Ten years' hydrological investigations at Danum have provided strong evidence of the effects of extremes of drought, as in the April 1992 El Niño southern oscillation event, and flood, as in January 1996. The 1.5 km2 undisturbed forest control catchment experienced a complete drying out of the stream for the whole 1.5 km of defined channel above the gauging station in 1992, but concentrated surface flow along every declivity from within a few metres of the catchment divide after the exceptional rains of 19 January 1996. Under these natural conditions, erosion is episodic. Sediment is discharged in pulses caused by storm events, collapse of debris dams and occasional landslips. Disturbance by logging accentuates this irregular regime. In the first few months following disturbance, a wave of sediment is moved by each storm, but over subsequent years, rare events scour sediment from bare areas, gullies and channel deposits. The spatial distribution of sediment sources changes with time after logging, as bare areas on slopes are revegetated and small gullies are filled with debris. Extreme storm events, as in January 1996, cause logging roads to collapse, with landslides leading to surges of sediment into channels, reactivating the pulsed sediment delivery by every storm that happened immediately after logging. These effects are not dampened out with increasing catchment scale. Even the 721 km2 Sungai Segama has a sediment yield regime dominated by extreme events, the sediment yield in that single day on 19 January 1996 exceeding the annual sediment load in several previous years. In a large disturbed catchment, such road failures and logging-activity-induced mass movements increase the mud and silt in floodwaters affecting settlements downstream. Management systems require long-term sediment reduction strategies. This implies careful road design and good water movement regulation and erosion control throughout the logging process.
This reconnaissance study of radon concentrations in the Great Cave of Niah in Sarawak shows that in relatively deep pits and trenches in surficial deposits largely covered by protective shelters with poor ventilation, excavators are working in a micro-environment in which radon concentrations at the ground surface can exceed those of the surrounding area by a factor of > x 2. Although radon concentrations in this famous cave are low by world standards (alpha track-etch results ranging from 100 to 3075 Bq m(-3)), they still may pose a health risk to both excavators (personal dosemeter readings varied from 0.368 to 0.857 mSv for 60 days of work) and cave occupants (1 yr exposure at 15 h per day with an average radon level of 608 Bq m(-3) giving a dose of 26.42 mSv). The data here presented also demonstrate that there is considerable local variation in radon levels in such environments as these.
Ocean sediments give information on the paleoclimatic evolution in the geological past which gives detailed information on both the age of the sediments and both paleoceanographic and paleoclimatic conditions during sedimentation. One possible way to date sediments is with 210Pb method which can be used to date sediments up to 100 years. In this study, two core samples labelled as JB15 and JB17 were collected using pledging corer, analysed and measured for the activity of 209Po and 210Po using the alpha spectrometer. Applying the methods, average sedimentation rates for JB15 and JB17 were calculated as 0.38 cmyr-1 and 0.43 cmyr-1, respectively. Assuming that the sedimentation rate values are accurate, this might imply that the sediments at the depth of 30 cm were deposited 70 years ago.
Identification of a possible source of engineering geological hazard in the limestone area such as cavities, sinkholes and an underground cavern have become necessity for site investigation before any construction of roads, bridges and buildings are carried out. The study is also necessary for tunneling and underground mining works where knowledge of the engineering properties of the rock mass is very important in order to assess the suitability and safety of a proposed building. Geophysical techniques have been widely used in engineering geological study to deal with such problems that normally arise at construction sites with limestone bedrock. In this study, shallow seismic reflection technique and dipole-dipole geoelectrical methods were used to detect the presence of cavity in lime stone area of Batu Cave, Kuala Lumpur. The exact location and depth of cavities in the area were determined from the existing borehole data and report provided by the Geological Survey Department of Malaysia. Based on the borehole data, several cavities that were filled-up with water and fine silt are encountered at depths of 15.7m to 17.8m, 20.2m to 21.1m and 21.4m to 25.7m. Three shallow seismic reflection profiles were established on the cavity area and the results show that the cavities in the limestone occur in the form of 20 to 30m long subterranean channel of 15 to 30 m depth. Dipole-dipole resistivity survey conducted on seismic lines one and three also indicates the presence of the channel and cavities in the limestone.
