Contaminated marine sediments from Cantabrian estuaries have been compacted and fired to produce sintered ceramic materials. The effect of sintering on the leaching behaviour has been investigated by means of the comparison of concentrations of species proposed by the European Waste Landfill Directive present in leachates and regulatory limits for them. The impact of the specimens on the environment is assessed. In order to reach this objective, unfired and fired samples of marine sediments and clay were subjected to the Compliance Leaching Standard Tests EN 12457 1-2 using different liquid to solid ratios (L/S = 2 and 10). The concentrations of Se, As, Cr, Sb, Zn, Cd, Pb, Ni, Ba, Mo, Cu, fluoride, chloride and sulphate in leachates were analyzed, and the results compared with regulatory limits collected in 2003/33/CE Directive. The results revealed that the firing process decreases the leaching of the species analyzed, except for As. The comparison of the metal and metalloid concentrations in leachates and regulatory limits showed that all species fulfilled them, excepting As, fluoride, chloride and sulphate in unfired specimens. Thus, the potential environmental risk in relation to the leaching behaviour associated to the sintered contaminated marine sediments can be considered to be low versus to commercial clay. | This work was conducted under the framework of the Spanish Ministry of Education and Science Projects CTM 2005-07282-C03/3 and CTM 2006-07960. R. Alonso-Santurde was funded by the Spanish Ministry of Education and Science by means of an F.P.I. fellowship.

Fluoride, a common phytotoxic air, water and soil pollutant is commonly released to the environment by a number of industrial processes. Agricultural soils high in fluoride are common due to long term accumulation of fluoride from multi-sources and extensive application of phosphate fertilizers. The effect of sodium fluoride (0, 50,100,150 mM) on growth, pigments content, changes in biochemical parameters, along with fluoride and other ions accumulation was investigated in Salicornia brachiata grown in solution cultures under controlled conditions. With fluoride treatment growth as fresh or dry mass accumulation increased marginally. However, higher concentrations decreased the biomass and shoot tip became blunt; margin of the shoot changed its colour to reddish brown and developed necrotic spots. Photosynthetic pigments (chlorophylls and carotenoids) content decreased, while, anthocyanin content increased significantly with fluoride treatment. Peroxidase (POX), superoxide dismutase (SOD), ATPase and acid phosphate activities were negatively regulated. In addition F-, Na⁺, Mn²⁺ and Fe²⁺ ions concentration increased while, K⁺, Ca²⁺ and Mg²⁺ contents decreased with fluoride treatment. To our knowledge this is the first report on fluoride tolerance in a marshy halophytes using as high as 150 mM concentration and the results suggest that S. brachiata is a moderately fluoride tolerant annual halophyte and may be useful to vegetate the fluoride contaminated marshy lands.

POPs are still a priority environmental problem, but can be used as a scientific tool for understanding the distribution phenomena. Both high mountains and polar areas are seen as priority zones for contamination studies. In this context, two altitudinal series of soil samples were analysed for several classes of Persistent Organic Pollutants (PCBs, DDTs, HCHs, HCB and chlordane). Two transects were carried out - one in the Peruvian Andes (Cordillera Blanca) and the other in the Italian Alps (Mount Legnone). In these two areas, POP composition and levels both gave different results, linked to regional emission history. The Italian samples were characterized by high levels of industrial type compounds, and by surprisingly high DDT contamination, due to a defined consistent local source in Northern Italy. The Peruvian samples, on the other hand, were characterized by generally low POP levels with relatively high DDT contamination. The concentration increase in line with elevation was evident only in the Italian transect, where higher precipitation intensities and an increasingly higher precipitation gradient in accordance with altitude was found present. Precipitations are considered a key factor for enhancing the condensation effect at high altitudes and for reducing summer revolatilisation, as they lower soil temperature. In the Italian altitudinal gradient, evidence of fractionation processes, with a shift of the PCB composition towards less chlorinated congeners, and a vegetation effect with a mean woodland/grassland enrichment factor between 2 and 4 were also observed.

