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Comparative study of activities of Sawmilling Industry on the Environment of two selected locations within Southern Nigeria

Masterarbeit 2011 100 Seiten

VWL - Umweltökonomie










1.1 Statement of the problem
1.2 Justification of the study
1.3 Objectives

2.1 The Nigerian environment
2.1.1 Danger due the environment
2.1.2 Threats to the marine environment
2.2 Utilization of forest resources
2.2.1 Wood processing technology and waste generation
2.2.2 Environmental degradation due to utilization of forest wood resources Wood allergens Noise pollution Surface water recipient of large quantities of waste Air quality Wood utilization impact on the soil
2.3 History of sawmills

3.1 Study area
3.2. Waste measurements
3.2.1 Waste generated
3.2.2 Analysis of sawmilling waste
3.2.3 Data Analysis
3.3 Environmental impact assessment
3.3.1 Determination of water quality Water quality analysis
3.3.2 Noise survey Chainsaw operating conditions Sound pressure level measurement Analysis of noise pollution
3.3.3. Air quality
3.3.4 Soil sampling Soil analysis Data analysis for soil

4.1 Log parameters and waste
4.1.1 Total waste
4.1.2 Types of sawmilling waste
4.1.3 Bark volume
4.1.4 Sawdust
4.1.5. Kerfs and basics of saw blade selection
4.2. Noise quality
4.4 Air quality

5.1 Environmental justice
5.2 Effective use of residual by industries
5.3 Noise control
5.4 Sustainable management of water resources
5.4.1 Commercial use of the coastline
5.5 Need for further research and development
5.6 A sustainable Nigerian environment


Acronyms and definition of some terms


Dedicated to “LIFE”, My Grandparents Chief and Mrs. James Alaga Inah who sacrificed all to sustain my choice, setting up the standard I strive to reach and making sure I never gave up.

Importantly, ALMIGHTY GOD who gave me “LIFE”, power and the ability to generate out light of Literacy.


This Thesis would not have been completed without the mercy and blessings of GOD. Words cannot express my appreciation to the following persons for all their loving kindness and tolerance.

I commend my major supervisor; Professor Grace C. U. Onuoha, late Professor A. E. Akachuku and the head of department Dr. Michael C. Dike, for their human nature and mastery of patience, which induced their endurance during this research study. I remain ever appreciative of their financial assistance, academic and moral advice in my academic endeavour. Most grateful to Dr. (Mrs) Caroline Akachuku my academic Mother whose LOVE and courage kept me going even in the midst of great turbulences.

My profound and sincere heartfelt gratitude goes to Abi Local Government Council, the Cross River State Government and Senator Victor Ndoma-Egba who awarded me Bursary and Scholarship to complete the programme. I am also greatly indebted to the Executive Governor of Cross River State, His Excellency Senator Dr. Liyel Imoke, his friends and Family, Professor Ivara Ejemot Esu, Elder Bolaji Anani Commissioner Revenue Mobilization and Fiscal Commission – Abuja for their financial support.

I am also grateful to the entire staff of the Nigerian Institute for Oceanography and Marine Research, Victoria Island, Lagos, Nigerian Institute of Meteorology Ikeja, Lagos, GA JUM International Limited Warri Office for logistics.

Finally, I remain ever grateful to the unflinching support of members of my family, namely my mother, Madam Juliana Lily Alaga, and my siblings Pastor Hephzibah Kenieka, Nzamelefa, Felicia and John. I marvel at their support. My sincere thanks go to my daughter Princess-Liyel Chinyere and her mother Affiong Theresa; the entire staff and students of Michael Okpara University of Agriculture Umudike, I wonder my plight if they had refused me. I pray that GOD in HIS infinite mercies would reward them quite abundantly.


Table 2.1.Common Wood Allergens

Table 2.2 OSHA- Permissible noise exposures for an 8-hr work day

Table 2.3 Major Categories of water Pollutants

Table 3.1 Analytical methods used

Table 4.1 Parameters of logs Sawn in Nigerian Sawmills

Table 4.2 Output of Sample Saw mills

Table 4.3 The wood species sawn in Nigerian sawmills used for this study

Table 4.4 Dust properties

Table 4.5 Showing Noise Measurement

Table 4.6 Summary estimates, expressed as RR5 dB(A), for the association between noise exposure, hypertension, and ischemic heart diseases, adjusted for sex and age

Table 4.7 Physicochemical parameters of the study stations of Benin River at Sapele from August 2008 -April 2009 (Minimum and maximum values in parentheses) Values are; Mean ± S.E

Table 4.8 Shows Atmosphere Gaseous content part per million by volume ppmv(µL/L)

Table 4.9 U.S National Ambient Air Quality Standards (NAAQS) (Cunningham et al, 2007)

Table 4.10 The fractions of modified BCR sequential extraction (Mossop and Davidson, 2003)

Table 4.11 The chemical and physical properties of the sampled soils

Table 4.12 Pseudototal, Easily Mobilise able for the land use groups defined

Table 4.13 The toxicity of major metals in polluted soils


Fig. 4.1 Log volume

Fig. 4.2 Log form

Fig. 4.3 Showing position for Chain saw noise measurement

Fig. 4.4 Graph on noise pollution

Fig. 4.5 Rainfall

Fig. 4.6 Relative Humidity

Fig. 4.7 Box showing priority of sub-cell selection within the sampling cell

Fig. 4.8 Fractionation of the metals by means of BCR sequential extraction, 100% indicates the ∑ of step 1-4 of the sequential extraction. The concentrations are expressed in mg/kg


Plate 4.1 Sawn timber transportation along the mangroves swamps

Plate 4.2 Taking measurements to determine Form factor

Plate 4.3 Measurements at a chainsaw site during the study

Plate 4.4 Residual of sawmill waste unutilized for other products

Plate 4.5 Form factor determination and total waste generated

Plate 4.6 Total waste determination at a chainsaw site in the forest during the study