Pengecaman punca bencana geologi kejuruteraan di kawasan batu kapur seperti lohong batu kapur, kewujudan lubang benam dan gua-gua batu kapur telah menjadi amat penting dalam penyiasatan tapak sebelum sesuatu pembinaan seperti jalan raya, jambatan dan bangunan dilakukan. Begitu juga dalam kerja-kerja penerowongan dan perlombongan, pengetahuan asas sifat kejuruteraan jasad batuan amat perlu diketahui untuk menitai kesesuaian dan keselamatan bangunan yang bakal dibina. Teknik geofizik telah digunakan secara meluas dalam kajian geologi kejuruteraan untuk menangani masalah yang terdapat di tapak-tapak binaan yang mempunyai batu kapur sebagai batuan dasar. Dalam kajian ini teknik seismos pantulan cetek dan kaedah geoelektrik dwikutub-dwikutub telah digunakan untuk mengesan rongga batu kapur yang terdapat di kawasan Batu Caves, Kuala Lumpur. Kedudukan dan kedalaman rongga batu kapur di kawasan kajian telah ditentukan melalui data lubang gerudi dan laporan yang diperoleh daripada Jabatan Kajibumi Malaysia. Berdasarkan data lubang gerudi tersebut terdapat beberapa rongga yang terisi air dan pasir halus berlodak di kedalaman 15.7 m hingga 17.8 m, 20.2 m hingga 21.1 m dan 21.4 m hingga 25.7 m. Tiga profil seismos pantulan cetek telah dibuat di kawasan berongga tersebut dan hasil survei menunjukkan rongga dalam batu kapur tersebut membentuk palung sepanjang hampir 20 - 30 m pada kedalaman antara 15 m hingga 30 m. Rentisan survei geoelektrik dwikutub yang dilakukan pada profil seismos satu dan tiga juga memperlihatkan kehadiran lohong dan palung dalam batu kapur tersebut.
An extensive study was conducted to determine the activity concentrations of natural and artificial radionuclides 226Ra, 232Th, 40K, and 137Cs in soil samples of each governate of Jordan. A total of 370 samples have been measured using a high-purity germanium detector. The activity concentration for 226Ra, 232Th, 40K, and 137Cs has mean values of 42 ± 3, 23 ± 3, 309 ± 21, and 3.7 ± 0.9 Bq kg-1, respectively. The highest mean activity concentration for 226Ra was found to be 138 ± 4 Bq kg-1 in the Alkarak governate. In the Ajloun and Jarash governates, the highest mean activity concentration was 35 ± 3 Bq kg-1 for 232Th, and 14.2 ± 1.9 Bq kg-1 for 137Cs, respectively. Geological influence on the activity concentrations was investigated using the one-way analysis of variance (ANOVA) and independent samples. The ANOVA results indicate that there are strong significant differences between the activity concentrations of 232Th, 40K, and 137Cs based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to 226Ra activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg-1, and 0.266, respectively.
A statistical prediction of terrestrial gamma radiation dose rate has been performed, covering the Kota Tinggi district of Peninsular Malaysia. The prediction has been based on geological features and soil types. The purpose of this study is to provide a methodology to statistically predict the gamma radiation dose rate with minimum surveying in an area. Results of statistical predictions using the hypothesis test were compared with the actual dose rate obtained by measurements.
The analysis of the spatial data has been carried out in many disciplines such as demography, meteorology, geology and remote sensing. The spatial data modelling is important because it recognizes the phenomenon of spatial correlation in field experiments. Three main categories of the spatial models, namely, the simultaneous autoregressive (SAR) models (Whittle, 1954), the conditional autoregressive (CAR) models (Bartlett, 1971), and the moving average (MA) models (Haining, 1978) have been studied. Whittle (1954) presented a form of bilateral autoregressive (AR) models, whereas Basu and Reinsel (1993) considered the first-order autoregressive moving average (ARMA) model of the quadrant type. Awang, N. and Mahendran Shitan (2003) presented the second-order ARMA model, and established some explicit stationary conditions for the model. When fitting the spatial models and making prediction, it is assumed that, the properties of the process would not change with sites. Properties like stationarities have to be assumed, and for this reason, it was therefore imperative that the researchers had made certain that the process was stationary. This could be achieved by providing the explicit stationarity conditions for the model. The explicit conditions, for a stationary representation of the second-order spatial unilateral ARMA model denoted as ARMA(2,1;2,1), have been established (Awang, N. and Mahendran Shitan, 2003) and in this paper, some explicit conditions are established for a stationary representation of the second-order spatial unilateral ARMA model, denoted as ARMA(2,2;2,2).
