Heavy Metals

Heavy metal contamination affects large areas worldwide. Hot spots of heavy metal pollution are located close to industrial sites, around large cities and in the vicinity of mining and smelting plants. Agriculture in these areas faces major problems due to heavy metal transfer into crops and subsequently into the food chain.

The most important heavy metals with regard to potential hazards and occurrence in contaminated soils are: arsenic, cadmium, chromium, mercury, lead and zinc.

Here is how each of these metals specifically affects the environment:

Arsenic. Arsenic is well-known as a poison and a carcinogen. It has an average concentration in the soil of 5 to 6 mg/kg. Its amount in the soil is related to rock type and industrial activity.

Cadmium. Its toxicity is linked with reproduction problem because it affects sperm and reduces birth weight. It is a potential carcinogen and seems to be a causal factor in cardiovascular diseases and hypertension. Large concentrations of Cd in the soil are associated with parent material (black slates) and most are manmade (burning of fossil fuels, application of fertilizers, sewage sludge, plastic waste).

Chromium. It is required for carbohydrate and lipid metabolism and the utilization of amino acids. Its biological function is also closely associated with that of insulin and most Cr-stimulated reactions depends on insulin. However, excessive amount can cause toxicity. Toxic levels are common in soils applied with sewage sludge.

Lead. This has been known to be toxic since the 2nd century BC in Greece. It is a widespread contaminant in soils. Lead poisoning is one of the most prevalent public health problems in many parts of the world. It was the first metal to be linked with failures in reproduction. It can cross the placenta easily. It also affects the brain, causing hyperactivity and deficiency in the fine motor functions, thus, it results in damage to the brain. The nervous systems of children are especially sensitive to Pb leading to retardation. It is also cardiotoxic and contributes to cardiomyopathy (disease of the heart muscle leading to the enlargement of the heart).

Mercury. This heavy metal is toxic even at low concentrations to a wide range of organisms including humans. The organic form of mercury can be particularly toxic, and the methyl-and ethyl-forms have been the cause of several major epidemics of poisoning in humans resulting from the ingestion of contaminated food, e.g. fish. Two major epidemics in Japan were caused by the release of methyl and other mercury compounds from an industrial site followed by accumulation of the chemicals in edible fish. The poisoning became well-known as Minamata disease.

Nickel. Nickel occurs in the environment only at very low levels. Humans use nickel for many applications like the use of nickel as an ingredient of steel and other metal products. Foodstuffs have low natural content of nickel but high amounts can occur in food crops growing in polluted soils. Humans may also be exposed to nickel by inhalation, drinking water, smoking, and eating contaminated food. Uptake of high quantities of nickel can cause cancer, respiratory failure, birth defects, allergies, and heart failure (www. Lenntech.com/periodic-chart-elements/Ni-en.htm)

References

Oliver, M.A. 1997. Soil and human health: a review. European Journal of Soil Science 48: 573-592. Puschenreiter M., O Horak, W. Friesel and W. Hartl. 2005. Low-cost agricultural measures to reduce heavy metal transfer into the food chain- a review. Plant Soil Environ 51: 1-11.
Susaya JP. 2007. MSc thesis. Institute of Tropical Ecology, Visayas State University, Baybay, Leyte, Philippines.

Soil Erosion

Soil erosion affects both agriculture and the natural environment. Soil loss, and its associated impacts, is one of the most important (yet probably the least well-known) of today's environmental problems. (BBC 2000; Guardian 2004)

"The threat of nuclear weapons and man's ability to destroy the environment are really alarming. And yet there are other almost imperceptible changes - I am thinking of the exhaustion of our natural resources, and especially of soil erosion - and these are perhaps more dangerous still, because once we begin to feel their repercussions it will be too late." (p144 of The Dalai Lama's Little Book of Inner Peace: 2002, Element Books, London)

Those are pretty strong words. Just recently, in my fourth grade class, we were discussing ecosystems and how abiotic (non-living things) are very important to ecosystems. These include sunlight, water, and of course soil. Even fourth graders understand the importance of soil to plants and, consequently, to animals that rely on those plants to survive. We learned that farmers must loosen soil up to plant crops more effectively, but a result of loosening the soil is that the soil can get washed away or blown away easier, making it tough on the insects that live in that soil. But that is not what we’re dealing with when we talk about soil erosion.

A GLASOD study estimated that around 15 per cent of the Earth's ice-free land surface is afflicted by all forms of land degradation. Of this, accelerated soil erosion by water is responsible for about 56 per cent and wind erosion is responsible for about 28 per cent.

The cumulative impact of soil erosion may, over a long timescale, be severe.

Erosion of soil removes the “cream of the soil” or the upper horizon of soil, where the nutrients are rich and the water-holding capacity decreases. This negatively affects the agriculture and the ability to grow good crops. Africa and Asia are dealing with this first hand, but it may also be a concern for more affluent countries in the future.

