON
 HYDROGEN
 NITROGEN

The cycling process
 The
4 elements -- O, C, N, and H – are
cycled constantly between 2 parts of
nature:


LIVING ORGANISMS
PHYSICAL ENVIRONMENT
 The
cycling of these elements is dependent
on two types of processes in order to work:


BIOLOGICAL PROCESSES
GEOLOGICAL PROCESSES
The cycling process

BIOLOGICAL PROCESSES


The cycling of these elements requires LIVING
ORGANISMS, which make up the BIOSPHERE of
Earth.
What are some examples of BIOLOGICAL
PROCESSES?





Respiration
Photosynthesis
Decomposition
Assimilation
Excretion
GEOLOGICAL PROCESSES

The cycling of these elements require the
PHYSICAL ENVIRONMENT, which INCLUDES:




AIR – ATMOSPHERE
LAND – GEOSPHERE
WATER - HYDROSPHERE
What are some examples of GEOLOGICAL
PROCESSES?





FOSSILIZATION
EROSION
COMBUSTION/BURNING
WEATHERING
SEDIMENTATION
3 types of cycles
 CARBON
CYCLE
 NITROGEN
 OXYGEN
CYCLE
CYCLE
The carbon cycle p 62-65
 DEFINITION

The cycling of carbon
through the
atmosphere, the
physical environment,
and ecosystems.
The carbon cycle
 YouTube
Video
 See also Figure 3, p. 63
Carbon and the biosphere
 HOW

IMPORTANT IS CARBON for LIFE?
Carbon is the ELEMENT that is the BACKBONE
for ALL LIFE on Earth. In other words, we are
CARBON-BASED life forms.
 HOW
DOES CARBON MOVE THROUGH
LIVING ORGANISMS?

The two main PROCESSES that help cycle
CARBON through the BIOSPHERE are:
 PHOTOSYNTHESIS
 CELLULAR
RESPIRATION
Carbon and non-living systems


WHERE IS CARBON STORED IN THE NON LIVING
PHYSICAL ENVIRONMENT?
2 TYPES OF CARBON STORAGE:
1.
ORGANIC RESERVOIRS
Carbon that has been stored as the result of
decomposition of living organisms. These
processes are VERY SPECIFIC and take MILLIONS
OF YEARS to complete.
 When DETRITUS gets TRAPPED UNDER:



PEAT, it forms COAL
OCEANS, it forms OIL and NATURAL GAS
Carbon and non-living systems
2.
INORGANIC RESERVOIRS
3



MAIN AREAS:
AIR – 0.03 % of air is carbon
OCEANS – both dissolved (CO2 gas) and in shells
(CaCO3 – calcium carbonate)
LAND – in sedimentary rocks, which can be
released during volcanic eruptions
The nitrogen cycle p.66-67
 DEFINITION:

The movement of nitrogen through the
atmosphere, physical environment and
ecosystems.
The nitrogen cycle
 Animation
Nitrogen and the biosphere

WHAT IS NITROGEN USED FOR IN LIVING
ORGANISMS?

Nitrogen is used to make DNA and PROTEINS.


DNA is the GENETIC MATERIAL found in every living
cell.
WHERE IS MOST NITROGEN FOUND ON EARTH?

Most nitrogen on Earth is found in the air.
The air is 79% NITROGEN.
 This atmospheric nitrogen is in the form N2, a gas.
 Although nitrogen is plentiful in the air, it is
UNUSABLE to most living organisms (we cannot
simply “breathe in” nitrogen).

Nitrogen and the biosphere
 HOW
DO LIVING ORGANISMS GET
NITROGEN?
 Plants and animals cannot use N2 gas.
 We can use nitrogen in TWO FORMS:


AMMONIA, NH3
NITRATES, NO3-
 WHAT
ARE THE KEY NITROGEN CYCLE
PROCESSES?


NITROGEN FIXATION
DENITRIFICATION
Nitrogen cycles

NITROGEN FIXATION


Also known as NITRIFICATION
Gaseous nitrogen, N2, is converted
to usable forms in TWO WAYS:


By LIGHTNING
By NITROGEN-FIXING BACTERIA


These bacteria are found in the
ROOT NODULES of LEGUMES such as
ALFALFA and CLOVER.
DENITRIFICATION

DENITRIFYING BACTERIA convert
usable forms of nitrogen back into
gaseous nitrogen, N2.

These bacteria are found in the soil.
Human impact on the
 CARBON

CYCLE
GLOBAL WARMING and the GREENHOUSE
EFFECT
 NITROGEN

CYCLE
AQUATIC
 EUTROPHICATION
Global warming and the
greenhouse effect
 Humans
have DISRUPTED the CARBON
CYCLE in TWO MAIN WAYS:

Burning FOSSIL FUELS –
 Increased

CO2
DEFORESTATION –
 Decreased
O2 production by plants
 Increased CO2
 These
INCREASES in CO2 Levels have led to
an ENHANCED GREENHOUSE EFFECT.
Greenhouse gases
 WHAT
ARE GREENHOUSEGASES?
 Gases that have the ability to HOLD HEAT IN
the atmosphere.
 These gases are important to keep the
Earth warm enough to sustain life.
3 main greenhouse gases
1.
CARBON DIOXIDE CO2

Sources:
 Cellular
Respiration
 Combustion (burning)
3 main greenhouse gases
2.
METHANE CH4

Sources:
 Fossil
fuel production and transportation
 Decomposition
 Livestock
 LINK
 LINK
 LINK
3 main greenhouse gases
3.
NITROUS OXIDES NOx

Sources:
 Combustion
 Agricultural
Fertilizers
 Industrial Emissions
Global warming 101
 Humans
have DRAMATICALLY INCREASED
the amount of greenhouse gases in the
atmosphere, leading to the ENHANCED
GREENHOUSE EFFECT, or GLOBAL
WARMING.
Possible effects of global
warming
 Increased
spread of disease
 Rising sea levels and loss of polar ice caps

Figure on bottom is 1979 versus 2005
 Loss
of freshwater sources
 More extreme weather
 Accelerated species extinction
Should we be taking global
warming seriously ?
 Ice
gone by 2019 video
 6 degrees video
 Polar Bears video
Aquatic eutrophication
2.
Humans have impacted the nitrogen cycle by
releasing 2 substances into AQUATIC
ECOSYSTEMS:
FERTILIZERS
UNTREATED HUMAN SEWAGE

WHAT ARE FERTILIZERS?

1.



Chemicals used to improve crops in agriculture
and to aid in lawn care at individual homes.
Fertilizers, and untreated human sewage, contain
NITRATES and PHOSPHATES.
These chemicals LEACH into water ways through
groundwater, road runoff, etc.
Aquatic eutrophication
 Lakes
that have HIGH LEVELS of phosphates
and nitrates can undergo EUTROPHICATION
 AQUATIC EUTROPHICATION:

A transformation from an OLIGOTROPHIC
LAKE to a EUTROPHIC LAKE.
Aquatic eutrophication
OLIGOTROPHIC LAKE
EUTROPHIC LAKE
LOW levels of nitrates and phosphates
HIGH levels of nitrates and phosphates
LOW numbers of microorganisms
HIGH numbers of microorganisms
HIGH diversity and numbers of fish
LOW diversity and numbers of fish
CLEAR, DEEP, COLD
TURBID, SHALLOW, WARM
HIGH d. O2
LOW d. O2
Not prone to ALGAL BLOOMS
HIGH RATES of ALGAL BLOOMS
algal bloom video
 Something
to Think About video