Characteristics and formation of rain forest soils from Quaternary basalt in Leyte, Philippines

The classical view about soils of tropical rain forest ecosystems is that these soils are old, acidic, and infertile. It is now widely acknowledged that this view which has greatly influenced research and management of the fragile rain forest ecosystem during the last several decades is largely a misconception. Although highly weathered soils (Oxisols or Ferralsols) are the most dominant soils in the humid tropics, tropical soils range from relatively young fertile soils (e.g. Inceptisols) to the highly weathered infertile soils (e..g. Oxisols). The extent of highly weathered soils is less in geologically young areas like in much of SE Asia.

More detailed investigations of rain forest soils are vital for the sustainable management of this threatened ecosystems. These could also lead to a better understanding of the response of rain forests to climate change.

Navarrete et al. (2009) recently conducted a study to evaluate the physical, chemical and mineralogical characterisitics of rain forest soils in Leyte, Philippines. Some of the important findings of that study include:

1) Soils along the catena studied showed minimal variations in their morphological, physical and chemical properties. This has important ecological implications as it tends to not support the idea that high soil spatial variability at short distances in rain forest ecosystems is a major factor for its high biodiversity.

2) The dominant soil-forming processes that produced the soils in the study area are weathering, loss of bases and acidification, desilification, ferrugination, clay formation and translocation, and structure formation. The loss of bases and acidification due to rapid leaching are shown by the low base saturation, very low exchangeable bases, acidic pH, and the low contents of total Ca, Na, Mg, and K. The degree of desilification is almost unifrom in all soils and may have reached 12-19% of that found in the parent material. Ferrugination is shown by the increased loss of bases, halloysitic and kaolinitic mineralogy, high contents of iron oxides and low base saturation. Clay formation and translocation are reflected by the high clay contents particularly in the middle part of the soil profile. Soil structure formation is exhibited by the good soil physical condition.

3) The nature of the basalt parent rock and the climatic condition prevailing in the area as well as its relief appear to be the dominant factors affecting the development of the soils.

Reference

Navarrete IA, K Tsutsuki, VB Asio, R Kondo. 2009. Characteristics and formation of rain forest soils derived from late Quaternary basaltic rocks in Leyte, Philippines. Environmental Geology 58: 1257-1268.

Lead pollution due to vehicular emissions in urban areas in the Philippines

Lead (Pb) has been known to be toxic since ancient times. It is a widespread contaminant in soils and Pb poisoning is one of the most prevalent public health problems in many parts of the world. It was the first metal to be linked with failures in reproduction. It can cross the placenta easily. It also affects the brain, causing hyperactivity and deficiency in the fine motor functions, thus, it results in damage to the brain. The nervous systems of children are especially sensitive to Pb leading to retardation. Pb is cardiotoxic and contributes to cardiomyopathy (disease of the heart muscle leading to the enlargement of the heart).

Pb is released into the environment from the weathering of Pb-containing rocks, the industry, and the combustion of fossil fuels. Emissions from vehicles are thus a major source of environmental contamination by Pb especially in cities. Ona et al. (2006) conducted a study that looked into Pb pollution in selected urban areas in the Philippines with the following objectives: (1) to determine the levels of Pb in soil from selected urbanized cities in central region of the Philippines; (2) to identify areas with soil Pb concentration values that exceed estimated natural concentrations and allow- able limits; and (3) to determine the possible sources that contribute to elevated soil Pb concentration (if any) in the study area.

The study focused on the determination of Pb levels in soils of selected cities in Luzon, Philippines. The sites included: Site 1 – Tarlac City in Tarlac; Site 2 – Cabanatuan City in Nueva Ecija; Site 3 – Malolos City in Bulacan; Site 4 – San Fernando City in Pampanga; Site 5 – Balanga City in Bataan; and Site 6 – Olongapo City in Zambales. Soil samples were collected from areas along major thoroughfares regularly tra- versed by tricycles, passenger jeepneys, cars, vans, trucks, buses, and other motor vehicles. Soil samples were collected from five sampling sites in each of the study areas. Samples from the selected sampling sites were obtained approximately 2 to 3 meters from the road. Analysis of the soil samples for Pb content was conducted using an atomic absorption spectrophotometer.

