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Bacteria interact with a multitude of other organisms, many of which produce antimicrobials. Selection for resistance to these antimicrobials has the potential to result in resistance to clinical antibiotics when active compounds target the same bacterial pathways. The possibility of such cross‐resistance between natural antimicrobials and antibiotics has to our knowledge received very little attention. The antimicrobial activity of extracts from seaweeds, known to be prolific producers of antimicrobials, is here tested against Staphylococcus aureus isolates with varied clinical antibiotic resistance profiles. An overall effect consistent with cross‐resistance is demonstrated, with multidrug‐resistant S. aureus strains being on average more resistant to seaweed extracts. This pattern could potentially indicate that evolution of resistance to antimicrobials in the natural environment could lead to resistance against clinical antibiotics. However, patterns of antimicrobial activity of individual seaweed extracts vary considerably and include collateral sensitivity, where increased resistance to a particular antibiotic is associated with decreased resistance to a particular seaweed extract. Our correlation‐based methods allow the identification of antimicrobial extracts bearing most promise for downstream active compound identification and pharmacological testing. [ABSTRACT FROM AUTHOR]

Abstract: Several cases have been described in the literature where different ligands enhanced lead (Pb) bioavailability over what would have been expected on the basis of equilibrium models such as the biotic ligand model (BLM). These exceptions compromise the development of BLMs for this metal, and mechanistic knowledge of the involved processes is still insufficient. The present study shows that the hydrophilic organic ligand citrate enhances Pb internalization by Chlamydomonas reinhardtii for both the wild and the wall‐less strains. Despite the high Pb internalization fluxes shown by this alga, which may be near the limits set by diffusion through the boundary layer, and its capacity to assimilate citrate (and potentially Pb‐citrate complexes), neither of these mechanisms could quantitatively account for the observed increase in Pb internalization in the presence of this ligand. However, algal‐driven pH increases in the boundary layer and concomitant changes in Pb speciation successfully explained the observed results. This study suggests that information on bulk solution chemistry is not enough to predict metal bioavailability for organisms that can substantially modify the chemical composition of their boundary layer, as observed for C. reinhardtii. [ABSTRACT FROM AUTHOR]

Many communities depend on Lake St. Clair for drinking water and recreational uses. In addition, it is an important transport route for natural resources and manufactured products. The St. Clair River, which flows into the lake from the northeast, is a major source of sediment. The upstream area is known as 'chemical valley' due to a large amount of industrial activity located along the river. Sediment sampling surveys were conducted in 1970, 1974, and 2001 by Environment Canada as part of a continuing monitoring program. Two approaches to the representation, analysis, and visualization of lead contamination were used: a two-dimensional Geographic Information System-based approach using kriging and a three-dimensional approach that utilized the interpolated kriging surfaces overlaid on bathymetry data. The results of combining this analytical method with a three-dimensional representation appear to show that Lake St. Clair generally has lower levels of sediment contamination away from the main flow and circulation patterns leading to its Detroit River outlet. Lead levels declined below the threshold effect level in 2001 compared with the higher concentrations seen in 1970 and 1974. In addition, lake-wide spatial distributions are better visualized using the kriging spatial interpolation results when they are overlaid on the bathymetry data. L'emploi d'outils de géovisualisation pour évaluer la contamination par le plomb des sédiments dans le lac Sainte-Claire De nombreuses communautés utilisent les eaux du lac Sainte-Claire à des fins d'approvisionnement (eau potable) et récréatives. De même, il sert d'axe principal pour le transport des ressources naturelles et des produits transformés. La rivière Sainte-Claire, qui se jette dans le lac depuis le nord-est, déverse d'importantes quantités de sédiments. La zone située en amont abonde de produits chimiques en raison des nombreuses activités industrielles en opération de part et d'autre de la rivière. Des échantillons de sédiments ont été prélevés par Environnement Canada en 1970, 1974 et 2001 dans le cadre d'un programme de surveillance continue. Deux démarches ont été mises en œuvre en vue de représenter, analyser et visualiser la contamination par le plomb : une première s'appuie sur un système d'information géographique à deux dimensions utilisant une modélisation par krigeage, et une seconde à trois dimensions utilisant les surfaces d'interpolation obtenue par krigeage superposées aux données bathymétriques. Cette méthode d'analyse conjuguée avec une représentation en trois dimensions permet d'observer une diminution générale du degré de contamination sédimentaire du lac Sainte-Claire en retrait du courant du chenal principal menant à la décharge de la rivière Détroit. En 2001, les concentrations de plomb ont baissé au-dessous du niveau de l'effet de seuil par rapport aux valeurs plus élevées observées en 1970 et 1974. En outre, une meilleure visualisation des répartitions spatiales du plan d'eau est obtenue grâce aux résultats tirés de l'interpolation spatiale par krigeage lorsque ceux-ci sont superposés aux données bathymétriques. [ABSTRACT FROM AUTHOR]

