Assessment of the phytoextraction potential of high biomass crop plants

A hydroponic screening method was used to identify high biomass crop plants with the ability to accumulate metals. Highest values of shoot accumulation were found in maize cv. Ranchero, rapeseed cv. Karat, and cardoon cv. Peralta for Pb (18 753 mg kg(-1)), Zn (10 916 mg kg(-1)), and Cd (242 mg kg(-1)), respectively. Subsequently, we tested the potential of these three cultivars for the phytoextraction of a metal spiked compost, finding out that, in cardoon and maize plants, increasing Zn and Cd concentrations led to lower values of root and shoot DW. By contrast, rapeseed shoot growth was not significantly affected by Cd concentration. Finally, a metal polluted soil was used to check these cultivars' phytoextraction capacity. Although the soil was phytotoxic enough to prevent the growth of cardoon and rapeseed plants, maize plants phytoextracted 3.7 mg Zn pot(-1). We concluded that the phytoextraction performance of cultivars varies depending on the screening method used.     

Effect of mono-ortho and di-ortho substituted polychlorinated biphenyl (PCB) congeners on leopard frog survival and sexual development

We tested the effect of mono-ortho and di-ortho PCB congeners on northern leopard frog (Rana pipiens) hatching success, survival and sexual development. Embryos and tadpoles were exposed to two levels (0.5 and 50 microg/l) of two PCBs. PCBs 101 and 70 were selected because they were present in amphibians collected in the Fox River-Green Bay ecosystem and they have the theoretical structural requirements to be able to bind to the estrogen receptor and mediate estrogenic responses. The exposure of leopard frog embryos and tadpoles to PCB 70 and 101 did not significantly affect hatchability, survival, deformities or growth. There were significant departures from the expected 50:50 sex ratio in tadpoles/froglets exposed to PCB 101 and PCB 70. In all the cases of significant departure, the bias was towards higher number of females. Decrease in the proportion of male gonads and increase in the proportion of intersex gonads were observed with increasing PCB tissue concentrations. The effects of PCB congeners on sexual differentiation occur at concentrations higher than observed in frogs in the Fox River/Green Bay ecosystem.     

Multiscale analysis of heavy metal contents in Spanish agricultural topsoils

This study characterized and mapped the spatial variability patterns of seven topsoil heavy metals (Cr, Ni, Pb, Cu, Zn, Hg and Cd) within the Ebro river basin (9.3 million ha) by Multivariate Factorial Kriging. The variograms and cross-variograms of heavy metal concentrations showed the presence of multiscale variation that was modeled using three variogram models with ranges of 20km (short-range), 100km (medium-range) and 225km (long-range). Our results indicate that the heavy metal concentration is influenced by bedrock composition and dynamics at all the spatial scales, while human activities have a notorious effect only at the short- and medium-range scale of variation. Sources of Cu, Pb and Zn (and secondary Cd) are associated with agricultural practices (at the short-range scale of variation), whereas Hg variation at the short- and medium-range scale of variation is related to atmospheric deposition.     

Genotoxicity detected in wild mice living in a highly polluted wetland area in south western Spain

A field study was carried out in the south of the Iberian Peninsula in an industrial area in the neighbourhood of Huelva city, SW Spain, and in a natural area (Do?ana National Park) for comparison, to estimate the genetic risk induced by environmental pollution in wild mice. Genotoxic effects in a sentinel organism, the Algerian mice (Mus spretus) free living in the industrial area were compared with animals of the same species living in the natural protected area. The single cell gel electrophoresis, or Comet assay, was performed as a genotoxicity test in peripheral blood of mice. Our results clearly show that mice free living in the contaminated area bear a high burden of genetic damage as compared with control individuals. The results suggest that the assessing of genotoxicity levels by the Comet assay in wild mice can be used as a valuable test in pollution monitoring and environmental conservation.     

Analysis of perfluorooctanoate (PFOA) and other perfluorinated compounds (PFCs) in the River Po watershed in N-Italy

C7-C11 perfluorinated carboxylates (PFACs) and perfluorooctansulfonate (PFOS) were analysed in selected stretches of the River Po and its major tributaries. Analyses were performed by solid-phase extraction (SPE) with Oasis HLB cartridges and methanol elution followed by LC-MS-MS detection using 13C-labelled internal standards. High concentration levels ( approximately 1.3 microg l(-1)) of perfluorooctanoate (PFOA) were detected in the Tánaro River close to the city Alessandria. After this tributary, levels between 60 and 337 ng l(-1) were measured in the Po River on several occasions. The PFOA concentration close to the river mouth in Ferrara was between 60 and 174 ng l(-1). Using the river discharge flow data in m3 s(-1) at this point (average approximately 920 m3 s(-1) for the year 2006), a mass load of approximately 0.3 kg PFOA per hour or approximately 2.6 tons per year discharged in the Adriatic Sea has been calculated. PFOS concentration levels in the Po River at Ferrara were approximately 10 ng l(-1).     