In addition to its on-site effects, the soil that is detached by accelerated water or wind erosion may be transported considerable distances. This gives rise to 'off-site problems'.

Water erosion’s main off-site effect is the movement of sediment and agricultural pollutants into watercourses. This can lead to the silting-up of dams, disruption of the ecosystems of lakes, and contamination of drinking water. In some cases, increased downstream flooding may also occur due to the reduced capacity of eroded soil to absorb water.

We have known about the dangers of soil erosion for a century and have done much research in the subject.

Erosion is measured and further understood using tools such as the micro-erosion meter (MEM) and the traversing micro-erosion meter (TMEM). The MEM has proved helpful in measuring bedrock erosion in various ecosystems around the world. It can measure both terrestrial and oceanic erosion. On the other hand, the TMEM can be used to track the expanding and contracting of volatile rock formations and can give a reading of how quickly a rock formation is deteriorating.

Tactics for preventing erosion in the future have been under investigation by scientists and geologists all over the world. Today, the most effective method for erosion prevention is soil surface cover. In this method, some type of permeable material, left over crop residue for example, covers the soil surface, which includes rock and sediment debris. This decreases the deteriorating capabilities of the impact from rain, animals, machinery, or any other type of eroding agent. As a result, surface runoff is controlled which helps eliminate the transportation of eroded particles elsewhere, thus slowing the process of erosion as a whole.

Sources: soilerosion.net

War

“Warfare is inherently destructive of sustainable development. States shall therefore respect international law providing protection for the environment in times of armed conflict and cooperate in its further development, as necessary.” – 1992 Rio Declaration


The application of weapons, the destruction of structures and oil fields, fires, military transport movements and chemical spraying are all examples of the destroying impact war may have on the environment. Air, water and soil are polluted, man and animal are killed, and numerous health affects occur among those still living.

The continent of Africa alone is rife with Civil Wars. These wars are mainly fought in densely populated regions, over the division of scarce resources such as fertile farmland. There are many environmental effects, such as biodiversity loss, famine, sanitation problems at refugee camps and over fishing.

In Hiroshima and Nagasaki, over 200,000 people were either killed instantly or eventually. Besides the direct casualties, the environment took a severe hit as well, affecting those who survived the initial bombing. The blasts caused air pollution from dust particles and radioactive debris flying around, and from the fires burning everywhere. Many plants and animals were killed in the blast, or died moments to months later from radioactive precipitation. Radioactive sand clogged wells used for drinking water, thereby causing drinking water a problem that could not easily be solved. Surface water sources were polluted, particularly by radioactive waste. Agricultural production was damaged; dead stalks of rice could be found up to seven miles from ground zero. In Hiroshima the impact of the bombing was noticeable within a 10 km radius around the city, and in Nagasaki within a 1 km radius.

Obviously, this is an extreme example. We have never seen anything like the A-bomb since. But all wars and act of wars not only take its toll on the people it is meant to harm, but the environment is irreparably damaged for some time.

"In some sort of crude sense which no vulgarity, no humor, no overstatement can quite extinguish, the physicists have known sin; and this is a knowledge which they cannot lose."–J. Robert Oppenheimer

There have been countless wars in world history, so it would be futile to try to describe the environmental impact each of them had here. But, in an example closer to home, the World Trade Center bombing in 2001 had serious environmental impacts that we are still reading about, ten years later. Many people present at the WTC at the time of the attacks are still checked regularly, because of long-term effects. It is thought there may be an increased risk of development of mesothelioma, which comes from exposure to asbestos. Airborne dioxins in the days and weeks after the attack may increase the risk of cancer and diabetes. Infants of women that were pregnant on September 11 and had been in the vicinity of the WTC at the time of the attack are also checked for growth or developmental problems.

I’m not going to make any political stands here. Wars are necessary when governments feel they have no other choice. Our wars in Iraq and Afghanistan have been a hot-button topic for a decade. But this blog’s purpose is to highlight the causes of environmental issues, and war certainly does a lot of damage to the environment. I doubt there is a eco-friendly way to fight a war, and you don’t need to hear from me what kind of impacts war can have on people.

I’m also not a big science-fiction guy, but I think if aliens decided to come to Earth and take over, humans would quickly see how dumb it was to be fighting each other for so long.


"Drafted to go to Vietnam

To fight communism in a foreign land.

To preserve democracy is my plight

Which is a God...Given...Right.

Greenery so thick with hidden enemies

Agent Orange is sprayed on the trees.

Covering me from head to toe

Irate my eyes, burns through my clothes.

Returned home when my tour was done

To be told "You have cancer, son".

Agent Orange is to blame

Government caused your suffering and pain.

