Chemical Dynamics of Water Pollution


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gulf oil spill

When there’s an oil spill, immediate cleanup is necessary to avoid harm to the biosphere. Image by NOAA

Chemistry has a long history – is it now time to turn our attention to repairing the damage chemical pollution has inflicted on the environment?

The origins of today’s scientific chemistry date to the turn of the 18th century from experimentation on water, combustion, medicine, and the study of heat.

With the experiments of Joseph Priestly, Antoine Lavoisier, Joseph Black, and Robert Boyle, modern-day chemists learned to understand the differences between alchemy and physical science.

Furthermore, the modern foundation helped to delineate organic chemistry from inorganic chemistry —  the chemistry of carbon molecules from non-carbon molecules.

Early Chemists

Although modern chemistry is a relatively new undertaking, the basis of chemistry lies within the origins of civilization. Although some recall the alchemists as early chemists, Alchemy originated from shamanic practices-inspiring their art with mysticism.

The first chemists were pragmatists-their discoveries came from necessity. The original science came from the hunter-gatherers who foraged for grubs, berries and discovered properties of the bark of the Willow tree (a source of primitive aspirin).

Other propitious discoveries included utilizing the foxglove plant for angina and the carrot for pigmentation. Moreover, several thousands of years later, primitive metallurgists utilized iron and bronze for plowing the earth and for weapons. Thus, between then and now, the science of chemistry grew to be appreciated and respected.

From soaps and diabetes medications to paints and gasoline, chemistry made our lives better and simpler.

The Dual-Edged Sword of Chemistry

Many lives have been saved, and riches have been amassed from the modern science of chemistry. However, many lives have also been ruined, and our world’s ecosystem is imperiled from a reckless use of chemistry.

Sadly, we have been poor stewards of the bigger picture. Every day, large volumes of chemicals pollute the  water. The sheer volume appears unimaginable, but it has initiated changes in the biosphere.

Organic chemicals include oil spills, agricultural runoff, and litter ranging from plastic bags to automobile tires.

Inorganic chemicals include litter, smoke and ash from coal-powered plants, and toxic metals (Cobalt, Arsenic, Antimony, Tin and Nickel).

This is the dual-edged sword of chemistry-it is a human aspect.

deformed frog

Man-made changes have a cascading effect, resulting in abnormalities down the line. Image Courtesy Pieter Johnson, University of Colorado at Boulder.

The pollutants are linked to abnormalities in invertebrate species (frogs and fish) and a higher incidence of human birth abnormalities have spiked in the last quarter century.

Biodiversity and Ecosystems

One measure of the health of our ecosystems is a measure of biodiversity.

A biodiverse environment contains a large number of different species of plant and animal thriving in unison. Moreover, biodiversity is a measure of ecological health because where life thrives, we know the hydrological (water) and carbon (carbon dioxide to oxygen) cycles are functioning properly.

However, the introduction of organic chemicals into the environment has reduced different types of organisms within many ecosystems-bioorganisms that were once present have either died off or found other niches.

Our interferences to the biosphere could not have come at a worse time, as climate change becomes a daunting problem for the planet. The phenomenon of climate change resulted from human activity upon the environment-an uncontrolled release of molecules that warmed Earth’s climate.

The warming of the climate results in dangerous, uncontrolled weather phenomena.  The introduction of foreign chemicals into the biosphere forces us to be mindful of our place on Earth-coupled with climate change, we stare at calamity.

physicochemical definition

The term ‘physicochemical’ derives from the two words, ‘physical’ and ‘chemical.’ Copyright image by Decoded Science, all rights reserved.

Understanding the physicochemical implications of biosphere poisoning would help Mankind reach a resolution-preventing or lessening biosphere damage in the future.

Hydrocarbons as an Illustration

We hear frequently of organic pollutants fouling a local eco-system, and clean-up efforts to mitigate the disaster.

Ecological nightmares like the Deep Water Horizon oil spill in the Gulf contributed to coral and animal disruption and an ultimate loss of biodiversity.

We know the end-results of how unwanted chemicals are spoiling eco-systems, but there are certain insights to be gained from the physical chemistry. Understanding chemical-chemical interactions prior to bio-interactions helps us learn how to view the impending problems.

For example: Molecules from an oil spill are carbon-rich and not (readily), water miscible – that means they are not easily able to mix with water in all proportions. These particles of ‘crude’ clump together while in the presence of water – but tend to dissolve into fatty, animal tissue.

Hydrocarbons in Ocean Ecosystems

What may come across as a shocking revelation, of all oil-spill debacles dating from the 20th century onward, is only within the last 15 years have scientists forged a physical-chemical understanding.

marsh oil spill

This is what an oil spill looks like when located in a marsh – an area of high biodiversity. Image courtesy of NOAA Habitat Conservation.

Firstly, experiments have been performed to simulate crude oil spills. The results indicate that if control of the spill area is not achieved in the first 24 hours, the damage to biodiversity may take decades to remediate fully.

These (optimistic) conclusions are based, in part, upon a permitted, controlled spill in the North Sea (September 2009). The study cites the following observations:

  • During the initial hour of the spill, the crude oil will fractionate into three portions- (1) volatile (evaporable) hydrocarbons, (2) a sheen or slick, and (3) denser crude (that begins to sink to the ocean floor).
  • Evaporation and dissolution rates increase with higher ocean temperatures. The phenomenon is similar to any dissolving medium-hot (warm) water dissolves substances in a relatively more rapid pace.
  • Colder weather (lower ocean temperatures) fractionates the crude further-resulting with a greater amount moving to the bottom. (Most crude oil contains differing quantities of hydrocarbon-certain hydrocarbons readily evaporate at 50 degrees Fahrenheit but remain as liquid at 40 degrees Fahrenheit.)
  • Damages to the biodiversity are most telling from hydrocarbon components in turbulent water-the damage can occur in less than a day (possibly less than 12 hours).
  • The addition of dispersants increases the amount 0f crude that sinks to the ocean bottom. (Dispersants force less evaporation of crude and allow it to sink into the sea.)

The obvious conclusion that may be drawn is that any ‘spill’ must be treated like it is as critical as putting out a house fire. We must put measures need to be put in place, so the crude is immediately contained upon an accident.

Perhaps, the oil industry may achieve containment by utilizing a temporary, hermetic reservoir that does not allow the crude access to the ocean-a failsafe. Rather rely upon mechanical valves that have failed repeatedly in the past-it may prove more ecologically effective to contain the spill than to stop the flow in the first 24 hours.

Chemistry as the Answer

The human aspects of chemistry created the problems, but a solution presents itself. Ecological stewardship entails an understanding of chemistry as a big picture science. Each day, many of us go through the motions of life, not realizing that chemistry is central to our activities, as well as the world around us.

Not everyone is meant to be practicing in the laboratory, but chemistry can be a source of enjoyment as well as life. The first chemists were practical – they did not wear lab coats. Their discoveries were a natural progression from non-chemistry problems.

Loosely paraphrasing Albert Einstein-the solution to the chemical ecology problem must arise from outside of the chemical box.

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