Huge quantities of wastes which are indiscriminately disposed into uncontrolled dumpsites and flowing waters around residential areas are generated from Ibadan, metropolis. These may adversely affect soil, surface- and ground-water qualities and the fauna. Limited information exists on toxic effects that wastes from these nondesignated sites have on associated fauna. Earthworms are one of the dominant fauna in soils and are pollution bioindicators. Therefore this study was designed to investigate physico-chemical parameters, earthworm diversity and abundance, and acute toxicity of contaminated-water on some fauna in selected dumpsites in Ibadan. One-hundred and twenty water samples from streams (Irefin, Gege, Gbagi, Odinjo, and Omi-Adio) receiving domestic wastes; 60-composite soil samples each from dumpsites (Ojokondo, Olodo, Moniya, Idi-Ope and Oremeji) and stream banks; composite soil samples from a control site at University of Ibadan (UI); 72 groundwater samples from wells around the dumpsites and UI were purposively collected once every two months from March 2008 to February 2010. Earthworms from top-soil were sampled using 0.25×0.25 m2 quadrat, handpicked, identified and density determined following standard procedures. Earthworm species’ diversity and evenness were determined using Shannon-Wiener diversity index and Shannon’s evenness, respectively. Water samples were analysed for physico-chemical parameters [including Dissolved-Oxygen (DO), Biochemical-Oxygen-Demand (BOD), and Chemical-Oxygen-Demand (COD)] and soil samples including lead and zinc using standard methods and results were compared with NESREA standards. The 48-hour-LC50 of stream-samples were determined for Cloeon perkinsi (mayfly) larvae (CP); while 96-hour-LC50 for Rana temporaria tadpoles, Clarias gariepinus frys (CG1) and fingerlings (CG2) were determined using Probit method. Data were analysed using descriptive statistics and ANOVA at p=0.05. Three earthworm species (Eudrilus euginiae, Dichogaster modigliani and Hyperiodrilus africanus) were identified at UI, streams and dumpsites. Highest density of Eudrilus euginiae (30.0±13.7/m2) was recorded at UI and this was significantly different from other sites, while lowest (6.4±2.2/m2) was recorded at Ojokondo. Highest densities of Hyperiodrilus africanus (32.7±14.6/m2) and Dichogaster modigliani (40.0±0.0/m2) were recorded at UI and Gbagi, respectively; while lowest value of 4.0±0.0/m2 was recorded at Irefin and Gege. Eudrilus euginiae and Dichogaster modigliani were not found at Gege and Idi-Ope, respectively, while Hyperiodrilus africanus was not found at Odinjo, Moniya and Olodo. Earthworm diversity (0.5) was highest in UI and lowest (0.3) at Gege. Earthworms were most evenly distributed at Odinjo (2.4) and least at Ojokondo (0.8). The DO (mg/L) for streams ranged from (0.4±0.4) to (2.6±0.6) and were lower than permissible limit for aquatic life. Lead (260.6±77.7mg/kg, 269.6±46.4mg/kg) and zinc (456.9±69.9mg/kg, 1685.1±420.3mg/kg) values in Gege and Ojokondo soils, respectively were significantly higher than NESREA limits. In all groundwater samples, BOD (46.7±21.0mg/L) and COD (154.0±7.0mg/L) exceeded NESREA limits. The 48-hour- LC50 of stream-water to CP (Irefin, 12.7%; Gege, 8.6%), and 96-hour-LC50 to CGI (Gege, 0.8%; Gbagi, 2.8%) and CG2 (Gege, 3.3%; Irefin, 0.6%) indicated high toxicity of the sites. The low earthworm abundance, poor physico-chemical qualities and high toxicity of the study sites revealed that the soil, streams and groundwater were polluted in Ibadan. Consequently, there is need for adequate management and disposal of solidwastes to prevent further environmental contamination. Keywords: Uncontrolled dumpsites in Ibadan, Earthworm abundance, Physicochemical qualities, Acute toxicity.
1.1 Waste Wastes are substances or objects which are disposed off or are intended to be disposed off or are required to be disposed off by the provisions of national laws (Basel Convention, 1989). They are unwanted residues that are usually perceived to be of negative value (Hamer, 2003). According to Taylor and Allen (2006), waste can be loosely defined as any material that is considered to be of no further use to the owner, hence discarded. It is generated universally and is a direct consequence of all human activities. It can also be defined as any unavoidable material resulting from an activity, which has no immediate economic demand and which must be disposed off (NISP, 2003). The major classification of wastes include solid, liquid and gaseous. Solid waste as defined by Olexa et al. (2003) includes garbage, refuse, yard trash, clean debris, white goods, special waste, ashes, residuals (sludge), solid, or semi-solid material, or contained gaseous material. The definition specifically includes agricultural, commercial, domestic, governmental, and mining wastes. The definition specifically excludes pollution. Liquid wastes are wastes dissolved in water emanating from industrial processes known as effluent, domestic liquid, acid waste and waste oil from workshop (NISP, 2003). While gaseous wastes are waste substances in the air (neither solid nor liquid) and they move freely to fill any available space. These include wastes resulting from gas flaring, particulate dust, waste gases from stack, cement factories, stone crushing, excavation activities, lime dust, asbestos dust, acid fumes from automobiles and cigarette fumes (NISP, 2003). 