Plate 4.7 Sawdust collection point

Plate 4.8 A Freud industrial blades with red Teflon coating

Plate 4.9 Log rafts from Delta Region at Oke Baba, Ebute-Metta Market

Plate 4.10 Impact of wood extractives on water body

Plate 4.11 Showing air pollution caused by smoke during coal production using sawmill waste


This work examines the comparative study of activities of Sawmilling Industry on the Environment of two selected locations within Southern Nigeria, Lagos and Delta States between August 2008 and September 2009. The primary data were collected through oral interview and field experiments. While secondary data were from printed materials. The focus has been to compare the various waste generated, its uses and environmental impact on the two locations. Experiments were conducted in the rainy and dry season for the comparative study. The study has been divided into three main areas: volume of waste generated and various uses, effect of type of chain-saw machine used, and impact of sawmilling activities on the environment of the two locations. A natural logarithm transformation of the data was used for some datasets to satisfy assumption of normality and variance homogeneity, means and standard error were back transformed for presentation, specific treatment pairs were compared using a t-test. The study result was as follows; Total Solid Waste (TSW) ranged from 22.5 to 65.5%. In logs that (i) have high form factor (ii) are straight and (iii) are sound, TSW decreased as log volume increased; the value of r2 was 60%. Results shows that out of a total waste of 40% bark volume contributed 3.7%, sawdust 12.2%, while the remaining components contribute 24.0% in both locations, showing no significant difference in the rainy and dry season. The effect type of chain-saw machine has great significant difference in Sapele compared to Lagos, showing a result of r2 =60% for Sapele and r2 = 40% for Lagos. The environmental impact case study: the water quality variables, conductivity, dissolved oxygen; BOD5, Nitrate-nitrogen, phosphate-phosphorus and Transparency were significantly different (P< 0.05) among the stations. Orthogonal comparison using Duncan’s multiple range test showed that station 2 (the impacted site) was the cause of the difference. Water pollution is very high in Lagos compared to Sapele due to the high volume of logs and waste emptied into the lagoon. The data analysis for air quality measured nitric oxide (NO), ammonia (NH3), methane (CH4), hydrogen sulphide (H2S), nitrogen dioxide (NO2), total nitrogen oxide (NOx), sulphur dioxide (SO2), particulate matter (PM10) and ozone (O3) recorded at Lagos urban, and Sapele showed higher volume concentration in Lagos compared to Sapele. The sea-land breeze recirculation provided O3level increase. The formation of the convergence zone in low wind speed allowed pollutants accumulation. Ozone did not show a simple positive correlation with NOxemissions, suggesting the diffusion of air masses of different photochemical age to the study sites. The background ozone, PM10and SO2peaks recorded in the rural sites during the sea-land breeze days lagged behind those measured in the urban area. Noise level showed high values of above 90 decibels over an 8 hour work period. The human bioaccessible content was estimated taking into account the relationships between pseudototal content and selected soil parameters. For the case, the prediction of human bioaccessibility based on pseudototal content, organic matter and soil texture produced statistically significant models, with r2 = 0.62 for Cu, r2 = 0.55 for Pb and r2 = 0.44 for Zn. The primary data results showed significant difference in Lagos compared to Sapele indicating a negative correlation between the context and flow of environmental assessment. A major barrier to environmental assessment is instability in governance and continuous changes in policies or non implementations of well tailored policies.



It is quite obvious that as long as man continues to use resources, wastes are inevitable. According to Woodwell (1970) “everything modern man touches turns to waste product sooner or later”. And when wastes accumulate beyond a certain limit, it becomes impossible for natural processes in the ecosystems to harbour them. In this regard, it becomes a nuisance and can even be toxic.

It is now common knowledge that human activities tend to upset the balance, harmony and interdependence of the whole environment. As noted by Gregersen et al (1995), it is crucial for policy makers, interest groups and the public to obtain reliable information on the environmental, social and financial values of the forests in order to move towards optimum use and conservation of forests.

The most critical negative environmental impact of the activities of forest industries that requires urgent attention is the destruction of forest cover. Over the years, much exploitation of the forest has been carried out in order to meet the increasing demand of the teeming population. This has resulted in serious depletion of the resource base to the extent that some favoured timber species have become drastically reduced in number while others have become extinct in certain ecological zones. Geomatics (1998), reported that the land area occupied by high forest in Nigeria decreased by 11,254km2 between 1976 and 1995, while the land areas occupied by savannah decreased by 90,593km2 during the same period.

The huge oil production, Educational development, Information quart, Industrialization, sophisticated life styles of Nigerians; have dramatically increased the number of industries that make use of wood products as major raw materials. Nigeria has different grades of wood and wood products; these include: fuel wood, poles, lumber, pulp and paper and wood based panels.

Sawmilling is one of the principal forest industries that engage in the processing and the efficient utilization of the timbers, a producer of semi finished intermediate goods for other sectors. Pollution of water ways by organic discharges in Nigeria is perhaps a serious threat posed to the Nigerian inland waters. Sources of pollution of the inland waters of Nigeria are well known. The most notable point source arises from the dumping of untreated or partially treated sewage into the River (Adakole and Anunne, 2003), Wood shavings and leachates are source of inert solid as well as toxic pollutants that directly clog fish gills and lethal to lower aquatic forms (FAO, 1991) and indirectly reduced light penetration which limits productivity, contamination of the aquatic environment, makes aquatic organisms vulnerable. All these are the consequence of sawmill discharging its wastes into the water bodies.), discharge of bio-degradable wood wastes from sawmill located along the lagoon (Nwankwo et al., 1994; Nwankwo, 1998).

Wastes are rejected, superfluous, unused materials put away by the industries, if not properly disposed of, results in pollution which courses change in air, water and soil quality.

The resultant effects on the environment are enormous and include:

1). Nuisance and aesthetic insult.
2). Property damage
3). Disruption of natural life support systems at local regions and global levels.
4). Damage to human health, plants and animal life.