Land disposal of treated human and animal effluent through pumice sand soils is a common practice around Rotorua, in the central North Island of New Zealand. There is increasing concern about the possibility of contamination of shallow pumice sand aquifers associated with this practice. In this study, we investigated the transport and attenuation of F-RNA bacteriophages and Escherichia coli in saturated pumice sand aquifer media using a field tracing experiment, and laboratory batch and column studies. The influence of dissolved organic carbon on microbial transport was also investigated by conditioning the 18 cm-long column with ultrafiltered sewage. The CXTFIT curve-fitting program was used to model the experimental data and to determine transport and attenuation parameters. Batch studies showed more than 90% adsorption of both microbial indicators onto pumice sand. High mass removal of microbial indicators was shown in the field (>99% for phage MS2 and E. coli at 2 m down gradient of the injection well; not detected at 6 m) and in the 'clean sand' column (65% for phage MS2 and 90% or E. coli). These results suggest that uncontaminated pumice is an effective sorbent capable of retaining microbial contaminants due to high surface area and porosity. However, in the column, with additional dissolved organic carbon, phages showed a progressive reduction in mass removal and retardation between experiments (93%, 75%, and 63% removal; retardation factor: 3.5, 2.5 and 1.2). This suggests that the organic matter competed with phages for the sorption sites, thus promoting phage transport. As a result, viral transport rates may be significantly greater in contaminated compared with uncontaminated pumice sand aquifers.

The geochemical characteristics of rills draining pyrite-chalcopyrite tailings impoundments and of bordering streams were investigated at the ophiolite-hosted Libiola and Vigonzano abandoned massive sulphide mines, northern Apennines Italy. Water samples were analysed for major and trace chemical composition, hydrogen and oxygen isotope composition, and sulphur isotope composition of aqueous sulphate. Sulphur isotope composition was determined also for some samples of ore sulphides. At Libiola, the newly acquired chemical results on waters corroborate those from previous investigations, thus providing additional support to existing geochemical models in terms of metal distribution, solid phases precipitation, reaction path modelling and mixing reaction paths, and environmental problems. At Vigonzano, the chemical characteristics of waters are similar to those at Libiola. In both localities, solution-secondary phase equilibria estimated using an updated thermodynamic dataset account for mineralogy in the field, including poorly crystalline phases like jurbanite and hydrowoodwardite. The hydrogen and oxygen isotope composition of waters at Libiola and Vigonzano agrees with their meteoric origin. Acid to neutral mine waters do not show any significant isotope shift with respect to the initial water, in spite of the oxidation of even large amounts of pyrite/chalcopyrite ore. The sulphur isotope composition of aqueous sulphate in mine rills at Libiola (δ ³⁴S = 5.6 to 8.5[per thousand]; mean 6.5[per thousand]) matches that of massive sulphide ore (δ ³⁴S = -0.5 to 6.7[per thousand]; mean 5.8[per thousand]), in keeping with the supergenic origin of the sulphate and related isotope effects in the sulphide oxidation process. Sulphate in mine waters at Vigonzano displays lower δ ³⁴S values in the range 0.6 to 1.5[per thousand]. The δ ³⁴S signature of massive ore specimens is within the range reported for most volcanic-hosted massive sulphide deposits, including Cyprus-type deposits.

The aim of this in situ study was to investigate the fatty acid (FA) composition and content in roots and shoots of Lolium perenne and Trifolium repens, grown under heavy metal stress (Cd, Pb, Zn). The composition of FA was quite similar for the two plants and the two organs; main FA were palmitic acid (C16:0), oleic acid (C18:1), linoleic acid (C18:2) and linolenic acid (C18:3). For both plants, the major FA that characterized the roots was C18:2 whereas C18:3 was the prominent FA in shoots. For the first sampling (S1), in the roots of L. perenne and T. repens, polyunsaturated fatty acids (PUFA) were affected by metal contamination while, in the second sampling (S2), PUFA were affected in the shoots of the two plants. This alteration of PUFA was well correlated with the bioaccumulation factor of metals which decreased in roots and increased in shoots with the time. Moreover, a positive correlation was found between the PUFA decrease and the malondialdehyde (MDA) content, indicating the occurrence of a lipid peroxidation induced by the metal stress.

The commonly used plastic softener, di (2-ethylhexyl) phthalate (DEHP), also a known Endocrine Disrupting Compound, was found contaminated in various aquatic environments, including river water in Thailand. The data of adsorption kinetics from this study indicated that DEHP can adsorb onto pure bentonite and natural suspended sediment with average adsorption rate constants of 0.0056 and 0.0039 min⁻¹ respectively. The average distribution coefficients between suspended particles and water found in this study for pure bentonite and natural suspended sediment were 0.045 and 0.043 l g⁻¹ respectively. Although the studies were carried out in pH 4.0, 7.0 and 10.0, there were no obvious influences of pH on adsorption rates and distribution coefficients of DEHP onto both pure bentonite and natural suspended particles. The desorption rate was very small and was estimated to be less than 0.03 μg min⁻¹. The results indicated that suspended sediment could become a long term release of DEHP and facilitate the transport of DEHP mainly due to fast adsorption rate and relatively high adsorption capacity.

