1.1 Introduction
Heavy metals are natural elements with atomic number greater than 20, characterized by a relatively high density (at least 5 g cm−3), and are toxic even at low concentrations (Koller et al. 2018). They are characteristically existing components found in changing variation in the environments and are part of human daily activities, they are also found in important structures and in a range of other artificial mixes (Govind et al., 2014). The activities of human have greatly impacted on some heavy metal biochemical cycles and equalization of which a great number of heavy metals have found its use in various items such as cars and batteries (Oyeleke et al., 2016).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Research questions, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Heavy metals are natural components cannot be degraded or destroyed biologically. Life cannot develop and survive without the metal ions as life is as much inorganic as organic. Trace element to designate the elements which occur in small concentrations in natural biological systems concern over the deteriorating quality of the environment led to a trace element. The elementary constituents of plant, animal and human life may be classified as major and trace elements, the latter group comprising both essential and non-essential elements (including toxic elements).
Although the low level of heavy metals in fertilizers and pesticides in one-time use do not pose any hazard of soil or plant contamination, their long-term use in food crops production, especially in greenhouse vegetable production, contributed to the accumulation of heavy metals in the soils and consequently in food crops (Huang and Jin, 2008). However, up to now, heavy metal concentrations of greenhouse soil in Bosnia and Herzegovina and its pollution problem have been studied very little, especially there is no systematical investigation of the dynamics of heavy metals in the greenhouse soil-plant system in intensive tomato production.
Heavy metals such as Co, Cu, Fe, Mn, Mo, Ni, V, and Zn are required in minute quantities by organisms, excessive amounts of these elements can become harmful to organisms. Heavy metals such as Pb, Cd, Hg, and as (a metalloid but generally referred to as a heavy metal) do not have any beneficial effect on organisms and are thus regarded as the “main threats” since they are very harmful to both plants and animals, pollutant in the environment air, water and soil, may be poisonous or toxic and will cause harm to living things. Metals accumulate in ecological food chain through uptake at primary producer level and then through consumption at consumer levels and plants roots are the primary contact site for heavy metal ions. Whereas, in aquatic systems plant body is exposed to these ions and heavy metals are absorbed directly to the leaves due to particles deposited on the foliar surfaces. This paper briefly describes the nature and properties of soils pollution with heavy metals and its effect on the plant growth were reviewed.
The presence of increased level of heavy metals in the aquatic environment has been of much concern for the past decades due to adverse effect of some metals on living organisms in food chains leading to man. Pollutants are the cause of major water quality degradation around the world. Several toxic metals which are important to the environment and human health have been detected in aquatic media. These toxic metals include the non-essential meals and are no importance to humans (Borgman and Norwood 2002).
Trace amount of heavy metals are always present in fresh water from terrigenous sources such as weathering of rocks resulting into geo-chemical recycling of heavy metal elements in these ecosystem. Trace elements may be immobilised within the stream sediments and could be involved in absorption, co-precipitation and complex formation. Sometimes they are co-adsorbed with other elements as oxides, hydroxides of Fe, Mn, or may occur in particulate form.
Heavy metal may enter into aquatic ecosystem from anthropogenic sources, such as industrial wastewater discharge, sewage wastewater, fossil fuel combustion, and atmospheric deposition. Trace element in stream sediment compartment can be used to reveal the history and intensity of local and regional pollution. In this work, the of stream sediment contamination was assess using geo-accumulation index.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Heavy Metal Distribution in Sediment.
1.3 Statement of Problems
Investigation revealed that heavy metals pollution of aquatic ecosystem is becoming a potential global problem, pollution typically refers to chemicals or other substance in concentration greater than it would occur under natural conditions.
1.4 Aim and Objectives of Study
The aim of the study is to examine the Heavy Metal Distribution in Sediment using Akpabuyo Stream, Cross River Basin Southeastern Nigeria as a case study. In achieving this aim, the following specific objectives were laid out as follows:
- To estimate the anthropogenic input and to assess the pollution status on the area;
- To determine the total content of heavy metals in surface sediments of Akpabuyo; and
- To assess the extent and degree of metals, and the origin of these metals, using the geo-accumulation index of the metals.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What is the total content of heavy metals in surface sediments of Akpabuyo?
- What is the anthropogenic input and to assess the pollution status on the area?
- What is the extent and degree of metals, and the origin of these metals, using the geo-accumulation index of the metals?
1.6 Significance of Study
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.7 Scope of Study
The scope of the research is focused on the Heavy Metal Distribution in Sediment using Akpabuyo Stream, Cross River Basin Southeastern Nigeria as a case study.
1.8 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
1.9 Study Area
The study area which is located in Akpabuyo, Cross River State lies between longitudes 8022I30II E – 80 30I 0IIE and latitude 40 52I 30II N – 40 57I 30II N (figure 2). With an area of 126,4032 Square Km. Although many stream samples where collected but few was selscted for the heavy metal analysis. The various Locations in Akpabuyo which sediment samples were collected and used to carry out the analysis are EsukMbat stream(L1), EsukEkpoEyo Stream(L2), Ikot Akwa Stream(L3), Dan Archibong Stream(L4), Itu Stream(L5), Ikot Ndarake Stream(L6), Asioha Stream(L7), Ikot EkpoEne Stream(L8), Ekpene Ikot Imo Stream(L9), Ikot Nakanda(L10), and their following coordinate shown respectively (table 1.3) . It originate from a hilly region and flows through several villages and farmland.