A total of 20 landfills are located in State of Selangor, Malaysia. This includes the Ampar Tenang landfill site, which was closed on 26 January 2010. It was reported that the landfill has been upgraded to a level I type of sanitary classification. However, the dumpsite area is not being covered according to the classification. In addition, municipal solid waste was dumped directly on top of the unlined natural alluvium formation. This does not only contaminate surface and subsurface soils, but also initiates the potential risk of groundwater pollution. Based on previous studies, the Ampar Tenang soil has been proven to no longer be capable of preventing pollution migration. In this study, metal concentrations of soil samples up to 30 m depth were analyzed based on statistical analysis. It is very significant because research of this type has not been carried out before. The subsurface soils were significantly polluted by arsenic (As), lead (Pb), iron (Fe), copper (Cu) and aluminium (Al). As and Pb exceeded the safe limit values of 5.90 mg/kg and 31.00 mg/kg, respectively, based on Provincial Sediment Quality Guidelines for Metals and the Interim Sediment Quality Values. Furthermore, only Cu concentrations showed a significantly decreasing trend with increasing depth. Most metals were found on clay-type soils based on the cluster analysis method. Moreover, the analysis also differentiates two clusters: cluster I-Pb, As, zinc, Cu, manganese, calcium, sodium, magnesium, potassium and Fe; cluster II-Al. Different clustering may suggest a different contamination source of metals.
Rainfall-runoff information is critical for water resource and river basin management. Runoff can be estimated by using two methods; gauged method (direct measurement) and ungauged method (indirect formula and equation). The in-situ measurement provides real-time and accurate yet required time-consuming operation and inaccessibility topography. Therefore, the runoff estimation modelling and equation was developed to overcome the limitation of in-situ measurement. SCS-CN is a simple model of ungauged method, where runoff volume (Q) resulting from rainfall (P) is formulated using equation of (Q= (P-Ia) 2 / (P-Ia + S). It was known as the best technique to be adopted for large basin study where time and manpower also accessibility are limited. SCS-CN method also is widely use in prediction software as it taken into consideration of the effects of soil, properties, land cover and antecedent moisture. Curve Number is well developed in USA for the agriculture purpose with many investigations to validate and calibrate the values of curve number. It was applied in numerous river basins in temperate and other regions e.g. US, Argentina, India, China, South Korea, Palestine and Malaysia. However, the reliability of the CN in the tropics is doubtable due to different land use characteristics, soil type, climate, geological features and rainfall pattern and variability. Based on the reviewed conceptual and applications of SCS-CN in temperate and tropics, numerous studies found the SCS-CN method is reliable and practical for runoff estimation in tropics region.
An appraisal of the regional reconnaissance geophysical, geochemical and geological data obtained under the Central Belt Project in 1977 – 1978 appeared to constitute favourable uranium exploration targets. Follow-up surveys conducted until the year 1990 have proposed the exploration area to be divided into three transects. Transect 1 covers the western part of the state of Kelantan, northwest Pahang and the eastern half of Perak. Transect 2 covers southeastern tip of Perak, west Pahang, eastern half of Wilayah Persekutuan, eastern portion of Selangor, and the northwest portion of Negeri Sembilan. Transect 3 covers central Kelantan, northwestern of Terengganu and northern portion of Pahang. Results of the study indicate that the Main Range, Bujang Melaka, and Bukit Tinggi Plutons are most fertile with uranium spectrometric rock values range from 13 to 25 ppm. Further investigations to zero down the target areas for uranium mineralization are strongly recommended over these areas.
Detailed geophysical investigations have been carried out using integrated geophysical methods with a view to characterising the subsurface lithologic features that might indicate suitable places for structural developments. An overview of the subsurface resistivity distribution has been achieved employing 8Vertical Electrical Soundings with the Schlumberger array and 4 2D resistivity imaging using Wenner array. In order to constrain the results of the electrical resistivity methods, we carried out a ground magnetic survey along E-W direction using the Proton precession magnetometer at 1m sampling interval. Analysis of well logs data available and VES results showed 4 to 5 geoelectric layers corresponding to sand, clayey sand, clay, silty sand and sandy clay. The 2D resistivity imaging sections showed relative decrease of apparent resistivity with depth implying a geological transition from sand with high resistivity value of about 508Ωm to clay with low resistivity value 16Ωm at depths of 0-20m and 25-50m respectively. The magnetic profiles showed that the study area was characterised by short wavelengths and amplitudes ranging from –3800 to 700 nT. The highs and lows of the magnetic responses occasioned by lithological variations and structural features were magnetically resolved. In view of the identified subsurface structures, the suggested depth to the competent layer is about 20m for low to medium structures while above 50m would be suitable for heavy or massive engineering structures. The use of integrated geophysical methods for the delineation, identification and imaging of the subsurface geological structures which could provide clues to the nature and type of foundation suitable for the development of the study area has been successfully achieved.
