Risto Piispanen

Degradation products and the hydrolytic enzyme activities in the soil humification processes

Abstract Humification of spruce ( Picea abies ) needles, aspen ( Populus tremula ) leaves and pine-bog peat was studied with emphasis on the determination of the amounts of proteins, lipids, sugars, starch, amino acids, cellulose and lignin in fresh and decomposed litter materials. The concentrations of starch, proteins and free sugars decreased rapidly, that of total lipids more slowly and that of cellulose and lignin very slowly during the decomposition of spruce needles and aspen leaves. The proteins in the peat remained undecomposed for relatively long periods since most of the original N in 2 m deep peat was still largely preserved in the form of polymerized N. Celluiase and polyphenoloxidasc activities increased while proteolytic and lipase activities decreased during the decomposition of all the materials studied. Additionally caloric values of the litter and peat were also measured, and the results confirm the increase of caloric values during the humification.

Acidification of groundwater in water-filled gravel pits - a new environmental and geomedical threat

Swimmers and users of motor boats frequenting old, water-filled gravel pits in Kiiminki, Northern Finland, found in August 1993 that they were suffering from painful irritation of the eyes and that their boats had developed a finely polished surface on their aluminium hulls, evidently due to the corrosive action of the water. Subsequent measurements carried out by the water authority showed that the pH of the water in some of the pits was extremely low, reaching a value of 3.4 at its lowest. To find out the causes of the abnormally low pH values, the present authors began systematic measurements of the pH and determination of the chemical composition (Si, Al, Ca, Mg, K, Na, Fe, Mn, Cu, Pb, Ni, Cd, Cl-, NO3-, SO42-) of the water in 23 gravel pits. In addition, a series of laboratory experiments was carried out to examine the interaction of water with samples of the soil and bedrock of the area to evaluate the role of this process as a possible cause of the acidification. The results show that the reaction of water with the moderately to intensively weathered sulphide and jarosite-bearing black schists, typical of the bedrock of the area, can bring about aqueous solutions similar in pH and sulphate--nitrate ratios to those found naturally in the gravel pits. The contribution of other possible mechanisms, e.g. acidic precipitation as such or combined with enhanced evaporation, the possible use of the pits as dumping sites for acidic waste or the flow or seepage of acidic peat-bog waters into the pits from the surrounding wetlands, cannot be ruled out entirely, but their contribution seems to be of minor importance. Since the concentrations of several heavy metals (notably Pb, Cd, Ni, Fe and Mn) and of sulphate and aluminium has increased in the pit water as a result of the acidification process and exceed the norms laid down in the EU Drinking Water Directive, acidification of water in gravel pits due to the oxidation of sulphides must be regarded as a new, serious environmental and geomedical threat which has so far remained poorly known or unrecognised.

Water hardness and cardiovascular mortality in Finland.

In Finland, where mortality rates of cardiovascular diseases are as a rule among the highest in the world, significant areal differences in these figures are encountered especially between the eastern and western parts of the country. To test the hypothesis that these differences,( the reason of which has long been a subject for a lively debate in Finland), may result from geochemical factors such as variations in the hardness or calcium or magnesium content of well water a correlation analysis was carried out in which the geochemical properties in each of the countrys individual administrative districts, or communes (444 in all, excluding Åland) were compared with the percentage of heart diseases among the causes of death from diseases in 1991. The results show a poor or extremely low correlation nation-wide (r ranging from −0.039 to +0.045), indicating a virtual absence of any causal relationship. On the other hand, taken pairwise, the extreme western and eastern provinces, Vaasa andNorthern Karelia, show marked differences both in their geochemical and mortality data, the percentage of deaths caused by cardiovascular diseases being markedly lower in the province of Vaasa, where the hardness and the magnesium content of well water (but not the calcium content) are significantly higher (p < 0.001 and 0.002 respectively). This inverse relationship is in line with the supposition that in addition to other factors, geochemical differences may have an effect on mortality.

Changes in concentrations of free amino acids during humification of spruce and aspen leaf litter

Abstract Concentrations of amino acids and related compounds formed by natural degradation and microbial synthesis during the degradative humification of spruce ( Picea abies ) and aspen ( Populus tremula ) leaf litter were studied using natural in situ material. A general tendency for the amounts of amino acids to decrease was found with advancing humification, with the notable exceptions of proline, omithine, arginine and γ-aminobutyric acid, which showed slightly increasing concentrations in the more humified samples. The amounts of various ammonium compounds remained relatively stable, and the concentrations of 42 other compounds show a clear decrease during humification. A few unidentified ninhydrin-positive compounds also appeared, although in relatively low concentrations.

Correlation of cancer incidence with groundwater geochemistry in northern Finland

The correlations of age-adjusted incidences of various forms of cancer with the geochemical composition of well water and other forms of groundwater in northern Finland have been studied using standard statistical methods. Available geochemical maps showing the hardness of the water and its uranium, iron and nitrate content and maps depicting the areal distribution of the incidences of ten forms of cancer, were decoded point by point to numerical concentration or incidence values by placing a transparent sheet carrying a regular rectangular grid over each. The grid covering the north of Finland (north of 65 ° N latitude) comprised 261 observation points distributed at regular intervals of about 25 km on the ground.The calculated Spearman product-moment and rank correlation coefficients between the geochemical and medical variables suggest that a strong, statistically significant (p<0.001) positive correlation prevails between the hardness of the water and several forms of cancer, especially total cancer (all forms of cancer combined) in the female population (r = 0.66). On the other hand, iron and, somewhat surprisingly, nitrates, which are commonly thought to promote cancer, show a low degree of correlation with the forms of cancer studied. Also, contrary to expectation, a negative correlation between most forms of cancer with groundwater uranium is indicated, a result which, because of its unexpectedness, calls for further research work based on larger data sets before a conclusion can be drawn that it can be interpreted as an implication of a trend that an appropriate level of uranium in the groundwater and the resulting gentle dose of natural radioactive irradiation can help to prevent the early development of cancer in human tissues and cells.The positive correlation between water hardness and most forms of cancer studied suggests that hard drinking water may be an initiator and promoter of cancer, although it is admitted that the establishment of a positive correlation between the geochemical and medical variables does not necessarily prove a cause-and-effect relationship between them.

