Metals are a commonly used substance which has properties that allow different applications that range from accessories to construction. Though there are many different types of metals, there are certain metals that have more use than others such as aluminum and copper. These metals are seen everywhere from currency to food storage! Though metals such as these are versatile in their properties and uses, they also bring about concern as their disposal may cause issues on the environment and specifically the soil.
What’s the Big Deal?
When metals are exposed to rainwater, due to the slight acidity of the rainwater, a process called ion exchange can occur! Ion exchange is when the atoms of the metal swap places with another similar atom in the soil. This process is common among clay minerals as they contain layers of “silicon-oxygen” which are stacked in a particular
way. Due to the shape of these “silicon-oxygen” layers, the silicon can be replaced by a metal, particularly an aluminum atom! Now, what’s the problem with that? Well when an aluminum atom swaps places with a silicon atom, that aluminum atom becomes negatively charged and attracts other positively charged atoms (opposites attract, especially in chemistry!). These positively charged atoms and metals spell bad news for the environment that they’re in because these compounds can end up in rivers, lakes or streams making those environments very hazardous and detrimental to the aquatic life there.
Where Can This Happen?
Sadly, these types of chemical reactions and abundance of metals is common. In fact, the students of University of San Diego went into the Tecolote Canyon in March 2018 to see what they could dig up when it comes to the metals found in the soil. Using their scientific instrumentation, they were able to detect traces of copper, zinc, chromium, rubidium, arsenic, molybdenum, mercury and even lead! (Yikes!) Though metals can be detrimental to the environment, heavy metals cause even more damage and can stick around longer than lighter metals! The students were able to determine that there were 10.8 ppb of copper, 1.52 ppb of chromium, and 29.8 ppb of lead throughout the canyon. Luckily, these numbers are below the EPA limit in soil however, the presence of some of the other metals maybe a cause for concern.
So, Where Do We Go from Here?
Thankfully, cities and states work towards treating the soil and water to ensure that these metals do not exceed the recommended EPA standards. However, a way that we can personally help is by properly disposing of metal materials and recycling! Though this may seem obvious, recycling and proper disposal of metals can reduce the environmental damage one can at a time.
By Candy Pham
De Haan, David et al. USD environmental chemistry lab notebook