Pump-and-treat (P&T) is one of the most common methods for remediation of groundwater contaminated
by hazardous wastes. However, this method suffers from serious disadvantages, due a series of
subsurface processes. Using experimental data and mathematical model simulations, the role of sorption/
desorption and dissolution of non-aqueous phase liquids on the effectiveness of P&T remediation
was examined. The results showed that the remediation of groundwater depends directly on the physical/
chemical properties of the contaminants and the hydrogeology of the site. With the exception of
water-soluble contaminants occupying relatively small parts of relatively homogeneous and water-permeable
geologic media, the remediation of groundwater contaminated by hazardous waste using P&T
is, for all practical purposes, impossible and prohibitively expensive.
Fly ash (FA) and fluidized bed ash (FBA) solutions were evaluated as amendments for acid-disturbed
lands, more specifically for treating acidic and metal contaminated soil. While titrating the ash materials
with different volumes of acid, pH changes were monitored as a function of time and the acid volume
added. The release of metals from the ash materials as a function of pH was also monitored. An
acid mine drainage (AMD) solution was equilibrated with ash materials and clay and the metal removal
from the solutions evaluated. Both FA and FBA produced solutions of high initial pH. However, FBA
indicated a higher buffering capacity resulting in a steeper titration curve. The system pH strongly
impacted metal release from the ash materials. The leaching experiment indicated a pattern whereby
the basic metals (Ca and Na) were released at higher pH and the acidic metals (Fe and Cr) at lower
pH. Limestone had almost double the buffer intensity but a lower initial pH than ash materials.
Comparison of ash materials with two types of clay revealed that ash materials were better alternatives
for treating acidic and high metal content wastes. Albeit both ash materials were able to treat AMD,
their overdose could lead to trace metal accumulation with negative consequences to the environment.
Testing was conducted with anionic diphenyloxide disulfonate (DPDS) surfactants (C12 and C16 alkyl
moieties) with naphthalene in aqueous systems and phenanthrene in soil systems to investigate the
influence of these surfactants on biodegradation of hydrocarbons. A potential for enhancement in the
degradation of naphthalene was seen in C12-DPDS amended assays at low surfactant concentrations,
predominately below the critical micelle concentration (CMC). The overall trend for both C12- and
C16-DPDS assays indicated decreasing efficiency in degradation of naphthalene with increasing surfactant
concentration, with no correlation to the CMCs. In the soil-slurry assays, surfactant-free controls
and assays with the lowest (sub-CMC) surfactant additions demonstrated the first phenanthrene
mineralization responses followed by the mid-level (sub-CMC) surfactant-amended assays.
Approximately 3 months later, a supra-CMC C12-DPDS sample had a strong response. In saturated
soil (mud) systems, mineralization only occurred in the surfactant-free controls and in assays with the
lowest (sub-CMC) additions during 5 months of testing. The lowest surfactant additions, however, were
effective in enhancing mineralization of phenanthrene, with the first-order constant for the C12-DPDS
amended assays being increased by a factor of 5 over that of the surfactant-free controls.
In the Mediterranean region, fire is a natural factor, which contributes in the shaping of landscape and
the preservation of a high degree of biodiversity. However, often repeated burning has negative impacts
on the forested landscapes. When the processes of natural or artificial regeneration are efficient and
the fire frequency is sufficiently low to enable the recovery of vegetation, recovery time T can be used
as a tool for setting priorities for the preservation of ecological and social functions of the forested
landsapes. Using a simple linear approach, we argue that their situation can be considered as acceptable,
when the percentage of the yearly burned area in relation to the total forested area is much lower
than 100/T (for practical purposes just lower than 10/T). This empirical rule was applied to the Greek
forested landscapes. In the case of pine forests of Pinus halepensis and Pinus brutia, it was found that
the condition implied by the rule was not satisfied and, therefore, a reduction of the yearly burned areas
of these lowland conifer forests is necessary. However, as far as the other types of forests, as well as
macchia and phrygana are concerned, the condition is satisfied.
The concentrations of ten industrial metals (Pb, Cd, Ni, As, Cr, Zn, Fe, Cu, Al and Mn) in 20 samples of
rainwater collected at the station of Athens University Campus (AUC) during the cold period 1/10/97 -
31/3/98 were determined. In general, low concentrations were observed. The Spearman correlation coefficients
for different metals were calculated in order to reveal common sources. Principal Component
Analysis (PCA) was used to identify the factors that affect the presence of metals in rainwater.
