Issue 3 [November] ( Papers presented at 9th International Conference on Protection and Restoration of the Environment - PRE9, June 30 - July 3, 2008, Kefalonia, Greece
)
Abstract The performance of a biological treatment of a PAH-contaminated soil was evaluated with
respect to its physicochemical and ecotoxicological properties. After six months, the biological
treatment led to an significant reduction of 2- and 3-ring PAHs and to a lesser extent to 4-ring
PAHs. As a consequence a significant decrease of the acute ecotoxicity was observed
passing from highly ecotoxic before treatment to non-ecotoxic according to Lactuca sativa
seedling and growth inhibition test and Eisenia fetida mortality test. This could be related to
the bioavailability of PAHs. Indeed, tests performed on aqueous leachates of the soil showed
a strong decrease of 2- and 3-ring PAHs correlated with a significant reduction of acute and
chronic ecotoxicity responses. The biological treatment led to the mutagenicity reduction and
the genotoxicity disappearance in the leachate. Thus, bioassays are complementary to
chemical analyses to evaluate the efficiency of a bioremediation process and to evaluate the
bioavailability of the organic pollutants as the total concentration of a contaminant is not the
only criterion to consider. The comparison of the ecotoxic responses allowed us to underline
the best sensitivity of the earthworm, Microtox, Alga and Ames bioassays among the tested
set. These bioassays could thus be good candidates to build a toxicity evaluation procedure
for PAHs contaminated/ remediated soils.
Abstract Radiocaesium is an isotope that can enter the food chain after having been absorbed by
plants from soil. Our ability to predict the consequences of an accidental release of 137Cs
depends mainly on the level of understanding of the mechanisms involved in 137Cs
interactions with different components of agricultural and natural ecosystems and their
formalization into predictive models. In this study the impact of some environmental and
physiological factors, such as root density and presence of AM (Arbuscular mycorrhizal)
fungal hyphae, on the ability of plants to uptake and accumulate radiocaesium through the
roots was investigated. Three plant species were used: pea, soybean and oats. Experimental
data suggested that, as roots explore new volumes of soil during growth, the plant will
continue to accumulate this radionuclide at high rates in the early stages of ontogenesis. If
plants are established on a contaminated site they may not be able to remove all of this
radionuclide from soil, especially if a substantial amount of the radionuclide has been leached
below the root zone which is commonly 30-40 cm in depth. Laboratory experiments indicate
that certain plants may be able to remove radionuclides, especially 137Cs, from soil over a
time period of 5-20 years.
Abstract Stabilization/solidification (S/S) processes were utilized to immobilize lead (Pb) and tungsten
(W) in contaminated soils, the inclusion of W motivated by the use of the new W-based
ammunition. Artificially contaminated soils were prepared by mixing either kaolinite or
montmorillonite with 10% Pb and 1% W (all percentages by dry weight). Type I/II Portland
cement (PC), silica fume cement (SFC) and cement kiln dust (CKD) were used as S/S agents.
The S/S agents were added at 5, 10 and 15 % for a curing time of 1-, 7- and 28-days. The
toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching
procedure (SPLP) were used to evaluate the effectiveness of the treatments. X-ray powder
diffraction (XRPD) was used to investigate the crystalline mineral phases responsible for Pb
and W immobilization. The TCLP results showed that regardless of clay type and stabilizing
agents, the Pb concentrations decreased with increasing pozzolan content. PC and SFC
exhibited similar performance depending on the particular sample (not consistent with soil
type, dosage, and curing time). The most effective stabilizing agent on Pb leachability was PC
despite SFC being silica-enriched which should have contributed to its greater immobilization
of Pb. TCLP-W was immobilized below 1 mg l-1 in every case. The most effective stabilizing
agent on the SPLP-Pb leachability was CKD, consistently demonstrating among the lowest
concentrations for each soil type due to pH control. PC and SFC exhibited similar
performance depending on the particular sample (not consistent with soil type, dosage, and
curing time). The W concentrations in SPLP leachate were very low in most samples
indicating that W could be immobilized upon S/S processes even though W solubility is very
high at elevated pH conditions (662.9 mg l-1 at pH~11), and would remain immobilized under
SPLP exposure conditions. The XRPD results revealed that the formation of lead silicate
(Pb4SiO6), stolzite (PbWO4) and lead tungsten oxide (Pb0.29WO3) were strongly associated
with the immobilization of Pb in the S/S matrix.
Abstract Τhis paper focuses on optimal management of aquifers with pollution problems. Genetic
algorithms are used as the optimization tool, while advective pollutant transport is simulated
by means of a moving point technique. The approach is illustrated by means of two
application examples. In the first we seek the maximum total clean water pumping rate Qs
from three production wells, situated in the same restricted area with two wells that inject
polluted water. Results show that Qs depends heavily on the dimensions of the available area.
In the second application example, the total flow rate of the production wells is fixed and the
minimum treatment cost of pumped water is sought. Best solutions resulting from a number of
runs are classified in 3 different patterns, which are comparatively evaluated. Some remarks
on taking into account dispersive mass transport conclude the paper.
