Riparian rehabilitation planning in an urban–rural gradient: Integrating social needs and ecological conditions

In the present context of global change and search for sustainability, we detected a gap between restoration and society: local communities are usually only considered as threats or disturbances when planning for restoration. To bridge this gap, we propose a landscape design framework for planning riparian rehabilitation in an urban–rural gradient. A spatial multi-criteria analysis was used to assess the priority of riversides by considering two rehabilitation objectives simultaneously—socio-environmental and ecological—and two sets of criteria were designed according to these objectives. The assessment made it possible to identify 17 priority sites for riparian rehabilitation that were associated with different conditions along the gradient. The double goal setting enabled a dual consideration of citizens, both as beneficiaries and potential impacts to rehabilitation, and the criteria selected incorporated the multi-dimensional nature of the environment. This approach can potentially be adapted and implemented in any other anthropic–natural interface throughout the world.     

Detection of organic pollutants in sandy soils via TDR and eigendecomposition

In this study, organic pollutants in sandy soils are detected using a time domain relectrometry (TDR) probe system and eigendecomposition technique. As a demonstration, four types of organic fluids (motor oil, diesel oil, methanol and ethanol) were examined. Samples were prepared with different combinations of deionized water and organic fluid contents. For each experiment, reflected signals were captured by an oscilloscope, and their characteristics were identified using eigendecomposition technique. Autoregressive modeling and singular value decomposition methods were utilized for calculating the eigenvalues. The most significant eigenvalues were then identified based on their relative magnitude. Experimental results indicated that the presented system is sensitive to both water and pore fluid organic contents. For saturated conditions, signature curves were determined for identification of organic and/or water contents in soil pore fluids.     

An integrated assessment of estrogenic contamination and biological effects in the aquatic environment of The Netherlands

An extensive study was carried out in the Netherlands on the occurrence of a number of estrogenic compounds in surface water, sediment, biota, wastewater, rainwater and on the associated effects in fish. Compounds investigated included natural and synthetic hormones, phthalates, alkylphenol(ethoxylate)s and bisphenol-A. The results showed that almost all selected (xeno-)estrogens were present at low concentrations in the aquatic environment. Locally, they were found at higher levels. Hormones and nonylphenol(ethoxylate)s were present in concentrations that are reportedly high enough to cause estrogenic effects in fish. Field surveys did not disclose significant estrogenic effects in male flounder (Platichthys flesus) in the open sea and in Dutch estuaries. Minor to moderate estrogenic effects were observed in bream (Abramis brama) in major inland surface waters such as lowland rivers and a harbor area. The prevalence of feminizing effects in male fish is largest in small regional surface waters that are strongly influenced by sources of potential hormone-disrupting compounds. High concentrations of plasma vitellogenin and an increased prevalence of ovotestes occurred in wild male bream in a small river receiving a considerable load of effluent from a large sewage treatment plant. After employing in vitro and in vivo bioassays, both in situ and in the laboratory, we conclude that in this case hormones (especially 17 alpha-ethynylestradiol) and possibly also nonylphenol(ethoxylate)s are primarily responsible for these effects.     

PM10-bound polycyclic aromatic hydrocarbons (PAHs) in the Greater Area of Athens, Greece

Polycyclic aromatic hydrocarbons (PAHs) associated to ambient PM10 were determined at four sites within the Greater Athens Area (GAA), Greece, during the period May 2001-June 2002. Daily average PM10 samples were collected using reference samplers installed in two urban locations (Maroussi, MAR and Aristotelous, ARI), a mixed urban-industrial location (Elefsina, ELE), and a background location (Thracomacedones, THR). Spatial and temporal variation of ambient PAH levels and possible relationships with conventional air pollutants and meteorological parameters were investigated. Moreover, source identification was attempted using diagnostic ratios. The PAH concentrations observed in this study, even in downtown Athens, were towards the lowest end of the range of values reported for other European urban locations. The mean concentration of the well known carcinogen B[alpha]Py was at all four sites below the proposed value of 1 ng m-3 (annual average assessment threshold). Automobile traffic was identified as the major PAH source in the GAA exhibiting greatest contribution in the urban sites.     

The evaluation of electrical energy per order (E(Eo)) for photooxidative decolorization of four textile dye solutions by the kinetic model

Photooxidative decolorization of four textile dyestuffs, C.I. Acid Orange 7 (AO7), C.I. Acid Orange 8 (AO8), C.I. Acid Orange 52 (AO52) and C.I. Acid Blue 74 (AB74), by UV/H2O2 was investigated in a laboratory scale photoreactor equipped with a 15 W low pressure mercury vapour lamp. The decolorization of the dyes was found to follow pseudo-first-order kinetics, and hence the figure-of-merit electrical energy per order (E(Eo)) is appropriate for estimating the electrical energy efficiency. The E(Eo) values were found to depend on the concentration of H2O2, concentration and basic structure of the dye. This study shows that these textile dyes can be treated easily and effectively with the UV/H2O2 process with E(Eo) values between 0.4 and 5 kW h m-3 order-1, depending on the initial concentrations of dyes and H2O2. The kinetic model, based on the initial rates of degradation, provided good prediction of the E(Eo) values for a variety of conditions.     