The Bukit Lagong area is the most important aggregate supply centre in Selangor. Geological studies were carried out in four quarries in the Bukit Lagong area and samples were subjected to petrographic examination and accelerated expansion tests to assess the potential alkali-aggregate reactivity of granite aggregates. The granitic rocks comprise mainly of coarse grained megacrystic granite, minor medium grained megacrystic granite and microgranite. Petrographic examination showed that the primary minerals in these undeformed granitic rocks are not alkali reactive. Faulting and related alteration and mineralization have produced potentially alkali reactive minerals including microcrystalline and strained quartz and fine phyllosilicates. Marginally deleterious and deleterious expansion is shown by the accelerated mortar bar tests. Although alkali reactive rocks are present in some quarries in Bukit Lagong, their volume is small. When blended with the undeformed granitic rocks, the aggregates produced are not expected to cause alkali-aggregate reaction in concrete.
The new Genting Sempah tunnel represents an important part of the widening and upgrading of the main east-west road link between Kuala Lumpur on the west coast and Kuantan on the east coast of Peninsular Malaysia. The new tunnel is located between 18m to 30m north of the existing (old) tunnel which was constructed in 1975 and has a similar alignment. Engineering geological investigations and site characterization for the construction of the new tunnel were carried out in 1994 with drilling, aerial photograph interpretation, surface geological mapping, geophysical surveys and laboratory testing. Rock mass classification was carried out based on the Q classification system of Barton et at. (1974). Based on this classification, it was predicted that for the tunnel zone, 8.6 % of the length of the tunnel consisted of rock mass classified as very poor i.e. type two, 82.8% as extremely poor, i.e. type three and the remaining 8.6% as exceptionally poor, i.e. type four. Excavation of the tunnel between March 1995 and September 1996 together with engineering geological logging and rock mass classification revealed the following; type two, very poor 6.3%, type three, extremely poor 89.9%, type four, exceptionally poor 3.8%. These results show the general validity of the prediction of the rock mass quality.
Terowong kedua Genting Sempah merupakan suatu bahagian utama dalam pembesaran dan peningkatan taraf jalan timur-barat utama yang menghubungi Kuala Lumpur di pantai barat dan Kuantan di pantai timur Semenanjung Malaysia. Terowong kedua berkedudukan 18 m hingga 30 m ke utara terowong lama yang dibina pada tahun 1975 dan mempunyai penjajaran yang sama. Penyiasatan geologi kejuruteraan dan pemeriksaan tapak pembinaan terowong kedua dilaksanakan pada tahun 1994 dengan penggerudian, pentafsiran fotograf udara, pemetaan geologi permukaan, survei geofizik dan ujian makmal. Pengelasan kualiti jasad batuan dilakukan berdasarkan sistem pengelasan Q oleh Barton et al. (1974). Hasil pengelasan ini di zon terowong meramalkan 8.6% panjang terowong baru terdiri daripada jasad batuan berkualiti sangat rendah, iaitu jenis dua, 82.8% berkualiti tersangat rendah, iaitu jenis tiga manakala 8.6% panjang terowong terdiri daripada jasad batuan berkualiti luarbiasa rendah, iaitu jenis empat. Penggalian terowong di antara Mac 1995 dan September 1996 dengan rakaman geologi kejuruteraan dan pengelasan jasad batuan semasa penggalian menghasilkan keputusan seperti berikut; jenis dua, berkualiti sangat rendah 6.3%, jenis tiga, berkualiti tersangat rendah 89.9%, jenis empat, berkualiti luar biasa rendah 3.8%. Keputusan
The origin of formation water salinity variation in Chang 9 stratum, Jiyuan oilfield, Ordos basin is studied here. 91 formation water samples show that water salinity is characterized by a wide range and a complex plane distribution. In order to find out the main cause of such distribution complexity and reveal the relationship between formation water and evolution of reservoir traps, core data, chemical analysis result of formation water and log data are analyzed from perspectives of diagenesis and tectonism. And then, their characteristics are presented as the followings. In high salinity area, tuffaceous mudstone interlayer is found growing. Besides, the condition of Na++K+ is opposite to that of Ca2+, for its rate of concentration increase slows down with total salinity accumulating. In low salinity area, while, with fracture and faults developing, some formation water of CaCl2 type turns into MgCl2, NaHCO3 or Na2SO4 type. The cause is thus proposed to be composed of two aspects. One covers tuff alteration and later diagenesis for the high salinity. To be specific, montmorillonite, developed from tuff alteration, absorbs cation selectively and then ions migrate, during which more Na++K+ get lost, while more Ca2+ reserved. Afterwards, those reserved Ca2+ get released with montmorillonite transforming to illite, which results in a loss of Na++K+ and accumulation of Ca2+. Lots of ions are released into formation water during that process and later diagenetic process, which leads to the high water salinity. The other aspect is the development of faults and fractures, through which, the upper low salinity formation water gets connected. And that is the main cause of low salinity. At last, geological significance is discussed from two angles. Firstly, tuff alteration and later diagenesis are pivotal to reservoir reconstruction; and secondly, faults and fractures play an important role in oil transportation and storage.
