viernes, 20 de abril de 2007

Air pollution

Air pollution is a chemical, physical (e.g. particulate matter), or biological agent that modifies the natural characteristics of the atmosphere. The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.

Worldwide air pollution is responsible for large numbers of deaths and cases of respiratory disease. Enforced air quality standards, like the Clean Air Act in the United States, have reduced the presence of some pollutants. While major stationary sources are often identified with air pollution, the greatest source of emissions is actually made up by mobile sources, mainly the automobiles. Gases such as carbon dioxide, which contribute to global warming, have recently gained recognition as pollutants by some scientists. Others recognize the gas as being essential to life, and therefore incapable of being classed as a pollutant.

There are many substances in the air which may impair the health of plants and animals (including humans), or reduce visibility. These arise both from natural processes and human activity. Substances not naturally found in the air or at greater concentrations or in different locations from usual are referred to as 'pollutants'.

Pollutants can be classified as either primary or secondary. Primary pollutants are substances directly produced by a process, such as ash from a volcanic eruption or the carbon monoxide gas from a motor vehicle exhaust.

Secondary pollutants are not emitted. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog.

Note that some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants.

miércoles, 18 de abril de 2007

Environmental science

Environmental science is the study of the interactions among the physical, chemical and biological components of the environment; with a focus on pollution and degradation of the environment related to human activities; and the impact on biodiversity and sustainability from local and global development. It is inherently an interdisciplinary field that draws upon not only its core scientific areas, but also applies knowledge from other non-scientific studies such as economics, law and social sciences. Physics is used to understand the flux of material and energy interaction and construct mathematical models of environmental phenomena. Chemistry is applied to understand the molecular interactions among natural systems. Biology is fundamental to describing the effects within the plant and animal kingdoms.

While the concept of environmental science has existed for centuries, it came alive as a substantive, active field of scientific investigation in the 1960s and 1970s driven by (a) the need for a large multi-disciplined team to analyze complex environmental problems, (b) the arrival of substantive environmental laws requiring specific environmental protocols of investigation and (c) the growing public awareness of a need for action in addressing environmental problems.

Environmental science encompasses issues such as climate change, conservation, biodiversity, groundwater and soil contamination, use of natural resources, waste management, sustainable development, air pollution and noise pollution. Due to the inherent interdisciplinary nature of environmental science, teams of professionals commonly work together to conduct environmental research or to produce Environmental Impact Statements, as required by the U.S. National Environmental Policy Act (NEPA) or under state laws. There are professional organizations that engender work in environmental science and aid in communication among the diverse sciences.

Atmospheric sciences examines the new phenomenology of the Earth's gaseous outer layer with emphasis upon interrelation to other systems. Atmospheric sciences comprises meteorological studies, greenhouse gas phenomena, atmospheric dispersion modeling of airborne contaminants,[1][2] sound propagation phenomena related to noise pollution, and even light pollution

Taking the example of the global warming phenomena, physicists create computer models of atmospheric circulation and infra-red radiation transmission, chemists examine the inventory of atmospheric chemicals and their reactions, biologists analyze the plant and animal contributions to carbon dioxide fluxes, and specialists such as meteorologists and oceanographers add additional breadth in understanding the atmospheric dynamics.

Ecology studies typically analyze the dynamics among an interrelated set of populations, or a population and some aspect of its environment. These studies could address endangered species, predator/prey interactions, habitat integrity, effects upon populations by environmental contaminants, or impact analysis of proposed land development upon species viability.

An interdisciplinary analysis of an ecological system which is being impacted by one or more stressors might include several related environmental science fields. For example one might examine an estuarine setting where a proposed industrial development could impact certain species by water pollution and air pollution. For this study biologists would describe the flora and fauna, chemists would analyze the transport of water pollutants to the marsh, physicists would calculate air pollution emissions and geologists would assist in understanding the marsh soils and bay muds.

Environmental chemistry is the study of chemical alterations in the environment. Principal areas of study include soil contamination and water pollution. The topics of analysis involve chemical degradation in the environment, multi-phase transport of chemicals (for example, evaporation of a solvent containing lake to yield solvent as an air pollutant), and chemical effects upon biota.

an example study, consider the case of a leaking solvent tank which has entered the soil upgradient of a habitat of an endangered species of amphibian. Physicists would develop a computer model to understand the extent of soil contamination and subsurface transport of solvent, chemists would analyze the molecular bonding of the solvent to the specific soil type and biologists would study the impacts upon soil

The natural environment

The natural environment, commonly referred to simply as the environment, is a term that comprises all living and non-living things that occur naturally on earth or some part of it (e.g. the natural environment in the United States). This term includes a few key components:

Complete landscape units that function as natural systems without massive human intervention, including all plants, animals, rocks, etc. and natural phenomena that occur within their boundaries.
Universal natural resources and phenomena that lack clear-cut boundaries, such as air, water and climate.
Natural features which occur within areas heavily influenced by man (such as wild birds in urban gardens).