The Forestry Advisory Commission of the Western State of Nigeria (Akachuku, 2000), classified wood waste into unavoidable and avoidable waste. Unavoidable waste cannot be prevented even where the kerfs’ is small and the mill workers are efficient. This includes sawdust, inconvertible slabs and strips. Avoidable waste is caused by lack of:

1). Pre-inspection of logs
2). Saw maintenance; and sub-standard lumber which is inaccurately processed because of faults in the circular re-saw machine.

The proportion of waste varies accordingly in the wood base industries, and most of the wastes have economic value. Efficient log conversion techniques should be practiced in order to improve lumber recovery and reduce the demand for round logs. The establishment of integrated wood industries should be encouraged. Value added products such as particle boards and wood briquettes may be produced from industrial wood residue (Fuwape, 2001). This will improve the efficiency of wood utilization, reduce the demand for round log and reduce the destruction of forest cover.

Water is essential for life on earth. Within organisms, water provides the medium within which the complex metabolic processes necessary for life take place. Organisms simply cannot function without water and if deprived will rapidly die. In addition the water must be clean. Human beings, the most complex of organisms, are affected by the most subtle variations in water chemistry and supply. Mankind has been polluting water since the early days of civilization. This is because they have been attracted to live by river environments where there is a continuous supply of water for drinking and farming activities. Much of the waste is degraded by microbes in the water through a natural process called self purification. When populations are large and excessive amount of waste are produced which end up in the water supplies, the natural process of self-purification cannot keep pace with the input of pollutants, so the water quality rapidly deteriorates (Pickering and Owen, 1995). In Australia, the third largest tourist attraction in the country, Sydney’s Bondi Beach, is unsafe for bathing on two out of every five days because of the deposit of raw sewage and industrial waste (Beder, 1990).

The solution of any problem including deterioration of urban environment demands first the understanding of its nature (Akintola, 1978). Various scholars have attempted to define the causes of the environmental deterioration in cities of the third world. Abraham (1970) thinks of these problems in terms of poor housing conditions and squatter settlement, resulting in human environmental pollution. In Nigeria, only recently has serious efforts been made to respond to the various problems of environmental pollution through the creation of Federal Ministry of Environment and State Ministry of Environment In regions with large existing population, Hines (1974), argued that vital land and water resources can be endangered or seriously damaged if waste disposal and land use decisions made, fail to account for the existence of certain pollution hazards. These hazards are basically a function of several interacting factors.

1. The type, location and emission characteristics of pollution sources
2. The proximity and sensitivity of land and water resources to these pollution sources.
3. The existence of one or several critical physical condition that may affect the generation transportation and distribution of pollutant in the environment.

Smoke contributes to acute respiratory infections that cause an estimated 4 million deaths annually among infants and children according to Sule (2001).

In many ways man in the developed world has made his urban environment more habitable in the past few years than his contemporaries in the countries of the developing world

Over population in the urban areas and industrialization have contributed in various ways to the general deterioration by pollution of the environment from where man derives his livelihood.

The most crucial problem facing solution is the question of management research; it is essential and more operational to approach wood waste disposal mechanism in a scientific way.

1.1 Statement of the problem

The most critical environmental impact of the activities of wood based industries that require urgent attention is the destruction of forest cover.

The darkening of the lagoon near its bank by the sawdust thrown into it and the solution of some of the multi-coloured extractives of the sawdust from many tree species, reduces the rate of photosynthesis carried out by chlorophyll – bearing plants, including planktonic algae.

Wood extractives are toxic and this is the reason why their presence in the wood protects it from insect, fungal and bacterial attacks.

When lagoon is severely polluted, the environment within stinks and is unsuitable for human occupation. However, the locality in densely populated areas which ought to be a resort and centre for tourism has become an eyesore and a serious health hazard. Waste water and burning wood waste in several locations have caused contamination and poor visibility.

1.2 Justification of the study

It has become imperative for massive environmental improvement and management for sustainable conservation.

The ever increasing technological growth ;being evolved by man, and Nigeria being the most populated black country in the World, generally calls for effort to accelerate good environmental culture. More so constraints impending environmental improvement and maintenance, if identified and addressed would assist Nigerians to improve on environmental cleanliness.

1.3 Objectives

The objectives of this study were therefore to determine:

1. Volume of waste generated and various uses by sawmilling industries in different geographical locations
2. Effect of type of chain-saw machine used.
3. Impact of sawmilling activities on the environment of Oke-Baba, Lagos and Sapele in Delta State
4. Make useful recommendation at the end of the research.

The findings of this study will provide an insight into the cost and benefit of environmental management especially in Nigeria. Also, it will provide useful information to the environmental policy makers.



2.1 The Nigerian environment

Liveability is a general concept based on people’s response to the question “Do you like living here, or would you rather live somewhere else?” Crime, pollution, recreational, cultural and professional opportunities, as well as many other social and environmental factors, are summed up in the subjective answer to that question. The key to having a liveable city is to provide heterogeneity of residences, businesses, stores and to keep layouts on human dimensions so that people can meet and conduct business incidentally over coffee in a sidewalk cafe. According to Gore (1992), for civilization as a whole, the faith that is so essential to restore the balance now missing in our relationship to the earth is the faith that we do have a future and work to achieve it and preserve it, or we can whirl blindly on, behaving as if one day there will be no children to inherit our legacy. The choice is ours; the earth is in the balance

2.1.1 Danger due the environment

The Lagos State Governor, Mr. Babatunde Fashola; his Ondo State counterpart, Dr. Olusegun Agagu; and other stakeholders on Thursday January 8,2009; raised the alarm over the increasing danger to the environment due to access to technology and resources. They also called for urgent steps by government and other stakeholders to combat the myriad environmental problems currently facing the country. Agagu, who was the guest speaker at the seventh Chief S.L Edu memorial lecture, which took place at the Nigerian Institute for International Affairs in Lagos, said the country’s physical environment was characterised by a combination of natural features, which made it uniquely susceptible and highly fragile. The event was organised by the Nigerian Conservation Foundation in collaboration with Chevron Nigeria Limited. While presenting the lecture titled, Threats to the Nigerian Environment -A call for Practical Action, Agagu listed other factors that made the threat more realistic as man-made threats arising from population growth, exploitation for firewood, petroleum exploration, uncontrolled logging, open cast mining and depreciating environment. As a concrete step towards addressing the environmental threat, he said urgent steps must be taken to review, update, re-enact and vigorously enforce enabling law on environmental compliance (Affe, 2009).