Geochemical interpretation of cancer maps of Finland.

In order to reveal possible cause-and-effect relationships and correlations between geochemical variables and the incidences of various forms of cancer, geochemical maps (soil and groundwater) and cancer maps of Finland are compared using standard methods of correlation analysis. The cancer incidence maps published by the Finnish Cancer Registry and soil and groundwater geochemical maps published by the Geological Survey of Finland, both in colour, were decoded to numerical incidence or concentration values by placing a rectangular grid of 684 evenly spaced observation points over each map representing the entire area of the mainland of Finland,i.e. the points were located at intervals of about 25 kilometres on the ground. Bivariate correlation coefficients were calculated between the variables for cancer incidence and the geochemical data matrices. As a general rule, the results show a low degree of correlation between the variables (r = 0.00 – 0.40), which suggests that the types studied of cancer are not related to the geochemical variables. There are a few possible exceptions, however, such as cancer of the colon in males and females in relation to arsenic and uranium in the soil and hardness of the groundwater, where the Spearman product-moment correlation coefficients are 0.59, 0.55 and 0.51 respectively, so that the cancer case may have a geochemical factor implicated in their aetiology, albeit very vaguely. The relatively high correlation coefficients (0.61, 0.62 and 0.63 respectively) recorded for the dependence of total cancer in females on groundwater hardness and uranium and arsenic in till must be regarded as meaningless in view of the multicausative aetiology of total cancer (all forms combined).

Radon and lung cancer in Finland: are there signs of radiation hormesis?

Prolonged exposure to any level of radon in indoor air is generally thought to be hazardous to human health and to give rise to lung cancer. On the other hand, low or moderate levels of radon in indoor air may, according to the radiation hormesis hypothesis, be beneficial to human health and even inhibit the growth of cancerous cells. An attempt is made here to test these contrasting views by comparing mortality rates from lung cancer during the 10-year period 1986–1995 with average indoor radon levels in the 435 communes (municipalities) of Finland (excluding Åland). The results show a very low, statistically non-significant correlation between radon and lung cancer mortality (r = −0.0331), which in turn implies that at least in this case neither the possible beneficial hormetic effect of radon nor its cancer-provoking hazardous effect can make itself apparent against the dominant and masking effect of cigarette smoking, the main cause of lung cancer.

Radiation hormesis — fact or fiction?

Deriving from the Greek verbhormein, which means to stimulate and excite, hormesis literally refers to any kind of stimulation and excitation. As a medical and geomedical term (though of unsettled status) it has a more restricted meaning however, indicating merely the putative or real stimulatory and beneficial effects observed when a biological system is exposed to a low dose of an agent known to be toxic or hazardous at a significantly larger dose. Depending on the type of stimulatory agent, one can speak of chemical or physical hormesis, radiation hormesis being a member of the latter group. The present paper reviews and evaluates the history and origins of the concept of radiation hormesis and its present status — fact or fiction. It is concluded that despite the numerous, sometimes undeniably strong, individual pieces of evidence that have been presented in favour of this phenomenon, the bulk of the evidence is so far not strong enough to establish it as a scientifically proven fact. It is also evident that, instead of speaking of radiation hormesis as an entity, one should pay attention separately to the effects of alpha, beta and gamma radiation, the deleterious and possible beneficial hormetic effects being different in each case.

Comparison of health patterns in two geochemically contrasted areas of northern Finland.

In order to prepare the ground for a discussion of possible causal relationships between health patterns and the geochemistry of an area, health patterns in the form of age-adjusted cancer incidence values and rates of mortality due to (1) cancer of the stomach, colon or rectum, (2) lung cancer and (3) ischaemic heart diseases are compared between the populations of two geochemically contrasted communes of northern Finland (Kemijärvi and Kuusamo). Statistically significant differences (p < 0.001) are encountered in the mortality rates due to ischaemic heart diseases and marked differences in the incidence values of lung cancer, the former being higher in Kuusamo and the latter in Kemijärvi. The higher incidence of lung cancer observed in Kemijärvi is in accordance with previous results reported from the USA, where higher incidences have been observed in areas of granitic bedrock. Regarding the higher mortality rate due to ischaemic heart diseases In Kuusamo, which is geochemically characterised by higher potassium (p < 0.002) and calcium (p < 0.004) and lower Zn, V, Ti, and Fe (p > 0.002) in the soil (actually, in the fine till fraction), no easily demonstrable cause- and-effect relationship can be established.

Autoradiography and scanning electron microscopy combined with energy-dispersive spectrometry (SEM-EDS) in the service of geochemical exploration

Abstract The importance of the identification of the mineral phases in the heavy fractions of geochemical samples is emphasized. A knowledge of the chemical composition with information about the anomalous contents of the economically interesting metals in the samples is not sufficient, it is also essential to know the mineralogical source of the metals especially when the exploitation possibilities of the searched-for deposits are being estimated. A version of autoradiography suitable for the location and quantitative determination of radioactive minerals in the heavy fractions of geochemical samples is described. Furthermore, the use of a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) in the identification of the heavy minerals is also described. An example of the use of SEM-EDS identification of radioactive minerals, located by the autoradiography, is described.