Home About us Contact
|
Home About us Contact | ||
|
|
||
Toxic Heavy Metal (toxic + heavy_metal)
Selected AbstractsRole of mineral nutrition in minimizing cadmium accumulation by plantsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2010Nadeem Sarwar Abstract Cadmium (Cd) is a highly toxic heavy metal for both plants and animals. The presence of Cd in agricultural soils is of great concern regarding its entry into the food chain. Cadmium enters into the soil,plant environment mainly through anthropogenic activities. Compounds of Cd are more soluble than other heavy metals, so it is more available and readily taken up by plants and accumulates in different edible plant parts through which it enters the food chain. A number of approaches are being used to minimize the entry of Cd into the food chain. Proper plant nutrition is one of the good strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain. Plant nutrients play a very important role in developing plant tolerance to Cd toxicity and thus, low Cd accumulation in different plant parts. In this report, the role of some macronutrients (nitrogen, phosphorus, sulfur and calcium), micronutrients (zinc, iron and manganese), and silicon (a beneficial nutrient) has been discussed in detail as to how these nutrients play their role in decreasing Cd uptake and accumulation in crop plants. Copyright © 2010 Society of Chemical Industry [source] Effects of Xenobiotic Compounds on Cell Activities in Euplotes crassusTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2005FRANCESCA TRIELLI It is now widely accepted that Protists are relevant bioassays to be exploited for the study of environmental modifications due to the presence of xenobiotic compounds. In this work, we evaluated the possibility of utilizing Euplotes crassus, an interstitial marine ciliate, for the pre-chemical screening of environmental sites, such as estuarine and coastal sediments. With this aim, we tested the sensitivity of E. crassus to exposure to three classes of pollutants: an organophosphate neurotoxic drug, basudin, largely used for pest control in agricultural sites, a toxic heavy metal, mercury (HgCl2), and an aromatic polycyclic hydrocarbon, benzopyrene (BP). We found a dose-dependent effect of these compounds on cell viability at concentrations ranging from 1/102 v/v to 1/107 v/v for basudin, from 5 ,M to 0.1 ,M for HgCl2, and from 50 ,M to 1 ,M for BP. In particular, 100% mortality was caused by a 1-h exposure to 1/105 v/v basudin, or 2 ,M HgCl2, or 25 ,M BP, and by a 24-h exposure to 1/106 v/v basudin, 0.5 ,M HgCl2, or 5 ,M BP. A significant decrease in the daily mean fission rate (P<0.001) was found after exposure to 1/107 v/v basudin, or 0.25 ,M HgCl2, or 1 ,M BP. Moreover, as it is well known that the inhibition of acetylcholinesterase (AChE) activity represents a specific biomarker for neurotoxic drugs, we first detected this enzyme activity in E. crassus, using cytochemical, spectrophotometric, and electrophoretic methods; then, AChE activity was characterized by its sensitivity to specific AChE inhibitors and to variations in pH and temperature. Like AChE present in higher organisms, the AChE activity detected in E. crassus was inhibited by exposure to basudin. Conversely, exposure to HgCl2, or PB did not inhibit AChE activity, but caused a significant reduction in lysosomal membrane stability. [source] Regional Spatial Modeling of Topsoil GeochemistryBIOMETRICS, Issue 1 2009C. A. Calder Summary Geographic information about the levels of toxics in environmental media is commonly used in regional environmental health studies when direct measurements of personal exposure is limited or unavailable. In this article, we propose a statistical framework for analyzing the spatial distribution of topsoil geochemical properties, including the concentrations of various toxicants. Due to the small-scale heterogeneity of most geochemical topsoil processes, direct measurements of the processes themselves only provide highly localized information; it is thus financially prohibitive to study the spatial patterns of these processes across a large region using traditional geostatistical analyses of point-referenced topsoil data. Instead, it is standard practice to assess geochemical patterns at a regional scale using point-referenced measurements collected in stream sediment because, unlike topsoil data, individual stream sediment geochemical measurements are representative of the surrounding area. We propose a novel multiscale soils (MSS) model that formally synthesizes data collected in topsoil and stream sediment and allows the richer