2.1.2 Threats to the marine environment

Previously, little was known about ocean currents carrying pollution from faraway countries to Nigeria coast or about the fact that discharges of hazardous chemicals on other continents could be transported all the way to Svalbard (Quammen, 2003). Only in the past ten years or so did it become clear that pollution poses a serious threat not only to national rivers, lakes and coastal areas, but also to the environment of the high seas.

2.2 Utilization of forest resources

2.2.1 Wood processing technology and waste generation

The FAO (2006) reports that Nigeria has about 11.0 million hectares of forest, which is 12% of the total land area, but largely savannah woodland with limited commercial potential except for the highly destructive production of charcoal. Forest reserves total 9.6 million hectares, but 75% of this is located in the savannah zone and only 2.0 million hectares in the high forest zone (FAO, 2003).Artisanal sawing which was initially confined to the forest zones around large towns is now expanding into the remote areas of the forest; this sector produces income and employment of labourers and despite the danger posed, it is more completely beyond the control of the forestry administration. Adam et al. (2007) identified four main categories of workers involved in milling operations: tree fellers, porters, tree scouts and loading boys. In general, the size of the operation gangs ranged from six to nine. With the exception of the tree feller and porters, who may be migrants, most of the workers were hired locally. Marfo et al., (2009) observed that it was not entirely accurate to suggest that sawmillers had failed to supply timber products; the issue has often been the quality of timber, as most sawmill supplies are so-called “rejects.”

According to Pulki (1989), waste in this activity result from crude method, felling and bucking technique. Illegal felling activities are carried out in the night, conversion of wood into lumbers are horridly done in most cases, the number of planks that could be extracted out of the forest is more paramount to them than the volume recovery from logs (Adebagbo, 1992). Waste generation starts right from the forests. Crooked logs, off-cuts, large branches and saw-dust are abandoned in the forests. In the factories, wastes are generated in the form of slabs; saw-dust and half-processed materials, the various stages of conversion of the wood from our forests are associated with the generation of substantial amount of waste as currently seen, as a problem which starts right from the forests (Onosode, 1988). For instance, FAO (1990), observed that less than two-thirds of harvested trees are finally taken away from the forest for further processing. The mechanical processing of wood in sawmills and ply mills in this country has also been found to be associated with considerable amount of wood residue generation in form of trimmings, off-cuts, peelers, slabs and saw dust (Fabiyi and Oyagade, 2003).

It was observed by Badejo (2001) that about only 50-55% of the original wood brought to these mechanical processing industries end up as marketable portion while as much as 45-50% ends up as waste. This situation is unacceptable both from the efficient and sustainable utilization of resources’ point of view.

2.2.2 Environmental degradation due to utilization of forest wood resources

In this age of globalisation, there are enormous challenges one of which is environmental degradation in alarming proportion (Lemmers, 2002). It is of varying degree and emanated from environmental mismanagement due to combination of non-challant attitude of people to environmental conservation as well as general effects of economic recession. Over logging has led to the phenomenon of desertification of the Sahel, sahelization of the savannah and savanization of the forest (Anon, 1994). At the current rate, the entire Northern part of Nigeria is at risk of losing its natural vegetation to desertification within the next 120years if urgent steps are not taken to stop desertification within the region (Achellenu, 2003). Gmelina arborea, which has now become the most popular plantation species in the country, was introduced from Sri Lanka in 1932. After independence in 1960, emphasis was shifted to forest exploitation for industrial development and increased foreign exchange earnings. This requirement accentuated the unregulated exploitation of the forest resources. In 1954 the country was divided into three administrative regions, each with its own forestry service. Each region enjoyed territorial power over its forest resources and was equally responsible for monitoring and supervising the activities of the native authority. The Federal Government, however, retained the aspects of forestry research and education. As more states were created, the authority over the forest resources was transferred to the state governments (FAO, 2003).

Wood shavings and leachates are sources of inert solids as well as toxic pollutants that directly clog fish gills (FAO 1991), and indirectly reduce light penetration which limits productivity. Contamination of the aquatic environment, makes aquatic organisms vulnerable (FAO 1991), fish immune system in particular are weakened leading to increased incidence of parasites.

Manufacturing operations that produce raw wood, such as sawmill, paper mills and furniture manufacturers are the major source of pollution in the Nigeria water ways. Others include Agricultural and domestic wastes which find their ways into the river body (Vega et al., 1996). These wastes often contain significant spectrum of organic substances capable of producing adverse effects on the physical, chemical and biotic environment and indirectly affect human health (FAO 1991).

The Sapele section of Benin River in Delta State, Nigeria is a typical example of a stream receiving wood wastes from sawmill industries. There is clear scientific evidence that if improperly managed, wood residue can negatively impact the environment, contaminate and destroy fish habitat. Wood residue leachate is produced when water percolates, or flows, through wood residue; storing wood waste in pits where it has contact with groundwater creates another source of leachate (FAO 1991).

Typically, pure wood residue leachate is a black liquid with petroleum like odour that causes foaming water. Wood residue decomposition is a slow process that can result in decades of leachate production of substances found naturally in wood, such as resin acids, lignins, terpenes, fatty acids and tannins, dissolved from these concentrations. In fact, the leachate can smother spawning ground areas, decreasing fish variety and abundance (FAO, 1991). Wood allergens

Carbide Processors Incorporated reports of three hundred and seventy three 373 woods known to cause health problems. Exposure to any wood dust can cause health problems. Whether they affect someone and how badly the problems are depends on the amount of exposure and the body chemistry of the individual. Many of these are sensitizers and the health problems may not show up until a certain amount of exposure. Many of these have different common names and the scientific descriptions are somewhat imprecise especially at the retail level.