Traffic and catalytic converter - related atmospheric contamination in the metropolitan region of the city of Rio de Janeiro, Brazil

In this work, 24-h PM10 samples were collected in Rio de Janeiro, Brazil, and analysed for trace elements (Cd, Ce, Cu, La, Mo, Ni, Pb, Pd, Rh, Sb and Sn). The sampling was carried out at five locations (Bonsucesso; Centro, downtown city; Copacabana; Nova Igua?u and Sumaré) with different traffic densities and anthropogenic activities. An analytical method based on the EPA method for the determination of trace elements in airborne particulate matter (PM), using ultrasonic-assisted extraction and inductively coupled plasma mass spectrometry (ICP-MS) was applied. Our results suggest that vehicular traffic is the most important source of environmental pollution at the studied sites. The presence of Mo, Pd and Rh in the analysed filters reflects an additional source of pollution caused by the erosion and deterioration of automotive catalytic converters.     

Mineralization of the biocide chloroxylenol by electrochemical advanced oxidation processes

Electrochemical advanced oxidation processes (EAOPs) are environmentally friendly methods based on the destruction of organic pollutants in wastewaters with in situ electrogenerated hydroxyl radical. This species is formed in anodic oxidation (AO) from water oxidation at the anode and in indirect electro-oxidation methods like electro-Fenton (EF) and photoelectro-Fenton (PEF) also from reaction between catalytic Fe2+ and H2O2 continuously produced at the O2-diffusion cathode. The PEF method involves the irradiation of the treated solution with UVA light to enhance the photolysis of organics including Fe(III) complexes. In this work, the oxidation power of such EAOPs to decontaminate synthetic wastewaters of the biocide chloroxylenol (4-chloro-3,5-dimethylphenol) at pH 3.0 is comparatively examined with an undivided electrolytic cell containing a Pt or boron-doped diamond (BDD) anode and a stainless steel or O2-diffusion cathode. The initial chlorine is released as Cl(-) ion, which remains stable in the medium using Pt or is oxidized to Cl2 on BDD. The biocide solutions can be completely decontaminated using AO with a BDD anode, as well as PEF with a Pt or BDD anode. The PEF procedure with a BDD anode is the most powerful method leading to total mineralization in about 300 min, practically independent of current density. When current density rises, the degradation rate of processes increases, but they become less efficient due to the larger enhancement of waste reactions of oxidants. Chloroxylenol is much more rapidly removed in EF and PEF than in AO. 2,6-dimethylhydroquinone, 2,6-dimethyl-p-benzoquinone and 3,5-dimethyl-2-hydroxy-p-benzoquinone are identified as aromatic by-products, and maleic, malonic, pyruvic, acetic and oxalic acids are found as generated carboxylic acids. A general pathway for chloroxylenol mineralization by all EAOPs including the above by-products is proposed.     

A model for estimating the potential biomagnification of chemicals in a generic food web: Preliminary development

