Lead administered to laboratory rats in drinking water (0.1-0.8 %) as lead acetate solution tends to accumulate in collagen-rich tissues such as tendons and the skin. The amount of lead deposited (and also zinc present in the tissue without its supplementation) correlates with the blood supply to the tissue investigated. The highest deposits of lead were observed in placenta and chorionic membranes, though here only about 60% are collagen-bound. No differences in the drinking habits of the animals were observed and also at lower concentrations of lead in the drinking water no dose dependence was revealed. However, at 0.8 % of lead in drinking water considerable accumulation of lead was observed in all tissues investigated.
Celobronzové komponenty ochranné zbroje jsou fenoménem, který se ve středoevropském nálezovém fondu objevuje poprvé počátkem doby popelnicových polí. Na Moravě je dnes tato zbroj doložena kromě dvou částí bronzových přileb (Služín, Brno-Řečkovice) a starším nálezem náholenice (Kuřim) také zlomkem pancíře (Ivančice 4). Pouze u náholenice není znám nálezový kontext, ostatní artefakty pocházejí z depotů a jsou karpatské provenience. Typologicky i kontextem depotů jsou moravské nálezy bronzové zbroje datovány do rozpětí stupňů B D2 – Ha B1. Plech pancíře z depotu Ivančice 4 byl podle materiálové analýzy vyroben z klasického bronzu mechanickým tvářením s následným rekrystalizačním žíháním. V obvodovém lemu ramenního výkroje pancíře byla zakována tyčinka ze slitiny PbSn, která posloužila jako měkký podklad pro vykování ohybu okraje. Olovo bylo sice v době popelnicových polí vzácně již vyráběno a používáno, v technologické aplikaci při výrobě bronzového pancíře je však nálezem v depotu Ivančice 4 takto prokázáno poprvé. and Solid bronze armour components are a phenomenon that first appears in Central European find assemblages at the beginning of the Urnfield culture period. In addition to two parts of bronze helmets (Služín, Brno-Řečkovice) and an old find of a greave (Kuřim), this armour is also documented today in Moravia by a fragment of cuirass (Ivančice 4). The find context is unknown only in the case of the greave; the other artefacts come from hoards and are of Carpathian provenance. Typologically and based on the context of the hoards, the Moravian finds of bronze armour are dated to the period between stages B D2 and Ha B1. According to a material analysis, the sheet metal of the cuirass from the Ivančice 4 hoard is made from classic bronze that was mechanically shaped and subsequently treated by recrystallisation annealing. A bar from a PbSn alloy hammered into the edge of the shoulder cut-out of the cuirass served as a soft base for bending the edge. Although lead was occasionally made and used already in the period of the Urnfield culture, the find from the Ivančice 4 hoard marked the first time its technological application was demonstrated in the production of bronze cuirasses.
We investigated the lead (Pb) effect on chlorophyll (Chl) fluorescence and photosynthetic electron transport system in Talinum triangulare (Jacq.) Willd. Plants were exposed to different concentrations of Pb(NO3)2 (i.e. 0, 0.25, 0.5, 0.75, 1.0, and 1.25 mM) for seven days in hydroponic experiments. Pb-treated leaves exhibited a relative decrease in Chl fluorescence induction curve, which resulted in the decrease of maximal fluorescence yield, maximal quantum yield, and effective quantum yield of PSII, while nonphotochemical quenching, quantum yield of regulated and nonregulated energy dissipation of PSII significantly increased during Pb stress. Furthermore, Pb concentrations also caused a decrease in maximal P700 change, photochemical quantum yield, nonphotochemical quantum yield, and ETR of PSI. We suggested that the changes in these parameters were a manifestation of Pb interference in the electron transport chain in both PSII and PSI. The sensitivity of PSII was greater than that of PSI in T. triangulare leaves., A. Kumar, M. N. V. Prasad., and Obsahuje bibliografii
The effects of soil and water contamination by lead (Pb) and the consequences on plant growth and yield are of great concern worldwide. Limits of the Pb concentration in water have been established by governmental institutions but these differ from each other. In this study, Lactuca sativa (var. Reine de Mai) plants were exposed to low Pb(NO3)2 doses (0.05-20 mg L-1), including the recommended limit values for irrigation water by the Food and Agriculture Organization (FAO). After 28 d of exposure, lettuce plants did not present visible morphological alterations or growth impairment, but CO2 assimilation rate (PN), photochemical quenching, and effective quantum efficiency of PSII were negatively affected, while intercellular CO2 concentration, stomatal conductance, or transpiration rate were not influenced. Our results suggested that limitations on photosynthesis occurred from different reasons than due to the decrease of internal CO2 availability, alterations of photophosphorylation, and/or electron transport rate. Thus, this lettuce cultivar showed photosynthetic susceptibility to low doses of Pb, even at lower concentrations than those maximal allowed for irrigation water by FAO. Furthermore, PN seemed to be the most sensitive biomarker for evaluation of Pb susceptibility., S. Silva, G. Pinto, C. Santos., and Obsahuje bibliografii
