A detailed investigation was conducted to understand the contamination characteristics of a selected set of potentially toxic metals in Shanghai. The amount of Pb, Zn, Cu, Cr, Cd and Ni were determined from 273 soil/dust samples collected within urban area. The results indicated that concentration of all metals except Ni in soils was significant, and metal pollution was even severer in roadside dust. A series of metal spatial distribution maps were created through geostatistical analysis, and the pollution hotspots tended to associate with city core area, major road junctions, and the regions close to industrial zones. In attempt of identifying the source of metals through geostatistical and multivariate statistical analyses, it was concluded as follows: Pb, Zn and Cu mainly originated from traffic contaminants; soil Ni was associated with natural concentration; Cd largely came from point-sourced industrial pollution; and Cr, Ni in dust were mainly related to atmospheric deposition. Human activities have led to high accumulation of potentially toxic metals in urban soils and roadside dust of Shanghai.

The relative abundance and variation of Cr, Co, Cd and Pb in Ascophyllum nodosum and intertidal surface sediments from six locations around the coast were assessed over six seasons. Higher Cd and Pb levels in Galway Docks and Cork Harbour were attributed to localised inputs of these metals from municipal and domestic waste, while at a reference site (Ballyconneely), high algal Cr concentrations were considered a function of geological setting rather than anthropogenic loading. Little seasonal variation was observed, with the exception of higher Co levels in plants in winter, associated with growth dynamics and increased fluvial inputs. In comparison with previously published data for metals in A. nodosum from the North Atlantic, with the exception of localised hot spots, the Irish coastline is still a relatively pristine environment. A. nodosum may be successfully and easily used as a biomonitor of metal contamination in coastal waters. This paper provides details of an easily applicable, cost-effective and ecologically relevant approach to assessing the degree of metal contamination in coastal environments.

Soils from Aveiro, Glasgow, Ljubljana, Sevilla and Torino have been investigated in view of their potential for translocation of potentially toxic elements (PTE) to the atmosphere. Soils were partitioned into five size fractions and Cr, Cu, Ni, Pb and Zn were measured in the fractions and the whole soil. All PTE concentrated in the <10 μm fraction. Cr and Ni concentrated also in the coarse fraction, indicating a lithogenic contribution. An accumulation factor (AF) was calculated for the <2 and <10 μm fraction. The AF values indicate that the accumulation in the finer fractions is higher where the overall contamination is lower. AF for Cr and Ni are particularly low in Glasgow and Torino. An inverse relationship was found between the AF of some metals and the percentage of <10 μm particles that could be of use in risk assessment or remediation practices.

In this study, heavy metal content (Cr, Cu, Mn, Ni, Zn) was determined in sediments and different organs of Rumex obtusifolius L. and Polygonum lapathifolium L. (Polygonaceae), Urtica dioica L. (Urticaceae) and Xanthium strumarium L. (Asteraceae) species. These species grow ubiquitously and vigorously on the periodic flooding areas of Nilüfer stream which have been polluted by different local industrial activities. Below and above-ground parts of plant samples and their sediments were analyzed by ICP-MS for their elemental contents. In general, the variations in the heavy metal content in sediments are reflected in heavy metal status of plant organs. However, this variation depends on plant species and heavy metals. R. obtusifolius, U. dioica and X. strumarium species have elevated levels of Cr, Cu, Ni, and Zn whereas Mn was observed only in P. lapathifolium. The contribution of different organs to the accumulation capacity of the total phytomass is specific to species.

The pulp left after the extraction of juice from Citrus reticulate (kinnow), is a waste material, which was used as a potential sorbent for Cr(III) and Cr(VI) in the present study. The effect of experimental parameters such as pH, biosorbent dosage, biosorbent particle size, initial metal concentrations, temperature, shaking speed and sorption time on the Cr removal is apparent from the obtained results. The Freundlich isotherm and pseudo second order kinetic models fitted well to the data of Cr(III) and Cr(VI) biosorption by Citrus reticulata waste biomass. Effect of several pretreatments such as gases, natural coagulant and many other chemicals on Cr(III) and Cr(VI) sorption capacity of Citrus reticulata waste biomass was first time analyzed in the present study. The metal sorption capacity of Citrus reticulata waste biomass after a specific pretreatment was not only related to the nature of chemical but also strongly dependent on the oxidation state of the metal.

