Total topsoil 50th percentile Cu, Pb and Zn concentrations (n = 491) in the Sydney estuary catchment were 23 μg g−1, 60 μg g−1 and 108 μg g−1, respectively. Nine percent, 6% and 25% of samples were above soil quality guidelines, respectively and mean enrichment was 14, 35 and 29 times above background, respectively. Soils in the south-eastern region of the catchment exhibited highest metal concentrations. The close relationship between soil metal and road network distributions and outcomes of vehicular emissions modelling, strongly suggested vehicular traffic was the primary source of metals to catchment soils. Catchment soil and road dust probably make an important contribution to contamination of the adjacent estuary. The concentration of soil metals followed the land use trend: industrial > urban > undeveloped areas. A high proportion (mean 45%, 62% and 42%, for Cu, Pb and Zn, respectively) of metals in the soils may be bioavailable.

Identifying the factors responsible for the diversity of responses of biota to industrial pollution is crucial for predicting the fates of polluted ecosystems. A meta-analysis based on 49 field studies conducted around 47 point polluters demonstrated that the individual (growth and reproduction) and community (abundance and species richness) characteristics of bryophytes in polluted habitats are reduced to about a half of the values observed in unpolluted sites. Non-ferrous smelters cause a stronger reduction in species richness and larger changes in species composition than other types of polluters. The magnitudes of the effects of pollution on the abundances of individual bryophyte species are not linked with their taxonomic position, life form or Ellenberg indicator values for light, moisture and nitrogen. The variation in species’ responses to pollution is mostly explained by differences in their reproductive characteristics; bryophyte species that possess special forms of vegetative reproduction and those that produce abundant sporophytes are more successful in polluted habitats. Ranking of bryophyte species according to their sensitivity to pollution is independent of the type of the polluter. Changes in bryophyte cover follow changes in tree cover, but not changes in the cover of the vascular field layer in the same pollution gradients. Pollution impacts cause stronger adverse effects on bryophytes in warmer climates.

Non-destructive measurements of contaminated soil core samples are desirable prior to destructive measurements because they allow obtaining gross information from the core samples without touching harmful chemical species. Medical X-ray computed tomography (CT) and time-domain low-field nuclear magnetic resonance (NMR) relaxometry were applied to non-destructive measurements of sandy soil core samples from a real site contaminated with heavy oil. The medical CT visualized the spatial distribution of the bulk density averaged over the voxel of 0.31 × 0.31 × 2 mm³. The obtained CT images clearly showed an increase in the bulk density with increasing depth. Coupled analysis with in situ time-domain reflectometry logging suggests that this increase is derived from an increase in the water volume fraction of soils with depth (i.e., unsaturated to saturated transition). This was confirmed by supplementary analysis using high-resolution micro-focus X-ray CT at a resolution of ∼10 μm, which directly imaged the increase in pore water with depth. NMR transverse relaxation waveforms of protons were acquired non-destructively at 2.7 MHz by the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence. The nature of viscous petroleum molecules having short transverse relaxation times (T2) compared to water molecules enabled us to distinguish the water-saturated portion from the oil-contaminated portion in the core sample using an M ₀-T2 plot, where M ₀ is the initial amplitude of the CPMG signal. The present study demonstrates that non-destructive core measurements by medical X-ray CT and low-field NMR provide information on the groundwater saturation level and oil-contaminated intervals, which is useful for constructing an adequate plan for subsequent destructive laboratory measurements of cores.

The global cycle of mercury (Hg) is reasonably well-understood, as are some of the natural and anthropogenic sources of Hg to the atmosphere. Less well understood are the regional and local characteristics of Hg deposition and subsequent watershed-scale transport, important parameters for assessing human risk to various avenues of Hg exposure. This study employed a two-part strategy for understanding coupled deposition and transport processes in central Indiana (USA), including Indianapolis, a typical large city with multiple coal-fired electric utilities and other Hg emission sources. A spatial analysis of Hg concentrations in surface soils revealed elevated Hg proximal to many of the large emission sources, with a distribution aligned along a southwest-northeast axis corresponding to the mean wind direction in this region. This soil distribution suggests some local depositional impact from local utilities, with wind modification affecting the regional pattern. Post-depositional transport of Hg was assessed using a series of streambank sampling arrays as the White River and various tributaries travelled through the urban core of Indianapolis. Streambank sediments had peak Hg concentrations in the urban core, where several local sources are present and where a number of subwatersheds join the main trunk of the White River, suggesting local emission and/or rapid Hg transport from urban subwatersheds due to their relatively high proportion of impervious surfaces. High Hg values persist in White River sediments into rural areas tens of kilometers south of Indianapolis, raising concerns for anglers collecting fish in this apparently “pristine” environment.

