Pollution could be said to be man's introduction of chemicals or energy into the environment that are likely to endanger human health, impair resources and ecological systems, degrade structures and amenities or interfere with lawful uses of the environment (Ramamohana, 2017). When materials accumulate in places where they are not desirable, pollution arises. Heavy pollution loads have been imposed on natural resources as a result of industrial development accompanied by population and consumption growth (Nasrabadi et al., 2010). Any outflow of material or energy into water, land, or air that causes or may cause severe or persistent harm to the Earth's ecological balance or decreases the quality of life is referred to as environmental pollution. Pollution is frequently classified as either point source or nonpoint source. In 2015, pollution claimed the lives of 9 million people throughout the world (Beil, 2017 and Carrington, 2017). Pollutants can cause either primary or secondary harm to the environment, such as small disturbances in the delicate equilibrium of the biological food web that are only evident over a lengthy period of time (Gheorghe, Iuliana and Barbu, 2011). Non-persistent pollutants are non-permanent or biodegradable and break down easily (You et al., 2018).
Plastic pollution is the buildup of plastic items and particles in the environment (e.g., plastic bottles, bags, and microbeads) that harms animals, wildlife habitat, and humans (Parker, 2018). People all around the world are on a never-ending quest for a better quality of life. As a result, there has been a rise in the consumption of products and services leading into waste creation. Plastics have become an inextricable aspect of human lives, with their widespread usage in a variety of industries and ever-expanding uses providing significant societal advantages (Olanrewaju and Oyebade, 2019). The focus on plastic pollution studies in seas recently may have been due to the fact that its buildup and effects were more visible in these ecosystems (Ryan et al., 2009). Plastic pollution is widespread and growing in both land and marine habitats across the world. Global plastic output was predicted at 299 million tonnes in 2013 up 3.9 percent from 2012 (Plastic Europe, 2015). Plastics are light and buoyant, making them easy to move large distances in a variety of settings making them widespread pollutants (Coe and Rogers, 1997). The majority of plastic in the environment is non-biodegradable and lasts a long time as waste (European Commission DG Environment, 2011). Plastic pollution is mostly carried by rivers which transport plastics from the terrestrial environment and human activity centers to the shore and oceans. Humans have generated 8.3×109 tons of plastic since the 1950s, with 60% of it ending up in landfills or as litter. (Geyer, Jambeck and Law, 2017). According to Jambeck et al. (2015) In 2010, 192 coastal nations (representing 93 percent of the world population) generated an estimated 275×106 tons of plastic garbage.
Plastics may be classified into three classes in ecotoxicological settings based on particle size following bulk degradation, physical breakdown, and mechanical breakdown. They are macro-plastics with a diameter more than 5mm, micro-plastics with a diameter less than 5mm, and nanometer-sized plastic particles with a diameter less than 100nm (Axelsson and Sebille, 2017; Koelmans, 2015; Andrady, 2011; Wang et al., 2016 and Kalogerakis et al., 2017). Plastic despite having a good number of benefits, plastic damages species in nature, assists in the transportation of pollutants and hazardous substances, and has an impact on ecosystem processes and services (Teuten et al., 2009; Rochman et al., 2015; Eerkes-Medrano and Thompson, 2018). Due to the durability of plastics it ends up in the environment and degrades slowly if not managed properly (Palm and Svensson, 2018). Plastics may be eaten and respired by both big and tiny creatures and bioaccumulation allows them to move down the food chain. (Bouwmeester, Hollman and Peters, 2015; Rochman et al., 2015).
Plastic leakage refers to the quantity of macro-, micro-, and nano-plastics that are not retained in a circular loop or appropriately handled at the end of their useful lives and so leak into the environment (IUCN, 2020). Sub-Saharan Africa has had a major problem with waste management (Asase et al., 2009) mostly due to a lack of recycling infrastructure, qualified staff and other related factors. Annual mismanaged plastic waste was calculated in a study by Lebreton and Andrady (2019) which indicated that Asia produces about 52 metric tonnes of plastic waste per year, Africa about 17 metric tonnes per year, Latin America about 7.9 metric tonnes, Europe about 3.3 metric toonnes, US and Canada raises 0.3 metric tonnes and Oceania rabout 0.1 metric tonnes per year (Sheth, 2019; Jambeck et al., 2015).
Nigeria produces around 42 million tonnes of solid garbage per year (0.49–0.95 kg per capita per day. plastic trash accounts for around 20% of total solid waste (Akinola et al., 2014). Demographic experts believe that Nigeria's high rate of urbanization, which is among the greatest in the world, has the potential to exacerbate environmental deterioration, which has led to Nigeria's unequal distribution and handling of plastic trash. Floods cause seasonal devastation in Nigeria, particularly in crowded metropolitan centers where plastic bottles, plastic bags, and other waste products have clogged drainage systems obstructing the free flow of water whenever it rains (Olanrewaju and Oyebade, 2019). According to a survey conducted by PCI Film Consulting, Nigeria's packaging sector contributed about 12% of the $4 billion achieved by Middle East and African markets in the previous five years. From 1996 to 2014 the total volume of plastics imported into Nigeria was projected to be 23.4 million tons (including plastics from motor vehicles from 1980 to 2010). Plastics produced in Nigeria are made from imported raw materials or recycled trash and so cannot be considered a new contribution source to the total volume of plastic produced in Nigeria (Elias and Omojola, 2015).