Findings revealed Pb levels ranging from 1.5 to 251 mg kg–1 in all the soil samples collected from the 30 sampling sites in the six cities. Elevated soil Pb levels i.e.greater than 25 mg kg–1 Pb) were observed in five out of the six cities sampled. Site 4 showed the highest Pb concentration (73.9 ± 94.4 mg kg–1), followed by Site 6 (56.3 ± 17.1 mg kg–1), Site 3 (52.0 ± 33.1 mg kg–1), Site 5 (39.3 ± 19.0 mg kg–1), and Site 2 (38.4 ± 33.2 mg kg–1). Soil Pb level in Site 1 (16.8 ± 12.2 mg kg–1) was within the estimated natural Pb concentration range of 5 to 25 mg kg–1. The study found that the average soil Pb concentration from the six cities studied were below the maximum tolerable limit according to World Health Organization (WHO) standards. The high Pb concentration in Site 4 was attributed by the authors mainly to vehicular emission.

The researchers concluded that "only one (San Juan in Site 4) of the thirty sampling sites showed a Pb concentration above the WHO permissible limit of 100 mg kg–1. San Juan in Site 4 had a Pb concentration of >250 mg kg–1. On the average, elevated Pb concentration was evident in the soil samples from San Fernando, Olongapo, Malolos, Balanga, and Cabanatuan. The average soil Pb concentrations in these cities exceeded the maximum estimated natural soil Pb concentration of 25 mg kg–1. Average soil Pb concentration in Site 1 (16.8 mg kg–1) was well within the estimated natural concentration range of 5 to 25 mg kg–1. Data gathered from the study areas showed that elevated levels of Pb in soil were due primarily to vehicular emissions and partly to igneous activity."

Reference
Ona LF, Alberto AMP, Prudente JA and Sigua GC. 2006. Levels of lead in urban soils from selected cities in a Central Region of the Philippines. Environ Sci & Pollut Res 13 (3) 177 – 183

The causes of the Guinsaugon landslide

On 17 February 2006, a catastrophic landslide buried the village of Guinsaugon, the second largest village of St. Bernard town (Southern Leyte, Philippines) killing more than a thousand residents and displacing approximately 19,000 people. The landslide originated on an approximately 800 m high escarpment produced by the Philippine Fault that bisects Leyte and the major islands of the Philippines. In a recent article which synthesized the papers presented during an international conference in Leyte 2008 and published in the international journal Bulletin of Engineering Geology and the Environment, Guthrie and co-workers (2009) arrived at the following conclusions:

"The approximately 15 million m3 landslide was a result of progressive failures and tectonic weakening in a region made especially vulnerable by the inter-reaction of geological/tectonic, climatic and cultural factors. In southern Leyte, geology and tectonics (including historical seismicity, the progressive disintegration of the rock mass, the development of smectite layers and the continuous development and movement of shears within the Philippine Fault Zone) combine in steep rugged terrain to produce a series of massive landslides ([10 million m3) of which the Guinsaugon event is the latest."

"The presence of rice paddies in the valley bottom had a major effect on the mobility of the rock avalanche, which increased the vulnerability of communities established to tend these fields. Having considered the available evidence, it is concluded that the landslide was not triggered by a seismic event that occurred several minutes afterward and that the recorded seismic signature was not a trace of the landslide itself. Rather, it is considered that the earthquake could be a result of tectonic unloading after the landslide occurred, or completely independent of the landslide event."

"The role of climate is, in some respects, similar to that of the seismic event. In terms of the trigger, the storm rainfall that occurred several days prior to the landslide undoubtedly raised pore water pressures in the source rock mass. However, progressive failure relies less and less on pore water pressure as failure becomes imminent. The danger of relying on triggers to ascertain the probability of failure is exemplified by the Guinsaugon event; in the lag time between the end of the period of heavy rainfall and the occurrence of the rockslide-debris avalanche, evacuated residents had returned to their homes. Possible trigger mechanisms can be incidental to the landslide itself; however, the progressive development of a large failure often produces telltale signs that are observable by a community of non-experts."


