Michelle Smith
Biogeochemistry Paper
Introduction

Biogeochemistry is an emerging science and further research in biogeochemical cycles ought to be at the forefront of scientific research. In “Better Living Through Biogeochemistry”, Schlesinger articulates the need to better understand the chemical environment in which we live, and how life on our planet interacts with it’s chemical system. As the chemistry of the Earth changes, so will its effects on biota and climate. These changes in chemistry have the potential to cause destructive modifications to our environment and lead to devastating affects for life on Earth. Climate change is natural; however, the scientific consensus of the Intergovernmental Panel on Climate Change (IPCC) is that Earth’s climate is being affected by human activities. According to the IPCC, human activities are modifying the concentration of atmospheric constituents that either absorb or scatter radiant energy. Most warming occurring over the last 50 years is due to an increase in greenhouse gas concentrations, such as carbon dioxide, methane and nitrous oxide.(1) Many details regarding climate change remain unknown, thus providing ample grounds for research in biogeochemical cycles to provide a better foundation for understanding climate dynamics. This paper will review and discuss some of the impacts humans have on the global water cycle and global climate change.

The Role of Human Impacts and Their Vulnerability

The majority of biogeochemical research has focused on the carbon cycle. Humans play a substantial role in the global movement of chemicals and, by the

1) Naomi Oreskes, “The Scientific Consensus on Climate Change” ( Science VOL.306 December 3, 2004) pg. 1686

extraction of carbon-based fossil fuels from the Earth’s crust, humans add more than twenty-two billion tons of CO2 to the atmosphere on an annual basis. One fundamental concern is the impact humans have on the global cycle of water along with how climate change and population growth will affect the global water supply.

Over the coming decades, much of the world’s population growth will occur in already urbanized areas, which are expected to double in size by the year 2025. These urban areas will face major challenges in managing increased water pollution and water-borne disease. Arid and semi-arid regions will experience the additional challenge of water supply. Interactions among climate change and variability, surface and groundwater hydrology, water engineering and human systems need to be better understood to obtain a more complete view of future water vulnerabilites. (2)

As world population increases, humans will continue dominating ecosystems, steadily transforming them into degraded systems. Ecosystems collectively determine the biogeochemical processes that regulate the Earth. The potential ecological consequences of biodiversity loss are a huge player in how we plan to manage ecosystems in the future. For example, acid rain directly affects water quality. When the acidic rain flows through soils in a watershed with a low buffering capacity, aluminum is released into the lakes, streams and marshes located in that watershed. Low pH and increased aluminum levels are toxic. They harm and kill individual fish, reduce fish population numbers, eliminate fish species, and overall decrease biodiversity. Humans cause a general decline in diversity as well as predictable shifts in diversity as species

2) Charles J. Vorosmarty, Pamela Green, Joseph Salisbury, Richard B. Lammers, “Global Water Resources: Vulnerability From Climate Change and Population Growth” (Science VOL 289 July 14, 2000) pgs. 284-288

with a particular set of traits are replaced by other sets of species with different traits. As the environment changes, species acquire new traits to adapt and continue living. A large pool of species is required to sustain ecosystem properties such as productivity, decomposition rates and nutrient cycling, while further experiments are needed to identify if the dependence on diversity stems from the need of a few key species within the regional species pool or from the need for a rich assortment of species within particular ecosystems.(3) Experiments need to be standardized so that results are accurate and can be widely distributed.

Nutrient Cycling

Life on Earth relies on the cycle of chemical elements in the biosphere. The atmosphere would be depleted of all CO2 if it were not for the continuous recharging by respiration and fires. These self-regulating cycles have feedback mechanisms that make them conducive for life on Earth. What happens when humans begin to disrupt this seemingly perfect set of cycles via activities like burning fossil fuels and the selective removal of groups of organisms through the application of pesticides? The ecosystem in which we occupy interacts with the biogeochemical cycles of the Earth through a system of inputs and outputs. The main sources of inputs into the terrestrial ecosystem are geologic, meteorologic, and biologic.

Geological inputs are considered to be particulates brought into the system by water, colluvial processes or a combination of the two. Meteorologic inputs enter the system via the atmosphere and are composed of gaseous materials, dissolved particulates in precipitation, dust and other wind blown elements. Biologic inputs are those resultingfrom animals, like fecal matter, or deposition from elsewhere. The addition of anthropogenic fertilizers is an example. The chemicals leave the system in essentially the same manner. (4)

3) M. Loreau, S. Naeem, P. Inchausti, J. Bengtsson, J.P.Grime, A. Hector, D.U. Hooper, M.A. Huston, D. Raffaelli, B. Schmid, D. Tilman, D.A. Wardle, “Biodiversity and Ecosystem Functioning: Current Knowledge and Future Challenges” (Science VOL 294 October 26, 2001) pgs. 804-808

4) F.H. Bormann and G.E. Likens, “Nutrient Cycling” (Science VOL. 155 January 27, 1967) pgs. 424-429

The time scales on which each of these sources interacts differ. Some of these biogeochemical cycles may occur within the time period of days or weeks, others may take years, decades, centuries and longer. For example, it takes roughly 1,300 years for one particle to transfer fully through the ocean conveyor belt. When scientific experiments are considered in the future, they should monitor the long term effects on the ecosystem, the response of human impacts, use of consistent methods and the proper archival of records for future research and comparison.

Conclusion
Further research in biogeochemical cycles should be done to obtain a more concise understanding of the chemical environment in which we live, how life on our planet interacts with its chemical system, and the impact of humans on the global water cycle and climate change. We must learn more about the chemical environment and ecosystem we inhabit to understand how to properly manage them in the future. Our quality of life is dependent upon it. Further research will only help provide a better foundation for understanding climate dynamics, and how Earth interacts with its chemical environment. The response of human impacts and long term effects on the ecosystem need to be monitored. These findings should be clearly articulated and made available to the public so that well informed decisions can be made. This can be accomplished through consistency of methods used and the correct archival of records for future research and comparison.