Urban rainfall-runoff residuals contain metals such as Cr, Zn, Cu, As, Pb and Cd and are thus reasonable candidates for treatment using Portland cement-based solidification-stabilization (S/S). This research is a study of S/S of urban storm water runoff solid residuals in Portland cement with quicklime and sodium bentonite additives. The solidified residuals were analyzed after 28 days of hydration time using X-ray powder diffraction (XRD) and solid-state ²⁹Si nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction (XRD) results indicate that the main cement hydration products are ettringite, calcium hydroxide and hydrated calcium silicates. Zinc hydroxide and lead and zinc silicates are also present due to the reactions of the waste compounds with the cement and its hydration products. ²⁹Si NMR analysis shows that the coarse fraction of the waste apparently does not interfere with cement hydration, but the fine fraction retards silica polymerization.

The concentrations of Pb, Cd, Cr, Mn and Fe were evaluated in leaves, stem and root of the Scirpus americanus and Typha latifolia aquatic macrophytes, which were collected from Tanque Tenorio, an artificial lagoon highly polluted by municipal and industrial wastewater. Some S. americanus and T. latifolia plants were collected from four different sites within Tanque Tenorio. The sites were chosen regarding their proximity with the main channel discharging wastewater into the lagoon. The results showed that S. americanus and T. latifolia have the ability to extract Pb, Cd, Cr, Mn and Fe from their water surroundings; on the whole, the roots presented higher concentrations of heavy metals than the stem and the leaves. The highest accumulation of heavy metals was observed in plants growing at the site near the channel entering the lagoon. S. americanus accumulated more Pb, Cr, Mn and Fe than T. latifolia; Cd concentrations were comparably the same in both species. This study provides information in relation to aquatic plants growing in polluted waters, which accumulate heavy metals. These findings are of interest pertaining to the removal processes for treating aquatic systems with heavy metal content.

The present study explained the effect of pretreatments on the biosorption of Cr (III) and Cr (VI) by Cassia fistula biomass from aqueous solutions. For this purpose Cassia fistula biomass was pretreated physically by heating, autoclaving, boiling and chemically with sodium hydroxide, formaldehyde, gluteraldehyde, acetic acid, hydrogen peroxide, commercial laundry detergent, orthophosphoric, sulphuric acid, nitric acid, and hydrochloric acid. The adsorption capacity of biomass for Cr (III) and Cr (VI) was found to be significantly improved by the treatments of gluteraldehyde (95.41 and 96.21 mg/g) and benzene (85.71 and 90.81 mg/g) respectively. The adsorption capacity was found to depend on pH, initial metal concentration, dose, size, kinetics, and temperature. Maximum adsorption of both the Cr (III) and Cr (VI) was observed at pH 5 and 2. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. The kinetic studies showed that the sorption rates could be described better by a second order expression than by a more commonly applied Lagergren equation.

The selectivity and uptake capacity of horticultural peat available in Romania was evaluated with respect to the removal of Cd(II), Cr(VI) and Pb(II) ions from aqueous solution. The kinetics, sorption capacities, selectivity and pH dependence of sorption were determined. The influence of metal concentration in solution is discussed in the terms of Langmuir and Freundlich isotherm and constants. Sorption capacities increased with increasing metal concentration in solution. For solutions containing 300 mg/l of metal, the observed uptake capacities were 20 mg Cd(II)/g peat, 15 mg Cr(VI)/g peat and 30 mg Pb(II)/g peat. The study proved that horticultural peat is a suitable material for the removal of the studied heavy metal ions from aqueous solutions, achieving removal efficiencies higher than 90%, and could be considered as a potential material for treating effluent polluted with Cd(II), Cr(VI) and Pb(II) ions.

A fungal strain possibly capable of removing hexavalent chromium was to be isolated from industrial effluent from a leather factory located in the city of Guadalajara, state of Jalisco, Mexico. The strain was identified as Trichoderma inhamatum by the D1/D2 domain sequence of the 28S rDNA gene. Batch cultures of T. inhamatum in media containing initial Cr(VI) concentrations from 0.83 to 2.43 mM Cr(VI) were prepared. Experimental results suggest that the fungus is capable of transforming hexavalent chromium to trivalent chromium; a transformation of a highly toxic contaminant to a low toxic form. The specific and volumetric rates of Cr(VI) reduction by T. inhamatum cultures decreased as the initial Cr(VI) concentration increased. The fungus exhibited a remarkable capacity to tolerate and completely reduce Cr(VI) concentrations up to 2.43 mM. These results indicate that the T. inhamatum fungal strain may have potential applications in bioremediation of Cr(VI)-contaminated wastewaters.