Fight for compensation is frustrating and slow

Brass cover-up, not wanting anyone to know.

From cancer many comrades have died

Medical Insurance have been denied.

Compensation I now receive

My health I hope to retrieve.

In Vietnam , I was spared my life

Just to be stabbed with an Agent Orange knife" Yvonne Legge, 2001



"We will live in the death smog for a while,

breathing the dust of the dead,

the 3 thousand or so who turn to smoke,

as the giant ashtray in Lower Manhattan

continues to give up ghosts.

The dead are in us now,

locked in our chests,

staining our lungs,

polluting our bloodstreams.

And though we cover our faces with flags

and other pieces of cloth to filter the air,

the spirits of the dead aren’t fooled

by our masks." Lawrence Swan, 05-10-2001

“My hands are tied

The billions shift from side to side

And the wars go on with brainwashed pride

For the love of God and our human rights

And all these things are swept aside

By bloody hands time can't deny

And are washed away by your genocide

And history hides the lies of our civil wars” – Guns ‘n Roses (Civil War)

Source: http://www.lenntech.com/

Air Pollution

Air pollution is the presence of one or more unwanted substances in the air. Air pollutants have negative impacts on humans, animals, plants and air quality.

The four most frequent categories of air pollutants are sulfur oxides, nitrogen oxides, Volatile Organic Compounds (VOS) and small dust particles (aerosols.)

Like most pollution, air pollution is mostly caused by human activity, such as industries, traffic, energy generation and agriculture. When large concentrations of these substances are emitted into the air, this negatively affects ecosystems, materials and public health.

Examples of the effects on the environment include:

Acid deposition – which causes more metals to dissolve in water and pollute the water, which kills the aquatic life.

Eutrophication – occurs when there is an increase in plant nutrients in water. The word “nutrients” sounds like a good thing, but this can cause certain plants and algae to grow so much, it blocks the sunlight and absorbs a lot of oxygen, which causes a disruption to the ecosystem.

Smog – has an effect on plants and animals. In people, this can cause eye and respiratory damage.

Ozone loss – Ozone is very important for all life on earth, because it absorbs harmful UV-B radiation from the sun. When the ozone concentrations decrease, a UV-B radiation may reach the earth. This radiation damages DNA and causes skin cancer. The radiation can also damage the human immune system, causing humans to become more susceptible to infections as well as cataract and nearsightedness. Ozone loss also affects plants, because it can decrease growth and photosynthesis. Primary crops, such as rice, corn and sunflower are susceptible to this, as well as trees. UV-B radiation also wreaks havoc on aquatic life up to twenty meters under the water surface. It is damaging to species, such as plankton, fish larvae, shrimps, crabs and seaweeds. Phytoplankton forms the basis of the aquatic food chain. When radiation causes phytoplankton to decrease in number it will affect the entire ecosystem.

Air pollution has been a problem long enough for humans to have at least developed a way to deal with it. Air pollution is easily detected using computer models. Wind speed, wind direction, temperature, air humidity and cloudiness are all ways to predict air pollution, which is beneficial to the inhabitants of certain places that may be affected by the pollution.

What do you tell a class of 4th graders about air pollution? That it’s bad? I think if you can detail some of the dangers of air pollution, without sounding too preachy, you can create enough awareness to pique their interest to learn ways to combat air pollution. A guest speaker, field trip and videos would be a great place to start. From there, if just a handful of kids are passionate enough about the environment and, specifically, air pollution, and feel like they want to spend their lives pursuing it as a career you’ve done a good job.

Source: http://www.lenntech.com

Population Growth

Population growth is another environmental issue. “Issue” is the word we have used instead of “problem” because it has a better connotation. When we talk about pollution, whether it is air or water, it is a problem. I’m not sure population growth is a problem, per se, but it is something that figures into every equation when we talk about the environment.

I have decided on this topic because there is an article in this week’s Time for Kids that we read today in class. The students automatically drew a correlation between the population’s growth and the impact on natural resources. As of this year, the world’s population was expected to pass 7 billion people. That is more than double that of just 50 years ago. In another fourteen years, that number is expected to reach 8 billion.

Population growth increases at an exponential rate. Many factors play into the rise of the population, including better medicines that are keeping people alive longer, better prenatal care, which decreases the number of miscarriages and stillbirths, and better fertility drugs for those who have trouble conceiving.

Since I’m taking STEM classes, this is an excellent opportunity to incorporate math into the topic, particularly reading a graph (like the one above). A simple line graph can show us the increase of the world’s population since 1900. If we follow the pattern, we can see an obvious increase and project what the next numbers on the graph will be in fifty years, 100 years, or even later than that.

