BIOGEOCHEMICAL CYCLES:  The RECYCLING of MATERIALS through living organisms and the physical environment. BIOCHEMIST: Scientists who study how LIFE WORKS at a 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.

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!

 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 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

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

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

CCARBON CYCLE NNITROGEN CYCLE OOXYGEN CYCLE

DEFINITION: The cycling of carbon through the atmosphere, the physical environment, and ecosystems.

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

2 TYPES OF CARBON STORAGE: 1) Organic Reservoirs: Carbon that has been stored as the result of decomposition of living organisms. PEAT, COAL, OIL and NATURAL GAS 2) INORGANIC RESERVOIRS: 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

DEFINITION: The movement of nitrogen through the atmosphere, physical environment and ecosystems.

Nitrogen is used to make DNA and PROTEINS. DNA is the GENETIC MATERIAL found in every living cell. 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).

HOW DO LIVING ORGANISMS GET NITROGEN? Plants and animals cannot use N 2 gas. We can use nitrogen in TWO FORMS: AMMONIA, NH 3 NITRATES, NO 3- WHAT ARE THE KEY NITROGEN CYCLE PROCESSES? NNITROGEN FIXATION DDENITRIFICATION

Also known as NITRIFICATION Gaseous nitrogen, N 2, is converted to usable forms in TWO WAYS: By LIGHTNING By NITROGEN-FIXINGBACTERIA These bacteria are found in the ROOT NODULES of LEGUMES such as ALFALFA and CLOVER.

DENITRIFYING BACTERIA convert usable forms of nitrogen back into gaseous nitrogen, N 2. These bacteria are found in the soil.

CARBON CYCLE GLOBAL WARMING and the GREENHOUSE EFFECT NITROGEN CYCLE AQUATIC EUTROPHICATION

Humans have DISRUPTED the CARBON CYCLE in TWO MAIN WAYS:  Burning FOSSIL FUELS – Increased CO 2  DEFORESTATION – Decreased O 2 production by plants Increased CO 2 These INCREASES in CO 2 Levels have led to an ENHANCED GREENHOUSE EFFECT.

Gases that have the ability to HOLD HEAT IN the atmosphere. These gases are important to keep the Earth warm enough to sustain life.

1) CARBON DIOXIDE CO 2 Sources: Cellular Respiration Combustion (burning) 2) METHANE CH 4 Sources: Fossil fuel production and transportation Decomposition Livestock

3) NITROUS OXIDES NOx Sources: Combustion Agricultural Fertilizers Industrial Emissions

Humans have DRAMATICALLY INCREASED the amount of greenhouse gases in the atmosphere, leading to the ENHANCED GREENHOUSE EFFECT, or GLOBAL WARMING.

 Increased spread of disease  Rising sea levels and loss of polar ice caps Figure below is 1979 versus 2005  Loss of freshwater sources  More extreme weather  Accelerated species extinction

Humans have impacted the nitrogen cycle by releasing 2 substances into AQUATIC ECOSYSTEMS: FERTILIZERS UNTREATED HUMAN SEWAGE Fertilizers, and untreated human sewage, contain NITRATES and PHOSPHATES. These chemicals LEACH into water ways through groundwater, road runoff, etc.

Lakes that have HIGH LEVELS of phosphates and nitrates can undergo EUTROPHICATION A transformation from an OLIGOTROPHIC LAKE to a EUTROPHIC LAKE.