GOAL, SCOPE AND BACKGROUND: Bioaccumulation and biomagnification of organic pollutants have been increasingly assessed and modeled during the last years. Due to the complexity of these processes and the large variability of food webs, setting generic assessments for these parameters is really difficult. Equilibrium models, based on a compound's lipophylicity, are the main tool in regulatory proposals, such as for identifying Persistent, Bioaccumulative and Toxic Substances (PBTs), although a refinement has been claimed by the scientific community. Toxicokinetic studies offer an alternative for these estimations, where biomagnification is modeled as a succession of bioaccumulation processes, each one regulated by toxicokinetic parameters. METHODS: A review of kinetic models covering species belonging to different trophic levels and with different ecological behavior has been conducted. The results were employed for setting a conceptual model for estimating the biomagnification potential in a generic food web, which was mathematically implemented through system dynamic models developed under data sheet software. Crystal Ball was then employed for allowing Monte Carlo based probabilistic calculations. Bioaccumulation laboratory assays have been performed to estimate toxicokinetic parameters in mussels (Mytilus edulis) with two PAHs (chrysene and benzo[a]pyrene). The contamination was delivered via food. The exposure period lasted more than one month followed then by a depuration phase. The contaminant content was determined on an individual basis on five replicates. RESULTS AND DISCUSSION:. The reviewed information suggested the development of a tiered conceptual biomagnification model, starting with a simplified food chain which can be refined to more realistic and complex models in successive levels. CONCLUSIONS: The mathematical implementation of the conceptual model offers tools for estimating the potential for bioaccumulation and biomagnification of chemicals under very different conditions. The versatility of the model can be used for both comparative estimations and for validating the model. RECOMMENDATIONS AND PERSPECTIVES: Since bioaccumulation and biomagnification processes are crucial elements for a proper risk assessment of chemicals, their estimation by mathematical models has been widely tested. However, inregulatory assessments, too simplistic models are still being used quite often. The biomagnification model presented in this study should be amore accurate alternative to these models. In comparison to other previously published biomagnification models, the present one covers the time variation of bioaccumulation using just a few toxicokinetic parameters.     

Levels of perfluorochemicals in water samples from Catalonia,Spain: is drinking water a significant contribution to human exposure?

Background, aim, and scope  In recent years, due to a high persistence, biomagnification in food webs, presence in remote regions, and potential toxicity, perfluorochemicals (PFCs) have generated a considerable interest. The present study was aimed to determine the levels of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and other PFCs in drinking water (tap and bottled) and river water samples from Tarragona Province (Catalonia, Spain). Materials and methods  Municipal drinking (tap) water samples were collected from the four most populated towns in the Tarragona Province, whereas samples of bottled waters were purchased from supermarkets. River water samples were collected from the Ebro (two samples), Cortiella, and Francolí Rivers. After pretreatment, PFC analyses were performed by HPLC-MS. Quantification was done using the internal standard method, with recoveries between 68% and 118%. Results  In tap water, PFOS and PFOA levels ranged between 0.39 and 0.87 ng/L (0.78 and 1.74 pmol/L) and between 0.32 and 6.28 ng/L (0.77 and 15.2 pmol/L), respectively. PFHpA, PFHxS, and PFNA were also other detected PFCs. PFC levels were notably lower in bottled water, where PFOS could not be detected in any sample. Moreover, PFHpA, PFHxS, PFOA, PFNA, PFOS, PFOSA, and PFDA could be detected in the river water samples. PFOS and PFOA concentrations were between <0.24 and 5.88 ng/L (<0.48 and 11.8 pmol/L) and between <0.22 and 24.9 ng/L (<0.53 and 60.1 pmol/L), respectively. Discussion  Assuming a human water consumption of 2 L per day, the daily intake of PFOS and PFOA by the population of the area under evaluation was calculated (0.78–1.74 and 12.6 ng, respectively). It was found that drinking water might be a source of exposure to PFCs as important as the dietary intake of these pollutants. Conclusions  The contribution of drinking water (tap and bottled) to the human daily intake of various PFCs has been compared for the first time with data from dietary intake of these PFCs. It was noted that in certain cases, drinking water can be a source of exposure to PFCs as important as the dietary intake of these pollutants although the current concentrations were similar or lower than those reported in the literature for surface water samples from a number of regions and countries. Recommendations and perspectives  Further studies should be carried out in order to increase the knowledge of the role of drinking water in human exposure to PFCs.     

New metallothionein assay in Scrobicularia plana: heating effect and correlation with other biomarkers

Metallothionein (MT) and other biomarker levels were measured in Scrobicularia plana clams to assess pollution of the Guadalquivir Estuary possibly affected by metals released from Aznalcóllar pyrite mine in 1998. After optimizing reagent concentrations for monobromobimane derivatization, MT levels were quantified by reversed-phase high-performance liquid chromatography coupled to fluorescence detection (RP-HPLC-FD) in heated or unheated digestive gland extracts and compared to those obtained by differential pulse polarography (DPP). MT content assayed by RP-HPLC-FD in unheated samples was higher than that obtained by DPP and correlated better with metals and anti-oxidant activities. MT assay by RP-HPLC-FD in unheated extracts would be preferable for assessing metal pollution, due to its greater sensitivity and specificity. In addition to MT induction, glyoxalase II inhibition was well correlated with metal contents. Our results suggest that metals at the estuary do not originate from Aznalcóllar spill, but from those carried along by the river and deposited at its concave bank.