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 the 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 depend on insulin. However, excessive amounts 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 the 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 a low natural content of nickel but high amounts can occur in food crops grown 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

F.A. Fallou: The Father of Soil Science

History is one of the most complicated and subjective academic fields since it is greatly influenced by the knowledge, experience, interest, and personal taste of the authors who reconstruct the history of a given event or human endeavour. It also depends on the availability and accuracy of historical records as well as on the degree of detail of the historical account. The renowned historian Norman Davies author of the book "Europe: A History" (Pimlico, London, 1365pp) wrote that "history can be written at any magnification. One can write the history of the universe on a single page, or the life-cycle of a mayfly in forty volumes." Thus, it is not unusual to read many different versions or revisions of the historical account of a past event.

The history of soil science is no exception. Some aspects of it are still controversial such as the one about its founder. Although the Russian geographer Vasilii Vasilevich Dokuchaev (1846-1903) is widely considered as the founder of soil science on the basis of his book “Russian Chernozem” of 1883 which discussed soil formation as a function of the factors climate, parent material, organism, relief and time, a close examination of historical records would reveal that another scientist had made a major contribution two decades before him. He was Friedrich Albert Fallou.

F.A. Fallou (1794-1877) from Zörbig, a small town in Sachsen, Germany is considered by several important authors as the founder of soil science (Blanck, 1949; Joffe, 1949; Strzemski, 1975; Schroeder, 1983; Feger and Makeschin, 2007). In his seminal book Pedologie oder allgemeine und besondere Bodenkunde (Pedology or General and Special Soil Science) of 1862, Fallou justified why soil is a natural body that needs to be studied and argued for the recognition of soil science as an independent natural science. He also introduced the concept of soil profile, discussed the physical and chemical properties of soils and established a soil classification based on parent rock (Asio, 2005).

Contrary to popular notion, it was Fallou in his book of 1862 who first recognized the soil as a natural body and not Dokuchaev who only published his important work two decades later. This was in fact acknowledged by K.D. Glinka (1867-1927) in his lecture during the first international congress of soil science in 1927 although he appeared to downplay Fallou’s contribution and gave the credit to his teacher and countryman Dokuchaev (Glinka, 1927). Dokuchaev’s fame was further enhanced by the fact that Glinka was widely read in North America especially since he was the first president of the International Society of Soil Science. That Dokuchaev who was only about 16 years old and still a young student when Fallou’s influential book of 1862 (Fallou’s sixth book) was published, reinforces the notion that he was influenced by Fallou although according to Johnson et al. (2005) Dokuchaev cited Fallou only once in his important work on chernozem. Whether or not this omission was intentional is unknown. Interestingly, the American landscape pedologist David J. Brown noted that Dokuchaev’s “geologic-geographic investigations” and soil maps were apparently based on the geographic maps (e.g. climate-vegetation maps) of Russia developed by the great natural scientist and founder of geography Alexander von Humboldt (1769-1859) but this was not acknowledged by Dokuchaev in his book (Brown, 2006).

Until now very little is known about Fallou’s book. This can be seen from the fact that most books and papers that discuss soil science history only make brief mention of Fallou’s soil classification which is only part of Fallou’s trailblazing book. The book is divided into two parts. Part I (p. 1–198) is about the general knowledge of soils and Part II (p. 199–487) presents a detailed description of his soil types based on parent rock and is relatively known.

In the preface of Part I, Fallou wrote that "the current books on soil science are just compilation of mixed materials (an aggregate of unorganized materials) from geology, geography, agricultural chemistry and plant physiology." In contrast, he stated that his book "presents for the first time the existing soil knowledge as an interconnected, concise and organized body of knowledge" and thus, as a science. He wrote: "This is the first attempt of this nature; I have blazed a trail that others may follow and improve, it does not matter if it will lead to an entirely new building of knowledge based on other principles and in another style, so that the poor and unrecognized soil science will once and for all be accorded the honor and that it will likewise be recognized as a science."

In the 22-page introduction, Fallou discussed the nature and aims of soil science, justified why soil science should be an independent natural science, and why soil is a natural body that deserves to be studied. In Chapter 1 on Entstehung des Bodens (p. 23–52), Fallou discussed the origin of soils, particularly the role of weathering and related processes like transformation and leaching, although he did not yet use the term leaching.

Chapter 2 on Wesen des Bodens (p. 54–82) is a comprehensive discussion about the nature, origin, and characteristics of the inorganic and organic soil components.

Chapter 3 on Beschaffenheit des Bodens (p. 83–107) is about soil properties such as color, structure, weight, and density, porosity, penetrability, solubility (now erodibility), and moisture content.

Chapter 4 on Räumlichkeit (p. 108–130) is actually about the dimension of the soil body. It focuses on the horizontal dimension in terms of soil distribution in the landscape as well as the vertical dimension in terms of soil depth or thickness. Fallou also discussed the distribution and thickness of the soil in the landscape in relation to elevation and slope and thus, was a recognition of the effect of relief on soil characteristics.

Chapter 5 (p.131–144) is about the inner part of the soil body in terms of the nature of soil layering. Other chapters are about differences between soils (Chapter 6), classification of soils (Chapter 7), and the role of soil in the hydrologic cycle and in plant and animal growth as well as the changes of soil with time (Chapter 8).

In Chapter 8, he wrote that "everything changes itself in form and substance with time... the soil will, like all other things in this world, get not younger but older and in the end will lose its productivity." On his discussion about the chemical processes of soil change with time, Fallou wrote that "weathering in the soil body involves transformation and rearrangement... the most important is the dissolution of the unweathered rock material to release its nutrients for plants use thereby transforming it completely to soil."

Because of the great impacts of their contributions to the development of soil science, Fallou, Dokuchaev, and Liebig are considered by some authors as co-founders of soil science. Some others notably Joffe made a slightly different distinction: Fallou as the father of soil science; Dokuchaev as the founder of modern soil science.

(Note to readers: details of all references can be requested from me)