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The widespread use of ethylenediaminetetraacetic acid (EDTA) has requested an urgent monitoring program regarding surface and drinking water. Analyzing EDTA at low-level concentrations such as µg l in the environmental samples is quite complex using conventional methods. In this study, a simple, quick and sensitive capillary electrophoretic technique — large volume stacking using the EOF pump (LVSEP) — has been developed for determining EDTA in drinking water for the first time (EOF: electroosmotic flow). It is based on a precapillary complexation of EDTA with Fe(III) ions, followed by LVSEP and direct UV detection at 258 nm. The curve of peak response vs. concentration was linear between 5.0 and 600.0 µg l, as well as between 0.7 and 30.0 mg l. The regression coefficients were 0.9988 and 0.9990, respectively. The detection limit of current technique for EDTA analysis was 0.2 µg l with additional 10-fold preconcentration procedure, based on the signal-to-noise ratio of 3. As opposed to the classical capillary electrophoresis (CE) method, a 1 000-fold concentration factor could be smoothly achieved on this LVSEP method. To the best of our knowledge, it represents the highest sensitivity for EDTA analysis via CE. Several drinking water samples were tested by this novel method with satisfactory results.

A comprehensive collection, critical analysis and interpretation of the data published for complexation of trace metals by natural organic matter (refractory humic-type substances and non degraded biota material) and filtered whole natural waters have been undertaken. Our interpretation framework considers the role of metal loading conditions and analytical detection windows on the complexation data in a systematic way. Its application has shown that the same patterns are observed for complexation of a range of trace metals with different types of natural organic matter: apparently stronger binding sites are utilised at lower metal ion loadings, progressively weaker sites contribute to metal complexation at higher loadings. Taking into account the detection window of the technique employed greatly improves the internal consistency of the overall data. Despite the widely recognised role played by natural organic matter in trace metal fate in aquatic systems, and the enormous number of publications in this field, there is in fact very few data available for metals other than copper, and that were determined at environmentally relevant pH values and metal loading conditions. This situation hinders reliable determination of complexation parameters with predictive value.

A 33-amino acid peptide corresponding to the helix-turn-helix motif of the calcium binding site I of calmodulin has been synthesized and its binding loop stabilized by a specific disulphide bond. Analysed by electrospray mass spectrometry (ES-MS), circular dichroism (CD) and fluorescence, such a cyclic peptide is found to bind calcium, cadmium, terbium and europium ions with native-like affinity, and with 30±1 µM and 8±4 µM dissociation constants for calcium and cadmium ions, respectively. Metal binding induces an ordered conformation in the peptide, resembling that of the calmodulin site I. Interestingly, uranium, in the uranyl form, binds this peptide, as revealed by ES-MS, CD and fluorescence spectroscopy. Sequence mutation aiming to increase the binding cavity suppresses binding of calcium, cadmium and uranium ions, but preserves binding of lanthanide ions, showing that metal selectivity can be modulated by specific mutation in the binding loop. Such disulphide-stabilized peptide may represent a useful model to engineer new metal specificity in calmodulin variants. These novel proteins may be useful in the development of new biosensors to monitor metal pollution and to augment metal binding capability of bacterial and plant cells that can be used in biosorption techniques to (bio)remediate soils and waters contaminated by heavy metals.

Coal ash obtained by coal combustion in the "Nikola Tesla A" power plant in Obrenovac near Belgrade (Serbia) is suspended in river water then carried by a pipeline to a dump. In order to predict the leachability and possible environmental impact of selected elements due to ionic strength of river water, we extracted coal ash with distilled water and 0.002 M–2 M solutions of KNO. The results show that changes in river water ionic strength could significantly influence pollution by calcium, chromium and manganese ions, but not by zinc, nickel and copper ions. In the case of lead, magnesium, arsenic and iron ions it is difficult to predict the effects of ionic strength on pollution processes in the vicinity of the dump. Further, pollution by cadmium ions is unlikely because extractable cadmium is not detectable within the applied ionic strength range.

Extensive urbanization in Hawai’i, and Honolulu in particular, during the 20 century presents an opportunity to examine the effects thereof upon the storm-driven transfer of terrestrial material from the land to the ocean. This contribution focuses on the variability of Pb, Zn, Cu, Ba, Co, As, Ni, V, and Cr concentrations in streams during storm events in the small subtropical Ala Wai Canal Watershed in Honolulu, O’ahu. As expected, a comparison of metal loads for particulate and dissolved phases revealed the dominance of suspended particulate matter as a means of metal transport through the watershed. Particulate Pb, Zn, Cu, Ba, and Co displayed enhanced concentrations and elevated particulate loads during storm flow in the urbanized lower watershed. Enrichment of these metals likely derives from automotive or industrial-related sources. Agricultural fertilizer use in conservation areas, particularly the association of As with phosphate, appears to be responsible for an upper watershed enrichment of particulate As concentrations and loads. Storm-derived concentrations and loads of particulate Ni, V, and Cr exhibited a relative spatial invariance throughout the watershed, suggesting primarily mineralogical controls on their distributions. Principal components analysis (PCA) was applied to the particulate metal concentrations from samples collected in both the upper and lower portions of the watershed. PCA established eigenvalues explaining 77% of the total variance and separated particulate metals into two distinct factors. Factor 1 elements, including particulate Pb, Zn, Cu, Ba, and Co, were interpreted to represent metals exhibiting anthropogenic enrichment in the urban watershed. The association of particulate As, Ni, V, and Cr within Factor 2 likely denotes metals whose concentrations do not display enhancements in urban segments of the watershed. Examination of solid phase metal concentrations during a “Kona” storm (offshore low-pressure system) revealed that the downstream transport of relatively unimpacted upper watershed material during tradewind-derived rains results in an approximately 3-fold dilution in the urban concentrations of Pb, Zn, and Cu.