Our own field investigations have shown two important aspects of the landslide not very well taken up in the report. The first is about the role of the thin layers of mudstone in between thick layers of sandstone/siltstones which could have served as lubricant for the landsliding process. The other is the great possibility that the Guinsaugon village developed on old landslide debris. This was clearly shown by the fact that the lower hills not affected by the recent landslide showed comparable materials as the landslide area. Also, the behaviour of the stream tells us a very important information.

It is very likely that the stream was covered by landslide debris in the past which is the reason why it changed its course and appeared to go around the community. Early settlers may have found the sligthtly elevated part of the area convenient to build their houses since it was elevated (and thus not prone to flooding) but without any idea that it was a landslide debris. The tragic landslide was waiting to happen. It was just a matter of time. Unfortunately, the people were not aware of this.

The role of the paddy fields as claimed by the paper needs more scientific investigation. I am not convinced that it played a major role considering the fact that the debris itself was already saturated with water. The clayey soil material from the hillside probably had more influenced on the movement of the debris than the paddy soil.

Reference

R. H. Guthrie, S. G. Evans, S. G. Catane, M. A. H. Zarco, and R. M. Saturay Jr. 2009. The 17 February 2006 rock slide-debris avalanche at Guinsaugon Philippines: a synthesis. Bulletin of Engineering Geology and the Environment 68:201–213

The problem of high levels of nickel in soils and plants in the ultramafic area in Samar, Philippines

Contributed by Janice P. Susaya, Sejong University, Seoul, Korea


One of the heavy metals that commonly occur in elevated amounts in natural ecosystems is nickel (Ni). Ni is considered an essential micronutrient for plants, humans, and animals. It can exist in trace amounts in air, food, drinking water, and soils. Although Ni plays an important role in the metabolism of humans and animals, its intake in excesssive amounts or over a prolonged period could pose health ricsks. Studies have shown that children living in polluted areas have hypertrophy of tonsils, enlarged lymphatic nodes, and enlarged livers. There is also evidence that soluble Ni particulate is linked to acute lung injury.

High Ni levels in natural ecosystems commonly come from ultramafic rocks (also called ultrabasic rocks). These are intrusive igneous rocks containing less than 45% silica (SiO2) with high concentrations of Ni, Mg, Fe, Cr, and Co. They are found in many places around the world and are common in many places in the Philippine like in Salcedo in the island of Samar.The watershed has a highly weathered soil (Oxisol) derived from the weathering of ultramafic rock. Previous studies conducted in the watershed revealed excessive levels of Ni, Cu, and Cr in the soil. Many farmers also complain of unexplained health problems which may be related to heavy metal toxicity.

In a study conducted in the Salcedo watershed and recently published in the international scientific journal Environmental Monitoring and Assessment, Susaya and co-workers (Susaya et al., 2009) evaluated the degree of Ni contamination in soils and plants in the watershed. The plants sampled included native species (non-food) such as Phyllanthus amarus, Melastoma affine, and Stachytarpeta jamaicensis as well as cultivated food crops like Calocasia esculenta, Citrullus vulgaris, Artocarpus heterophylla, Moringa oleifera, Psidium guajava, Lycopersicon esculentum, and Solanum melongena.

Results of the study showed that the quantity of total Ni in the soil was significantly high with a mean of 1,409 mg kg-1 while the available Ni was low with a mean of 8.66 mg kg-1. As the levels of total Ni greatly exceeded the maximum allowable concentration for agricultural soils, the site is not suitable for agricultural purposes. Available Ni levels were low due to the tight binding between Ni and the soil components. This explains why all plants investigated did not met the criterion for a Ni hyperaccumulator plant. Comparison of Ni levels between the food plants sampled and its recommended daily intake (RDI) suggests that consumption of a particular food plant grown in the study area is unlikely to pose health problems. However, prolonged consumption of a given food plant with high Ni level or combined consumption of different food plants with high Ni levels can induce accumulation of Ni above the RDI and thus could cause health problems.

Reference

Susaya JP, KH Kim, VB Asio, ZS Chen, and IA Navarrete. 2009. Quantifying nickel in soils and plants in the ultramafic area in Philippines. Environmental Monitoring and Assessment (now available online at http://www.springer.com/environment/environmental+toxicology/journal/10661)

A superheavy new element is named "copernicium"

Source: Website of GSI Helmholtz Center for Heavy Ion Research, Darmstadt

Element 112 in the periodic table is named in honor of the great astronomer Nicolaus Copernicus (1473-1543). Copernicus discovered that the Earth orbits the Sun ("heliocentric theory"), thus paving the way for our modern view of the world.