The natural environment is contrasted with the built environment, which comprises the areas and components that are heavily influenced by man. A geographical area is regarded as a natural environment (with an indefinite article), if the human impact on it is kept under a certain limited level (similar to section 1 above). This level depends on the specific context, and changes in different areas and contexts. The term wilderness, on the other hand, refers to areas without any human intervention whatsoever (or almost so).

Challenges in the natural environment
It is the common understanding of natural environment that underlies environmentalism—a broad political, social, and philosophical movement that advocates various actions and policies in the interest of protecting what nature remains in the natural environment, or restoring or expanding the role of nature in this environment. While true wilderness is increasingly rare, wild nature (e.g., unmanaged forests, uncultivated grasslands, wildlife, wildflowers) can be found in many locations previously inhabited by humans.

Goals commonly expressed by the environmentalists include: reduction and clean up of man-made pollution, with future goals of zero pollution; reducing societal consumption of non-renewable fuels, development of alternative, green, low carbon or renewable energy sources; conservation and sustainable use of scarce resources such as water, land and air; protection of representative or unique or pristine ecosystems; preservation and expansion of threatened or endangered species or ecosystems from extinction; the establishment of nature and biosphere reserves under various types of protection, and, most generally, the protection of biodiversity and ecosystems upon which all human and other life on earth depends.

More recently, there has been a strong concern about climatic changes such as Global warming caused by anthropogenic releases of greenhouse gases, most notably carbon dioxide, and their interactions with human uses and the natural environment. Efforts here have focused on the mitigation of greenhouse gases that are causing climatic changes (e.g. through the Climate Change Convention and the Kyoto Protocol), and on developing adaptative strategies to assist species, ecosystems, humans, regions and nations in adjusting to the Effects of global warming.

A more profound challenge, however, is to identify the natural environmental dynamics in contrast to environmental changes not within natural variances. A common solution is to adapt a static view neglecting natural variances to exist. Methodologically this view could be defended when looking at processes which change slowly and short time series, while the problem arrives when fast processes turns essential in the object of the study.

martes, 17 de abril de 2007

Pollution and its effect effect on ecosystems

Sulfur dioxide and oxides of nitrogen can cause acid rain which reduces the pH value of soil.
Soil can become infertile and unsuitable for plants. This will affect other organisms in the food web.
Smog and haze can reduce the amount of sunlight received by plants to carry out photosynthesis.
Invasive species can out compete native species and reduce biodiversity. Invasive plants can contribute debris and biomolecules (allelopathy) that can alter soil and chemical compositions of an environment, often reducing native species competitiveness.

Effects on human health and pollution

Adverse air quality can kill many organisms including humans. Ozone pollution can cause respiratory disease, cardiovascular disease, throat inflammation, chest pain and congestion. Water pollution causes approximately 14,000 deaths per day, mostly due to contamination of drinking water by untreated sewage in developing countries. Oil spills can cause skin irritations and rashes. Noise pollution induces hearing loss, high blood pressure, stress and sleep disturbance.

International monitoring

The Kyoto Protocol[7] is an amendment to the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty on global warming. It also reaffirms sections of the UNFCCC. Countries which ratify this protocol commit to reduce their emissions of carbon dioxide and five other greenhouse gases, or engage in emissions trading if they maintain or increase emissions of these gases.[7] A total of 141 countries have ratified the agreement. Notable exceptions include the United States and Australia, who have signed but not ratified the agreement. The stated reason for the United States not ratifying is the exemption of large emitters of greenhouse gases who are also developing countries, like China and India.[8]

Monitoring in China

China's rapid industrialization has substantially increased pollution. China has some relevant regulations: the 1979 Environmental Protection Law, which was largely modelled on U.S. legislation. But the environment continues to deteriorate.[5] Twelve years after the law, only one Chinese city was making an effort to clean up its water discharges.[6] This indicates that China is about 30 years behind the U.S. schedule of environmental regulation and 10 to 20 years behind Europe.