Accumulation Of Au Research Articles

Accumulation and toxicity of biologically produced gold nanoparticles in different types of specialized mammalian cells.

The biologically produced gold nanoparticles (AuNPs) are novel carriers with promising use in targeted tumor therapy. Still, there are no studies regarding the efficacy of nanoparticle internalization by cancer and noncancer cells. In this study, AuNPs were produced by Fusarium oxysporum and analyzed by spectrophotometry, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and Zetasizer. Obtained AuNPs were about 15nm in size with a zeta potential of -35.8mV. The AuNPs were added to cancer cells (4T1), noncancer cells (NIH/3T3), and macrophages (RAW264.7). The viability decreased in 4T1 (77 ± 3.74%) in contrast to NIH/3T3 and RAW264.7 cells (89 ± 4.9% and 90 ± 3.5%, respectively). The 4T1 cancer cells also showed the highest uptake and accumulation of Au (∼80% of AuNPs was internalized) as determined by graphite furnace atomic absorption spectroscopy. The lowest amount of AuNPs was internalized by the NIH/3T3 cells (∼30%). The NIH/3T3 cells exhibited prominent reorganization of F-actin filaments as examined by confocal microscopy. In RAW264.7, we analyzed the release of proinflammatory cytokines by flow cytometry and we found the AuNP interaction triggered transient secretion of tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ). In summary, we proved the biologically produced AuNPs entered all the tested cell types and triggered cell-specific responses. High AuNP uptake by tumor cells was related to decreased cell viability, while low nanoparticle uptake by fibroblasts triggered F-actin reorganization without remarkable toxicity. Thus, the biologically produced AuNPs hold promising potential as cancer drug carriers and likely require proper surface functionalization to shield phagocytizing cells.

A Biomimetic Nanoplatform with Improved Inflammatory Targeting Behavior for ROS Scavenging-Based Treatment of Ulcerative Colitis.

Ulcerative colitis (UC), a refractory disease, has become a global problem. Herein, a biomimetic nanoplatform (AU-LIP-CM) comprising Au cluster enzymes (AU)-loaded liposomes (AU-LIP) camouflaged with the fusion membrane (CM) consisting of neutrophil (NC) and red blood cell (RBC) membrane is designed for the treatment of UC. Briefly, revealed by second near-infrared (NIR-II) imaging through collection of fluorescence emitting >1200 nm from AU, the improved inflammatory targeting behavior contributed by CM cloaking, which inherits abilities of inflammatory targeting and immune escape from NC and RBC, respectively, promotes specific accumulation of AU within inflammatory intestines with up to ≈11.5 times higher than that of bare AU. Afterward, AU possessing superoxide dismutase- and catalase-like activities realizes high-efficiency scavenging of reactive oxygen species (ROS), leading to repair of intestinal barriers, regulation of the immune system, and modulation of gut microbiota, which surpass first-line UC drug. In addition, study of underlying therapeutic mechanism demonstrated that the treatment with AU-LIP-CM can alter the gene signature associated with response to ROS for UC mice to a profile similar to that of healthy mice, deciphering related signal pathways. The strategy developed here provides insights of learning from properties of natural bio-substances to empower biomimetic nanoplatform to confront diseases.

Turning on the Antimicrobial Activity of Gold Nanoclusters Against Multidrug-Resistant Bacteria.

In this work, we show that the addition of thiourea (TU) initiated broad-spectrum antimicrobial activity of otherwise inactive D-maltose-capped gold nanoclusters (AuNC-Mal). For example, AuNC-Mal/TU was effective against multidrug-resistant Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) of 1 μg mL-1 (2.5 μM [Au]) while having 30-60 times lower in vitro cytotoxicity against mammalian cells. The reaction of AuNC-Mal and TU generated the antimicrobial species of [Au(TU)2 ]+ and smaller AuNCs. TU increased the accumulation of Au in bacteria and helped maintain the oxidation state as AuI (vs. AuIII ). The modes of action included the inhibition of thioredoxin reductase, interference with the CuI regulation and depletion of ATP. Moreover, the antimicrobial activity did not change in the presence of colistin or carbonyl cyanide 3-chlorophenylhydrazone, suggesting that AuNC-Mal/TU was indifferent to the outer membrane barrier and to bacterial efflux pumps.

