Brassica juncea tested on urban soils moderately contaminated by lead: Origin of contamination and effect of chelates

Urban garden soils are a potential repository of heavy metal pollution, resulting from either anthropogenic or geogenic origin. The efficiency of phytoextraction was compared on two garden soils with the same texture and topsoil Pb concentration (170 mg kg^?1) but not the same origin: one geogenic, the other anthropogenic. Two varieties of Brassica juncea were tested with citric acid (25 mmol kg^?1) or ethylenediaminetetraacetic acid (EDTA, 2.5 mmol kg^?1). Geogenic Pb was shown to be two times less available than anthropogenic Pb, as a result of which the phytoextraction efficiency was reduced by 59%. Pb mobility in the soil was solely enhanced with EDTA, which increased the Pb concentration in shoots of B. juncea by between 14 and 26 times in comparison with the control. The highest Pb concentration in shoots still remained low, however (i.e., 45 mg kg^?1 dry weight). Regardless of the chelates introduced, B. juncea 426308 accumulated roughly twice as much lead as B. juncea 211000, but only for the anthropogenic contaminated soil. Under these conditions, the amount of Pb accumulated by B. juncea (even when assisted by EDTA) was not high enough to envision achieving soil clean-up within a reasonable time frame.     

The relative impact of lichen symbiotic partners to repeated copper uptake

The relative impact of lichen photobiont and mycobiont was evaluated by submitting nine lichen species with: (i) different photobiont types; (ii) different lichen growth forms; and (iii) different nutrients, pH, humidity preferences; to a range of Cu concentrations (μM) supplied in repeated cycles to simulate the natural process of uptake under field conditions. The physiological performance of the photosystem II photochemical reactions was measured using F_v/F_m and the metabolic activity of the mycobiont was evaluated using ergosterol and intracellular K-loss as indicators. Lichens with higher cation exchange capacity showed higher intracellular Cu uptake and their ecology seemed to be associated with low-nutrient environments. Thus the wall and external matrix, mainly characteristic of the mycobiont partner, cannot be ignored as the first site of interaction of metals with lichens. No common intracellular Cu concentration threshold was found for the physiological impacts observed in the different species. Most physiological effects of Cu uptake in sensitive lichens occurred for intracellular Cu below 200 μg/g dw whereas more tolerant species were able to cope with intracellular Cu at least 3 times higher. Cyanobacterial lichens showed to be more sensitive to Cu uptake than green-algal lichens. Within the Trebouxia lichens, different species showed different sensitivities to Cu uptake, suggesting that the mycobiont may change the microenvironment close to the photobiont partner providing different degrees of protection. Despite the fact that the photobiont is the productive partner, the metabolic activity of the mycobiont of lichen species adapted to environments rich in nutrients, showed to be more sensitive to Cu uptake than the photochemical performance of the photobiont.     

The extent of lead fragmentation observed in deer culled by sharpshooting

Sharpshooting is a proven management technique to lower white-tailed deer (Odocoileus virginianus) densities in areas where hunting is precluded. A donation program that allows for the consumptive use of these culled deer is often necessary to gain public approval for such a program. We culled 40 deer in Indiana using sharpshooting methods (head and neck shot placement) and radiographed the carcasses to determine if lead fragmentation spread throughout the skeletal muscle system. In 30 deer where shot placement was between the cranium and fourth cervical vertebrae, we observed no lead fragments in any thoracic or crural muscle tissue. Of 10 deer where shot placement was between the fifth and seventh cervical vertebrae, 8 deer experienced lead fragments in the extensor spinae muscle. Deer culled with highly frangible bullets via sharpshooting in the cranium or upper cervical spine have minimal risk of experiencing lead fragmentation in the thoracic or crural muscle systems. Deer shot in the lower neck may experience lead fragmentation in the anterior extensor spinae muscle, and up to 40 cm of that muscle should be removed before consumption. © 2011 The Wildlife Society.     

Intermittent Right Ventricular Outflow Tract Capture due to Chronic Right Atrial Lead Dislodgement

A 58 year old male, known case of type 2 diabetes and hypertension, had undergone implantation of a dual chamber pacemaker(DDDR) in 2007 for complaints of recurrent syncope and trifascicular block with a normal ejection fraction andnormal coronaries. His post implantation parameters were normal at that time.He now presented to our pacemaker clinic where his ECG done showed two types o fpaced complexes. The first few complexes were consistent with atrial sensed right ventricular apical pacing with left superior axis. Later complexes showed loss of atrial sensing with pacing from right ventricular outflow tract(inferior axis) with subtle oscillation in it''s axis. On application of magnet, two pacemaker spikes were visible withinterspike interval of 120 ms and paced complexes with inferior axis starting from the first spike suggesting that the atrial lead was responsible for RVOT depolarization. On interrogation of the pacemaker, atrial EGM showed sensed activity from atrium followed by large sensed ventricular complex. Fluoroscopy confirmed that the atrial lead was dislodged and was intermittently prolapsing into the RVOT. Since the patient was asymptomatic, he refused any intervention and subsequentlyhis atrial lead was switched off by telemetry. The above case signifies that asymptomatic lead dislodgement is no talways manifested as loss of capture and even subtle variation of the axis o fthe paced complexes can provide us with a clue that can be confirmed by telemetry of the pacemaker and fluoroscopy.     

Metal‐Oxide‐Free Methylammonium Lead Iodide Perovskite‐Based Solar Cells: the Influence of Organic Charge Transport Layers

Metal‐oxide‐free methylammonium lead iodide perovskite‐based solar cells are prepared using a dual‐source thermal evaporation method. This method leads to high quality reproducible films with large crystal domain sizes allowing for an in depth study of the effect of perovskite film thickness and the nature of the electron and hole blocking layers on the device performance. The power conversion efficiency increases from 4.7% for a device with only an organic electron blocking layer to almost 15% when an organic hole blocking layer is also employed. In addition to the in depth study on small area cells, larger area cells (approx. 1 cm^?2) are prepared and exhibit efficiencies in excess of 10%.     