Eight soils from the Gulf of Kalloni in Lesvos Island, Greece, most of which were of low clay and low organic matter content, were used in a series of leaching experiments. The aim was to investigate the role of sewage sludge on Zn leaching and determine the soil properties that affect it. It was found that sludge addition at a low application rate (10 t ha⁻¹) decreased Zn leaching significantly by 30%. From a regression analysis it was found that eluted Zn was reduced with increasing Fe oxides content, probably due to Zn adsorption onto them, and that Zn transport increased with clay content. This indicates that Zn leaching was facilitated by the downward movement of clay particles, which was also suggested by the erratic Zn breakthrough observed in many soils. This was further confirmed by the fact that colloid concentrations increased with clay content in the soils (R = 0.85, P < 0.05). The results show that the addition of sewage sludge to low organic matter and clay content soils at moderate application rates enhances soil organic carbon and increases metal retention capacity.

Laboratory experiments were carried out to examine the effects of chelating agents on heavy metal extraction from slightly contaminated dredged sediments from the port of Livorno (Italy). Ethylene diamine tetraacetate (EDTA), citric acid (CA) and humic substances (HS) were tested in two different concentrations each: 120 and 480, 500 and 2,000, 500 and 1,000 mg/l, respectively. Solubilisation of heavy metals (Cu and Zn) was observed for both EDTA and HS in the extraction kinetic experiments: 58% of the total Cu and 50% of the total Zn in the sediment were mobilised from the solid matrix using EDTA (480 mg/l) and 32% of the total Cu and 5% of the total Zn, using HS (1,000 mg/l). It was observed that solubilized metal levels were positively related to the chelating agent concentration. HS performance in the heavy metals mobilisation and phyto-toxicity tests was considered promising. HS represent an innovation in enhanced phytoextraction techniques: they can be considered an environmentally non-impacting bio-agronomic amendment. CA induced no significant effects on heavy metal mobilisation and it also negatively affects seed germination (Germination Index < 40%). Laboratory experiments with plants showed that none of the treatments significantly affected the biomass production and a trend could only be detected for the heavy metal uptake into shoots of Paspalum vaginatum sp. Transplantation of seashore paspalum is useful as a pre-treatment of contaminated dredged sediments, since it is a salt-tolerant species and it can be easily adaptable on a nutrient poor and fine textured medium.

Phytoremediation is a method in which plants, soil microorganisms, amendments, and agronomic techniques interact to enhance contaminant degradation. We hypothesized that bermudagrass (Cynodon dactylon L) and an appropriate amount of N fertilizer would improve remediation of pyrene-contaminated Captina silt loam soil. The soil was contaminated with 0 or 1,000 mg pyrene/kg of soil and amended with urea at pyrene-C:urea-N (C:N) ratios of 4.5:1, 9:1, 18:1, or unamended (36:1). Either zero, one, two, or three bermudagrass sprigs were planted per pot and -33 kPa moisture potential was maintained. Pyrene concentrations, inorganic-N levels, shoot and root parameters, and pyrene degrader microbial numbers were measured following a 100-day greenhouse study. At a C:N ratio of 4.5:1, the presence of plants increased pyrene biodegradation from 31% for the no plant treatment to a mean of 62% for the one, two, and three plant treatments. With no plants and C:N ratios of 4.5:1, 9:1, 18:1, and 36:1, the mean pyrene biodegradation was 31, 52, 77, and 88%, respectively, indicating that increased inorganic-N concentration in the soil reduced pyrene degradation in the treatments without plants. Additionally, none of the one, two, or three plant treatments at any of the C:N ratios were different with a mean pyrene degradation value of 69% after 100 days. Pyrene resulted in reduced shoot and root biomass, root length, and root surface area, but increased root diameter. The pyrene degrading microbial numbers were approximately 10,000-fold higher in the pyrene-contaminated soil compared to the control. At the highest N rate, bermudagrass increased pyrene degradation compared to the no plant treatment, however, in the unvegetated treatment pyrene degradation was reduced with added N.