Turning on the Antimicrobial Activity of Gold Nanoclusters Against Multidrug‐Resistant Bacteria**

AbstractIn this work, we show that the addition of thiourea (TU) initiated broad‐spectrum antimicrobial activity of otherwise inactive D‐maltose‐capped gold nanoclusters (AuNC‐Mal). For example, AuNC‐Mal/TU was effective against multidrug‐resistant Pseudomonas aeruginosa with a minimum inhibitory concentration (MIC) of 1 μg mL−1 (2.5 μM [Au]) while having 30–60 times lower in vitro cytotoxicity against mammalian cells. The reaction of AuNC‐Mal and TU generated the antimicrobial species of [Au(TU)2]+ and smaller AuNCs. TU increased the accumulation of Au in bacteria and helped maintain the oxidation state as AuI (vs. AuIII). The modes of action included the inhibition of thioredoxin reductase, interference with the CuI regulation and depletion of ATP. Moreover, the antimicrobial activity did not change in the presence of colistin or carbonyl cyanide 3‐chlorophenylhydrazone, suggesting that AuNC‐Mal/TU was indifferent to the outer membrane barrier and to bacterial efflux pumps.

Geology and Controls on Gold Enrichment at the Horne 5 Deposit and Implications for the Architecture of the Gold-Rich Horne Volcanogenic Massive Sulfide Complex, Abitibi Greenstone Belt, Canada

Abstract The Archean Horne 5 deposit, located in the Rouyn-Noranda district in the southern Abitibi greenstone belt, Canada, contains a total resource of 172.4 t Au (5.6 Moz) from 112.7 Mt of ore grading at 1.53 g/t Au. The deposit is part of the Au-rich Horne volcanogenic massive sulfide (VMS) complex that also includes the past-producing Horne mine (i.e., the Upper and Lower H zones plus small subsidiary lenses) that yielded 325.4 t Au (10.5 Moz Au) from 53.7 Mt of ore grading at 6.06 g/t Au. Combined, the Horne mine and Horne 5 deposit contain ~500 t Au (16 Moz), making them the world’s single largest accumulation of VMS-related Au. The Horne 5 deposit consists of stacked lenses of massive to semimassive sulfides alternating with extensive zones of disseminated and stringer sulfides. The mineralization is hosted within thick accumulations of steeply dipping dacitic to rhyodacitic volcaniclastic units of transitional to calc-alkaline magmatic affinity. Dacitic-rhyodacitic synvolcanic units (lobes, sills, and/or domes) intrude the host succession, which is also crosscut by a series of post-ore mafic and younger intermediate to felsic feldspar ± quartz porphyry dikes. A broad and diffuse halo of distal sericite-chlorite-epidote alteration extends outboard of intensely sericite-altered zones proximal to the sulfide lenses. Gold is interpreted to be synvolcanic on the basis of Au-rich massive sulfide clasts in the volcaniclastic units, the presence of preserved Au-rich primary pyrite, Au zones limited to the sulfide envelope, crosscutting deformed but unaltered and barren dikes, and the absence of typical syndeformation, orogenic-style alteration and mineralization despite overprinting high-strain corridors and faults. Gold is spatially associated with pyrite, sphalerite, and chalcopyrite, and its distribution is largely controlled by the higher porosity and permeability of the volcaniclastic host rocks, which are interpreted to have facilitated hydrothermal fluid circulation in the subseafloor environment. Synvolcanic intrusions and fine-grained tuffs overlying auriferous zones also influenced the distribution of the mineralization by acting as cap rocks to ascending fluids. Evidence suggests that Au enrichment at the Horne 5 deposit is due to efficient transport and precipitation of Au in the subseafloor environment, a favorable geodynamic setting (transitional to calc-alkaline magmatism over thick crust), and possible input of magmatic fluids as suggested by high Te and Cu in the mineralization. Minor and very local remobilization of metals occurred in response to regional deformation and associated greenschist facies metamorphism. The detailed study of the Horne 5 deposit geology and a review of the available information on the Horne mine and recent 3-D modeling indicate that the Horne 5 deposit may have formed higher in the stratigraphy than the Upper and Lower H orebodies of the former Horne mine, which originally formed a single lens. Therefore, the Horne Au-rich VMS complex originally formed as a stacked system in which the Horne 5 deposit was deposited above the Upper and Lower H zones and not in a distal or lateral position as previously proposed, indicating that a robust hydrothermal system was responsible for the formation of the world’s largest Au-rich VMS complex.

