Chapter One
INTRODUCTION
1.1 Overview
2
1.2 Aims and Objectives
3
1.3 Organisation of Thesis
5
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1.1 Overview
Since the 19th century, development in Singapore has resulted in the loss
of a rich natural environment. Where dense jungle once blanketed Singapore,
with tropical rainforests covering 82% of the island, mangroves 13% and
freshwater swamps 5% (Lu et al, 2005), today, Singapore is considered to be
100% urbanised (UNPD, 2008). While there are still green spaces in Singapore,
over the past 190 years, 95% of the native rainforest in Singapore has been
cleared (Castelletta et al, 2000). This has made protecting the last 5% of primary
forests in Singapore crucial.
Being one of the last remaining patches of primary forest on the island,
and the oldest forest reserve in Singapore, Bukit Timah Nature Reserve (BTNR)
“has survived against all odds to become a major source of scientific research,
educational field trips and recreational enjoyment” (Waller, 2001: 133). Being only
8km from the city centre, surrounded by roads, including the eight lane Bukit
Timah Expressway, and mere minutes walk away from several shopping centres,
the urban pressure on the nature reserve is plain to see (Corlett, 1988). While,
there is no risk that the reserve will be cleared for development (Lum and Sharpe,
1996), the reserve still faces many threats, including the isolation of the forest
and the high pedestrian traffic within (Corlett, 1995a).
In recent years, the National Parks Board (NParks), the government body
that manages the reserve, is concerned that the Central Catchments Nature
Reserve (containing BTNR) is becoming more affected by anthropogenic
acidification. With domestic air pollution present, anthropogenic air pollution
travelling into Singapore from the region already high, and pollution to increase
as Southeast Asia (SEA) continues to industrialise, this issue is rising in
importance.
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Acidification brings with it a myriad of impacts, related not just to a direct
lowering of pH levels in an ecosystem, but to the changes in the biogeochemical
cycling of trace metals and nutrients caused by acid deposition. This includes
affecting vegetation growth and a loss of species biodiversity. BTNR, being a
primary forest, is particularly important. The acidification of BTNR is already
suspected as a cause for the decline of Johora Singaporensis, an endemic
freshwater crab species which lives within the forest streams.
As such, in 2005, a stream-water chemistry monitoring programme was
established in BTNR, located at Jungle Falls stream. This ongoing project is
examining the water quality within the reserve, to see if the wildlife within is
potentially being affected by acidification. This will then aid in the management of
the forest reserve. Unfortunately, there is a lack of historical data monitoring the
environmental changes within this stream, and thus, conditions of the stream
prior to anthropogenic pollution are unknown. Supplementing this programme,
this research plans to fill this gap in knowledge regarding the acidification history
of the stream.
1.2 Aims and objectives
The primary aim of this study is to employ paleolimnological analysis in
order to evaluate the potential acidification of Jungle Falls stream, BTNR. In order
to conduct this paleolimnological analysis, a selection of cores will be collected
from a sediment accumulation behind a brick dam at Jungle Falls stream. As
acidification issues within SEA are rising and there is currently a lack of scientific
research in the area, a secondary aim of this study is to evaluate the potential for
the use of paleolimnological indicators for acidification studies in the region and in
tropical environments in general.
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The aims are addressed through the following objectives:
1) Physical analysis of core
a. To provide a stratigraphical description of the core using the Troels-Smith
system. This would serve as a foundation for examining changing
environmental conditions within the stream.
b. To determine the organic carbon content of the core. As there should not
be significant variations in organic carbon content within the sediments,
with the environment at the reserve not changing radically over the last
century, any variation present would provide a straightforward method to
enable multiple cores to be correlated.
2) Biological analysis of core
a. To examine the diatoms present within the core. As these microscopic
algae are highly sensitive to environmental change, particularly
acidification, changes in the diatom assemblage, moving from older to
younger sediments, could be indicative of a lowering pH of the stream.
3) Geochemical analysis of core
a. To quantify the vertical distribution of sulphur, lead, zinc, sodium,
potassium, iron and manganese within the core. Sulphur, lead and zinc
concentrations within a sedimentary profile would provide an insight into
the levels and impact of atmospheric contamination into the stream.
Sodium and potassium concentrations will aid in examining whether the
concentrations of sulphur, lead and zinc are affected by changes in
erosional intensity within the catchment. Iron and manganese levels are
an indicator of whether sediment diagentic processes have an impact on
sulphur, lead and zinc profiles.
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1.3 Organisation of Thesis
This thesis is divided into seven chapters. In this chapter, a general
background of the research is given, along with the aims and objectives of this
study. Following that, in chapter two, the issue of acid deposition is discussed,
looking at its history, causes and impacts. It concludes by examining future
trends of acid deposition in Asia. It is shown that acidification research within Asia
is lacking and the problem is intensifying, making this study of the acidification of
a tropical stream in Singapore highly pertinent. Chapter three discusses the
difficulties faced by acidification researchers due to a lack of historical monitoring
data and finding a suitable study site. This shortage of historical data has made
paleolimnological analysis crucial in acidification research. It is, however, difficult
to find a study site which is undisturbed and contains a record with the required
time span and resolution, particularly in the tropics where there are fewer lakes
than in temperate areas. Chapter three then examines the paleolimnological
techniques employed in acidification research, looking at the rationale behind the
techniques and providing examples of how they are applied.
Chapter four is a background of the study site, combining the issues
examined in chapter two and three into a Singaporean context. Information
regarding the acidification problem in Singapore is provided, along with a
description of BTNR and Jungle Falls stream within it. This elucidates why Jungle
Falls stream is an ideal location for a study of acidification. Moving on to the
primary data collection, chapter five details the methodology conducted in this
study. Chapter six is a description and analysis of the results, demonstrating that
there are signs of acidification within Jungle Falls stream. Chapter seven
summarises this research and evaluates the contribution of this study to wider
acidification studies within the region. Lastly, possible research extensions are
suggested.
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... 190 years, 95% of the native rainforest in Singapore has been cleared (Castelletta et al, 2000) This has made protecting the last 5% of primary forests in Singapore crucial Being one of the last... combining the issues examined in chapter two and three into a Singaporean context Information regarding the acidification problem in Singapore is provided, along with a description of BTNR and. .. historical monitoring data and finding a suitable study site This shortage of historical data has made paleolimnological analysis crucial in acidification research It is, however, difficult to find a