The term ‘landfill’ can be defined as a form of waste disposal whereby solid waste materials are buried on. The establishment of landfills has more so been a common practice for different industrial organizations that disposes all its solid industrial waste materials in the landfills. Aside from the vast industrial organizations, most institutions have also adapted to the use of landfills for waste disposal and ultimately, waste management. Even though the University has designed its own landfill as a route and platform for solid waste disposal, research has consequently established the problem of soil pollution within environs that are at a close proximity with the landfill site. Landfills, which are regarded as the oldest form of waste treatment and disposal is currently viewed by majority of erudite researchers as being the worst cause of land or earth pollution. Additionally, landfills have been found to result to devastating contamination rates on the underground water basins, aquifers, and soil. Frequent cases of waste disposal in the landfills causes a general uncontrolled buildup of the waste, which may then result to the formation of the methane gas which is then released to the atmosphere as one of the most prevalent forms of greenhouse gases. The unprecedented and alarming increase of methane gas in the atmosphere eventually worsens the rate of global warming which is today an issue of great concern to the world.
In order to assess and analyze the effects of landfills on the soil environment surrounding it, various procedures had to be followed in a sequential order. Foremost, there had to be collection of soil samples within a specified area zone. This was later followed by carrying out sample processing and chemical analysis, after which test plant species were planted on the soil samples under investigation. Lastly, a phytotoxicity test was performed to analyze and identify any toxic components that could be found on the collected soil samples.
- Using a corer, the soil samples were collected from 5 randomly selected points within the landfill site at a depth of 10cm.
- The soil samples were then placed in well-sterilized plastic containers after which the containers were labeled.
- The soil samples were thereafter taken to the laboratory to be analyzed for the availability of heavy metals such as Lead, Copper, Zinc, Nickel, Manganese, Cobalt and Mercury.
Sample Processing and Chemical Analysis
- The collected soil samples were air-dried before being sieved.
- A small portion of the soil sample was used for the microwave digestion analysis process
- 200 mg of the dried and homogenized soil sample were used for partial digestion in the microwave oven using 3ml of concentrated Nitrate solution and 9ml of concentrated Hydrochloric acid at 2000C and 1000W for approximately 30 minutes.
- An electro-thermal atomic adsorption electrometer was then used to determine the presence of certain heavy metals such as Cobalt, Zinc, Manganese, Copper, Nickel, and Lead.
- On the other hand, the presence of mercury component in the soil samples was confirmed by using a one purpose atomic absorption spectrometer.
Test Plant Species
- The selected plant for this experiment was the mustard. This is because of the fact that the mustard plant is highly sensitive to a wide range of different chemicals (Lehmann, 2007).
- The mustard seeds were first soaked for 3 minutes on sodium hypochlorite which had been added 2 drops of tween-20 solution. This procedure was done so as to surface-sterilize the mustard seeds.
- The sterilized mustard seeds were then placed and rinsed on sterile distilled water.
- The earthen pots were loosely filled with 200 g of the collected soil samples.
- Approximately 60 sterilized mustard seeds were then randomly scattered on the soil surface after which the seeds were covered with a thin layer of silica.
- To avoid cases of evaporation of the water contained in the soil, a glass plate was placed to cover the planted mustard soil.
- A control experiment was done using a specialized and sterilized soil that promotes the growth of the mustard plant.
- Both mustard seeds were grown under laboratory conditions.
Landfills usually serve as an effective option for waste disposal and management. Indeed, environment conservation and preservation is a paramount issue that the world seeks to achieve. This is because of the fatal effects that environment pollution has had on the climate and on the general health of the vast population of people who have had to face the negative consequences of waste mismanagement (Lehmann, 2007). Today, the world thrives to ensure that the aesthetic condition of the environment is well maintained and preserved. It is with this profound reason that landfills have become an important part and parcel of proper waste management.
Some of the heavy metals found on the soil samples in high concentrations included; Copper, Zinc, Lead, Cadmium, and Manganese. In addition, mercury was found in low concentration on the soil samples. Although these heavy metals naturally exist in rocks and can also be found in incorporated soils in variable amounts, an increased concentration of these metals in the soil is usually regarded as a health hazard to most of the living species inclusive of plants, insects, animals, and human beings (Adamcová et al., 2016).
After two weeks, the mustard seeds which had been planted on the contaminated soils had not yet indicated any signs of germination. On the other hand, the mustard seeds that had been grown on the sterilized specific soil germinated after one week. This controlled experiment proved that the soils that were used as a media of growth for the mustard plants were contaminated by substances that inhibited the germination of the mustard seeds. However, after one month, the mustard seeds whose germination had been prolonged finally sprouted out. Nevertheless, the mustard plants’ leaves were yellowish in color in comparison with the normal green color of the mustard plant leaves.
In conclusion, the soil environment around the landfill site was confirmed to be contaminated by the solid wastes that had been buried on the landfill. Additionally the alarming increase in heavy metal concentration in the soil was found to be as a result of the toxic forms of solid wastes that were continuously being disposed on the landfills. Increase in heavy metal components in the soil also contributed to the change of the soils pH, which disrupted the normal soil biota. Thus, waste disposal on the landfills has proved to be more disadvantageous than beneficial. The negative effects of earth pollution include; the disruption of the soil life, inhibition of plant’s germination process, stunted growth of plants, and health risks to both the animals and human beings (Adamcová et al., 2016).
Adamcová, D., Vaverková, M. D., Bartoň, S., Havlíček, Z., & Břoušková, E. (2016). Soil contamination in landfills: a case study of a landfill in Czech Republic. Solid Earth, 7(1), 239-247.
Lehmann, E. C. (2007). Landfill research focus. New York: Nova Science Publishers.