The discovering team of scientists at the GSI Helmholtzzentrum für Schwerionenforschung (Center for Heavy Ion Research) in Darmstadt, Germany, led by Professor Sigurd Hofmann (photo) suggested the name „copernicium“ with the element symbol “Cp” for the new element 112. A few weeks ago, the International Union of Pure and Applied Chemistry, IUPAC, officially confirmed the discovery. In around six months, IUPAC will officially endorse the new element's name. This period is set to allow the scientific community to discuss the suggested name "copernicium" before it is finally accepted by IUPAC.

Copernicus was born 1473 in Torun and died 1543 in Frombork, Poland. His discovery that the planets circle the Sun refuted the then accepted belief that the Earth was the center of the universe (or the "geocentric theory"). This finding was pivotal for the discovery of the gravitational force, which is responsible for the motion of the planets. It also led to the conclusion that the stars are incredibly far away and the universe inconceivably large, as the size and position of the stars does not change even though the Earth is moving. Furthermore, the new world view inspired by Copernicus had an impact on the human self-concept in theology and philosophy: humankind could no longer be seen as the center of the world.

With its planets revolving around the Sun on different orbits, the solar system is also a model for other physical systems. The structure of an atom is like a microcosm: its electrons orbit the atomic nucleus like the planets orbit the Sun. Exactly 112 electrons circle the atomic nucleus in an atom of the new element “copernicium”.

Element 112 is the heaviest element in the periodic table, 277 times heavier than hydrogen. It is produced by a nuclear fusion, when bombarding zinc ions onto a lead target. As the element already decays after a split second, its existence can only be proved with the help of extremely fast and sensitive analysis methods. Twenty-one scientists from Germany, Finland, Russia and Slovakia have been involved in the experiments at GSI that led to the discovery of element 112.

Since 1981, GSI accelerator experiments have yielded the discovery of six chemical elements, which carry the atomic numbers 107 to 112. The discovering teams at GSI already named five of them: element 107 is called bohrium, element 108 hassium, element 109 meitnerium, element 110 darmstadtium, and element 111 is named roentgenium.

The goal of the scientific research conducted at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt (founded in 1969) is to understand the structure and behavior of the world that surrounds us. In addition to broadening our understanding of the world, this knowledge also serves as a basis for technological progress in all areas of our lives.

GSI operates a large, in many aspects worldwide unique accelerator facility for heavy-ion beams. Researchers from around the world use the facility for experiments that help point the way to new and fascinating discoveries in basic research. In addition, the scientists use their findings to continually develop new and impressive applications.

The research program at GSI covers a broad range of activities extending from nuclear and atomic physics to plasma and materials research to biophysics and cancer therapy. Probably the best-known results are the discovery of six new chemical elements and the development of a new type of tumor therapy using ion beams.

Heavy metals in the environment and their health effects

Heavy metals have a density of 6.0 g/cm3 or more (much higher than the average particle density of soils which is 2.65 g/cm3) and occur naturally in rocks but concentrations are frequently elevated as a result of contamination. The most important heavy metals with regard to potential hazards and occurrence in contaminated soils are: arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb) and zinc (Zn).

The sources of heavy metal pollutants are metal mining, metal smelting, metallurgical industries, and other metal-using industries, waste disposal, corrosions of metals in use, agriculture and forestry, forestry, fossil fuel combustion, and sports and leisure activities. Heavy metal contamination affects large areas worldwide. Hot spots of heavy metal pollution are located close to industrial sites, around large cities and in the vicinity of mining and smelting plants. Agriculture in these areas faces major problems due to heavy metal transfer into crops and subsequently into the food chain.

Health effects of selected heavy metals

Arsenic (As). Arsenic is well-known as a poison and a carcinogen. It has an average concentration in the soil of 5 to 6 mg/kg. Its amount in the soil is related to rock type and industrial activity.