1.2 Solid waste Solid wastes as defined by Omofonmwan and Eseigbe (2009) are residual from homes, businesses and institutions and are referred to as trash, garbage, rubbish, refuse, discards and throwaways that are no longer of any relevance to the disposer. Solid waste also means unwanted materials or substances that are left or discarded after use, also included are by-products of process lines or materials that may be required by law to be disposed off (Okecha, 2000). According to Omofonmwan and Eseigbe (2009), solid waste can be classified in a number of ways, on the basis of source, environmental risks, utility and physical property. On the basis of source which is commonly used, solid wastes are classified as: municipal solid wastes, industrial solid wastes, agricultural solid wastes, mining and mineral wastes, construction and demolition wastes, healthcare wastes, radioactive (nuclear) wastes, human and animal wastes. Improved standard of living contributes to increased quantities of solid wastes (Pandard et al., 2006). In the core, rural or local areas, there are high quantities of organic wastes like leaves used for wrapping food, faeces, and so on, while in the high class areas there are huge quantites of metallic wastes like tins for packaged or processed food. The generation of solid waste from household, industries, markets, abattoir and shops result in improving the standard of living of the inhabitants (Omofonmwan and Eseigbe, 2009). Solid-waste generation and composition in Ibadan is at the rate of 153/Kg/pers./year with paper 15%, food 43%, plastics 4%, glass 6%, metals 21%, textiles 1% and other wastes 10% (Onibokun and Kumuyi, 1999). Oni (2010) also observed solid waste composition in Aba-eku landfill in Ibadan to constitute polyethylene plastics 11.5 %, rigid plastics 3.76 %, papers 17.59 %, glass or ceramics 6.62 %, metals 24.79% , food wastes 6.49 %, biodegradable humus 5.86 %, textiles 3.39 %, leather 2.29 %, wood, bones and straw 2.24 %, health care wastes 2.07 %, rubber 2.07 %, construction materials 1.58 %, car parts 0.30 %, polystyrene packaging plastics 0.21 % and miscellaneous fraction 9.25 %. Amber et al. (2012) observed solid wastes composition in Ibadan to include food/organics 58.5 %, paper/polythene 37.6 %, textile 1.4 %, glass and metal 0.6 %, others (dust, ash, rubber, soil, bones, ceramics 8.9 % and moisture content 23.52 %. Literatures from different research studies indicated that urban areas produce more waste than the rural areas and this might be as a result of the high income that is being generated by the urban dwellers and also a lot of industries being located in urban areas (Ogu, 2000; Babanyara et al., 2010; Aliyu, 2011). 1.3 Categories of solid wastes Solid wastes have been categorized by various authors. According to Hamer (2003), some of the main categories of solid waste include: municipal solid waste (domestic, market and trade wastes); construction industry and demolition waste; fuel production and energy-generation waste; food, beverage and agro-industry waste; catering industry waste; forestry and forest product industry waste; amenity area and garden waste; slurries from intensive animal husbandry (animal manures); slaughterhouse solid waste (including specified materials) and diseased carcasses; waste sewage sludge (treated or untreated) and night soil; and septic hospital waste. These could further be categorized as : non-biodegradable inorganic matter; recalcitrant synthetic organic matter; biodegradable natural organic matter; off-specification and fire- and water-damaged chemicals of unknown composition and characteristics; toxic organic compounds; metals, metalloids and their derivatives; and partially biodegradable natural organic matter. Taylor and Allen (2006) made a simple classification of waste into broad categories according to its origin and risk to human and environmental health, these are: household waste; municipal waste (MSW); commercial and non-hazardous industrial wastes; hazardous (toxic) industrial wastes; construction and demolition waste; health care wastes – waste generated in health care facilities (e.g. hospitals, medical research facilities); human and animal wastes; and incinerator wastes. 