Beta-Catenin in Pseudoexfoliation Syndrome

To find whether it is possible that beta-catenin, associated with the development of serious systemic diseases, as well as the neoplastic process, plays a role in the development of pseudoexfoliation syndrome (PEX). If so, identifying PEX, an age-related, vision-threatening disorder of elastic fibers, which is manifested in eyes by the accumulation of an abnormal fibrillar material on the tissues of the anterior segment, with its poorly understood pathogenesis, may be an early indicator of other systemic diseases. The specimens of anterior lens capsules were obtained during routine cataract surgeries from patients with PEX (study group) and those without it (control group). Patients with previously diagnosed renal, cardiac or neoplasm diseases were excluded. In order to determine the localization of β-catenin at the ultrastructural level, the post-embedding colloidal gold (AU) method was used. For the analysis of the presence of proteins involved in cell–cell junctions, including β-catenin, fluorescence staining was performed. An enhanced accumulation of AU in the area of cell junctions in the PEX group was observed in comparison to control patients. A statistically significant increase in the level of β-catenin expression in lens epithelial cells (LECs) for the PEX group (MFI = 808.98) in comparison to the control patients (MFI = 731.6) was also noted. Our study presented the increase in the β-catenin in LECs of PEX group in comparison to control patients. It might be possible for PEX, due to it being easily recognizable, to be the first indicator of serious kidney or cardiac diseases, as well as cancer metastases. Further studies are needed in order to confirm this hypothesis.

The substitution mechanism of Au in In-, Fe- and In-Fe-bearing synthetic crystals of sphalerite, based on the data from EPMA and LA-ICP-MS study

Research subject.Sphalerite (ZnS) is a widespread mineral that can be found in various depositional environments. During formation, this mineral can accumulate minor and trace impurities, with gold being one of the most valuable component. The issue of the chemical state of Au in sphalerite has been much discussed recently.Methods.Samples of In-, Fe- and In-Febearing sphalerite with a composition ranging from 0 to 2.5 mol.% In2S3 and 0 – 40 mol.% FeS were synthesized in an Ausaturated system using gas transport and salt flux techniques. The resulting products were subsequently investigated using EPMA and LA-ICP-MS.Results.All the elements under investigation are found to be homogeneously distributed within the sphalerite matrix. After quenching, sphalerite is shown to retain Au. Our data indicates that the observed increase in Au concentration is caused by the presence of In (up to 1.02 wt % Au) and, to a lesser extent, by that of Fe (up to ≈600 ppm Au). These elements substitute Zn in the crystal structure of sphalerite following the scheme Au+ + In3+(Fe3+) ↔ 2Zn2+, which is in good agreement with previous data obtained using the XAS method.Conclusions.A higher sulphur fugacity in the system leads to a more significant accumulation of Au in sphalerite. The concentration of Au in pure sphalerite does not exceed 10 ppm under our experimental conditions and does not depend on the activity of sulphur in the system.

