What is Pollution from an Ecological Perspective

Julio F. Campos

I have been quite often asked questions about pollution.

What it is, it's different types, what products are considered to be pollutants, how the environment deals with it or what can we do to prevent it.

Here I'll briefly answer those questions explaining what pollution from the ecological perspective is. How, why, when an ecosystem is considered polluted and what can it do about it.

But first, it is necessary to bring two fundamental ecosystem structural characteristics.

A) The carrying capacity

Carrying capacity is the capacity of any ecosystem to sustain a number of individuals of a given species. That could the number of different species, the number of predators, the volume of human use of its resources and, as we will see, the quantity of waste that it can process through its recycling species.

As such, every ecosystem has an intrinsic set of carrying capacities for its innumerous species which are derived from its complex internal interactions between its components, both biotic and abiotic.

The carrying capacity, however, has an unknown limit, it can’t sustain an indefinite number of individuals.

It also doesn’t operate at its limit. There will never be at an ecosystem the maximum amount of individuals of any given species when in balance. If any species in an ecosystem operates near its limits, if the system is impacted the changes of that species to collapse are high, and as consequence, the resilience can be compromised or even lost, collapsing the entire ecosystem.

So there is a flexibility so, in case of any impact, the oscillation of the species won’t affect the entire system.

B) The ecosystem functions

The complex interaction of species / abiotic system of an ecosystem results in a broad set of functions that the system can provide. Those functions are perceived by us as services.

Below are listed the main four ecosystem function:

Regulation Functions Regulation of global and local energy balance Regulation of the chemical composition of the atmosphere Regulation of the chemical composition of the oceans Global and local climate regulation Regulation of runoff and flood control Control of soil erosion Soil formation and fertility maintenance Fixing of solar energy and biomass production Stock and recycling of organic matter Stock and waste recycling Regulation of biological control mechanisms Maintaining migration and reproductive habitats Biodiversity maintenance

Production Functions Oxygen Water (human supply, irrigation, industrial use, etc.) Foods Genetic resources Medical resources Raw material for civil construction, industrial/commercial use, etc. Biochemicals Fuel / Energy Fertilizers Ornamental resources

Support Functions Housing and human settlements Cultivation (agriculture, pasture, aquaculture, etc.) Power Conversion Recreation and Tourism Nature protection measures Transportation and communication

Information Functions Aesthetic Information Religious and Spiritual Information Historical information Cultural and artistic inspiration Scientific and educational information

The recycling capacity

The number of ecosystemic functions is a direct result of its biodiversity. The biodiversity depends on the system carrying capacity to sustain those species, which is limited.

Therefore the recycling capacity results of the capability of a system to sustain a set of species that will provide the services, including the recycling services. Which, as the carrying capacity, are limited, and this is important to remember.

So every ecosystem has a capability to recycle its wastes and at its most stable point and that recycling capacity operates at its optimum level, but not at it maximum.  As seen that is not coincidental for it allows the system to have some flexibility to cope with the influence and interference of other systems, as ecosystems don't work as closed, isolated, systems, interacting with other ecosystems.

The fact that there is some flexibility allowed us for almost our whole history to use the unused recycling capacity to recycle our own waste, usually dumping it into rivers. Since until the industrial revolution our waste was basically from organic origins, food remains and sewage, and its amount was inside the limit that the ecosystem could sustain and recycle, that was not a problem.

Yes, natural ecosystems do produce waste and relies on it to survive

If the recycling capacity doesn’t operate at its limit, any disturbance that affects it will not result in potential damage to the entire ecosystem. Therefore an ecosystem can process a certain amount of external waste besides that produced internally.

That capability, however, is proportionally reduced as it reaches its limit. So the closer to its capability to recycle limit, the less it can recycle.

But what kinds of external waste can an ecosystem can recycle?

Actually, that's not the right question. What should be asked is how long does it take for it to recycle any given waste. That's because if we consider a period of time long enough the ecosystem can recycle any kind of the waste.

It's a matter of time, not quality.