1.4 Solid waste disposal patterns Disposal as defined in Florida Statutes 403.703 (2010) means the discharge, deposit, injection, dumping, spilling, leaking, or placing any solid waste or hazardous waste or any constituent thereof may enter other lands or be emitted into the air or discharged into any waters, including groundwaters or otherwise enter the environment. There are different methods of solid waste disposal; Hamer (2003) described simple methods of waste disposal which solid waste management industry finds its origin in as local terrestrial dumping (landfill), dumping into both fresh and marine waters and uncontrolled burning. According to Nelson (2007) solid waste disposal methods are: Source Reduction – This involves the reduction of the amount of solid waste that is initially produced. This is meant to be the ideal solution, but so far, has been unsuccessful. According to USEPA (1999), source reduction is often called waste prevention and it is any change in the design, manufacturing, purchase or use of materials or products (including packaging) to reduce their amount of toxicity before they become municipal solid waste. Reducing waste volume. Pigs – Initially pigs were domesticated to consume peoples’ left overs and convert them into pork and bacon (Commons abundance network, 2015). In the United States, this method was a major source of reducing food wastes until in the 1960’s when the practice was stopped because diseases were spread in this manner (Nelson, 2007). However, it was banned in European Union when there was an outbreak of Foot and Mouth disease in pigs in 2001 and it was thought that the outbreak of the disease was due to feeding of pigs with catering waste (Commons abundance network, 2015). In-sink garbage disposal – A garbage diposal unit is an electrically powered device that is installed under a kitchen sink between a sink’s drain and the trap (https://www.geapplianceparts.com/store/parts/category/disposers). It shreds food wastes into small pieces (generally less than 2 mm or 0.079 inches) to pass through a plumbing system (Shpiner, 1997). However, the method doesn’t really reduce the volume of waste; rather, it transfers the waste into the sewer system (or into the septic tanks) (Nelson, 2007). Composting – The nature’s way of recycling is composting. It biodegrades organic wastes and turns them into valuable organic fertilizers (Ecochem, 2014). This method of recycling works very well to reduce the volume of organic wastes and the wastes can then be used in gardens, fields etc (Nelson, 2007). Recycling – This is a process of converting waste materials into new products to prevent wastes of potentially useful materials, reduction of consumption of fresh raw materials, reduction of energy usage, air pollution reduction (from incineration), reduction of water pollution (from landfilling) by reducing the need for conventional waste disposal and lower greenhouse gas emissions as compared to plastic production (Letsrecycle.com, 2006; The league of women voters, 1993). Open dumps and sanitary landfills – Open dump is the improper disposal of any waste including household trash, garbage, tyres, barrels, demolition/construction waste, appliances, shingles, pipes, metal or any metal material which will rust, rot or burn (St. Clair County Health Department, 2014). Open dumps are often sited in wetlands, they are unlined and this makes them very unsafe, in terms of water contamination (Nelson, 2007). The uncontrolled disposal of municipal solid wastes (refuse) on land is sanitary landfilling. Sanitary landfills are covered up daily, to reduce vermin and smell (Nelson, 2007). Sanitary landfills are engineered disposal systems that are operated in accordance with environmental protection standards (USEPA, 1994). Incineration – The treatment for a wide range of wastes is incineration. In most waste treatments, the objective of waste incineration is to treat waste so as to reduce its volume and hazard, whilst capturing (and thus concentrating) or destroying potentially harmful substances (European Commisssion, 2006). The means to enable recovery of energy, mineral and/or chemical content from waste is also provided by incineration (European Commisssion, 2006). Incineration is beginning to play a much larger part in solid waste disposal and incinerated waste has a much smaller volume as ash, which is a lot easier (and safer) to dispose off (Nelson, 2007). Ocean dumping – This is the act of depositing all the waste materials from plastics, factories and industries, tankers and ships, and