Besides these, and many other woods, there can be grave health risks in glue, epoxies, finishes and similar used in wood working. Anything that is used as a liquid and dries to a solid has a solvent that evaporates. These solvents are volatile to extremely volatile and can have very serious health effects. Table 2.1 shows common wood allergen.

Table 2.1.Common Wood Allergens

illustration not visible in this excerpt

Source: Carbide Processors, Inc; /wood-allergens.htm Noise pollution

Noise pollution is the presence of noise in the environment that is offensive or harmful to the human ear and that interferes with the normal enjoyment of life and of the environment. Sounds of high frequency are more annoying and potentially more damaging than low frequency sounds. The principal factor in noise that causes damage is the noise intensity which is measured in decibel (dB) (Bellamy, 2007). The word noise comes from the Latin word noxia meaning "injury" or "hurt".

The sources of most noise worldwide are transportation systems, motor vehicle noise, but also include aircraft noise and rail noise (Hogan and Latshaw, 1973; US Senate, 1972). Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential area. Other sources are car alarms, office equipment, factory machinery, construction work, grounds keeping equipment, barking dogs, appliances, power tools, lighting hum, audio entertainment systems, loudspeakers and noisy people.

Human health effects

Effect of noise on health are both health and behavioural in nature. The unwanted sound is called noise. This unwanted sound can damage physiological and psychological health. Noise pollution can cause annoyance and aggression, hypertension, high stress levels, tinnitus, hearing loss, sleep disturbances, and other harmful effects (Rosen et al 1965 and Field, 1993).Furthermore, stress and hypertension are the leading causes to health problems, whereas tinnitus can lead to forgetfulness, severe depression and at times panic attacks (Field, 1993; Kryter, 1985)

Chronic exposure to noise may cause noise-induced hearing loss. Older males exposed to significant occupational noise demonstrate significantly reduced hearing sensitivity than their non-exposed peers, though differences in hearing sensitivity decrease with time and the two groups are indistinguishable by age seventy-nine (Rosenhall, et al., 1990). A comparison of Maaban tribesmen, who were insignificantly exposed to transportation or industrial noise, to a typical U.S. population showed that chronic exposure to moderately high levels of environmental noise contribute to hearing loss (Rosen and Olin, 1965).

Table 2.2 OSHA- Permissible noise exposures for an 8-hr work day

illustration not visible in this excerpt

Source: 29 CFR 1910.95

High noise levels can contribute to cardiovascular effects and exposure to moderately high levels during a single eight hour period causes a statistical rise in blood pressure of five to ten points and an increase in stress (Rosen and Olin, 1965), and vasoconstriction leading to the increased blood pressure noted above as well as to increased incidence of coronary artery disease.

Noise pollution is also a cause of annoyance. A 2005 study by Spanish researchers found that in urban areas households are willing to pay approximately four Euros per decibel per year for noise reduction (Jesús, et al., 2005)

Noise can have a detrimental effect on animals by causing stress, increasing risk of mortality by changing the delicate balance in predator/prey detection and avoidance, and by interfering with their use of sounds in communication especially in relation to reproduction and in navigation. Acoustic overexposure can lead to temporary or permanent loss of hearing; an impact of noise on animal life is the reduction of usable habitat that noisy areas may cause, which in the case of endangered species may be part of the path to extinction. One of the best known cases of damage caused by noise pollution is the death of certain species of beach whales, brought on by the loud sound of military sonar (Balcomb, 2003).

European Robins living in urban environments are more likely to sing at night in places with high levels of noise pollution during the day, suggesting that they sing at night because it is quieter, and their message can propagate through the environment more clearly (Fuller et al., 2007). Interestingly, the same study showed that daytime noise was a stronger predictor of nocturnal singing than night-time light pollution, to which the phenomenon is often attributed.

Zebra finches become less faithful to their partners when exposed to traffic noise. This could alter a population's evolutionary trajectory by selecting traits, sapping resources normally devoted to other activities and thus lead to profound genetic and evolutionary consequences (Milius, 2007). Loss of hearing due to noise pollution is known as sociocosis. Table 2.2 shows occupational safety and health administration permissible noise exposures for an eight hour work day.

Table 2.3 Major Categories of water Pollutants

illustration not visible in this excerpt Surface water recipient of large quantities of waste

Table 2.3 shows examples of major categories of water pollutants. Surface waters (rivers, lakes, and seas) are sources of water for household, agricultural, and industrial uses. As such, they are also the recipient of large quantities of industrial, agricultural, and domestic waste, including municipal sewage. Contamination of surface waters, containing known and unknown compounds, could pose serious public health and aquatic ecosystem threat (White and Rasmussen, 1998, Ohe et al., 2004 and De’Moraes et al., 2007). Heavy contamination of the Songhua River is due to industrial waste water and domestic sewage. In a previous study (Jin et al., 1998), 138 organic compounds were detected in the Songhua River by gas chromatography/mass spectrometry (GC/MS). Of these compounds, polycyclic aromatic hydrocarbons (PAHs) were the most prevalent, followed by nitrobenzene and phenylamine, phenols, phenolic acids, and esters. A total of 44 of 138 (31.9%) organic compounds were the priority pollutants of US Environmental Protection Agency (EPA). Zhang (2002) reported that 185 organic compounds were detected by GC/MS in water samples taken from the Songhua River. In these compounds, 27.0% were aromatic compounds, 16.8% were diolefine compounds, 16.2% were PAHs, and 40% were other compounds. Of the total number of 185 organic compounds, 45 (24.3%) organic compounds possess genotoxicity and 18 organic compounds belong to the priority pollutants of the EPA. An epidemiological investigation indicated that the organic contamination in the Songhua River was a risk factor for tumour development among the residents who lived along the Songhua River (Zhu et al., 1985). These contamination sources were either partially treated or untreated discharges from chemical industries, petrochemicals industries, oil refineries, oil spills, rolling steel mills, untreated domestic sludges and pesticides runoff. These studies demonstrated that these environmental mixtures contained many toxicants which may have carcinogenic potential.