In the absence of ‘a priori’ information about the probable distribution of heavy metals in soils, it is relevant to carry out multiple parameter analyses of soil concentrations and to take into account a variety of factors. A method was developed to group existing soil data from the Predvolgie region of the Tatarstan Republic to forecast concentrations of heavy metals in similar soil environments. The predicted concentration of heavy metals in soils is obtained by applying a model that combines soil data using iterative statistical procedures of functional clustering and fuzzy sets. Currently, researchers do not have enough data from experimental and field research to construct adequate maps of soil pollution and estimates of the ecological state of the environment. Our proposed method permits a preliminary solution of these problems.

In order to assess the efficacy of phytoremediation, the thallium (Tl)-hyperaccumulator plants kale, L. cv. Winterbor F1, and candytuft, Guers., were grown in several Tl-contaminated soils. These soils differed in their total Tl concentration (1.4 to 153 mg Tl kg soil), the origin of pollution (anthropogenic vs. geogenic), as well as Tl binding forms, which were characterized by a sequential extraction. In soils with geogenic Tl the percentage of easily accessible fractions was relatively low amounting to 5% of total Tl. In contrast, in soils with anthropogenic Tl pollution the pool of easily accessible Tl was large amounting to 23% of total Tl in the soil polluted by deposition from cement plant. As a consequence, the partition ratio of shoot Tl concentration vs. total soil Tl concentration ranged from 1 to 12 for soils contaminated by geogenic and anthropogenic sources, respectively. In general, there was no relationship between Tl uptake by the hyperaccumulator plants and the total Tl concentration of the soils. The plant uptake of Tl depended on the capacity of the soils to replenish the soil solution with Tl as well as the replenishment from less accessible binding forms.

Due to a low environmental impact, phytoremediation could become an attractive method to remove heavy metals from contaminated soils. The work reported here describes preliminary results for the recovery of mercury from contaminated soils by phytoextraction. This process involves the removal of mercury by plants followed by combustion of the plant biomass to recover the extracted mercury. Three agricultural crop plants, barley, wheat and yellow lupin, were tested in a field experiment. Mean Hg content of the soil were 29.17 µg g for the 0–10 cm horizon and 20.32 εg g for 10–40 cm horizon with less than 2% of the total Hg being bioavailable. The results of a field experiment showed that all the crops extracted mercury with Hg concentration reaching up to 0.479 εg g for wheat. The low Hg uptake by the plants was attributed to the low availability of the mercury in the soils. The best Hg phytoextraction yield was obtained for barley reaching up to 719 mg ha. Further efforts are being made to improve the fraction of bioavailable mercury (by means of solubilization agents) and the biomass crop yields.

The natural ability of plants to accumulate, exclude or stabilize elements could be exploited to remediate soils contaminated with metals. To implement this alternative technology termed phytoremediation, it is crucial to better understand the various processes controlling metal mobilization or immobilization, uptake, and sequestration by the plants. Metal chelation is recognized as a vital biological process that regulates metal solubility, bioavailability, and internal storage in plants. Natural ligands, e.g. soil humates, root exudates components, or synthetic chelators, i.e. ethylene-diaminetretraacetic acid or EDTA, can interact in a yet-to-be-defined way to influence metal uptake and sequestration by plants. Here, we investigated the interactive effect of Cd and soil humates on metal acquisition and translocation in wheat plants. Metal contents in tissues and root exudates composition were determined, using X-ray fluorescence for metals and gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) for organic exudates. Cd inhibited biomass production, from −55% to −65% on tissue dry weight basis, and greatly reduced root exudation, of about −84% by dry weight. Cd treatment also resulted in a substantial co-accumulation of transition metals (Fe, Ni, Cu, Zn) and Cd in wheat roots. Moreover, co-treatment with humates alleviated some of the Cd effect showing biomass inhibition reduced by about 10% for the tissues and 17% for the exudates, while accumulation of some metals (Zn, Cu, Ni, Cd) in the root was enhanced. Thus, under Cd treatment, with or without humate, the enhanced accumulation of metals was not mediated via root exudation. This is contrary to the exudate-mediated Fe acquisition under Fe deficiency. The mechanism for this phenomenon is being sought.

Accumulation of toxic metals in agricultural soils is an issue of health concern because toxic metals may be transferred to plants and food. The reclamation of metal-polluted soils, e.g. by using chemical extractants, is usually difficult and incomplete. An alternative option is to try to decrease the transfer of heavy metals from soil to plant by inoculating the soil with microorganisms selected for their ability to biosorb heavy metals. Here, we isolated one fungus, two actinomycetes and two bacteria from soil contaminated by cadmium. These microbes were found to grow in the presence of high cadmium level in laboratory conditions. The fungus and the actinomycetes have the best growth capacity in the soil extract in presence of 10 mg Cd l which is representative of their ability to soil colonization. The bacillus, despite a low resistance to high cadmium concentrations, is very efficient in presence of 1 mg Cd l. The percentage of cadmium biosorbed in the medium (up to 50% in presence of 10 mg Cd l) and the specific biosorption (80 to 140 mg Cd g of biomass) led to determine that one actinomycete and the bacillus are the most efficient microorganisms that will be used to later bioremediation experiments in soil microcosms.