Abstract The importance of the development and application of groundwater simulation mathematical
models in the protection of aquifer systems is nowadays recognised as an undisputable fact.
In this paper a mathematical model that was developed in order to simulate the operation of
the Upper Anthemountas aquifer in Chalkidiki, Greece, is presented. The case study
application investigated concerned the possible malfunction of the Waste Water Treatment
Plant located within the study area. According to this scenario a possible malfunction of the
treatment plant could pollute the underlying aquifer. A network of observation wells located
downstream of the plant could detect the pollution and predict the time needed to reach the
productive wells surrounding the area. This allows the local water resources managers to
formulate a priori action-plans including, the alteration of the pumping schedule in order to
prevent polluted water to be abstracted from the nearby wells and at the same time protect
the public health, along with necessary measures concerning the prevention of further
pollution and the restoration of the groundwater aquifer system.
Abstract Simulations were performed of the 3-D hydrodynamic circulation and of the associated
water quality behavior in Mornos Reservoir, under real environmental conditions, during
the period 2003-2005. The water quality simulations, guided by observations taken at
the contributing tributaries and at the surface of the Reservoir, generated in-depth profiles
of pH, DO, NO3, NH4, TN, TKN, PO4, TP, TOC and of Chl-a, along with surface and indepth
horizontal distributions of these quantities, giving an overview of the variation of
the Reservoir’s water quality. Comparison of plots of the simulated quantities with field
data indicates that the Reservoir remains indeed oligotrophic; it also shows the potential
of the tools used, and the need for acquiring more systematic “in situ” observations by
EYDAP (the water authority company responsible for managing Mornos Reservoir).
Abstract Tungsten in solution may exist as a wide variety of species depending on concentration, pH,
and aging time. Despite a substantial number of studies on this topic, the speciation of
tungsten in aqueous solutions is still not completely understood. To address issues of fate,
transport and potential bioavailability, it is necessary to be able to assess the speciation of
tungsten in environmental systems. This study investigates the use of Laser
Desorption/Ionization mass spectrometry combined with a Time-of-Flight mass analyzer (LDITOF)
as well as Raman spectroscopy as potential techniques in speciation studies. Raman
spectroscopy has been successful in identifying the dominant species under a narrow range
of conditions. The ultimate goal is to extend the range of conditions and concentrations while
also identifying subordinate species.
Abstract The speciation of Cr(VI) in Cromite Ore Processing Residue was investigated by means of
bulk XRD, and a combination of micro-XRF, - XAS and –XRD at the Advanced Light Source
(ALS), Berkeley, CA, U.S.A.. Bulk XRD yielded one group of phases that contained explicitly
Cr(VI) in their structure, Calcium Aluminum Chromium Oxide Hydrates, accounting for 60% of
the total Cr(VI). Micro-analyses at ALS yielded complimentary information, confirming that
hydrogarnets and hydrotalcites, two mineral groups that can host Cr(VI) in their structure by
substitution, were indeed Cr(VI) sinks. Chromatite (CaCrO4) was also identified by micro-
XRD, which was not possible with bulk methods due to its low content. The acquisition of
micro-XRF elemental maps enabled not only the identification of Cr(VI)-binding phases, but
also the understanding of their location within the matrix. This information is invaluable when
designing Cr(VI) treatment, to optimize release and availability for reduction.
Abstract A mathematical model to simulate microbial growth and lag time is proposed in the present
work in accordance with Sengor et al. (2009). The model is verified experimentally for a mixed
microbial culture growing at metal free and at Cr(III) or Cr(VI) contaminated environments.
The model is further verified using a monoculture of Pseudomonas sp. growing at metal free
and Zn(II) contaminated environment. The effect of temperature on microbial growth and lag
is also simulated by the model. The simulation results show for the mixed culture that growth
rate decrease with parallel increase in lag time, with the rise of either Cr(III) or Cr(VI)
concentration. For Pseudomonas sp., the simulation indicated that there is almost nil lag time
for growth at 35 ºC, while approximately 10 h lag time is calculated for growth at ambient
temperature (20 ºC). The lag time increases by approximately 6 more hours when 0.01 mM
Zn(II) is added in the growth medium (at ambient temperature). The increase of lag time with
temperature reduction is explained by the fact that the biochemical reactions are slowed down
at lower temperatures. A good correlation between model predictions and simulation results is
observed.
Abstract The volume mixing ratios of non-methane hydrocarbons including saturated, unsaturated and
aromatic ones (C2 to C8 as non methane hydrocarbons, NMHCS) were measured at three
distinct sites (natural, rural, urban) in the lower troposphere of the Eastern Mediterranean
from February 2006 to March 2007. Average concentrations for most of the NMHC show clear
seasonal variations along the year mainly attributed to photochemistry. Significant
correlations found among various hydrocarbons indicate contribution from mobile and
stationary sources (exhaust and combustion). Leakages from natural gas (NG) or liquefied
petroleum gas (LPG) probably from the continental platforms may account for important
sources for the background concentration of ethane and propane in the area. Isoprene has
been found to have mostly a biogenic source but its dual anthropogenic–biogenic origin was
also evident at the rural site.
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