Dissolved organic matter (DOM) in natural waters is one of the most dynamic reservoirs of organic carbon in the carbon cycle with the amount in the lakes and oceans estimated to be equal to the CO2content of the atmosphere (Hansell and Carlson 2001). Aquatic photochemistry of the absorbing portion of DOM (Chromophoric Dissolved Organic Matter, CDOM) has been studied for more than 25 years and the interest in this area continues to be strong (Mopper et al., 1991; Nelson et al., 1998; Whitehead et al., 2000; Twardowski and Donaghay 2001; Goldstone et al., 2002; Stedmon et al.,. 2007a; Murphy et al., 2008). The interest in dissolved organic matter results from several aspects of its chemistry:

1. As a major absorber of sunlight in natural waters;
2. Is widely thought to be the source of reactive oxygen species in natural waters;
3. May also serve as a source of carbon and other nutrients in aquatic systems,
4. Is extremely important in water treatment.

Yet we know very little about the structure and reactivity of this heterogeneous carbon ‘polymer’ and almost nothing about the fundamental chemical reactions. The photolysis of CDOM results in numerous reactive species, the most widely studied are those known as reactive oxygen species: singlet oxygen (O2), superoxide ion radical, (O·22), hydroxyl radical paper to review these in detail (see for example, Cooper and Zika 1983; Cooper et al., 1988,1989; Cooper and Zepp 1990; Shao et al., 1994; Vaughan and Blough 1998; Andrews et al., 2000; Thomas-Smith and Bough 2001; Blough and Sulzberger 2003; Wang et al., 2007). Recent studies have focussed on the contribution of black carbon (BC) and soil organic matter (SOM) to the partitioning of persistent organic pollutants (POPs) in soils, sediments, and atmospherically transported particles, and their environmental longevity (e.g. Beyer et al., 2000; Persson et al., 2002; Meijer et al., 2003; Bucheli et al., 2004; Burgess and Lohmann, 2004; Cornelissen and Gustafsson, 2004, 2005; Lohmann et al., 2005). POP is a generic term, encompassing several families of compounds. They have certain features in common; they are persistent in the environment, have low aqueous solubilities and high affinities for lipids and organic matter. Indeed, their partitioning to OM strongly contributes to their environmental persistence. Many POPs are also ‘semi-volatile’ under ambient temperatures and may exist in the vapour phase in the atmosphere. They may be subject to long-range atmospheric transport (LRAT) and undergo repeated air–surface exchange (‘hopping’), so that they may reach remote environmental compartments/sinks over time (Wania and Mackay, 1993; Beyer et al., 2000; Klecka et al., 2000; Meijer et al., 2003; Sweetman et al., 2005). For example, POPs includes the polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and some organochlorine (OC) pesticides. Related chemical classes include the polybrominated diphenyl ethers (PBDEs) and the polycyclic aromatic hydrocarbons (PAHs). Different POPs have different sources into the environment. Some have been intentionally produced (e.g. the PCBs and PBDEs), others have been deliberately released into the environment (OC pesticides). Others are formed and released accidentally during incomplete combustion, such as the PCDD/Fs and PAHs. Some may be either accidentally formed or incidentally released from various combustion processes (co-PCBs, PCBs and PBDEs). Some POPs may therefore enter the environment as an atmospheric emission associated with BC, from a range of incomplete combustion processes. Examples include: natural (e.g. forest) fires, domestic burning of coal or wood, accidental fires, ‘trash’ or ‘backyard burning’ and vehicle exhausts. Several of these have been implicated as sources for PCDD/Fs (Sakai et al., 1993; Yasuhara et al., 2003). There is also evidence that BC can be an important component of the atmospheric aerosol, capable of influencing POPs partitioning and transport (Ribes et al., 2003; Bucheli et al., 2004; Lohmann and Lammel, 2004; Cornelissen and Gustafsson, 2005). BC is typically a few percent of the atmospheric aerosol burden; it constitutes several hundred ng/m3 in air in rural locations and several thousand ng/m3 in urban centres (Lohmann and Lammel, 2004). POPs sources may be numerous, diverse and with uncertainties over their relative contribution. For example, hexachlorobenzene (HCB) is a pesticide, an industrial chemical and intermediate, and a combustion by product, as well as being re-volatilised from environmental surfaces, but it is rather unclear which source dominates (Barber et al., 2005) There are also uncertainties over whether the environmental occurrence of co-PCBs are primarily caused by accidental formation during combustion (Sakai et al., 1993; Yasuhara et al., 2003), volatilization from technical PCB mixtures containing traces of co-PCBs (Breivik et al., 2002b; Takasuga et al., 2006) or incidental combustion of such mixtures (Breivik et al., 2002a,b). International regulations are restricting production and emissions of POPs (UNECE, 1979; UNEP, 2001). Soils are important to the global cycle of POPs; they receive POPs via atmospheric deposition or direct applications and have substantial storage capacity for POPs, which is a function of their OM content/type. A series of articles draws attention to the role of background soils (i.e. those in rural/remote areas and receiving only atmospheric deposition) in global POPs budgets and air–surface exchange and the influence of SOM on these processes (Meijer et al., 2002, 2003; Hassanin et al., 2004; Nam et al., 2008). Atmospheric N deposition increased dramatically during the second half of the 20th century, at scales ranging from highly localized to regional or even global (Galloway et al., 1995; Erisman et al., 2003). Air quality

Due to the high population density and intensive industries, anthropogenic Nitrogen (N) emissions from cities have inevitably become prominent sources for elevated regional N pollution, which influences the air quality of cities and poses threats to surrounding ecosystems (Jung et al., 1997; Cowling et al., 1998; Krupa, 2003). Therefore, it is important to identify the sources and behaviour of urban-derived atmospheric N pollutants, which is of great value for reducing urban N release and protecting the environment around cities. However, atmospheric N deposition includes a wide range of gaseous compounds, aerosols and particulates, which has made it very difficult and expensive to undertake long-term instrumental monitoring and simultaneous measurements (Solga et al., 2005; Pitcairn et al., 2006). Therefore, information of N deposition variation around cities is really rare. On the regional scale, the daytime sea breeze and the night time land breeze circulations caused by the differences in thermal properties of land and water surfaces limit the diffusion of an air mass by recirculation of contaminants (Bouchlaghem et al., 2007); Helena et al., (2006); Viana et al., (2005); Puygrenier et al., (2005); Pérez et al., (2004); Gangoiti et al., 2001); Kassomenos et al., (1998); Ziomass, (1998) and Millan et al., (1996).