Cadmium (Cd). Its toxicity is linked with reproduction problem because it affects sperm and reduces birth weight. It is a potential carcinogen and seems to be a causal factor in cardiovascular diseases and hypertension. Large concentrations of Cd in the soil are associated with parent material (black slates) and most are manmade (burning of fossil fuels, application of fertilizers, sewage sludge, plastic waste).

Chromium (Cr). It is required for carbohydrate and lipid metabolism and the utilization of amino acids. Its biological function is also closely associated with that of insulin and most Cr-stimulated reactions depends on insulin. However, excessive amount can cause toxicity. Toxic levels are common in soils applied with sewage sludge.

Lead (Pb). This has been known to be toxic since the 2nd century BC in Greece. It is a widespread contaminant in soils. Lead poisoning is one of the most prevalent public health problems in many parts of the world. It was the first metal to be linked with failures in reproduction. It can cross the placenta easily. It also affects the brain, causing hyperactivity and deficiency in the fine motor functions, thus, it results in damage to the brain. The nervous systems of children are especially sensitive to Pb leading to retardation. It is also cardiotoxic and contributes to cardiomyopathy (disease of the heart muscle leading to the enlargement of the heart).

Mercury (Hg). This heavy metal is toxic even at low concentrations to a wide range of organisms including humans. The organic form of mercury can be particularly toxic, and the methyl-and ethyl-forms have been the cause of several major epidemics of poisoning in humans resulting from the ingestion of contaminated food, e.g. fish. Two major epidemics in Japan were caused by the release of methyl and other mercury compounds from an industrial site followed by accumulation of the chemicals in edible fish. The poisoning became well-known as Minamata disease.

Nickel (Ni). Nickel occurs in the environment only at very low levels. Humans use nickel for many applications like the use of nickel as an ingredient of steel and other metal products. Foodstuffs have low natural content of nickel but high amounts can occur in food crops growing in polluted soils. Humans may also be exposed to nickel by inhalation, drinking water, smoking, and eating contaminated food. Uptake of high quantities of nickel can cause cancer, respiratory failure, birth defects, allergies, and heart failure (www. Lenntech.com/periodic-chart-elements/Ni-en.htm)

References

Oliver, M.A. 1997. Soil and human health: a review. European Journal of Soil Science 48: 573-592.
Puschenreiter M., O Horak, W. Friesel and W. Hartl. 2005. Low-cost agricultural measures to reduce heavy metal transfer into the food chain- a review. Plant Soil Environ 51: 1-11.
Susaya JP. 2007. MSc thesis. Institute of Tropical Ecology, Visayas State University, Baybay, Leyte, Philippines.

Environmental pollution and the safety of herbal and alternative medicinal products

There is scientific evidence that many over-the-counter health foods, neutraceuticals, and alternative medicinal products may not be safe. This was revealed in a paper written by Dr. K. Chan of Hongkong Baptist University and published in the international scientific journal Chemosphere.

The paper concluded that “the increase in popularity of such products has brought concerns and fears over the professionalism of practitioners and the quality, efficacy, and safety of their treatment methods and products from herbal and natural sources. These products maybe contaminated with excessive or banned pesticides, microbial contaminants, heavy metals, chemical toxins or adulterated with orthodox drugs."

"The excessive pesticides, microbial contaminants and heavy metals maybe related to the source of these herbal materials if they are grown under contaminated environment or during the collection of these plant materials. Chemical toxins may come from unfavorable or wrong storage conditions or chemical treatment due to storage. The presence of orthodox drugs maybe related to unprofessional practice of manufacturers."

Just a little explanation for the above. Plants growing in polluted soils may absorb the pollutants like heavy metals, pesticides and other harmful substances and store them in their tissues. Studies have shown (e.g. Susaya, 2007) that succulent plant species generally absorb high amounts of heavy metals from the soil. The pesticides may also come from excessive pesticide application to control pests during the production of the herbal plants.

The article is just a reminder to all of us. It may not be true to the products that you are now using. But it may turn out that the fresh herbal plants that we can get from our own backyard maybe safer than the beautifully packed but expensive ones produced somewhere else.

(Photo shows part of the medicinal plant garden of a 12th century castle along Rhein River in Germany.)

Reference

Chan K. 2003. Some aspects of toxic contaminants in herbal medicines. Chemosphere 52: 1361-1371