Dariusz Rozmus a jeho spolupracovníci dospěli v posledních letech k názoru, že hutníci ve Slezsku v 11. až 13. stol. používali k hutnění olověných rud originální, „později zapomenutou“ metodu, kterou nazývají „redukce olova železem“. Olověné rudy skutečně lze, při dodržení určitých podmínek, redukovat železem a/nebo kysličníkem železnatým. Základní podmínkou takové technologie je oddělení vsázky od paliva, neboť uhlík a kysličník uhelnatý jsou podstatně silnějšími reduktanty než železo a jeho sloučeniny. Oddělení vsázky a paliva nebylo na studovaných objektech prokázáno. Co si však z výzkumu zaslouží pozornost (a co autoři opomněli podrobněji studovat), je prokazatelné použití železářských strusek jako součásti vyzdívky či výmazu olovářských pecí. and Dariusz Rozmus and his co-workers have come to the conclusion in recent
years that metallurgists in Silesia between the eleventh and thirteenth centuries used an original and ‘later forgotten’ method to smelt lead ores in a process they describe as the ‘reduction of lead by iron’. When certain conditions are maintained, lead ore truly can be reduced by iron and/or iron oxide. The basic condition for using this method is the separation of the charge from the carbon-containing fuel (wood, charcoal) in the furnace – for example by placing the charge in crucibles. Carbon and carbon monoxide are stronger reductants than iron and its compounds. The division of the ore charge and the fuel were not proven in the studied features. Meriting attention from the research, however (something the authors neglected to study in great detail), is the demonstrable use of iron-making slag as part of the lining of the lead smelting furnace.
Soil-invertebrate feeding birds can be exposed to high doses of toxic metals trough their diet. Recently, we have shown that nestling rooks Corvus frugilegus from several rookeries in Poland have a cadmium (Cd) tissue level diagnostic for acute contamination as well as an elevated level of lead (Pb). To explain the potential pathway of bioaccumulation of 11 essential and non-essential elements, including two metals of primary concern (Cd and Pb), in target issues of these nestlings, we analyzed the relationships between the dietary characteristics of stomach content (mass of digesta, number of cereal grains, plant and animal items, and grit particles) and concentrations of metals in the liver, kidneys, lung, muscles and bones. Our analysis showed in total 17 (8 negative and 9 positive) statistically signigicant relationships between the five analyzed dietary characteristics of stomach content nad concentrations of metals in the liver, kidneys, muscles and bones. We found a significant positive relationship between the number of animal food items and Cd-level in kidneys; and a negative relationship bewteen the number of plant items and Pb-level in the liver, and between the number of grit particles and Pb-level in kidneys. Despite the limitations of our study due to the different degree of digestion of some food items, our findings suggest high bioavailability of Cd from animal food items and a low level or reduce gastrointestinal absorption of Pb from plant food (mainly cereals). We urge further research on absorption of Cd and Pb from different dietary components and application of diet analysis to explain the complex nature of bioaccumulation of anthropogenic contaminants in the internal organs and tissues of birds and other species of animals, especially in species with a mixed plant-animal diet.
The protective role of nutrition factors such as calcium, vitamin D and vitamin K for the integrity of the skeleton is well understood. In addition, integrity of the skeleton is positively influenced by certain trace elements (e.g. zinc, copper, manganese, magnesium, iron, selenium, boron and fluoride) and negatively by others (lead, cadmium, cobalt). Deficiency or excess of these elements influence bone mass and bone quality in adulthood as well as in childhood and adolescence. However, some protective elements may become toxic under certain condition s, depending on dosage (serum concentration), duration of treatment and interactions among individual elements. We review the beneficial and toxic effects of key elements on bone homeostasis., I. Zofkova, M. Davis, J. Blahos., and Obsahuje bibliografii