Environmental geotechnology, sometimes referred to as geoenvironmental engineering is an interdisciplinary field that originated by blending environmental engineering and geotechnology (1). Environmental geotechnology encompasses soil science and atmospheric sciences thereby linking the biogeochemical cycles, lithosphere, hydrosphere and geomicrosphere (2). Currently the population has been escalating drastically thereby upsetting the biogeochemical cycles and has resulted in a plethora of environmental issues. Although geoenvironmental technology is mainly concerned about soil and its associated factors, it is noteworthy to acknowledge the fact that the biogeochemical cycles are closely linked with each other and imbalance of one cycle would immediately reflect in the other cycles (3).
Geoenvironmental issues may either be natural or man-made. While issues like tsunami, earthquakes etc. come under natural causes, pollution is the major contributor to man-made environmental issues. Pollution refers to the introduction of any contaminant into air, water or soil that alters that natural environment (4). This report focuses mainly on pollution and its impact in the geoenvironment with the aid of case studies.
Contamination adversely affects the geoenvironment which in turn affects our quality of life. Improper waste disposal and inadequate engineering techniques to contain the large quantity of waste generated each day contribute to a strikingly unhygienic environment which, in addition to serving as a breeding ground for vector-borne diseases also upset the natural microbial flora (5). Municipal dump sites and improper waste containment and disposal has been indicated in studies as major sources of vector-borne disease origin and transmission (6).
When precipitation occurs in areas where waste has been indiscriminately dumped, it percolates into the ground while still carrying the dissolved contaminants that ultimately result in contamination of groundwater, generating a leachate (contaminated groundwater) (7). Depending on the waste dumped at the site, the leachate may contain harmless municipal waste contaminants to highly toxic heavy metals like lead, mercury etc. Groundwater generally tends to flow slowly and the level to which the leachate gets distributed largely depends on the plume behavior of the groundwater (8). After the groundwater has got contaminated, it can very quickly contaminate any enclosed water body nearby like a pond or lake. In case of flowing water bodies like rivers, the leachate gets carried even further contaminating an even larger area.
Most of the heavy metals and microelements can easily get incorporated into all living organisms. When fresh water sources are contaminated, the contaminants get trapped and is ingested by planktons and other aquatic organisms (9). When these algae, fishes etc. are consumed by animals and humans, heavy metal poisoning and a variety of other diseases result. In addition, plants can also easily absorb and incorporate these contaminants when this water is used for irrigation and agriculture which in turn also result in a variety of diseases.
One of the proven cases of heavy metal poisoning was the Kodaikanal mercury poisoning incident that resulted from mercury (Hg) contamination by Hindustan Unilever, a company that manufactures clinical thermometers. This was an eye-opening case that happened in Kodaikanal in Tamil Nadu, India in 2001 which ultimately raised the issue of corporate negligence and resulted in the closure of the factory. Hindustan Unilever was set up in Kodaikanal in 1987 (10) where it imported mercury from the United States, manufactured clinical thermometers and exported it back to the US and Europe. The issue of mercury poisoning stirred up when several workers at the factory became susceptible to kidney and liver problems and the Tamil Nadu Alliance Against Mercury (TNAAC) involved and alleged improper waste disposal by the factory after discovering broken glass thermometers and mercury in parts of the Shola forest (11).
Later, several local organisations and Greenpeace, an international environmental organization allied with TNAAC and instigated a public protest leading the factory to shut down in addition to making the company admit that they did dispose of untreated waste in the forest. In 2002, Unilever admitted that it did not dump that waste in the environment but rather had sold 5.3 metric tonnes of broken glass thermometers which contained 0.15% mercury to a scrap recycler (12). The company further quoted that it did not result in any impact on the health of the workers or the environment based on a report by an international environmental consultant (11).
However, the protests didn’t die down and the organizations began calling for ‘reverse dumping’. The protests soon gained pace and the company was forced to send 290 tonnes of mercury waste back to the factories in the US for proper treatment and remediation (13). The intense protests lead to a probe by the department of Atomic Energy of the Indian Government and the investigation revealed that the free Hg level in Kodaikanal was 1000 times the normal level. This quickly lead to further analysis of the nearby water bodies and fishes which also indicated high levels of Hg contamination (14).
The governmental and nongovernmental organizations further pressurised the company to remediate the contaminated environment and Unilever finally began working with the Tamil Nadu Pollution Control Board (TNPCB) and National Environmental Engineering Research Institute (NEERI) to remediate the soil and reduce the concentration of mercury to 20mg/kg of soil in 2009 (11). This is just one of the cases of improper waste disposal leading to heavy metal poisoning. There have been so many incidents of lead poisoning in China and other Asian countries. The minamata disease in Japan due to mercury poisoning is another well documented case of heavy metal poisoning due to improper and illegal waste disposal.
Most of the time wastes are dumped indiscriminately without proper segregation. Some of the chemicals present in old batteries, electrodes, sensors, probes etc. maybe be harmless by itself but might become highly toxic when it comes it contact with other chemicals or with changes in temperature, pH etc (15). These toxic chemicals might either leak out and contaminate the soil and water or in some cases, become combustible, explode and pollute the air in the site.