Induced accumulation of Au, Ag and Cu in Brassica napus grown in a mine tailings with the inoculation of Aspergillus niger and the application of two chemical compounds

This study evaluated the ability of Brassica napus for extracting gold (Au), silver (Ag) and copper (Cu) from a mine tailings, with the inoculation of two Aspergillus niger strains, and the application of ammonium thiocyanate (NH4SCN) or ammonium thiosulfate [(NH4)2S2O3]. After seven weeks of growth inoculated or non-inoculated plants were applied with 1 or 2 g kg−1 of either NH4SCN or (NH4)2S2O3, respectively. Eight days after the application of the chemical compounds, plants were harvested for determining the total dry biomass, and the content of Au, Ag, and Cu in plant organs. Application of (NH4)2S2O3 or NH4SCN resulted in enhanced Au-accumulation in stems (447% and 507%, respectively), while either (NH4)2S2O3+Aspergillus, or NH4SCN increased the Au-accumulation in roots (198.5% and 404%, respectively) when compared to the control. Treatments with (NH4)2S2O3 or (NH4)2S2O3+Aspergillus significantly increased (P ≤ 0.001) the accumulation of Ag in leaves (677% and 1376%, respectively), while NH4SCN + Aspergillus, and (NH4)2S2O3 enhanced the accumulation in stems (7153% and 6717.5%). The Ag-accumulation in roots was stimulated by NH4SCN+ Aspergillus, and (NH4)2S2O3+ Aspergillus (132.5% and 178%, respectively), when compared to the control. The combination of NH4SCN+Aspergillus significantly enhanced the Cu-accumulation in leaves (228%); whereas NH4SCN+ Aspergillus, or (NH4)2S2O3+ Aspergillus resulted in greater accumulation of Cu in stems (1233.5% and 1580%, respectively) than the control. Results suggest that either NH4SCN or (NH4)2S2O3 (with or without Aspergillus) improved the accumulation of Au and Ag by B. napus. Accumulation of Au and Ag in plant organs overpassed the hyperaccumulation criterion (> 1 mg kg−1 of plant biomass); whereas Cu-accumulation in stems and roots also overpassed such criterion (> 1000 mg kg−1) by applying either NH4SCN or (NH4)2S2O3 + A. niger.

Metal(loid) accumulation in aquatic plants of a mining area: Potential for water quality biomonitoring and biogeochemical prospecting

Aquatic bryophytes can accumulate extremely high levels of chemical elements because of their unique morphology and physiology which is markedly different from vascular plants. Four aquatic mosses—Fontinalis squamosa, Brachythecium rivulare, Platyhypnidium riparioides, Thamnobryum alopecurum—and a freshwater red alga Lemanea fluviatilis along with water samples from the streams of Góis mine region in Central Portugal were analyzed for 46 elements. Despite being below detection levels in the water samples, the elements Zr, V, Cr, Mo, Ru, Os, Rh, Ir, Pt, Ag, Ge and Bi were obtained in the plant samples. The moss T. alopecurum had the highest mean concentrations of 19 elements followed by B. rivulare (15 elements). Maximum accumulation of Rb, Ta and Au, however, was seen in the alga L. fluviatilis. Bioconcentration factors > 106 were obtained for a few metals. The investigation confirms that aquatic bryophytes can be suitable for water quality biomonitoring and biogeochemical prospecting in fresh water bodies owing to their high accumulative capacity of multi-elements from their aquatic ambient.

