**1. Introduction**

Pollution is a resultant detrimental effect on the ecosystem attributed to hazard discharges and mismanagement [1, 2]. Contamination on the other hand is attributed to presence of hazards in the biological systems and these act as sources of toxicity to flora and fauna [3]. Potential toxic elements (PTEs), another type of inorganic pollutant, make up one of the most significant groups of pollutants that are released into environment by chemical and allied industries such as pharmaceuticals, fertilizers, and refineries. These PTEs can pollute the environment if their concentration is higher than the allowable limits [4]. There is a possibility that these inorganic pollutants cannot be broken down by biological processes, and as a result, they remain in the environment for a while, ultimately causing disruptive effects, not only on public health but also on the flora and fauna of aquatic and terrestrial environment [5, 6]. Potentially toxic elements are a threat on a global scale since they are not biodegradable and have a propensity to build up in living organisms through the food chain. Different body organs in both humans and animals are impacted by a number of potentially toxic substances' causing acute and chronic toxic effects [1, 6]. In many Sub-Saharan African countries, anthropogenic activities that occur within an ecosystem, as well as the natural sources, are the two main contributors to PTEs pollution.

The vast majority of pollution is caused by human activities, such as the search for new sources of energy [7, 8]. Since the beginning of time, coal and oil have been sources of energy for a wide variety of applications across the globe.

In Uganda, oil exploration in the Lake Albert Graben that began as early as 1938 in Butiaba, Buliisa with geological explorations, has today evolved into the construction of an oil pipeline [9]. Such pipelines come along with the threat of pipeline accidents where oil spills are eminent [10]. The Uganda environmental policy stipulates that oil spills are one of the disasters whose level of contamination of the environment would warrant attention [9]. According to Kassim [2], oil resources should be managed in cognition of the negative effects such as pollution and contamination. The environmental policy stipulates that oil spills are one of the disasters whose level of contamination of the environment would warrant attention [11]. The pollution cited in this situation is that of potentially toxic elements, especially mercury and lead. Since "oil spill" is often a new phenomenon in the area, the ecosystems should be able to adapt in a compatible way otherwise the ecosystem collapses. The theory of sustainable utilization for oil resources in the Lake Albert Graben focuses on three main areas namely; availability of the resources, adaptability and flexibility, and homeostasis [12]. The resources targeted at the Albertine Graben include water, assets, and entitlements, and not so much of PTEs research [13]. For instance, much of the work executed about water levels of mercury, levels of mercury in fish, and risk burden thereafter, is documented better in developed countries compared to the developing countries, like Uganda. The use of consumption advisories is where most of the information in developed countries is stored. The assets in the biodiversity hot spot include flora and fauna uniquely found in this site [14]. In addition to the animal species and plants in the protected area, lies a whole new industrial park as part of the oil city. The much-anticipated livelihood from this oil city creates an entitlement to the community around the oil drilling area [14]. However, conflicts might result in negative catastrophes, such as oil leaks, if the delicate balance between entitlement and livelihood is not realized. In the Murchison Falls Conservation Area (MFCA), wildlife, domestic animals, and human ecosystems are documented as resilient systems, initiated by anthropogenic activities [15]. The presence of oil and gas prospecting in MFCA as major anthropogenic activities translates into ecosystem resilience, coping, and tolerance as a result of the possible oil spills [15]. Oil and gas production is one of the precursors of mercury in the environment, should there be an oil spill [16]. The surrounding communities are being empowered through a socioecological approach that focuses on sustainability of the ecosystem proponents.

This chapter, therefore, discusses the detrimental effects of mercury on an ecosystem that lies at the wildlife, domestic animal, and human interface. These effects are on around an oil spill framework that encompasses terrestrial and aquatic environments, species, and habitats as illustrated in **Figure 1**.

The likely exposure factors include exposure time, exposure quantity, and analytic chemicals, that is, mercury and lead. The species-related factors include species identity, development stage, generation time, feeding mode, and mobility. The habitat related factors include depth at which species thrive, environmental stressors, i.e., deforestations, erosion, anthropogenic activities and climatic conditions. These triad factors also are both inter and intra linked.

Location and habitat.

In the Lake Albert region, oil exploration often excites the population. However, the location of oil wells in MFCA biodiversity hot spots and forests has led to loss of habitat and ecosystem for biodiversity. The location of MCFA has been illustrated in **Figures 2** and **3**.

*Mercury Contamination and Spill-Over at Human-Wildlife-Environment Interface DOI: http://dx.doi.org/10.5772/intechopen.109492*

**Figure 1.** *Framework of oil spill burden on Ecosystem. Sources: [17, 18].*

**Figure 2.** *Map of Lake Albert region [19].*

Regardless of where the oil spill occurs, whether terrestrial or aquatic, the impacts are devastating, as they can lead to accumulation of potentially toxic elements, especially mercury in the terrestrial and aquatic environment, causing toxicities in animals and humans. Mercury in particular bioaccumulates and is magnified along trophic levels, often bioconcentrate in plants and animals and the flora acts as sources of the potentially toxic substances/mercury.

On the other hand, there have been positive impacts on development, that is, infrastructure, road networks, and improved livelihoods of the surrounding communities. A balance is needed in utilization of the oil resource since it is perishable but can also have vast negative impacts, which include the oil spills.

**Figure 3.** *Oil fields in Uganda [20].*