I asked my student’s if they ever didn’t finish their dinner, and had their parent say, “There are many starving people in the world, so eat your food!” Mine too. Now that I’m the parent (of a finicky five-year old girl) I’m always about to say it. But this is a big deal if the population continues to grow. Experts believe that there is enough food per country to feed everyone, but that we need to work harder to create less waste.

One of my students raised their hand and brought up natural resources. I served up the questions and they hit them out of the ballpark, including:

• If there are more people in the world, hence more people driving in the world, how does that affect the atmosphere?


• If more people need more paper to write on, what does that mean for trees?


• If we cut down more trees, what happens to all the extra carbon dioxide not getting absorbed?

If a family gets big, they can simply add an extension to their house. There is nothing we can do to make the earth bigger, so we need to be vigilant in protecting our resources and limiting our waste as much as possible.

Source: Time for Kids, lenntech.com

Fossil Fuels

Fossil fuels are a popular topic these days when we discuss environmental issues. Fossil fuels are non-renewable energy sources that we are running out of. This will cause prices to rise and animosity and stress to become more prevalent.

The three types of fossil fuels are natural gas, oil, and coal. We use these fuels because they are cheaper and more effective than the alternatives at this point. People knew as far back as the Industrial Revolution that these fuels wouldn’t last forever and that they weren’t good for the atmosphere, but it wasn’t their problem at the time.

The real issue of fossil fuels isn’t so much that we will run out of them someday, but that they are terrible for the environment. Burning fossil fuels is responsible for greenhouse gas accumulation, acidification, air pollution, water pollution, damage to land surface and ground-level ozone. Pollutants, such as sulfur and nitrogen, are naturally present in fossil fuel structures are released. Coal is the number one contributor of emissions to the atmosphere, followed by oil, which may end up in soil or water in raw form. Natural gas does not release as much carbon dioxide because of its methane structure.

I have done lessons on fossil fuels in my classroom. I focus on the terms “renewable” and “non-renewable” and have pictures of each on my SmartBoard. I have students drag the pictures into the appropriate categories. I teach them about alternate forms of energy (renewable) in the forms of wind and solar energy. We basically get all our energy from the sun, so it’s a matter of harnessing that energy.

A lesson we can do from that point is a Pro and Con of the types of energy. As bad as non-renewable energy sources are, we use them for a reason. But the cause and effect lessons won’t be lost on 4th graders: if we have a limited supply of something and keep using it, what do you think will eventually happen? We read recently about the cocoa bean being in shorter supply because of diseases to trees in South America. My students know a bit about supply and demand and understand that if there isn’t a lot of something, the prices go up. Last year, we read about electric cars in Time for Kids. I asked them if they noticed how their parents reacted every time they had to get gas. They all responded the same way; how their parents were constantly complaining about gas prices.

As an elementary school teacher, it’s all about creating awareness of issues like this and tying it in to how it affects the kids’ lives. I said to them, “you might not be the one paying for gas now, but the more money your parents spend on gas, the less money they’ll have to spend on you.”

source: http://www.lenntech.com/

Drinking Water Pollution

It’s funny how not-too-long-ago, bottled water was the new thing. I laughed when I saw how many people insisted on drinking bottled water and considered them foolish. I had been drinking tap water my whole life and everything was fine with me, so why pay money for water?

Now I buy bottled water, and refill them with my Brita. Subconsciously, I feel it is a “safer” water or “purer” water, but who really knows. I guess, depending on where you get your tap water, this might be true, and it could also be the exact opposite. However, after learning more about potential pollutants of drinking (tap) water, I almost feel safer drinking water that has gone through numerous steps of the purification process. These potential pollutants are:

· Coliform Bacteria – often caused by barnyard runoff, and can be indicative of pathogens.
· Yeasts and Viruses – can cause diarrhea, vomiting, stomach cramps and fever, and that’s for people with good immune systems.
· Nitrate – can reduce your blood’s capacity to carry oxygen; especially dangerous for infants.
· Lead – can lead to lead poisoning, which affects development in young people.
· Legionella – can cause flu-like symptoms, or worse, legionellosis, which can be fatal.

I’m not going to talk about the purification process here, but I would with my class. I teach fourth graders, so if I brought this kind of stuff up to them, they wouldn’t even brush their teeth with tap water! I wouldn’t scare them into all the pollutants that can get into the drinking water, even in theory. By now, they are all used to bottled water, as evidenced by how many of them bring bottled water to school.
But a rule of thumb I like to go by is if I find it interesting, I think I can make my class find it interesting. I would be interested to know how water is purified before it gets bottled into, say, a Poland Spring bottle. This would best be done with a field trip so they can see it and understand it for themselves. I wouldn’t attempt to try any kind of “water purification” experiment or demonstration myself in the classroom (at least not at this point) because I don’t feel confident enough to be able to pull it off.

source: www.lenntech.com