According to the basic rules and characteristics of the gold-polymetallic deposits of Beiya gold mine area in terms of mineralization and ore controlling, it is concluded that skarn deposit is the main ore deposit type in this area and the geological conditions are analyzed by the statistics of the physical parameters. Then, the tectonic, rocks, stratum, ore geophysical models have been treated by the forward modeling numerical simulation and the results are analyzed comprehensively. Based on the forward modeling results, combined with the relevant physical differences, the principle and exploration method test and research for the comprehensive geophysical exploration technology has been carried out, covering the induced polarization and magnetic prospecting for the ore body as well as the indirect geophysical exploration method by means of plane gravity data, audio-magnetotelluric sounding for rock mass and tectonics, the mineralization mode-physical forward modeling - geophysical exploration mode has been established and good results have been achieved. Therefore, a location forecast method has been put forward for the concealed skarn type Fe-Au deposit which is adaptive to the mineralized geological background of Beiya and other similar areas.
Borneo has gone through dramatic changes in geology and topography from the early Eocene until the early Pliocene and experienced climatic cycling during the Pleistocene. However, how these changes have shaped the present-day patterns of high diversity and complex distribution are still poorly understood. In this study, we use integrative approaches by estimating phylogenetic relationships, divergence time, and current and past niche suitability for the Bornean endemic land snail genus Everettia to provide additional insight into the evolutionary history of this genus in northern Borneo in the light of the geological vicariance events and climatic fluctuations in the Pleistocene. Our results show that northern Borneo Everettia species belong to two deeply divergent lineages: one contains the species that inhabit high elevation at the central mountain range, while the other contains lowland species. Species diversification in these lineages has taken place before the Pliocene. Climate changes during the Pleistocene did not play a significant role in species diversification but could have shaped contemporary species distribution patterns. Our results also show that the species-rich highland habitats have acted as interglacial refugia for highland species. This study of a relatively sedentary invertebrate supports and enhances the growing understanding of the evolutionary history of Borneo. Species diversification in Everettia is caused by geological vicariance events between the early Miocene and the Pliocene, and the distribution patterns were subsequently determined by climatic fluctuations in the Pleistocene.
Many residential areas of Kuala Lumpur are susceptible to landslides; this is seen in the frequency of landslide occurences in these areas. The objective of this study is to delineate landslide risk areas in support of development planning, monitoring and control of unstable areas. In this study, five landslide causative factors were extracted from satellite imagery and maps provided by the Geological Survey Department of Malaysia. Factors included in the study including land use, river density and lineament derived from Landsat ETM image, precipitation amount from rain gauge stations and lithology, were extracted from the geological map of the study area. Layers were analyzed and divided into subclasses. An average weightage score was applied to calculate the subclasses into percentage weights of influence on landslide. Overlay, geo-processing and geo-statistic techniques in GIS were used to discriminate these weighted subclasses into landslide susceptibility at low, medium and high levels of risk areas. Results showed very high susceptible areas covering 0.21% of Kuala Lumpur of which 5.02% were found in the highly urbanized areas. Meanwhile, a landslide susceptibility map was generated to show low, medium and high susceptible areas in Kuala Lumpur. Results were verified using recorded cases of landslides in Kuala Lumpur which showed a 77% agreement with the study.