Data reveals that GDP has a significant influence on plastic consumption, as seen by the fact that yearly per capita plastic consumption in Nigeria, Kenya, and Ghana was 4.4-8 kg/year from 2009 to 2015, whereas it was 13-19 kg/year in Algeria, Egypt, and Morocco, and 24.5 kg/year in South Africa (Babayemi et al., 2018; Jain, 2019; EUROMAP, 2016). Nigeria’s time trend shows a continuous increase in importation, 554,513 tonnes was imported in 1996 while 2010 about 2.93 metric tonnes was imported (17kg/cap/year). Imports of polymer construction products, such as roofing sheets, PVC tanks, PVC tiles, and PVC plumbing supplies, were particularly notable. Between 1996 and 2017, Nigeria imported around 19.87 Mt (worth $23.1 billion), accounting for about 16.9% of overall African consumption (Babayemi et al., 2018). Primary polymers (HS codes 3901–3914) are the most common plastic materials imported into Nigeria, accounting for 15.8 Metric tonnes while plastic products (HS codes 3915–3926) account for around 4 metric tonnes, 75 percent of all plastic imported into the nation was made up of primary polymers and plastic as a product. Primary polymers are mostly utilized in the manufacturing of packaging materials and domestic products such as cooking utensils, chairs, tables, and footwear. Imported goods, such as automobiles and electronics, account for the second and third highest levels of plastic use. These were about 2.9 Mt and 2.6 Mt, respectively, and were not imported under a plastic-related HS code (Babayemi et al., 2018).
Anambra State (the study area) arguably is the business hub of the South-eastern part of Nigeria, and has a massive output of plastic wastes daily, this have affected the beauty of the natural environment. Single-use plastics contribute significantly to this leakage, ill-disposed plastic bags are found all over the towns of her Metropolis. LGA within the metropolitan areas are faced with plastic waste pollution in their waters which affect aquatic life. Plastic bags is one of the most used forms of plastic in the study area, a recent study shows that 62.5 percent of individuals, reuse their plastic bags on a regular basis, whereas 35 percent dispose them after single use; 4.1 percent was reported to reuse big plastic bags as waste containers. The research also found that 55 percent of respondents do not support a reduction in the use of plastic bags, compared to 45 percent who support a reduction in the use of plastic bags. The study also reported that 7 percent and 8 percent respectively use an average of four to six bags and more than six bags (Iheukwumere et al., 2020). An average of three bags each day results in a total of 21 bags in seven days and around 90 bags in a month. The study area having proliferation of plastics as a result of increased human population, operations of businesses and industries needs to consistently monitor the impact of human activities on the ecosystem. Finding ways to stem this land-sourced plastic waste leakage requires understanding of its sources, and environmental aiding factors, therefore GIS based investigation on plastic leakage concentration is essential to identify areas that require more attention for plastic leakage reduction against low plastic leakage areas (Chukwuma et al., 2019).
The use of GIS have been a resourceful tool in proffering waste management ideas, some research work have been done to advance the management of waste in different locations in Nigeria: Uzoezie et al. (2018) used the QGIS platform to geospatially model suitable site for plastic waste collection points in the University of Calabar, Calabar, Nigeria. Njoku (2012) applied GIS in selecting suitable sites for collection of solid wastes in Ikenegbu extension layout in Owerri, Nigeria. Jimoh et al., (2019) worked on a GIS based appraisal of waste disposal for environmental assessment and management in Mainland Area of Lagos State, Nigeria. Chukwuma et al (2019) applied geospatial technology in delineating vulnerable areas to plastic pollution in parts of Serdang in Malaysia. The study used statistical data on plastic generation to produce the plastic waste density thematic layer; this layer could be improved using field data of plastic accumulation spots as done in this study. Despite the endeavors of several research work in Nigeria in waste management using GIS, to the best of the author’s knowledge no study have considered the application of GIS in assessing vulnerable areas in Nigeria to plastic waste litter and eventually the production of leakage map as done in this study. Globally, there is dearth of literature in vulnerability assessment of plastic leakage using land based features that models plastic leakage. This study is therefore essential in the decision making to preserve aquatic animals, for higher agricultural output and productivity; and in application of strategic waste management especially for high risked areas located in the coastal region, this is critical in mitigation of plastic leakage to the ocean, of which the study area is a case in point. The aim of this study is geospatially model the vulnerability or risk posed by plastic accumulation in an area, by integrating geospatial related features in the model, using Anambra state as a case study. The following specific objectives were considered in the realization of the research aim: to analyse spatial distribution of plastic wastes in the study area; to geospatially model the risk associated with the various plastic leakage points and to proffer solutions to the impact of plastic mismanagement for the study area.