Phytoextraction potential of Manihot esculenta Crantz. (cassava) grown in mercury- and gold-containing biosolids and mine tailings

The potential of Manihot esculenta Crantz (cassava) to phytoextract Hg and Au from Hg- and Au-containing biosolids and mine tailings was successfully demonstrated for the first time. Removal of Hg by a hyperaccumulating plant species offers new options to clean up Hg-contaminated sites and at the same time harvest trace amounts of Au. Pre-rooted cassava cuttings with 5–7 nodes were grown in different combinations of biosolids-amended mine tailings to evaluate the best combination that will support optimum plant growth. The 75% biosolids – 25% mine tailings combination produced the best growth in cassava. Plant cuttings were also grown in hydroponics solutions amended with Hg and/or Au to determine root uptake of the two metals. Metals uptake was found to be greatest in the fibrous roots, accumulating up to 12.59gkg−1Hg and 18.99mgkg−1Au. Given its ease of cultivation and harvesting as well as the high accumulation of Hg and Au in its roots, cassava can be considered asa suitable candidate for Hg remediation and Au recovery from biosolids and mine tailings containing these metals.

COPT2, a plasma membrane located copper transporter, is involved in the uptake of Au in Arabidopsis

The mechanism of gold nanoparticle formation and genes involved in such processes, especially Au transport in plants are not understood. Previous reports pointed to the probable role of COPT2 in Au transport based on the transcript accumulation of COPT2 under Au exposure. Here, we provide evidence revealing the additional role of COPT2 for Au mobilization in yeast and Arabidopsis. The COPT2 transcripts significantly accumulated in the root of Arabidopsis under Au exposure. The expression of COPT2 restores Cu uptake ability in ctr1Δctr3Δ mutants and leads to Au sensitivity in yeast, which is comparable to Cu in growth kinetics experiments. The metal measurement data showed that the Au level was increased in COPT2, expressing yeast cells compared to vector transformed control. The copt2 mutant of Arabidopsis displayed a similar growth pattern to that of Col-0 under Au treatment. However, a notable phenotypic difference was noticed in three-week-old plants treated with and without Au. Consistent with yeast, Au uptake was reduced in the copt2 mutant of Arabidopsis. Together, these results clearly reveal the Au uptake capability of COPT2 in yeast and Arabidopsis. This is the first report showing the potential role of any transporter towards uptake and accumulation of Au in plants.

Agglomeration and long-range edge retraction for Au/Ni bilayer films during thermal annealing

The solid state dewetting of Au/Ni bilayer films from SiO2/Si substrates exhibits both homogeneous and localized dewetting of Ni and long-edge retraction for Au under isothermal annealing condition. The top Au layer retracted up to 1 mm from the edge of the substrate wafer to reduce the energetically unfavored Au/Ni interface. In contrast, Ni dewetted and agglomerated locally due to its limited diffusivity compared to Au. Film morphology and local chemical composition varied significantly across hundreds of micrometers along the direction normal to the retracting edge. The accumulation of Au from long-range edge retraction resulted into the separation of Au and Ni, which are affected by alloying between the two elements. The experimental observations suggest that alloying combined with unequal self-diffusion coefficient for the metal components control the bilayer dewetting process.

Gold nanoparticles do not induce adverse effects on terrestrial isopods Porcellio scaber after 14-day exposure

Despite the anticipated environmental release of anthropogenic gold nanoparticles (AuNPs), there is currently not enough data on their potential impact on terrestrial environment. In the current study, we investigated the effects of considerably low concentrations of AuNPs on terrestrial isopods (Porcellio scaber) after 14 days of exposure. The effects on mortality, weight change, feeding rate, avoidance/preference feeding behavior, and cell membrane destabilization of digestive gland cells were followed. In parallel, the accumulation of Au in the digestive glands was measured. Our results show that none of the tested parameters was affected in isopods under given exposure doses (10 and 60 µg Au/g dry leaf) and exposure duration. No Au was assimilated in the digestive glands. Also, the same doses of the reference chemical, AuCl3, showed no effect. We conclude that these concentrations of AuNPs are safe for terrestrial isopods. We encourage reporting the results showing no adverse effects of nanoparticles to balance the prevailing publication of their adverse effects. This will help to build a realistic public perception of the environmental risk of nanomaterials.