Adsorption Optimization of Lead (II) Using Saccharum Bengalense as a Non-Conventional Low Cost Biosorbent: Isotherm and Thermodynamics Modeling

In the present study a novel biomass, derived from the pulp of Saccharum bengalense, was used as an adsorbent material for the removal of Pb (II) ions from aqueous solution. After 50 minutes contact time, almost 92% lead removal was possible at pH 6.0 under batch test conditions. The experimental data was analyzed using Langmuir, Freundlich, Timken and Dubinin-Radushkevich two parameters isotherm model, three parameters Redlich—Peterson, Sip and Toth models and four parameters Fritz Schlunder isotherm models. Langmuir, Redlich—Peterson and Fritz-Schlunder models were found to be the best fit models. Kinetic studies revealed that the sorption process was well explained with pseudo second-order kinetic model. Thermodynamic parameters including free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated and reveal the spontaneous, endothermic and feasible nature of the adsorption process. The thermodynamic parameters of activation (ΔG ^#, ΔH ^#and ΔS ^#) were calculated from the pseudo-second order rate constant by using the Eyring equation. Results showed that Pb (II) adsorption onto SB is an associated mechanism and the reorientation step is entropy controlled.     

Applicability of Heavy-Metal Phytoextraction in United Arab Emirates: An Investigation of Candidate Species

Phytoremediation of contaminated calcareous desert land in the United Arab Emirates has been investigated. Soils from 12 northern UAE sites, suspected of metal contamination, were acid-extracted and analyzed by ICP-OES for Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. Twenty-two plants naturally growing at contaminated sites were sampled and analyzed for their uptake of Co, Cr, Cu, Mn, Ni, Pb, and Zn and eight commercially available plants, grown under controlled conditions, were also studied for their phytoextraction capabilities. The concentration of available Cr was found to be 1300 ± 150 mg/kg in the soil of the Ajman Industrial Zone and 80 ± 10 mg/kg of Pb was found at Bithna. Among the plants investigated, Portulaca oleracea and Iresine herbstii showed potential for Cr(VI) and Pb(II) accumulation, respectively, with bioconcentration factors (BCF) greater than unity. Atriplex halimus accumulated Co(II), Cr(III), and Cu(II) each with a BCF > 1.     

A Conceptual Framework for the Interpretation of Biological Markers for Environmental Exposure Assessment

Human exposure to environmental contaminants occurs via air, water, soil, dust, food, and other environmental media. Given this multitude of sources, environmental exposure assessment is moving away from single route exposure assessment to more integrated measures of exposure. Biological markers are frequently advocated as appropriate exposure assessment tools since they provide a measure of internal dose integrated over all routes of exposure. However, contributing sources may be difficult to identify through use of biological markers, and thus, have had limited utility in the regulatory community. To explore the different perspectives on the use and application of biological markers for exposure assessors, epidemiologists, and regulatory personnel, we have developed a biological marker conceptual framework. This framework is developed as a paradigm for the interpretation of biological markers for environmental exposure assessment linking the exposure assessment and the health effects assessment perspectives regarding biological markers. Further, it incorporates issues of source-specific exposures, aggregate exposure assessment, route-specific contributions, and biological variation in response to exposure. This structure provides an approach to explore the current constraints in using biological markers to evaluate source-specific exposures. This framework is discussed in the context of currently available biological markers for lead, carbon monoxide, and toluene. Biological markers represent a complex tool to assess human exposures to environmental contaminants; the biological marker framework presents a structure for their interpretation recognizing that many of the determinants of exposure, bioavailablity, and toxicokinetics are still being evaluated. The conceptual framework presented here provides another tool for the researcher in assessing the utility of biological markers in exposure assessment and epidemiology.     

Isotope Source Signatures for a Primary Lead Smelter Located Close to Todos os Santos Bay,Brazil

From 1960 to 1993, a primary lead smelter operated in the Santo Amaro region, close to Todos os Santos Bay in Brazil, using the classical sinter-roasting process followed by smelting and refining. A high lead content was found in the sediments from Todos os Santos Bay, which has a large circulation and receives the discharge from three rivers. Lead stable isotope ratios provide information about the ore mineralization and can be used to evaluate the origin and fate of the lead pollution. The objective of this study is to identify the isotopic signature of the major effluents of this lead smelter and correlate it with the origin of the galena concentrate that generated it. The X-ray microanalysis confirms that the lead occurs in the slag in the metallic state. The soil has a high lead content (about 0.90%) of oxidized lead. The lead isotopic ratios indicated that the slag isotopic ratios (²⁰⁸Pb/²⁰⁴Pb = 34.8; ²⁰⁷Pb/²⁰⁴Pb = 15.3; ²⁰⁶Pb/²⁰⁴Pb = 15.1) are close to the soil value (²⁰⁸Pb/²⁰⁴Pb = 36.2; ²⁰⁷Pb/²⁰⁴Pb = 15.9; ²⁰⁶Pb/²⁰⁴Pb = 16.4) and both agree with the values for the galena from the Boquira mine region (²⁰⁸Pb/²⁰⁴Pb = 34.6±1.1; ²⁰⁷Pb/²⁰⁴Pb = 15.3±0.4; ²⁰⁶Pb/²⁰⁴Pb = 14.7±0.2). These results indicate that no isotopic fractionation occurred in the roasting-smelting process, therefore the original Boquira isotope ratios can be used as the isotopic signature of the lead dispersed from the Santo Amaro smelter.