GLOBAL WARMING AND COASTAL ECOSYSTEM

HEALTH :

A Toxicological Perspective

Akbar TahirMarine Science DepartmentHasanuddin University

The Intergovernmental Panel on Climate Change (IPCC) published its third assessment report in 2001: the Earth is warming, which is

causing regional climate changes and influencing many physical, biological and

chemical processes.

Source: http://www.ncdc.noaa.gov/img/climate/research/2005/ann/global-blended-temp-pg.gif

Position of ice cores in Vostock Antarctica 

Carbon Dioxide (CO2)

The recent rapid rise in global temperature is caused by rising human emissions of greenhouse gases. Of these gases, carbon dioxide is by far the most important contributor (>50%) to global warming.

Nitrogen and oxygen make up the greater part of the gaseous composition of the atmosphere, but because of their molecular structure they do not absorb or reflect thermal (infrared) energy and thus do not contribute to the greenhouse effect.

The work of John Tyndall (mid 19th century), nitrogen and oxygen, comprise 99% of the atmosphere, are transparent to visible and infra-red radiation. But gases like carbon dioxide, water vapour and methane are not. These gases trap heat in the atmosphere leading to the green house effect (http://www.tyndall.ac.uk/general/ history/john_tyndall.shtml).

Other Things

Water vapour is the most important contributor to the natural greenhouse effect which ensures that the Earth has a temperature that is conducive to life; without this natural process the Earth would be 30°C colder than at present.

A number of other gases that absorb thermal (infrared) radiation also contribute to the greenhouse effect; these include methane (CH4), nitrogen oxide (N2O) and ozone (O3) as well as man made gases such as the chlorofluorocarbons (CFCs).

The effects of changing levels of carbon dioxide in the atmosphere on the Earth’s energy balance were calculated in 1895 by Svante Arrhenius who was concerned about the effects of human activity, particularly the burning of coal, the principal fossil fuel used at that time (http://earthobservatory.nasa.gov/Library/Giants/Arrhenius/arrhenius_2.html).

The carbon cycle is crucial to climate because it governs the amount of important greenhouse gases, such as carbon dioxide and methane in the atmosphere with the oceans playing a key role as the major reservoir of carbon. Methane adds to the carbon dioxide trend as it is mostly converted to CO2 in the atmosphere over an approximately ten year period.

A schematic representation of the carbon cycle (Sarmiento and

Gruber, 2002).

Different ‘reservoirs’ and the fluxes between them for both the natural carbon cycle and the human (anthropogenic) contribution. It is clear from these diagrams that the oceans have a dominant role in the carbon cycle and that the deep ocean is the main long-term depository for carbon. Without the oceans the rate of increase in atmospheric concentrations of CO2 would be much greater.

In the 2001 IPPC report projections calculated by a range of Global Climate Change models forecast a continuing rise in carbon dioxide by 2100 of between 540 and 970 ppm compared to 360 ppm in 2000.

The same models predicted that globally-averaged surface temperatures would rise between 1.4 and 5.8°C over the same period.

More recent modelling from the Hadley Centre includes feedback mechanisms from the oceans and land and has predicted much greater concentrations of 980 ppm within 100 years time, assuming that emissions continue to grow at their present rate. Global surface temperature would increase to 5.5°C (8°C on land) if carbon dioxide reached this level.

Key Points :

Increased CO2 on earth surface, including marine environment.

Increased CO2 levels affects : sea waters temperature, sea waters acidification (lowering pH).

Increased waters temperature affecting biota metabolic expenditures, leading to stress.

Some heavy metals may reversed their toxicity with low pH.

Differences in Heavy Metal Solubility in Sea Water/sediment with variation of pH condition. This condition also affecting metals species/form which available to organism.

The evolution of resistance to environmental stress may involve genetic change associated with reduced metabolic energy expenditure.

Under the stressful conditions likely at the limits of species' geographical ranges, physiological constraints may mean that the amount of energy required to counteract stress precludes survival. Metabolic limitations would therefore prevent spread into climatically more extreme habitats.

This means that postulated future climatic changes are likely to cause species extinctions, especially in species-rich coral-reef areas

Global Warming Effects on Coastal Ecosystem

Global Warming Effects on Coastal Ecosystem

Particle Size of Some Atmospheric Pollutants

Global Warming Effects on Coastal Ecosystem

MARINE POLLUTION

Marine and Coastal Pollution is defined as the introduction of chemical, physical, or biological material that degrades the quality of the water and sediments and affects the living organisms. This process ranges from simple addition of dissolved or suspended solids to discharge of the most insidious and persistent toxic pollutants (such as pesticides, heavy metals, and non-degradable, bioaccumulative, chemical compounds).

Anthropogenic Causes

In sufficiently high concentrations, these contaminant-laden waters and sediments may pose serious threats to coastal ecosystems, the sustainability of natural resources, and human health.

Marine and Coastal pollution due to contaminants such as organochlorine pesticides (OCP), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) petroleum hydrocarbons (PHCs), polychlorinated dibenzo-dioxins (PCDDs), heavy metals (mercury, cadmium, arsenic, cobalt, manganese, etc.) and nutrient salts, has become a global concern because of the accumulation of their residues in the tissues of various species of marine organisms and their bio-magnification through the food-chain leading to hazards to human health.

In case of nutrients, excessive concentrations of these salts in coastal waters can lead to eutrophication and proliferation of toxic algal blooms. 

Effects of Pollutants in Coastal Area

Effect of Oil Pollution on Coral Reef

Ecosystem Health

A notion of ecosystem health should involve both the structure (the species and populations involved) and function (the flow of energy and materials) of the ecosystem.

Costanza (1992) concluded that ecosystem health should include three components: vigor, organization, and resilience (V-O-R). Vigor embodies the throughput or

productivity of the ecosystem. Organization represents not only species

diversity, but also the degree of connectedness of the constituent species (complexity of trophic and other interactions).

Resilience refers to an ecosystem’s ability to maintain structure and patterns of behavior in the face of stress. A resilient ecosystem can withstand sustained or repeated stress.

A healthy ecosystem, then, is one that is actively producing (V), maintains its biological organization over time (O), and is resilient to stress (R).

Example of Ecosystem Health Assessment

Concept of Toxicity

Concentration + Duration = Response

So, it is a must for a toxicant to be in direct contact with a receptor(s) in an organism.

Toxicological effects are dependent on the bioavailable fraction of pollutants, and concentrations at the target sites induce molecular effects that propagate to a variety of toxic manifestations in organisms.

Toxicity Mechanism of TCDD

Harmful Effect of Environmental Pollutants on Various Level of

Animal Organization

THANK YOU VERY MUCH

TERIMA KASIH