This study was carried out on the hilly topographic area in Kundasang, Sabah. This area is known to be extremely prone to landslides that occurred either naturally or by human interference to natural slopes. Aerial photographs interpretation was conducted in order to identify landslide distributions across three assessment years (2012, 2009 and 1984). These datasets were classified into two landslides groups based on their occurrences; natural and artificial. A total of 362 naturally occurring landslides were identified and another 133 are artificial slope landslides. Physical parameters which include lithology, slope angle, slope aspect and soil series were analyzed with each landslide group to examine the different influence of these parameters on each of the group. From the analysis, the landslide density for the natural landslide group shows that more than 35° slope angle and slope aspect facing east and southwest are prone to landslides. In terms of geological materials, high landslide density is recorded in the phyllite, shale, siltstone and sandstone lithologies group and the Pinosuk, Kepayan and Trusmadi soil series. In contrast, for the artificial
slope landslide, high landslide density is observed in the 25°-35° slope angle and similar density in every slope aspect classes. The geological materials however have similar landslide density across their factors’ classes. The landslide density technique was also used to generate the landslide susceptibility maps for both landslide conditions. Validation of the maps shows acceptable accuracy of 71% and 74%, respectively, for both natural and artificial slope landslide susceptibility maps and this shows that these maps can be used for future land use planning.
Investigations of land management impacts on hydrology are well developed in South-East Asia, having been greatly extended by national organizations in the last two decades. Regional collaborative efforts, such as the ASEAN-US watershed programme, have helped develop skills and long-running monitoring programmes. Work in different countries is significant for particular aspects: the powerful effects of both cyclones and landsliding in Taiwan, the significance of lahars in Java, of small-scale agriculture in Thailand and plantation establishment in Malaysia. Different aid programmes have contributed specialist knowledge such as British work on reservoir sedimentation, Dutch, Swedish and British work on softwood plantations and US work in hill-tribe agriculture. Much has been achieved through individual university research projects, including PhD and MSc theses. The net result is that for most countries there is now good information on changes in the rainfall-run-off relationship due to forest disturbance or conversion, some information on the impacts on sediment delivery and erosion of hillslopes, but relatively little about the dynamics and magnitude of nutrient losses. Improvements have been made in the ability to model the consequences of forest conversion and of selective logging and exciting prospects exist for the development of better predictions of transfer of water from the hillslopes to the stream channels using techniques such as multilevel modelling. Understanding of the processes involved has advanced through the detailed monitoring made possible at permanent field stations such as that at Danum Valley, Sabah.
In a reconnaisance soil geochemical and plant survey undertaken to study the heavy metal uptake by major food crops in Malaysia, 241 soils were analysed for cation exchange capacity (CEC), organic carbon (C), pH, electrical conductivity (EC) and available phosphorus (P) using appropriate procedures. These soils were also analysed for arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) using aqua regia digestion, together with 180 plant samples using nitric acid digestion. Regression analysis between the edible plant part and aqua regia soluble soil As, Cd, Cr, Cu, Hg, Ni, Pb and Zn concentrations sampled throughout Peninsular Malaysia, indicated a positive relationship for Pb in all the plants sampled in the survey (R2 = 0.195, p < 0.001), for Ni in corn (R2 = 0.649, p < 0.005), for Cu in chili (R2 = 0.344, p < 0.010) and for Zn in chili (R2 = 0.501, p < 0.001). Principal component analysis of the soil data suggested that concentrations of Co, Ni, Pb and Zn were strongly correlated with concentrations of Al and Fe, which is suggestive of evidence of background variations due to changes in soil mineralogy. Thus the evidence for widespread contamination of soils by these elements through agricultural activities is not strong. Chromium was correlated with soil pH and EC, Na, S, and Ca while Hg was not correlated with any of these components, suggesting diffuse pollution by aerial deposition. However As, Cd, Cu were strongly associated with organic matter and available and aqua regia soluble soil P, which we attribute to inputs in agricultural fertilisers and soil organic amendments (e.g. manures, composts).