sewareage waste materials into the oceans and seas (Marine Insight News Network, 2016). This practice is no longer allowed; although at one time it was fairly popular (Nelson, 2007). Illegal Dumping – This is the deliberate act or unauthorized dumping, tipping or burying of waste on unlicensed or unfit land (EPA Victoria, 2012). It is a prolific disposal method, whether individually (tossing trash out of a window while driving down the highway) or on a large scale by industries (Nelson, 2007). Globally, there are different forms of disposal and management of solid wastes depending on the development of each country. For instance, according to Commonwealth of Australia (1996) urban areas of Australia and New Zealand have adequate sewerage systems and waste disposal services but in recent years they have come under strain especially in the largest cities. In the case of Sao Paulo in Brazil, % of the garbage collected was disposed off in sanitary landfills, 32 % in controlled landfills and 30 % in open dumps (Gouveia and Ruscitto do Prado, 2010). In Western Europe, 66 % of municipal wastes went to landfills, 18 % was incinerated, 9 % was recycled, 6 % was composted and 1 % was treated in other ways (OECD, 1997). In some countries of West Asia, up to 50 % of waste generated is left uncollected; in their urban areas, disposal of waste is by open dumping and burning. In some Gulf Co-operation Council (GCC) countries, however, waste collection and sanitary landfills are highly efficient (Kanbour, 1997). In Latin America, 35 % of their wastes went to sanitary landfills while 25 % went to semi-uncontrolled landfills (PAHO, 1995). In North Africa, at least 20 % and as much as 80 % of urban solid wastes are disposed off by dumping in open spaces. Nigerian cities and towns are still facing waste handling disposal problems which are due to improper waste management. In Nigeria, dumping in open spaces is the most common form of waste disposal, uncontrolled burning and disposal in surface water bodies. There are some states that have pieces of land designated as legal or controlled dumpsites or sanitary landfills. Waste disposal in Ibadan involves direct dumping into water bodies, uncontrolled burning and disposal unto designated dumpsites or sanitary landfills. 1.5 Solid waste contamination of soil, surface water and groundwater 1.5.1 Soil Soil is a complex mixture of eroded rock, mineral nutrients, decaying organic matter, water, air, and billions of organic living organisms, most of them microscopic decomposers (Miller,1999). It is the major receiving medium of solid wastes. According to Marshal et al. (1996), the soil has traditionally been an important medium for organic waste disposal. The excessive input of unsorted municipal household wastes may likely lead to changes in soil physical and chemical characteristics and this can distort interrelationships among biophysical and chemical soil functions which may also lead to loading nitrates and heavy metals in soil and groundwater (Anikwe and Nwobodo, 2002). Soil pollution also arises when wastes are being leached from landfills and the most common pollutants are metals such as mercury, cadmium, copper, lead, etc (Raman and Narayanan, 2008). The potential effects of soil pollution are as follows: 1) Release of contaminants to the land surface, groundwater or surface water. 2) Uptake of contaminants by plants. 3) Direct contact by humans with contaminated soil. 4) Inhalation of dust particles or volatile substances. 5) Fire or explosion of landfill gases. 6) Corrosion of underground pipelines and other building components. 7) Generation of hazardous and secondary waste streams. 8) Conflict with proposed land use. 1.5.2 Surface water Water pollution is the undesirable change in physical, chemical and biological characteristics in the water bodies which may cause harmful effects on human and aquatic life (Tian et al., 2012). The function of the source quality, the nature of the physical, chemical and biological properties of contaminants and the re-aeration capacity of a system is the capacity of the surface water environment to assimilate contaminants and pollution (Olaniyan et al., 2009). Surface water is usually rain water that collects in surface water bodies, like oceans, lakes or streams, and also groundwater that discharges to the surface from springs (Surface Water Contamination Superfund USEPA. mht). It may also be referred to as water on the surface of the planet such as in a stream, river, lake, wetland, or ocean (http://imnh.isu.edu/digitalatlas/hydr/concepts/surfhyd/srfwtr.htm). Sources of water pollution are generally grouped into two categories based on their origin. These are point sources and non-point sources.Get Complete Materials