Soil contamination

Hi, I’m Gaby. I am from Lancaster Environment Centre, and my research is in soil contamination. Defined by the US Environmental Protection Agency, soil contamination happens when a substance in any form gets mixed with the soil. Officially, in the UK, a soil pollutant can be heavy metals, oils and tars, chemical substances, or even radioactive substances. These substances can be hazardous or not. For example, phosphorus is used as a nutrient for most of the plants, but at higher concentrations can be toxic for the plants and the animals, or even for the humans fed by those plants. When the contaminant has been in contact with the soil, the soil particles can trap the substance around them and in the small spaces between those.

Also, the soil can inadvertently have the contaminant to reach deeper areas, and the ground water as well. All this processes are driven by very specific circumstances, such as soil chemistry, physical laws, and even the weather. This makes each contaminated site unique, and needs to be treated as such if we want to clean it up. Soil contamination is generally a result of initialisation processes. As a consequence, most of the countries around the world have been dealing with this issue for a long time. In Europe, the Northwestern is the most affected region, and this includes the UK. Other severely affected areas are North America, Australia, and New Zealand.

Additionally, emerging soil contamination issues have started to be observed in the past few decades in other regions, such as the former Soviet Union, Central and South America, Asia, and Africa. It is difficult to accurately measure the extent of the problem, but experts guess that about 100 million people may be affected by soil contamination around the globe. The most common causes of soil contamination are human activities. Contaminated sites are usually located at former factories, mines, refineries, and landfills. Soil contamination can have a wide range of effects on humans and the environment. Those effects will depend on different factors, such as the type of characteristics of the pollutant, and exposure time and magnitude.

For example, an area by a petrol station can be affected by a minor diesel spill. Diesel is not considered to be particularly toxic, but its inhalation can result in short-term lung damage. Long-term effects of diesel, or any other contaminant, are often difficult to predict. However, as with all chemicals, unnecessary contact should be avoided if possible. This is why after a contaminated site has been detected, certain things must be done in order to control and remediate if possible this situation. The technologies commonly used for soil remediation include mechanical removal, evaporation, dispersion and washing, amongst other physical and chemical treatments. However, many of these technologies are expensive and can lead to incomplete decomposition of the contaminants.

On the other hand, biological remediation technologies are known to be cheaper, and into some extent less complicated. This is why my research is focused on the principle of phytoremediation, which is based on the use of plants as a tool to treat contaminated soil. The theory says that plants, or even just the roots of these, could be used as a tool to clean up contaminated soil. The problem is that it does not work all the time, or requires a long time. This is why, as a part of my PhD, I am looking at the optimal conditions to make phytoremediation work, and also ways to accelerate this process.

This goes from the selection of the plant species to various particular parameters, such as the time that the plant material has to be in the soil. My interest of this type of technology is that it could represent a cheap and easy way to clean up contaminated soil, which is a very important aspect in developing countries where complex and expensive technologies are not an option. For example, in Mexico, where I come from, the oil industry is responsible for at least 60% of the total contaminated land in the country, and most of this land is located in areas where it would be impossible to use expensive remediation technologies involving the use of complex equipment. With phytoremediation, only basic agricultural equipment is required.