Assessment of native plants and laboratory-scale phytoextraction tests are fundamental and preliminary steps in checking the feasibility and practice of low-cost and low-impact phytoremediation. In this study, we investigated the absorption of B by plants as a tool to remove boron in sediments from different areas of the Cecina River basin in Tuscany, Italy. The investigation was performed analyzing total and available B fraction in sediment samples as well as the B content in different tissues of native plants colonizing the contaminated areas. In laboratory scale, a phytoextraction screening test was performed. Selected high biomass crops (Brassica juncea, Zea mays, and Helianthus annuus) were evaluated in the most contaminated sample in two consecutive growing cycles. Results from field survey showed no hyperaccumulator native plant was present in the investigated areas although, high accumulation levels were found in native species from Bulera dump (Rumex crispus—259 mg kg−1 and Poa spp—203 mg kg−1). Results from laboratory phytoextraction tests showed a higher ability of B. juncea which removed about 18.5 mg B kg−1 sediment in after the two consecutive growing cycles, representing on the whole 45% of the initial available B fraction. The sediment characteristics affected by the phytoextraction processes were also discussed.

Diffused petroleum and chlorinated hydrocarbon contamination was detected in a sandy aquifer below a chemical plant in Southern Italy. The contamination was due to underground leaking tanks and pipes. The site is located near the shore line and is bordered by canals which, in combination with pumping wells, control the groundwater flow direction toward the sea. In this study, a comprehensive three-dimensional flow model was developed and calibrated to simulate the general groundwater flow system and to individuate a flow line. On this latter, a detailed field investigation was performed in order to determine the fate of dissolved hydrocarbons. Depth profiles obtained from multi-level samplers located along the modelled flow line, including measurements of hydrocarbons, all major ions and dissolved gasses, were used to constrain the conceptual model. These data were then included into a two-dimensional transport model in order to verify the efficacy of the hydraulic barrier (HB) in preventing the hydrocarbon plume to reach the shore line. Two different approaches were used in the transport simulation, one accounting for density-dependent flow and the other not. The calibrated models show that the plume length and consequently, the submarine groundwater discharge of contaminants is slightly different for the two approaches. For the simulation not accounting for the density contrast between freshwater and saltwater, the mass of contaminant discharged downstream to the HB was underestimated and also the reconstructed plume geometry was different than the observed. Moreover, the reconstruction of the saltwater intrusion interface (SWII) with the two different approaches was substantially different. This study demonstrates that at field site, variable density processes should be carefully taken into account not only when the modelling is devoted to the reconstruction of the SWII but also when the modelling is targeting the fate of hydrocarbons at sites affected by SWII, in order to provide accurate data on which soundly environmental management of the coastal zone can be based.

Humic substances are characterized by a strong binding capacity for both metals and organic pollutants, affecting their mobility and bioavailability. The understanding of the mechanisms of proton and metal binding to humic substances is of fundamental importance in geochemical modelling and prediction of cation speciation in the environment. This work reports results on copper binding on humic acids obtained through a thorough experimental and modelling approach. Two humic acids, a reference purified peat humic acid isolated by the International Humic Substances Society (IHSS) and a humic acid from a Greek soil, were experimentally studied at various pH values (4, 6 and 8), humic acid concentrations (ranging from 20 to 200 mg L−1) and ionic strength (0.1 and 0.01 M NaNO3). The binding of copper to humic acids was determined over wide ranges of copper ion concentrations using a copper ion selective electrode. The copper binding isotherms obtained at different conditions have shown that copper binding is dependent on the pH and ionic strength of the solution and on the concentration of both humic acids. Copper binding experimental data were fitted to non-ideal competitive adsorption NICA-Donnan model and the model parameter values were calculated. Both Cu2+ and CuOH+ species binding to humic acid with different binding affinities were considered. Two sets of the NICA-Donnan parameters have been calculated: one for humic acid concentrations of ≥100 mg L−1and one for humic acid concentration of 20 mg L−1. The meaning of the parameters values for each concentration level is also discussed.