When considering chemical disaster due to improper waste storage, Baia Mare cyanide spill is a well documented case wherein Aurul, a gold mining company at Baia Mara in Romania leaked cyanide into the Somes River that killed a huge number of fishes in Romania and Hungary in 2000 making it known as the worst environmental disaster after Chernobyl disaster. Aurul claimed that it had the provisions to remediate the toxic tailings which is a byproduct of gold mining by gold cyanidation. Hence, the toxic waste was stored in a dam in Maramures County (16). However, due to the extreme weather conditions, at night on Jan 30th, the dam burst liberating 100,000 cubic meters of contaminated water over farmlands and Somes river thereby increasing the cyanide concentration of the river more than 700 times the normal level (17).
The contamination affected the drinking water supply of more than 2.5 million Hungarians in addition to wiping out 80% of the aquatic organisms in that stretch. Around 62 fish species including 20 protected species were lost in the spill (18). In spite of the complete loss of the ecosystem, the Romanian government and the company claimed that statistics were exaggerated and that most of the fish had died due to cold (19). This prompted environmental organizations to protest against gold cyanidation although none of the protests have been successful so far. However, it is clear that such a disaster could have been avoided if the company had incorporated a properly engineered waste disposal mechanism taking into account the extreme winter conditions.
The other major concern is the stability and integrity of the nuclear waste disposal sites. Energy produced by nuclear power result in waste that can be highly radioactive which can act as a potential mutagen or carcinogen. Nuclear waste mainly comprise compounds like plutonium, uranium etc. which posses the ability to release harmful alpha, beta and gamma radiation (20). The general practice is to isolate the nuclear waste based on the half-life of the compound and either convert it into a more inert material or to dilute it so that it no longer pose a major threat to the geoenvironment or the biotic components (21).
Currently, techniques like nuclear fuel reprocessing and transmutation are being developed. Transmutation is eyed as an important technique as it converts the mutable nuclear compounds into stable compounds that can later be repurposed (22). However, these techniques are still in the development and testing stage and so the conventional dry cask storage and geologic disposal are mainly used for long term storage of nuclear waste.
Dry cask storage also referred to as above-ground storage involves sealing the nuclear waste along with an inert gas in an impermeable steel cylinder which is further sealed within a concrete cylinder to prevent any radiation from escaping (23).
Geologic disposal technique generally involves drilling a deep tunnel and dump the waste and seal it which makes it similar to a landfill. However, it has to be noted that these tunnels must be able to contain radioactive waste for years together. Hence, these tunnels are dug more than 500 to 1000 m deep with vaults in the geologically stable location and the nuclear waste are stored in them totally isolated from the human population (24).
Nuclear waste storage still sparks a lot of controversy especially when it comes to deep sea burial. Hence, new techniques are being experimented with for better containment and disposal.
Improper nuclear waste disposal was a major cause of concern especially during the second world war. One of the well known cases is the illegal nuclear contamination of the Techa river, located in the southern Ural Mountains in Russia. The origin of the river is at Ozyorsk a town in Chelyabinsk Oblast where nuclear weapons were secretly processed during the war.
In Ozyorsk, the Russian federation housed one of its biggest nuclear reprocessing plant, the Mayak Production Association (25). Between 1949 and 1956, the nuclear plant dumped about 76 million cubic meters of radioactive waste water with an estimated 2.75 MCi of radioactivity into the Techa river (26). During that period of 7 years, more than 28,000 residents depended solely on the Techa river with more than 40 villages established in the river banks. Around 23 villages were later evacuated but the damage was already done. For more than 50 years people continued to experience varying levels of radiation sickness which proved fatal for a huge population (27). This case again hints at the fact that improper containment facilities and breaching of legal disposal methods is a common cause of disaster once it flares up.
The case studies and environmental issues discussed in this write-up only amount to a handful of the geoenvironmental issues that we currently face. Scientists and academicians continue to work on the possible containment methods and repurposing of waste. However, even with existing techniques, the fact that several disasters occur mainly due to illegal disposal and lack of awareness hasn’t escaped the notice of many environmentalists. Continuous improvement while still adhering to proper and coordinated waste disposal methods can avoid most man-made disasters and help create a better environment
This write-up does not emphasize on the impact of municipal waste disposal but rather gives a generalized overview with special emphasis only on industrial waste disposal. However, the fact that municipal waste disposal does pose a huge risk to human and health and environment has to be acknowledged. In most cases, the waste is neither segregated appropriately nor is it treated appropriately. Some of the contaminants present in the municipal waste like the lead from paint, cadmium from batteries, DEET in insect repellents etc. can cause serious health effects that might be fatal.
Hence, in addition to the industries playing a role in waste management and disposal, the general public should also be educated about the proper waste disposal methods and should do their role in reusing, repurposing and in safe disposal of waste.
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