Issue 4 [December]

A considerable number of diseases are directly related to environmental impact. Toxic metals such
as Hg, Pb, Cd, and As may damage significantly the human health when they exceed certain levels
in the body. For example specific precautions should be taken for the diet of pregnant women and
the children. Lead concentrations exceeding the safe values can cause severe damage to the
development of central nervous system, as well as a general developmental delay of fetuses and
young children, interfering with the functioning of almost every brain neurotransmitter. In particular
for the pregnant women, it has been found that the exposure of the fetus on high lead values may
cause, apart from neurological and behavioral problems, low birth weight, pre-term delivery,
spontaneous abortion and stillbirth. Organic mercury (methyl mercury) is the most dangerous form of
mercury, because it is the most easily absorbed orally and crosses into the brain and fetus so
readily. Populations exposed to chemical compounds containing As, Ni, Cr, Cd, etc. are considered
of high-risk in developing cancer.
Environmental geochemical studies can help in assessing the quality of the environment as well as
the determination of the sources of pollutants, their behaviour and other characteristics. This
knowledge is necessary in any application of remediation methodologies and waste management for
the prevention of pollutants in getting into the food chain. It is also used in determining safe criteria
regarding the quality of soils, drinking water, construction of schools, playgrounds etc. In this work
the importance of environmental geochemical research and its applications towards the protection of
human health is demonstrated.

A noticeable decline of Quercus ithaburensis ssp. Macrolepis, a typical mediterranean species, has
been recorded in the past few decades throughout Greece. The triggers were mostly human
influences and specifically illegal cuttings, wildfires, and overgrazing. Regeneration and future
management of this species is therefore questionable. To investigate the effect of companion plants
on this decline as expressed by water availability and plant growth, a pot experiment was conducted
and oak seedlings were planted with Bromus sterilis and a mixture of Trifolium repens and T.
fragiferum as companion plants. Midday water potential from May to September and oak growth at
the end of the experiment were measured as factors affecting oak physiology. The results suggest a
different effect on the water potential of the oak seedlings depending on the companion plant
species and the time of the year. The presence of a companion plant that has completed its life cycle
by the end of spring may positively influence the water status of oaks during the summer months
due to shading and lower soil water evaporation. On the contrary, when the companion plants
continue their life cycle in the summer, the negative effect may be continued, specifically during the
very dry months. The negative effect of grass on the growth of oaks may be attributed to their
shading from the dense grass biomass. It can be concluded that control of competitive vegetation,
especially of grasses, is crucial for Quercus ithaburensis ssp. macrolepis regeneration by natural
(from acorns) or artificial (with up to one-year-old seedlings) methods. This control is necessary at
least in the first year after establishment, when seedling height is less than that of the competitive
vegetation. If the latter can not be removed by some ways (e.g. controlled grazing), then it is safer to
use taller oak seedlings of an older age in the reforestation projects.