Air pollution related problems, such as acidification, air quality and ground-level ozone, are recognized
as some of the important problems facing the people of the Czech Republic, whose health is damaged
by impacts of air pollutants. Also the impacts of these air pollutants on human health, forests and vegetation
are investigated. This paper presents evaluation of air pollution caused by sulfur dioxide, nitrogen
oxides, particulate matter and ozone, based on the readings of measuring site at Bílý Køí for the
six-year period 1994-1999. The evaluation of the status of the ambient air pollution is based on air pollution
limit values as specified by the new European Directives. Concern has been expressed about the
possible effects of ozone, nitrogen oxides, sulfur dioxide and particulate matter exposures on forested
areas, materials and human health. The main objective of this study is to examine the evolution
observed in the concentrations of these air pollutants considered. The reduction is observed for winter
air pollutants as sulfur dioxide and particulate matter from 1996 to 1999. In contrary, the ozone concentrations
increase considerably for the same period.
Electricity generation is the single most important sector in which CO2 reductions are achievable, with
advanced generation technologies available and the existence of a centralised production structure, if
compared to the transport or the industrial sector. It is a market undergoing a radical change in Europe,
with competition rising as it is enforced by the deregulation of the markets, though to varying degrees on
a national level. At the same time it is a sector characterised by efforts to support green energy systems
and also by the increasing significance of international trade. It is therefore of interest to examine the
impact of the technological and economic changes on the CO2 emissions due to electricity generation, in
order to try to assess the feasibility of the emissions reduction policies as foreseen by a series of treaties
and protocols. The points discussed in this paper focus on the interference of the recent market developments,
the policies and economic tools applied in Europe and the state of the art conventional and
renewable generation technologies, with respect to their contribution to the aim of reducing emissions.
Three hydrographic cruises were conducted during 1997-1999 in north Aegean Sea, in order to study the dissolved oxygen (DO) and nutrient distributions in Strymonikos Gulf impacted by the riverine waters of the Strymon River. The approaches used in this paper include a preliminary estimation of the nutrient load of Strymon River and the influence of the riverine waters upon the DO and nutrient distribution in Strymonikos Gulf. Nutrient levels recorded in Strymon River were similar with other international Rivers. The influence of Strymonas River on the DO and nutrient distributions was clearly detected during December 1997 and May 1998. On the contrary, during March 1999 the influence of Strymon River was not so clearly detected. High nutrient concentrations were recorded close to the mouth of the river. As mixing with offshore waters progressed, nutrient levels declined dramatically. Plots of atomic DIN:P (ratio of the total dissolved inorganic nitrogen to dissolved inorganic phosphorus), Si:P (ratio of dissolved silica to dissolved inorganic phosphorus) and Si:DIN ratios in Strymonikos Gulf, during the three sampling periods studied, indicated stoichiometric P-limitation in about 34%. Furthermore, the data indicated significant probable N-limitation (31.4%), while Si-limitation was not probable (2.9%). In particular, 31% of the data showed a defined P-limitation in December, whereas 30% of the data showed N-limitation. It is noteworthy that Si-limitation was not recorded. In May, the atomic DIN:P ratio indicated P-limitation in about 21% and N-limitation in about 46%. Si-limitation was not recorded. Finally, in March, the 51% of the data showed P-limitation, whereas only the 16% showed N-limitation and 8% showed Si-limitation.
Lake Pamvotis is a shallow lake, located in NW Greece, which during last decades has influenced by a lot of man-made impacts such as sewage discharge, water level fluctuation, e.t.c. Water quality for physicochemical and biological parameters was monitored seasonally in five sampling-stations from April 1998 to March 1999. Lake Pamvotis is an eutrophic ecosystem which has been influenced by the nutrients input, rates of nutrient cycling and plankton-fish dynamics. According to the nitrogen: phosphorus ratio, the limiting factor is phosphorous during spring while a nitrogen limitation is switched on during the warm season. Restoration management strategy requires reduction of external organic load, control of non-point pollution from the surrounding agricultural area and establishment of biomanipulation techniques.
The present study is performed with the aim to reduce the levels of polluting emissions from fuel combustion that produce acid rains and the greenhouse effect (NOx, CO2). The electric field effects on the processes of heat/mass transfer and propane combustion are studied in order to perform electric control of the levels of polluting emissions from the flame. The results of experimental studies show the direct influence of the electric field's enhanced mass transfer on local variations of the flame composition and fuel combustion. The related variations of the flame temperature, processes of soot formation, carbon capture and deposition along the flame channel flow are studied by varying the field strength and the equivalence ratio of the propane-air mixture. The results show that the electric field effect on soot for- mation, carbon capture and sequestration, for fuel-rich flame flow, can be used to reduce the levels of CO2 emissions from the flame. In addition, the field-enhanced heat/ mass transfer to the channel walls, for fuel-lean conditions, can be used to control the fuel combustion, flame temperature and temperature- sensitive levels of NOx emissions. The most pronounced electric field effects on fuel combustion and composition of the products are observed in the limit of the weak fields (U<1,2 kV, E<105 V m-1).