Issue 3 [October]

The hydrological basin of Keritis in Chania, Greece is mainly an agricultural area where
various agrochemicals are used. In topsoils, the total and available forms of Cu, Zn, Pb and
Cr were determined after their extraction with boiling Aqua Regia and DTPA respectively.
Although the total heavy metal concentrations in Keritis soils were similar to the total
concentrations in other agricultural areas, the studied soils can not be described as heavily
polluted. The bioavailable concentrations of Cu, Zn, Pb and Cr were low. The relative
availability and comparative mobility followed the order of Cu>Pb>Zn>Cr and was closely
related to the soil organic matter.

Metal pollution can have adverse effects on human health but also on environment. Usually,
risk is assessed on the basis of the total concentration of a trace metal in soils and sediments.
Nevertheless, for checking the short and long-term true environmental impact of a trace
element, one of the most crucial factors to consider is its mobility. Leachability of metals from
soils and sediments and, thus, their mobility, depends on several factors such as the soil type
on the basis of the parameters that affect metal interaction, the nature of the pollution in terms
of the deposition and composition, and finally the environmental conditions that may lead to
weathering. This study has been focused on the metal behaviour in some soil and sediment
profiles placed in the river-bed of a seasonal river from a semiarid mining Mediterranean area,
in SE Spain. Data from these analyses showed that a change of the environment conditions
could remobilise great amounts of Zn. In this sense, a change of acidic conditions could affect
mainly to the lower drill. Meanwhile a change of reducing or oxidizing conditions can affect to
middle and upper drills zinc remobilization. Middle stretch of the seasonal river shows a very
different behaviour in relation to zinc mobility, leachibility and distribution in soil profiles. For
this river stretch, metal accumulation in the soil profile is higher, and leachibility risks for
groundwater could be higher. Besides, the lower stretch of the seasonal river show a special
metal distribution because of the underlying materials are placed in the saturated zone
(marine aquifer), what can determinate a horizontal, more than a vertical, metal flux.

Pollution of the environment with uranium and associated health effects to human have
recently become of major concern, particularly due to the use of depleted uranium in armourbreaking
bullets. Indeed, uranium in environmentally significant concentrations is found near to
uranium mining and processing facilities and usually involves large volumes of wastewater.
Removal of uranium from such large volumes of wastewaters will require a cost effective
remediation technology. Conventional wastewater treatment technologies usually rely on
mineral adsorbents and chemical flocculating agents. On the other hand chemical behaviour
and migration of uranium species in the geosphere is strongly governed by
adsorption/desorption phenomena on the underlying rock formations. Hence, studies
regarding uranium adsorption on natural minerals and the evaluation of the corresponding
thermodynamic data is of fundamental importance with respect to the treatment of
contaminated waters and uranium migration in the geosphere.
The present paper reports about the adsorption of hexavalent uranium on dunite at various
experimental conditions (e.g. uranium concentration, amount of adsorbent, ionic strength, pH,
temperature and contact time) and discusses the effect of these parameters on uranium
adsorption. Evaluation of the experimental data shows that the optimum pH regarding uranium
adsorption on dunite is about 6.5. The experimental adsorption data are well fitted by the
langmuir isotherm and there is a linear correlation between adsorbent mass and amount of
uranium, indicating on the formation of inner-sphere complexes. Moreover, adsorption
experiments at various temperatures indicate on a spontaneous, entropy-driven processes
and kinetic measurements show that the adsorption process follows a first order rate
expression.

In coastal marine environments, with shallow, warm and calm waters, it is sometimes possible
to observe the presence of organosedimentary structures that are commonly flat and laminar
in shape. These structures are called algal mats or recent stromatolites due to their
remarkable similarities to fossil stromatolites. The aim of this work was the study of the
distribution of the various forms of Cu and Cd in the main layers of coastal algal mats in a
closed bay at Anavissos, on the coast of Saronikos Gulf.
Small sediment cores were collected from one point inside the cove on a seasonal basis and
the trace metals extracted according to the BCR sequential extraction method. The main
results of the study were:
Most of the labile Cd was associated with small inorganic grains or lime particles. The
contribution of the fraction associated with Mn and Fe oxides, was similar to that adsorbed to
organic compounds and sulfides. The high contribution of the labile Cd to the total element
(over 85%) was a strong indication of anthropogenic origin.
On the other hand, most of the Cu in the sediment was associated with the crystal lattice
(74%). Cu showed increased seasonal fluctuation; most of its labile forms were associated
with organic compounds and sulfides whereas the less abundant form was that associated
with Mn and Fe oxides.
On the whole, the sediments were slightly enriched in Cd, while the concentrations of Cu
were normal for the region.