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There are no clear dividing lines between chemistry and physics, between land and sea, between Iran and Iraq, between man and nature, except lines made in the human mind. With every breath you draw in, a part of the environment becomes part of you. With every breath you give out, a part of you becomes a part of the environment. The cycling waters of the earth flow through you, as do the cycles of carbon, of oxygen, of nitrogen, and of the other elements that make up your structure.

A drought in Kansas affects wheat prices in Ghana. Air pollutants released in England kill trees in Sweden.

Environmental Chemistry / — University of Bologna

Pesticides applied to agricultural fields may show up in groundwater 10 years later, and cause cancer 30 years after that. Many of these connections are traceable and knowable, if we are looking for them. But if our minds are not used to crossing conceptual categories and seeing interrelationships, we wilt not manage things very well, and we will receive some unpleasant surprises. It is useful to think of the world as organized into systems.

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A system is an interconnected set of elements that is coherently organized around some purpose. That is, a system consists of three kinds of things: elements, interconnections, and a purpose. Your digestive system consists of elements such as teeth, tongue, stomach, intestines, and enzymes. They are interrelated through the physical flow and transformation of food and through a whole set of chemical regulating signals.

The system called a football team has elements balled, players, coaches, field and ball. The purpose of the system could be to get exercise or to have fun or to win games or to make money. Notice that these different purposes could cause quite different system behaviours, even with the same elements and interrelationships.

Basic Concepts of Environmental Chemistry-Des W. Connell, Second Edition-CRC Press (2005)

A school is a system, and so is a city, a factory, a national economy. An animal is a system. A tree is a system, contained within the larger system of a forest. The earth as a whole is a system Gaia and so is the solar system and the galaxy. What is not a system?

Anything that has elements with no particular interconnections or purpose. A heap of sand is not a system. Some people say that an old city neighbourhood where people know each other and maintain a social order is a system, but a new apartment block full of strangers is not, until acquaintanceships slowly build a system again. When you begin to see things as systems, your mind draws boundaries and makes distinctions in new ways. For example, most people see a coal-burning power plant as a complex of machinery that takes in coal and puts out electricity.

But as a total system the coal plant also takes in human labour, air, cooling water, financial capital, and the metals and other materials of which it is composed. It puts out- in addition to electricity- wages, profits, discarded or obsolete equipment and buildings, heated-up water, ash, and a number of air pollutants.

Similarly, a non-systemic view of the practice of spraying pesticides is that the farmer sprays them, and the pest die. But from a systems point of view many other things happen. The pesticide may kill other insects than the target pest.

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Among them may be helpful insects that enrich the soil, or predators that would have eaten up the pest. Removing those predators may allow the pest to come back in larger numbers, because it no longer has natural enemies. Or the presence of the pesticide may cause the insect to evolve immunity to it. The pesticide may leach into groundwater and poison human beings. It may break up into other compounds, which may be harmless or may not. Residues of it may cling to the harvested crops. Managing pesticide use means managing this whole system.

When you see things in systems, you know that:. You can never do just one thing. A systems view of development means developing all sectors of the economy in balance: investing in the capacity to produce energy at the same rate as the economy needs energy; not slower and not faster; educating the labour force to be able to handle the jobs that are actually available; keeping roads and communications links sufficient for the loads put on them; enhancing, not degrading, basic productive resources like soils and forests.

It is an age-old observation, beginning with the ancient story of the blind men and the elephant, that a system is more than the sum of its parts. You may be able to name all the parts of the elephant- its trunk, its ears, its legs, its tail- but that does not tell you how the elephant will behave, or how to control it. To know that, you have to know the wholeness, the entirety, the total system called elephant. Therefore, we usually try to fix or control systems by changing parts.

If a team plays badly, we replace the coach or players. If a company performs badly, we fire someone. If a body is unhealthy we try to heal or even replace whatever organ seems to be malfunctioning. Sometimes that works. Putting a different element in the same system just produces the same behaviour. For example, telling people to conserve energy does not usually produce energy conservation.

Putting new people in the system will not change the result. Giving them different appliances that use less energy will help. Once a housing development in the Netherlands put the electricity meter in the front hall, so people could watch how fast they were consuming electricity before the meter was in the basement, where people seldom went.

Consumption dropped by a third, though nothing changed except the availability of information. A very powerful piece of information in any economic system is price. If all subsidies are removed from energy production, so that people pay the true cost of the energy including the cost of repairing environmental damage , energy consumption habits usually change very quickly.


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An even more powerful lever on a system is its purpose. A medical system behaves quite differently when its purpose is preventing disease, rather than treating disease. An enterprise works very differently when its purpose is to make a high-quality product than when it is trying to make a high-profit product or a high quantity of product. A national economic system geared toward producing an ever-higher flow of goods and services called the Gross National Product or GNP will be very different than one designed to provide basic human needs for everyone, or one designed to increase real human welfare with a minimum of material flow- through.

The amount of water in a reservoir is a stock. The amount being released from the reservoir into a downstream river is a flow. The amount of oil under the ground is a stock. The amount being pumped out by oil wells is a flow. The volume of wood in a forest is a stock. The amount by which the forest grows each year is a flow into the stock; the amount of wood cut down is a flow out. The concepts of stock and flow are simple and basic, but they are often confused. But irrigation requires a flow of water, not a stock. The Great Lakes are an immense stock maintained by relatively small inflows and outflows.

The St. Lawrence River, which is the outlet of the Great Lakes, represents the maximum sustainable flow that could be taken from the Lakes without draining them away. Its flow is only kilometers a year. If more water than that were taken out for irrigation, the stock of water in the Great Lakes would decline, and they would slowly become the Great Mud Holes.

Non-renewable resources, like oil, coat, or non- recharged groundwater, are huge stocks with no significant inflows. There is only so much of them. Human beings can drain them at almost any flow rate, but the faster the stock is used, the sooner it will be gone. The use of non-renewable stock- resource such as fossil fuels or fossil groundwater can be only temporary. The primary decision in managing them is the choice of how fast they should be used up, how long they should last. Obviously they should be used with utmost efficiency and never wasted- they are irreplaceable.

The best use of a non-renewable resource is to finance the creation of a stock of capital, technology, and training for the inevitable shift to a substitute renewable resource.

Renewable resources, such as forests, rivers, fish, soil nutrients, are moderate-size stocks with significant inflows. Furthermore, the inflows depend to some extent on the size of the stocks up to a limit. More wood will be added to the forest if there are already more trees there.

More fish will be brad the more parent fish there are. Human beings can only draw from renewable resources at a limited flow rate- only so much water flows down the river at a time- but if the resource is managed sustainably, that rate of use can go on forever. The sustainable yield from a renewable-resource stock is its inflow rate, not its entire content.

A forest can yield sustainably each year not the total amount of standing wood, but only the amount by which it grows. If more than that is taken, the stock declines, and so does the yield. The same is true for fish, for groundwater, for pasture grass, for livestock, for wildlife. Proper management of renewable resources involves balancing the flows; never permitting more outflow than there has been inflow.