Fungicides are used to prevent foliar diseases on a wide range of vegetable, field, fruit, and ornamental crops. They are generally more effective as protective rather than curative treatments, and hence tend to be applied before infections take place. Less than 1% of US soybeans were treated with a fungicide in 2002 but by 2006, 4% were treated. Like other pesticides, fungicides can move-off of fields after application and subsequently contaminate surface water, groundwater, and associated sediments. Due to the constant pressure from fungal diseases such as the recent Asian soybean rust outbreak, and the always-present desire to increase crop yields, there is the potential for a significant increase in the amount of fungicides used on US farms. Increased fungicide use could lead to increased environmental concentrations of these compounds. This study documents the occurrence of fungicides in select US streams soon after the first documentation of soybean rust in the US and prior to the corresponding increase in fungicide use to treat this problem. Water samples were collected from 29 streams in 13 states in 2005 and/or 2006, and analyzed for 12 target fungicides. Nine of the 12 fungicides were detected in at least one stream sample and at least one fungicide was detected in 20 of 29 streams. At least one fungicide was detected in 56% of the 103 samples, as many as five fungicides were detected in an individual sample, and mixtures of fungicides were common. Azoxystrobin was detected most frequently (45% of 103 samples) followed by metalaxyl (27%), propiconazole (17%), myclobutanil (9%), and tebuconazole (6%). Fungicide detections ranged from 0.002 to 1.15 μg/L. There was indication of a seasonal pattern to fungicide occurrence, with detections more common and concentrations higher in late summer and early fall than in spring. At a few sites, fungicides were detected in all samples collected suggesting the potential for season-long occurrence in some streams. Fungicide occurrence appears to be related to fungicide use in the associated drainage basins; however, current use information is generally lacking and more detailed occurrence data are needed to accurately quantify such a relation. Maximum concentrations of fungicides were typically one or more orders of magnitude less than current toxicity estimates for freshwater aquatic organisms or humans; however, gaps in current toxicological understandings of the effects of fungicides in the environment limit these interpretations.

In this study, the photocatalytic degradation of commercial azo dye (Remazol Red 133) in the presence of titanium dioxide (TiO2) suspensions as photocatalyst was investigated. The effect of various operational parameters, such as pH of dye solution and catalyst concentration on the photocatalytic degradation process, was examined. The mineralization of dye was also evaluated by measuring the chemical oxygen demand of the dye solutions. The extent of photocatalytic degradation was found to increase with increasing TiO2 concentration. For the Remazol Red dye solutions, a 120-min treatment resulted in 97.9% decolorization and 87.6% degradation at catalyst loading of 3 g/L. Experiments using real textile wastewater were also carried out. Textile wastewater degradation was enhanced at acidic conditions. The decolorization and degradation efficiencies for textile wastewater were 97.8% and 84.9% at pH 3.0, catalyst loading of 3 g/L, and treatment time of 120 min.

This research study used sewage sludge from urban wastewater treatment plants to restore road embankments. The results have been used to propose a series of basic principles for the application of sludge in this context. In the study, six experimental plots (each composed of one cut slope and one fill slope) were set up on a highway located in the province of Jaen (Spain). The soil and vegetation in the plots were restored by a conventional hydroseeding process, with each plot receiving a different sludge dosage. A control plot did not receive any treatment at all, whereas another plot was hydroseeded, but without any sludge added to the slurry mix. In the plots, soil evolution was controlled from the moment that the embankment was created and hydroseeded until the present. As part of the soil monitoring process, agronomic parameters and the heavy metal content of the soil were analyzed in the laboratory. Another parameter of analysis was the vegetation cover, which was studied on the basis of on-site visual inspections and the rasterization of images with a view to calculate the percentage of vegetation cover on each plot. Results showed the effectiveness of sewage sludge as an organic complement in the restoration of road embankments. Its viability is enhanced by the fact that the sludge can be applied with the same methods used in public highway construction. The results also showed the optimal sludge dosage to be used in the slurry mix during the hydroseeding process.