Bioaccumulation and Subchronic Toxicity of 14 nm Gold Nanoparticles in Rats.

Colloidal suspensions of 14 nm gold nanoparticles (AuNPs) were repeatedly administered intravenously at three dose levels (0.9, 9 and 90 µg) to male Sprague Dawley rats weekly for 7 weeks, followed by a 14-day washout period. After sacrificing, the amount of gold was quantified in the liver, lungs, spleen, skeleton and carcass using neutron activation analysis (NAA). During the study, pre- and post (24 h) administration blood samples were collected from both the test and control groups, the latter which received an equal injection volume of normal saline. General health indicators were monitored together with markers of kidney and liver damage for acute and subchronic toxicity assessment. Histopathological assessments were done on the heart, kidneys, liver, lungs and spleen to assess any morphological changes as a result of the exposure to AuNPs. The mass measurements of all the groups showed a steady increase with no signs of overt toxicity. The liver had the highest amount of gold (µg) per gram of tissue after 56 days followed by the spleen, lungs, skeleton and carcass. Markers of kidney and liver damage showed similar trends between the pre and post samples within each group and across groups. The histopathological examination also showed no hepatotoxicity and nephrotoxicity. There was accumulation of Au in tissues after repeated dosing, albeit with no observable overt toxicity, kidney or liver damage.

Improving the mechanical performance of Sn57.6Bi0.4Ag solder joints on Au/Ni/Cu pads during aging and electromigration through the addition of tungsten (W) nanoparticle reinforcement

Sn57.6Bi0.4Ag solder has been reinforced successfully through the addition of tungsten (W) nanoparticles at a concentration of 0.5wt%. With the addition of W nanoparticles, the solder matrix lamellar interphase spacing was reduced by 31.0%. Due to the dispersion of W nanoparticles and the consequently refined microstructure, the mechanical properties of the solder alloy were enhanced, as indicated by a 6.2% improvement in the microhardness. During the reflow of solder on Au/Ni/Cu pads, the entire Au layer dissolved into the molten solder rapidly and a large number of (Au,Ni)(Sn,Bi)4 particles were formed. The fracture path of the as-reflowed joint was within the solder region, showing ductile characteristic, and the shear strength was reinforced by 8.2%, due to the enhanced mechanical properties of the solder. During the subsequent aging process, the Au migrated back towards the interface and a thick layer of interfacial (Au,Ni)(Sn,Bi)4 IMC was formed, leading to the shift of the fracture path to the interfacial IMC region, the transformation to brittle fracture and the deterioration of the strength of the joint, due to Au embrittlement. By adding W nanoparticles, the migration of Au was mitigated and the thickness of the (Au,Ni)(Sn,Bi)4 layer was reduced significantly, which reduced the Au embrittlement-induced deterioration of the strength of the joint. During electromigration, the segregation of the Bi-rich and Sn-rich phases and the accumulation of the (Au,Ni)(Sn,Bi)4 layer at cathode interface were mitigated by the addition of W nanoparticles, which improved the electromigration resistance.

Ion exchange ability of N-octylpyridinium hexafluorophosphate in carbon ionic liquid electrode for efficient adsorptive preconcentration and selective determination of ultratrace gold chlorocomplexes

A new application of a carbon ionic liquid electrode (CILE) has been explored for preconcentration and quantification of trace amount of Au(III) chlorocomplexes. The procedure is based on the accumulation of tetrachloroaurate complexes at the electrode surface under an open circuit potential condition followed by cyclic voltammetry (CV) and differential pulse cathodic stripping voltammetry (DPCSV). An ion exchange mechanism has been proposed for efficient and fast accumulation of Au(III) chlorocomplexes. Effects of different experimental parameters such as electrolyte concentration, pH, and preconcentration time on the voltammetric signals were investigated. It was found that under the optimized experimental conditions, the linear range of measurement and the detection limit were 5.00 × 10−9–2.25 × 10−6 and 0.80 × 10−9 mol L−1, respectively. Possible interference from coexisting ions was also studied. The procedure was applied for determination of gold in water and human blood serum samples, and acceptable accuracy was achieved.

