EFFECTS OF ROOFING SHEETS ON HARVESTED WATER RUN OFF

ABSTRACT

Harvested water run-off from five different houses with stone coated roof were sampled in Ichida, Anambra state for the effect of the roof on the harvested water. The pH and metal content of the harvested water run-off were analyzed. The result of the analysis where compared with the World Health Organization standard. The results showed that the pH ranged from 6.4 ­– 7.2 and the concentration of the heavy metals for lead range from 0.143 –­­ 0.244, for copper 0.011– 0.066, for aluminum range from 0.00 – 0.085, for silicon range from 0.0191 – 0.748, for iron rage from 0.033 – 0.122, for zinc range from 0.323 – 0.665 and for chromium range from 0.108 – 0.213. it was observed that all the lead, silicon  content of all the 5 houses and aluminum content of house 2 and 5 were above the WHO standard, whereas others were all below the WHO standard. Harvested water run- off is hazardous to health.

CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF STUDY

Priestly in 1781 was the first to observe that the explosion of a hydrogen-and-oxygen gas mixture yields water vapour. Later, Cavendish established that the ratio by volume of hydrogen to oxygen in that reaction at constant temperature and pressure was 2:1. Water is one of the most important and abundant compounds of the ecosystem. All living organisms on the earth need water for their survival and growth. It rarely occurs in its pure form in nature (Ababio, 2005). It is the only substance that exists naturally on Earth in all three physical states of matter; gas, liquid, and solid.

Water has a number of unique chemical and physical properties that make it essential for life. Almost all liquids contract when they get colder and reach a maximum density when they solidify. As water cools, it contracts until it reaches 4°C, then it expands until it freezes at 0°C. Ice is less dense than water which allows ice cubes to float in a soft drink, icebergs to float in the ocean, and ponds and lakes to freeze from the top down so that aquatic plants and animals can survive in the unfrozen liquid below. Water molecules have a simple structure: two hydrogen atoms bonded to one oxygen atom H₂O. This simple structure is responsible for water’s unique properties. The bond between each hydrogen atom and the oxygen atom results from a pair of electrons shared between the two atoms. In water, the electrons in the shared pair are not shared equally between the hydrogen and oxygen atoms. The oxygen atom has a greater affinity for electrons than the hydrogen atom, and the electrons in the O–H bond are more attracted to oxygen. Because electrons have a negative charge, the unequal sharing in the O–H bond results in oxygen acquiring a partial negative charge (−) and hydrogen a partial positive charge (+). The H–O–H bond angle in water is 104.5°, which means that the molecule has a bent shape. This bent geometry and the accumulation of electrons on the oxygen side of the molecule cause the water molecule to have a negative charge on one side, the oxygen side, and a positive charge on the other side, the hydrogen side. Hydrogen bonding between water molecules gives water its unique properties. For example, hydrogen bonding is responsible for the lower density of ice, solid water, than of liquid water. Extension of this hydrogen bonding in three dimensions produces interconnected cages of water molecules in ice, with empty space inside the cages. When the solid melts, many of the hydrogen bonds are broken and the structure collapses, so liquid water is denser than the solid. Hydrogen bonding is also responsible for the six-fold symmetry of snowflakes, important interactions with biological molecules in living organisms, and for the unusually high boiling point, melting point, surface tension, and specific heat of water. Hydrogen bonding and the polarity of water also explain its solvent properties. (Shakhashiri, 2011).

There are various sources of water. They include rainwater, spring water, well water, river water, lake water, sea water and oceans. These are natural sources of water. Rain water is the purest form of natural water because it is formed as a result of the condensation of water vapour in the atmosphere i.e. it is a natural form of distilled water. Another type of water is treated water. This is usually prepared for special purposes. Examples include distilled water, pipe-borne water and chlorinated water for use in swimming pools.

The availability and quality of water always have an important role to play in determining not only where people can live but also their quality of life. Some of its uses include:

1. Commercial use: This includes fresh water from hotels, restaurants, office buildings etc.
2. Domestic use: This includes drinking water, water used in food preparation, bathing, washing, flushing toilets etc.
3. Industrial use: Water is used in various industrial processes such as processing, cleaning, transportation, dilution and cooling.
4. Irrigation use: This is the water artificially applied to a farm, orchard, pasture and horticultural crops in terms of agricultural activities. Nonagricultural activities include irrigation of public and private golf courses, football fields, parks etc.
5. Livestock use: This includes water for fish farms, farm animals.
6. Mining use: This includes water for the extraction of naturally occurring minerals.
7. Recreation use: It includes swimming water; waterfalls used for tourism.
8. Electricity use: Water is used in hydroelectric power generation, in nuclear power plants as a moderator.

Water to be used for human consumption must meet certain requirements. It must be free from micro organisms, low in concentration of compounds that are toxic or that have serious long term effects on health.

Rain water is an important source of fresh water. It constitute one of the largest sources of water for Nigeria, it however contains chemical compounds such as; carbon-dioxide (CO₂), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), fine particulate matter etc. in several residential areas, rain water is considered as one of the safest  and most suitable sources of drinking water. It is mainly harvested through the use of roofing sheet.

Roof tiles are designed mainly to keep out rain and are traditionally made from local available materials such as; Terracotta or slate. Modern materials such as concrete and plastic are also used. The different types of roof tiles include copper roof, aluminum roof, zinc roof, steel roof and tin roof.  A metal roof is made from metals or tiles in third century B.C copper roof shingles were installed at top the lovamahapaya temple in Sri Lanka. Roofing materials are subject to changes over time due to photo degradation via UV light from the sun, elevated temperature, moisture, and microbial growth (Berdahl et al., 2008).  Thus, since roofing materials change with age, it also is possible that the release of certain elements and compounds from a roofing material changes as the roof ages.

A stone coated metal roof is made from steel and other metals; the metal is then coated with stone chips and attached to the steel with an acrylic film. Stone coated metal roof was defined during an after world war two in the United Kingdom when the government requested materials that would protect corrugated steel roofs from the harsh climate. A coating of bitumen and subsequent covering by sand or other materials proved effective at protecting the metal roofs and serving as camouflage against potential attack. Its advantage over other roofing sheets is in its light weight, resistance to fire, resistance to wind, resistance against hail storm, resistance against snow and ice, resistance against earthquakes, energy efficient.

         Fig.1.1 Stone coated roof

1.2 AIM AND OBJECTIVES OF THE STUDY

1.2.1 AIM

The main objective of this study is to determine the effect in which heavy metals contained in stone coated roofing sheet has on harvested rain water in Ichida, Anambra state.

1.2.2 OBJECTIVES

The objectives of this study include;

1. Rain water harvested from stone coated roof tiles will be sampled.
2. Analysis of heavy metals will be carried out on the samples.
3. The result of the analysis will be compared with both local and international accepted standard.

1.3 SIGNIFICANCE OF STUDY

Absence of centralized treated water (pipe borne water) and the quest to have easily available source of water led to an increase in harvesting of rain water in Ichida, Anambra state. This has increased the health rate associated with either direct or indirect use of rain water since there is lack of bore-hole water. Hence there is a need to access the quality of the rain water harvested in this community and as well determine its portability for consumption to know whether it meets their acceptable standard for the protection of public health.

1.4 SCOPE OF STUDY

The scope of this study consists of:-

1. Collection of two samples each from five different houses with stone coated roofs for five days in Ichida, Anambra state.
2. The test to be carried out include; determination of pH and heavy metals such as; silicon, chromium, copper, lead, iron, aluminum and zinc.
3. Comparing of the result with the World Health Organization standard.

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