On the local scale, the fumigation of elevated plumes into the thermal boundary layer can trap pollutants and lead to an increase of ground level concentrations (Luhar and Hurley, 2004)). To better understand these processes, Ma and Lyons (2003) showed that if there is no strong synoptic forcing, the diurnal heating and cooling differences between the land and sea will determine the local wind circulations which affect the transport and diffusion of emission from surface sources. They proved that nocturnal emissions are swept out to sea by the land breeze only to be brought back over the land by the developed sea breeze leading to pollution episode. Ziomass (1998) study shows that the Mediterranean coastal areas are often characterised by significant photochemical air pollution episodes due to the intense solar radiation with local air pollution sources. Ozone is one of the most important pollutants in these Mediterranean areas as a consequence of the typical photochemical air pollution and dynamics of the Mediterranean regions (Millan et al., 1996).

The World Health Organisation estimates that some 5 to 6 million people die prematurely every year from illnesses related to air pollution; Heart attacks, respiratory diseases, and lung cancer are significantly higher in people who breathe dirty air, compared to matching groups in cleaner environments (Cunningham et al., 2007).

The most common route of exposure to air pollutants is by inhalation, but direct absorption through the skin or contamination of food and water also are important pathways. Because they are strong oxidizing agents, sulphates, SO2, NOx, and O3act as irritants that damage delicate tissues in the eyes and respiratory passages. Fine particulates penetrate deep into the lungs and are irritants in their own right, as well as carrying metals and other polycyclic aromatic hydrocarbons (PAHs) on their surfaces (Davis, 2002), Inflammatory responses set in motion by these irritants impair lung function and trigger cardiovascular problems as the heart tries to compensate for lack of oxygen by pumping faster and harder.

Carbon monoxide binds to haemoglobin and decreases the ability of red blood cells to carry oxygen. Asphyxiants such as this cause headaches, dizziness, heart stress, and can even be lethal if concentrations are high enough. Lead also binds to haemoglobin and reduces oxygen-carrying capacity at high levels. At low level lead causes long-term damage to critical neurons in the brain that result in mental and physical impairment and developmental retardation (Florig, 1997). Wood utilization impact on the soil

Soil is another great natural resource. It is a combination of mineral and organic matter structurally arranged in layers, and capable of supporting plants and animal life. Soils cannot exist without plants, and plants are dependent on soils for support, air, water, and nutrients. Soils are highly variable in nature. This variation includes their structure, layering, colour, range of particle sizes, chemistry, nutrients, acidity, temperature, water content, thickness, organic content, and its associated biota. These properties vary because of differences in the parent material, climate, topography, organic content, and the amount of time it has to develop. Changes in one or more of these factors may drastically alter the soil properties, changing its nature and ability to support particular plants species. These changes can happen very easily, having profound effects on the soil and the landscape such as vegetation reduction, soil erosion, slope instability, increased flooding, and more sediment in rivers. The major changes induced by human activities include chemical changes (salinization and laterization), structural changes (compaction), hydrological changes, and soil erosion. In many ways human health is closely related to the quality of soil and especially to its degree of pollution (Bityukova et al., 2000; Li et al., 2001; Romic and Romic, 2003; Stroganova et al., 1997; Tiller, 1992). Soil can be considered a sink, but also a source of pollution with the capacity to transfer pollutants to the groundwater, into the food chain and into the human body (Birke and Rauch, 2000; Burghardt, 1994; Paterson et al., 1996). In particular, in urban and industrial areas soil influences both the quality of life and the health of people (Birke and Rauch, 2000; Burghardt, 1994; Kamp et al., 2003). Apart from the negative influences on human health, soil pollution can also cause serious economic losses (Kamp et al., 2003). Soil contamination, be it locally concentrated or diffuse, is also recognised by the European Soil Strategy (European Commission, 2006b) as one of the main threats to soil quality. Sources of pollution include traffic, industrial emissions, waste disposal, and the weathering of building structures. Local communities are becoming more and more aware of and concerned by the consequences of soil pollution for their quality of life and welfare. Also governmental and regional institutions are devoting increased attention to soil pollution problems, recognising the essential ecological functions and ecosystem services of soils in terrestrial environments (European Commission, 2006a). Initiatives have been started to limit and prevent further soil degradation and to examine applicable soil remediation methods. Metals are the most studied soil pollutants because of their ubiquity, toxicity, and persistence. They occur naturally in the environment. Some are essential for the metabolism of living organisms at low concentrations (Alloway, 1995; Kabata-Pendias and Pendias, 2001; Wong et al., 2006). Above certain concentrations, all metals have adverse effects on human health (Davydova, 2005; Merian et al., 2004; Pierzynsky et al., 2005). The health of young children, who have a higher rate of absorption, is particularly at risk (Calabrese et al., 1991; Grøn and Andersen, 2003). Being chemical elements, metals are not subject to metabolic breakdown (Alloway, 1995; Bullock and Gregory, 1991; Romic and Romic, 2003). Some metals, such as cadmium, accumulate in the human body over a long period of time so that negative effects may appear only after a long period of chronic exposure. Metals differ in their reactivity and this influences their availability in soil for uptake by organisms and transfer into the food chain (Gupta et al., 1996; Romic and Romic, 2003; Tiller, 1989). In most countries, threshold values for soil metal pollution have been issued by legislation. Usually these values are based on the amount of metals that are extracted from the soil by means of strong acid digestion. Such extractions represent the total extent of pollution. Only a fraction of the contamination, however, poses an acute risk of being taken up by biota or leaching into waters.