As long as not near its limit the system, considering both the biotic and geologic activities, do can recycle anything, the problem is that some materials will take millenniums to be recycled, for only the geological activities can process them, such as glass.

What is pollution?

As we have seen,  any ecosystem has the capability to recycle whatever it receives, so why it gets polluted?

The answer is straightforward.

That capability depends on its recycling carrying capacity which I turn is limited and although given time,  it can recycle everything, there's an unknown limit to how much it can recycle.
When a volume of any kind of waste is added above the ecosystem capacity to recycle it, that extra amount of waste is pollution.

No matter what origin, too much waste is pollution. 

So what is a pollutant?

Anything can be a pollutant for a given species. For that, it only needs to be available above the amount that the system can deal with.

How much is too much?

Can we know how much waste an ecosystem can recycle? No!

For every single ecosystem and kind of waste there's a unique recycling capacity which, is paramount to remember, only avoids pollution if the system can recycle it faster than it's added, preventing it to accumulate until over its limits.

That's important because while some waste can be processed faster, as organic waste, others take so long to be recycled that any minimal amount of it becomes instantly a pollutant, as radioactive waste, which will keep producing undesired impacts (radioactive contamination) for as long as its raw source exists.

That leads to the next topic.

Can an ecosystem clean its pollution by itself?

That depends on how the pollutant is disposed into the ecosystem which can happen in two ways, acute or chronic.

Acute pollution occurs when a given amount of pollutant is disposed of once, and only once at the system. It can have two outcomes:

1. The impact of the pollution on the ecosystem components don't affect its resilience, it means, the waste won’t cause significant damage to the species.  In this situation, the ecosystem will keep recycling as much as it can until the pollutant (extra waste) is recycled.
2.  The impact does affect its resilience.  In this case, the ecosystem will have an abrupt structural change that may lead it to a new structure, transforming it into something different than it was but with the possibility of recovery, or it may lead it to total collapse from which it cannot recover.

Chronic pollution happens when, after we started to pollute an ecosystem, we continue to add the pollutant into it, not giving it time to process what it's receiving.  That’s the case of continuous river pollution and if the discharge doesn't stop, the only outcome of a chronic pollution is the ecosystem collapse.

Non-recyclable pollutants

There are pollutants that can’t be recycled by any means? Yes, sound, light, thermal and visual pollution are examples, as there is nothing in a system that can recycle it.

So how can they pollute?

At the beginning of this post, I wrote that the recycling capability is a service derived from functions provided by the biodiversity.

Any species to perform any kind of service, humans included, recycling or not needs an adequate environmental condition to perform at its best. An adequate amount of food and water, a comfortable temperature range, etc…

Those are the known as limiting factors.  Any individual of any species can’t operate near its survival limits due to the stress caused when at the limit.

Thermal limits are a good example. Whether too cold or too warm the temperature will compromise the individual metabolism. In mammals such ourselves who can control its temperature, as we get close to any of the limits we will start to consume more and more body energy to maintain our temperature, until we finally have too few energy left for our other body functions and we collapse and die, from hypothermia or heat exhaustion.

These kinds of pollution are harmful because of the level of stress that they cause to the organism, vegetal or animal, affecting its capability to operate and even leading to its death.

Each vegetable species, for example, needs a defined amount of light, during a defined amount of time, in order to survive. Too much light for too much time, or vice-versa, affect its capability to realize photosynthesis which results in less available energy and eventually its death.

Light also interfere with the circadian circle, sound interferes with our sleep and also scare away animals, affecting their behavior.

These kinds of pollution must be avoided at its source for no recycling is possible.

What should we do?

However, even if given the proper amount of time a system will clean itself, until it’s achieved the damages caused by the pollution can easily lead to species extinction, including ours.

So, letting the environment deal with pollution is not an intelligent approach since the outcome of the self-cleaning process can result in a new set of ecosystems and species, which may not include us, as the case of climate change.

Therefore the best approach is not pollute, and if we do, we must act to remove it before it causes any serious environmental damage.

Was this article interesting to you?
Please, share your experience with us bellow.
Want to write with us? Get in touch.