Bioavailability of contaminants estimated from uptake rates into soil invertebrates

It is often argued that the concentration of a pollutant inside an organism is a good indicator of its bioavailability, however, we show that the rate of uptake, not the concentration itself, is the superior predictor. In a study on zinc accumulation and toxicity to isopods (Porcellio scaber) the dietary EC(50) for the effect on body growth was rather constant and reproducible, while the internal EC(50) varied depending on the accumulation history of the animals. From the data a critical value for zinc accumulation in P. scaber was estimated as 53 microg/g/wk. We review toxicokinetic models applicable to time-series measurements of concentrations in invertebrates. The initial slope of the uptake curve is proposed as an indicator of bioavailability. To apply the dynamic concept of bioavailability in risk assessment, a set of representative organisms should be chosen and standardized protocols developed for exposure assays by which suspect soils can be evaluated.     

Enhancing bioremediation of diesel oil and gasoline in soil amended with an agroindustry sludge

This paper presents a study of the bioremediation of diesel oil and gasoline by a series of controlled laboratory tests. Sludge from an agroindustry was used to enhance bioremediation of both gasoline and diesel oil mixed with a soil mass to compare its efficiency with that of a mineral fertilizer. Effects of soil microbiology and soil mixtures were investigated by means of evolution of CO2, microorganism populations at 90 days, pH at 65 and 95 days, mineral nitrogen, and gas chromatographic analysis of the benzene, toluene, methyl tertiary butyl ether, C8, and C9+total aromatics at the end of the experiments. Treatments containing sludge showed better soil conditions after 170 days of treatment (inorganic nitrogen and microbiota activity) compared with gasoline and diesel oil without amendments. Samples had no detectable traces of the measured hydrocarbons at 170 days of treatment.     

Monitoring and toxicity of sulfonated derivatives of benzene and naphthalene in municipal sewage treatment plants

Monitoring benzenesulfonates (BS) and naphthalenesulfonates (NS) took place in five municipal sewage treatment plants (STP). A previously optimized method based on solid phase extraction with polymeric cartridges followed by ion-pair liquid chromatography-electrospray-mass spectrometry (SPE-IPC-ESI-MS) was used. This work confirmed the little or no effect of primary settlement on total organic carbon (TOC) and monosulfonated compounds removal, whereas the main reduction is obtained at the biological stage. However, the most polar compounds, such as naphthalenedisulfonates (NDS), were not effectively removed using the biological treatment. An aromatic sulfonated compound is suggested to be used as a tracer of the origin of industrial pollutants discharged into STPs. A bioluminescence inhibition test, Microtox assay, allowed toxicity determination of the most relevant aromatic sulfonated compounds detected and toxicity comparison between primary and secondary effluents.     

Temporal variation of trace metal geochemistry in floodplain lake sediment subject to dynamic hydrological conditions

Climate change and land use may significantly influence metal cycling in dynamic river systems. We studied temporal variation of sediment characteristics in a floodplain lake, including concentrations of dissolved organic carbon, acid volatile sulfide and trace metals. The sampling period included a severe winter inundation and a dramatic water level drop during summer. Temporal changes were interpreted using multivariate analysis and chemical equilibrium calculations. Metal concentrations in sediment increased with depth, indicating a gradual improvement of sediment quality. In contrast, dissolved metal concentrations were highest in top layers due to mobilization from oxyhydroxides and precipitation with sulfides in deeper layers. Inundation had a mobilizing effect as it stimulated resuspension and oxygenation of sediment top layers. Water table lowering combined with organic matter decomposition led to immobilization due to sulfide formation. The chemistry of the sediments was consistent with model calculations, especially for macro-elements. The results illustrate the importance of seasonality for metal risk assessment.     

Modeling mercury fluxes and concentrations in a Georgia watershed receiving atmospheric deposition load from direct and indirect sources

This paper presents a modeling analysis of airborne mercury (Hg) deposited on the Ochlockonee River watershed located in Georgia. Atmospheric deposition monitoring and source attribution data were used along with simulation models to calculate Hg buildup in the subwatershed soils, its subsequent runoff loading and delivery through the tributaries, and its ultimate fate in the mainstem river. The terrestrial model calculated annual watershed yields for total Hg ranging from 0.7 to 1.1 microg/m2. Results suggest that approximately two-thirds of the atmospherically deposited Hg to the watershed is returned to the atmosphere, 10% is delivered to the river, and the rest is retained in the watershed. A check of the aquatic model results against survey data showed a reasonable agreement. Comparing observed and simulated total and methylmercury concentrations gave root mean square error values of 0.26 and 0.10 ng/L, respectively, in the water column, and 5.9 and 1 ng/g, respectively, in the upper sediment layer. Sensitivity analysis results imply that mercury in the Ochlockonee River is dominated by watershed runoff inputs and not by direct atmospheric deposition, and that methylmercury concentrations in the river are determined mainly by net methylation rates in the watershed, presumably in wetted soils and in the wetlands feeding the river.