Ingestion of lead rifle bullet fragments found in discarded hunter-harvested ungulate gut piles negatively affects avian wildlife. Some large carnivores, such as grizzly bears, are also known to target these gut piles as a food source and are therefore potentially at risk of lead exposure. We investigated whether large carnivores in the greater Yellowstone ecosystem were exposed to lead, and if so, if ammunition ingested from gut piles was an apparent source of exposure. Grizzly bears ( Ursus arctos, n = 82) exhibited higher blood lead levels (median = 4.4 µg/dL, range 1.1-18.6 µg/dL) than black bears ( Ursus americanus, n = 35, median = 1.6, range 0.5-6.9 µg/dL), but blood lead levels did not increase during the autumn hunting season when potentially lead-tainted gut piles are available. Wolves ( Canis lupus, n = 21) and cougars ( Puma concolor, n = 8) showed lead concentrations near or below the minimum level of detection in both blood and tissue samples. Unlike findings in previous studies on avian scavengers, we did not find lead ammunition fragments to be a widespread source of lead exposure in large carnivores. Grizzly bears do, however, exhibit blood lead levels that are higher than what is considered safe in humans, but the source of this exposure remains unknown. © 2011 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Adsorption of lead(II) from water on carbon nanotubes (CNTs) was investigated using a series of batch adsorption experiments. The adsorption rate Was studied experimentally at various temperatures, contact times, and initial pH and lead(II) concentrations. It was observed that a considerable amount of lead(II) was adsorbed during the first 5 minutes of contact time. The pH of the solution strongly influenced the amount of adsorption, and the best results were obtained when pH value was approximately 6. For the adsorption isotherm, the experimental data were analyzed by three two-parameter isotherms (Langmuir, Freundlich, and Temkin) and four three-parameter isotherms (Redhich-Peterson, Sips, Toth, and Khan). The three kinetic models used to test the experimental data were Lagergren first-order, second-order, and the Elovich equation. The results obtained from the study of the thermodynamic parameters showed that the adsorption of lead(II) onto CNTs was a spontaneous and endothermic process. [ABSTRACT FROM AUTHOR]

Examines two types of deep tillage as possible management options for reducing lead pellet densities in wetlands in the Sacramento National Wildlife Refuge in California. Vegetation changes that resulted from tilling; Pellet density and depth; Effects of tillage on lead pellets.

Evaluates the long-term response of forest and associated aquatic ecosystems to declining inputs of atmospheric lead (Pb). Decline in the accumulation of Pb in the mineral soil at the Hubbard Brook Experimental Forest (HBEF); Impact of paleoecological studies on Pb accumulation in ecosystems; Potential for Pb pollution in drainage water.

This article reports that multiple factors caused elevated lead levels in the water delivered to District of Columbia Water and Sewer Authority (DCWASA) customers several years ago. The extensive study which is released by USEPA to discover the cause of the problem concluded that treatment changes starting in the mid-1990s at the U.S. Army Corps of Engineers Washington Aqueduct facility led to the release of lead from lead service pipes throughout Water and Sewer Authority's distribution system.

Discusses the environmental impact of the amount of lead in several fishing spots. Replacement of lead service connections and lead pipe joints in compliance with the Safe Drinking Water Act; Concept of NSF61 certification; Importance of a state-licensed professional engineer to every water purveyor.