Zonation of primary haloes of Atud auriferous quartz vein deposit, Central Eastern Desert of Egypt: A potential exploration model targeting for hidden mesothermal gold deposits

The Atud gold mine located in the Neoproterozoic diorite and metagabbro of the Central Eastern Desert of Egypt has been initially excavated during Pharaonic times. Between 1953 and 1969, the Egyptian Geological Survey and Mining Authority performed underground prospection in the auriferous quartz vein and metasomatic alteration zones in the main Atud area, estimating a principal gold lode of 19,000tones (16.28g/ton), and 1600tons of damp (1.24g/ton). Yet the potentiality of the deposit has not been exhausted. However, for exploration of hidden ore, quantitative characterization using trace elements zoning of mineralization haloes with 280 samples from surface and three underground mining levels is applied. This was through multivariate statistical analysis (Factor analysis) of 11 selected trace elements. Axial (vertical) extents of primary haloes above and beneath gently dipping orebody are also visualized to interpret the level of erosion, determine the direction of mineralizing solutions as well as to examine whether the hidden orebody is promising at the Atud mine.Axial zones of primary dispersion aureoles of trace elements are: Ag, As, S and U around the auriferous quartz veins; Cu, and Pb in the surface horizons; and Zn, Ni, Co, and U along the lower margin of mineralization zone. Gold contents in bedrock and quartz vein samples from level-42M are the highest (5.7 and 40.3ppm, respectively). In the transverse (lateral) direction, the maximum relative accumulation of Au and Zn occurs at the Northern Shaft; Pb, Cu, As, and U at the Main Shaft; and Ag, S, Co, and Ni at the Southern Shaft. The estimated axial zonation sequence of indicator elements using the variability index is Pb→Cu→Ag→Au→As→S→Ni→Co→U→Zn. According to this zonation, an index such as (Pb×Cu)D/(U×Zn)D can be a significant for predicting the Au potentiality at a particular depth. In addition, the Pb/U zonality index is an appropriate indicator for the degree of erosion at the Atud gold mine. The degree of surficial zonality of the mineralization as deduced from geochemical maps and the level of erosion of the geochemical anomalies as well as the decreasing of gold content with depth recorded throughout the different underground mine workings make it necessary for the prospection model to evaluate the drainage patterns dissecting the mineralized zone.The application of R-mode factor analysis estimated seven statistical factors, and factor score maps are portrayed. Factors 1 (Ag, Au, As, Co, S, U and Zn) and 2 (Zn, U, Co and S) significantly reflect the Au-mineralization (ore-controlled), and their score maps enable a more precise delineation of auriferous quartz veins and the area which may contain primary gold mineralization. The other factors reveal the distribution of Cu- and Pb-bearing minerals (supergene alteration factors), and Ba and Ni in the host diorite (lithologically-controlled). These are consistent with the calculated maximum relative accumulation of trace elements, proposing a potential model of exploration based on integrating underground geochemical data from old gold mine workings with spatial information from R-mode factor score maps.

Characteristics of the genetic mineralogy of pyrite and its significance for prospecting in the Denggezhuang gold deposit, Jiaodong Peninsula, China