stream sediment information to inform about the topsoil process, which in environmental health studies is typically more relevant. Our model accommodates the small-scale heterogeneity of topsoil geochemical processes by modeling spatial dependence at an aggregate resolution corresponding to hydrologically similar regions known as watersheds. We present an analysis of the levels of arsenic, a toxic heavy metal, in topsoil across the midwestern United States using the MSS model and show that this model has better predictive abilities than alternative approaches using more conventional statistical models for point-referenced spatial data. [source] Accumulation of toxic metals (Pb and Cd) in the sea urchin Diadema aff. antillarum Philippi, 1845, in an oceanic island (Tenerife, Canary Islands)ENVIRONMENTAL TOXICOLOGY, Issue 3 2010Ofelia Dolores Hernández Abstract This document shows the results obtained from a study on the concentration of toxic heavy metals in the internal tissue and exoskeleton of sea urchins, collected from their natural habitat. The levels of lead and cadmium were measured by Graphite Furnace Atomic Absorption Spectrometry. The mean concentrations of lead and cadmium in the internal tissue were 304.04 and 260.54 ,g/kg respectively, whereas in the shell they were 185.02 and 142.48 ,g/kg. We also performed a statistical analysis of the differences in the distribution of metals between their exoskeleton and their internal content, a correlation study of the metal content in internal tissue and shell and sampling areas, and a correlation study between the metal content and sample size. Since the sea urchin Diadema antillarum presents a wide range of variation in metal content, this study suggests that this species is an excellent bioindicator of heavy metal contamination. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010. [source] Adsorption of Cadmium Ion and Gallium Ion to Immobilized Metallothionein Fusion ProteinBIOTECHNOLOGY PROGRESS, Issue 6 2002Masaaki Terashima A fusion protein made from maltose binding protein (pmal) and human metallothionein (MT) was expressed using E. coli. The purified recombinant protein (pmal-MT) was immobilized on Chitopearl resin, and characteristics of pmal-MT for metal binding were evaluated. As expected from the tertiary structure of metallothionein, the pmal-MT ligand adsorbed 12.1 cadmium molecules per one molecule of the ligand at pH 5.2. The pmal-MT ligand also bound 26.6 gallium molecules per one molecule of the ligand at pH 6.5. Neither cadmium ion nor gallium ion bound to a control protein bovine serum albumin (BSA). Adsorption isotherms for both ions were correlated by Langmuir-type equations. Two types of binding sites have been elucidated on the basis of HSAB (hard and soft acid and base) theory. It was suggested that gallium ion specifically binds to amino acid residues containing oxygen and nitrogen atoms, while cadmium ion binds to specific binding sites formed by multiple cysteine residues. The pmal-MT ligand bound these metals in the concentration range of 0.2,1.0 mM, and the bound metal ions could be eluted under relatively mild conditions (pH 2.0). The pmal-MT Chitopearl resin was stable and could be used repeatedly without loss of binding activity. Thus, this new ligand would be useful for recovery of toxic heavy metals and/or valuable metal ions from various aqueous solutions. [source] Acid Mine Drainage and Heavy Metal Pollution from Solid Waste in the Tongling Mines, ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2008XU Xiaochun Abstract: Based on investigation of the characteristics of solid waste of two different mines, the Fenghuangshan copper mine and the Xinqiao pyrite mine in Tongling, Anhui province in central-east China, the possibility and the differences of acid mine drainage (AMD) of the tailings and the waste rocks are discussed, and the modes of occurrence of heavy metal elements in the mine solid waste are also studied. The Fenghuangshan copper mine hardly produces AMD, whereas the Xinqiao pyrite mine does and there are also differences in the modes of occurrence of heavy metal elements in the tailings. For the former, toxic heavy metals such as Cu, Pb, Zn, Cd, As and Hg exist mostly in the slag mode, as compared to the latter, where the deoxidization mode has a much higher content, indicating that large amounts minerals in the waste rocks have begun to oxidize at the earth surface. AMD is proved to promote the migration and spread of the heavy metals in mining waste rocks and lead to environmental pollution of the surroundings of the mine area. [source] | |||||||||||||