2.3 History of sawmills

The first ’modern’ sawmill was established in 1909 (Mackay 1946). The sawmilling industry in Nigeria is dominated by small-scale, privately owned establishments. These mills, located largely within city centre around the country, have individual production capacities of about 500 cubic metres of lumber per annum and well over 1,500 across the country (Sanwo, 1982; Fuwape 1990; Akande, 1993). They are a major employer of semi-skilled/unskilled labour and a facilitator of socio-economic development. Today, Ebute-Metta, the location of the first pit sawing in the Country, also has the largest concentration of sawmills, numbering about 200 (Olabode, 1995; Olorunisola, 1998).This accounts for 93.32% of the total number of wood based industries in Nigeria (Fuwape, 2001), fraught with the problem of low recovery rates. Recovery rates vary with local practices as well as species (FAO, 1990). The local timber resources upon which Ebute-Metta and other sawmills depend for survival have not been managed in a sustainable manner. Thus, Nigeria has suffered much deforestation like the rest of Africa and the tropical world particularly in the 1980s (Areola, 2001). As a result, the population of merchantable timbers in these forests has continued to decline. To be able to cope with the imminent difficulties in satisfying the ever-growing demand for lumber in the country, appropriate sawmilling practices which encourage high conversion efficiency and minimal waste generation, will be required. During conversion of logs, it has been estimated that the bark constitute about 12% of the residue while slabs, edgings and trimmings amount to about 34 %,saw dust is estimated to be about 12% of the log input. Further processing might take place resulting in another 8% waste (of log input) in the form of saw dust, and trim end (2%) and plainer shavings (6%) (Koopmans & Koppejan, 1997). The lumber recovery factor in most sawmills varies between 45 and 55% (Alviar, 1983; Fuwape, 1989). Badejo and Giwa (1985), gave an estimate of wood residue generated by Nigerian sawmills to be 1.72 million m3 for the year 1981 which rose to 3.87 million m3 by 1993 by Badejo, (2001) estimate. The natural forests, mainly rain-forests, which constitute just about 10 per cent of Nigeria’s total land area, are the sources of about 80 per cent of the timber needs of the Country (Ajakaiye, 2001; Akinsanmi and Akindele, 2002). The wood-based industries depend on the natural forests for the bulk of their wood raw materials. Akinsanmi and Akindele (2002) opine that although large areas of plantations exist, the natural forests are greater attraction to timber contractors due to their wide variety of species and sizes. Nevertheless, in recent times plantation forests have been churning out considerable volumes of timber to reduce the pressures on the natural forests to supply wood needs (Abayomi, 2001). This is also evident by the extensive exploitation of teak plantations in the south western parts of the country for various wood products.



3.1 Study area

The study was conducted in Southern Nigeria, situated at latitude 80 001 N, 40 001 S and longitude 20 101 E and 80 461 E; (Dada et al., 2006). The climate is of the equatorial type; the rainfall is heavy and the temperature is high and equable. The year is divided into a dry season (Dec – Feb) and a wet season (April - October) with the remaining months being transitional. The mean annual temperature is about 250 C. The mean daily maximum is about 310 C and the mean daily minimum is between 180 C and 240 C. The mean relative humidity at 9.00am is about 85% (Field Survey, 2009). Nigeria has a total population of 140,431,790; out of which Males are 71,345,488 and females 69,086,302 (FGN, 2009).

The sawmilling industries within third Mainland Bridge; Oko-Baba in Ebute-Metta region of Lagos Mainland Local government council with a population of 326,700 lies between latitude 60 341 N and longitude 30 591 E.

Sapele in Delta state with Benin River located in the coastal belt of Southern Nigeria at the Western boundary of the upper Delta and the lowlands (05o 451 – 06o 001 N, 05o 041 – 05o 421 E). This River drains the major rivers Ethiope, Ossiamo, Osse and Siluko into the Atlantic Ocean. It is approximately 93km long with average width of 3.0 and 1.4km in its downstream and upstream section respectively (Arimoro, et al, 2007).

3.2. Waste measurements

3.2.1 Waste generated

Two sample plots were demarcated at the locations of sawmilling industries at Oke – Baba, Lagos and Sapele, Delta locations, twenty logs were selected for the study in the two sites of Southern Nigeria where the sawmilling industry is well established.

3.2.2 Analysis of sawmilling waste

The conversion of 20 logs to lumber was studied to accomplish the objective of this study.

(a) The volume of each log and the volume of lumber produced from it were determined using appropriate formula of absolute form factor =V (Ag x H).

Where V =Volume of tree bark.

Ag =Cross sectional area of the log at its base.

H =Height of the log.

The volume of each log was the sum of the volume between base and Level, 0% to 100% top levels. The volumes of the sections were determined from their lengths and top base diameters.

(b) Total waste with difference between the volumes of:
(i) A log and
(ii) The lumber produced from it was expressed as a percentage of the log volume.

(c) The volume of a log converted to sawdust was computed from the width of saw kerfs and other variables.

(d) Bark volume was determined and expressed as a percentage of log volume.

(e) Form factor of each log was computed as the ratio of its volume to the volume of a cylinder with a cross – sectional area equal to that of the base of the log.

(f) Saw kerfs, that is the slit which was made on the log during sawing, was determined.

3.2.3 Data Analysis

Analysis of variance and regression analysis was computed using values of percentage waste generation after arcsine transformation of the data.

These transformations were necessary because such data have a binomial distribution and, contrary to the assumptions on which the analysis will be based, the variances are related to the means. A natural logarithm transformation of the data was used for some datasets to satisfy assumption of normality and variance homogeneity, means and standard error were back-transformed for presentation, specific treatment pairs were compared using a t-test. When means are given in the text a 95% confidence interval is given between brackets (Miller and Miller 2000) and the arcsine transformation (Snedecor and Cochran, 1967) analyzing of the water quality parameters (Magurran, 1988).



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comparative sawmilling industry environment southern nigeria




Titel: Comparative study of activities of Sawmilling Industry on the Environment of two selected locations within Southern Nigeria