This paper reports the variation rules for the typomorphic parameters of the pyrite and the gold enrichment rules of the Denggezhuang quartz vein gold deposit at a large-depth scale, providing the mineral signs for deep prospecting prediction through detailed study of the characteristics of crystal’ habits, chemical composition, the thermoelectricity of pyrites, and mineralogical mapping. This paper primarily discusses the correlation between the mineralization intensity and the space-time evolution of the mineralogical parameters, clarifies the physicochemical conditions during gold mineralization, and provides information useful for deep mineralization prediction. We demonstrate that the crystal habits of the pyrites are very complex, primarily occurring as {100}, {210}, and their combinate form. {210} and {100}+{210} have positive correlations with gold mineralization, and {100}+{210} therefore can be useful for locating rich ore segments. The composition of pyrites is characteristically poor in S and rich in As. Their typical trace elements are composed of Mo, As, Pb, Cu, Bi, Zn, Au, Co, Se, Sb, Ag, Ni, Cr, and Te. The average contents of trace elements in pyrites from various stages show that the crystallizing temperature gradually decreased from an early stage to the metallogenic episodes. The precipitation and accumulation of Au and Ag occur primarily in the quartz-pyrite stage (III) and the polymetal minerals stage (IV). The occurrence rate of P-type pyrites (P(%)) is 83.52%. There is a larger dispersion of the thermoelectrical coefficient of pyrite (α) in the Denggezhuang gold deposit than in other deposits in the Jiaodong Peninsula. The electrical conductivity assemblage of pyrites from I to V is characterized by P⩾N→P>N→P≫N→P≫N→P⩾N, which is usually considered beneficial for mineralization. The relative contents of As+Sb+Se+Te and Co+Ni are closely correlated to P-type and N-type average values and their occurrence rates. According to the crystallizing temperature of pyrite, the mineralization intensity, and the denudation degree, the mineralization temperature of the Denggezhuang gold deposit is in the range of 150–322°C and is of a medium-low temperature. The orebody has already become denuded to the top-middle of the orebody, and the size of the orebody is larger than 900 m. Based on the vertical zoning of the thermoelectrical coefficients of pyrites and P-type pyrite mapping, it is suggested that the segment between −425 and −800 m may have exploration potential to the northeast of line 94 of the No. I2-2 orebody.

Trace Elements in Peat Bogs of Tomsk Region (South Siberia, Russia)

16 peat bogs of Tomsk region (in Siberia) were used to study trace elements concentrations in ombrotrophic peat. The calculations of concentration coefficient in relation to the sedimentary rocks allowed us to determine some elements which tend to accumulate in ombrotrophic peat of Tomsk region. They are Au, Br, Sr, Ba, Fe, and Cr. For selective trace elements we considered spacial variability of their mean contents in the ombrotrophic peat of Tomsk region. Together with the study of vertical distribution of trace elements in the studied peat bogs we outlined factors influencing their accumulation in peat. Lithological and mineral composition of surrounding territories plays role in the accumulation of Cr, Sc, Br, Au, and lanthanides, climatic conditions and necessity for living plants cause Ca variations. Cr, Sc, lanthanides and U are also actively accumulated in the peat near industrial cities in the south of Tomsk region.

Trophic Transfer of Au Nanoparticles from Soil along a Simulated Terrestrial Food Chain.

To determine if nanoparticles (NPs) could be transferred from soil media to invertebrates and then to secondary consumers, we examined the trophic transfer of Au NPs along a simulated terrestrial food chain. Earthworms (Eisenia fetida) were exposed to Au NPs in artificial soil media and fed to juvenile bullfrogs (Rana catesbeina). Earthworm Au concentrations were continuously monitored so that the cumulative dose to bullfrogs could be accurately estimated throughout the experiment. We exposed a second group of bullfrogs to equivalent doses of Au NPs by oral gavage to compare the bioavailability of NPs through direct exposure to trophic exposure. We observed accumulation of Au in liver, kidney, spleen, muscle, stomach, and intestine in both treatment groups. Tissue concentrations decreased on average of approximately 100-fold with each trophic-step. The total assimilated dose averaged only 0.09% of the administered dose for direct exposure (oral gavage), but 0.12% for the trophic exposure. The results suggest that manufactured NPs present in soil may be taken up into food chains and transferred to higher order consumers. They also suggest that Au NPs may be more bioavailable through trophic exposure than direct exposure and that trophic transfer may influence the biodistribution of particles once absorbed.