Enrichment Of Zn Research Articles

Effect of dietary zinc pectin oligosaccharides chelate on growth performance, enzyme activities, Zn accumulation, metallothionein concentration, and gene expression of Zn transporters in broiler chickens1.

This study was to investigate the effect of zinc pectin oligosaccharides chelate (Zn-POS) on growth performance, serum enzyme activities, tissue zinc accumulation, metallothionein (MT) concentrations, and gene expression of zinc transporters (ZnT) in broilers. Five hundred forty 1-d-old Arbor Acres broiler chicks were randomly assigned to 5 dietary groups with 6 replicates of 18 birds per replicate. The diets were formulated with the same supplemental Zn level (80 mg/kg diet) but different amount of the Zn-POS: 0, 200, 400, 600, and 800 mg Zn-POS/kg diet. ZnSO4 was used to adjust to the desired amount of the Zn (80 mg/kg) in the Zn-POS diets. Broilers were fed with the experimental diets for 42 d including the starter (days 1 to 21) and grower (days 22 to 42) phases. Our results showed that dietary supplementation of Zn-POS linearly and quadratically increased (P < 0.05) the average daily gain and gain-to-feed ratio during 22 to 42 d and 1 to 42 d as well as body weight on day 42, whereas reduced (P < 0.05) the sum of mortality and lag abnormalities in broilers on day 42. Besides, serum alkaline phosphatase and copper-zinc superoxide dismutase activities increased (P < 0.05) linearly and quadratically in response to dietary Zn-POS supplemental level on day 42. Dietary Zn-POS supplementation increased Zn accumulation in serum (linear, P < 0.05), liver (linear, P < 0.05), and pancreas (linear and quadratic, P < 0.05). In addition, Zn-POS supplementation linearly and quadratically increased (P < 0.01, P < 0.05, respectively) MT concentrations in liver and pancreas of broilers. Pancreatic mRNA levels of MT, ZnT-1, and ZnT-2 increased (P < 0.05) linearly and quadratically, and the mRNA expression of metal response element-binding transcription factor-1 increased linearly (P < 0.05), in response to dietary Zn-POS supplementation. In conclusion, supplementation of Zn-POS in the diet increases Zn enrichment in the metabolic organs such as liver and pancreas and promotes productive performance in broilers.

Spatial Variation of heavy metal Pollution on road surfaces from Traffic sources in University of Nigeria, Enugu campus

This study aims to analyze heavy metal concentrations on road deposited sediment (RDS) using the road network within Enugu Campus of University of Nigeria, (UNEC) as a study site. RDS samples were collected at two transverse positions from different sites within a week in order to describe the influence of traffic on heavy metal emissions. The heavy metal concentrations of the RDS were determined by strong tri-acid digestion and atomic absorption spectrometry. The mean concentrations for Co, Mn, Zn, Ni and Fe were found to be 11.53, 99.92, 221, 44.23 and 216 mg kg-1 from samples near the curb and 12.37, 92.25, 248.87, 43.62 and 197.5 mg kg-1 from samples 1 m from the curb respectively. The mean electrical conductivity (EC), pH and total organic matter (TOM) were found to be 304μS/cm, 7.13, and 6.9% from samples near the curbS/cm, 7.13, and 6.9% from samples near the curb and 408μS/cm, 7.13, and 6.9% from samples near the curbS/cm, 7.33 and 5.57% 1 m from the curb, respectively. The results of the geochemical models: contamination factor (degree of contamination and enrichment factor agree to a very high level of contamination and enrichment of Zn in all the sampled sites. These results suggest a high anthropogenic influence on the heavy metals levels.

Assessment of trace elements pollution in the sea ports of New South Wales (NSW), Australia using oysters as bioindicators

In this study Sydney rock oysters (S. glomerata) from six major sea ports of NSW, Australia were used as bioindicators to assess the distribution and levels of trace element accumulation in the ports. Substantial enrichment of Cu, Pb and Zn in the oysters of the sea ports were detected when compared to their background samples and the US Environmental Protection Agency (USEPA) provisional tolerable intake standard. Enrichment of As, Al, Fe, Mn, Br, Sr were also found in the oysters at the port areas. The bioconcentration ratios of the trace elements illustrated significant Fe, Cu, Zn, As, Mn, Al, Pb and Cr accumulation in S. glomerate. The biota sediment accumulation factor suggested Cu, Mn and Zn accumulation at two of the ports (Port Yamba and Botany), indicating availability of these metals in the oysters as strong metal accumulators. In addition, integrated metal contamination illustrated notable Fe, Zn, Cu and Al contamination at port environment, whereas cluster analysis portrayed interconnection between the contaminants and the study sites.

Effect of Vapor‐phase‐treatment to CuZnZr Catalyst on the Reaction Behaviors in CO2 Hydrogenation into Methanol

AbstractCuZnZr catalysts prepared by co‐precipitation method were treated by vapor‐phase‐treatment (VPT) method, and used for the synthesis of methanol for CO2 hydrogenation. Compared with conventional co‐precipitation method, this VPT with TPABr (TPABr: tetrapropylammonium bromide) induces obvious increases in the particles size of CuO, ZnO and ZrO2, promotes the formation of the rod‐like structure, Zn and Zr enrichments on surface and the presence of more concentration of oxygen vacancies. Due to the increases of particle size especially for CuO particles, the activity of the catalyst for CO2 hydrogenation to CO (RWGS reaction) is furthest suppressed, leading to dramatical decrease in conversion of CO2. However, methanol productivity is affected relatively modestly due to the enrichments of Zn and Zr as another active species on the catalyst surface. In addition, catalyst properties and methanol selectivity can be regulated through adjusting the processing time. The catalyst with the processing time of 3 day (CuZnZr‐TPABr‐3d catalyst) shows a methanol selectivity above 90 % and no obvious deactivation appeared in a period of 100 h reaction.

Lead Isotope Geochemistry of Shales from the Wolverine Volcanogenic Massive Sulfide Deposit, Yukon: Implications for Pb Isotope Vectoring in Exhalative Ore Systems

Combined whole-rock lead isotope and high-precision trace element data are reported for shales from the Wolverine deposit and surrounding prospects (e.g., Puck, Fisher, Sable) to elucidate the source of Pb in the shales and their potential utility as an exploration vector. Shales exhibit distinct variations in time-integrated U/Th/Pb evolution with proximity to mineralization. Distal samples resemble the local crustal Pb isotope composition of the northern Cordilleran continental crust (i.e., shale curve). More proximal samples exhibit evidence for hydrothermal activity, but were not significantly mineralized. They have very high U/Th and U/Pb and anomalous present-day 206 Pb/204Pb (>20) coincident with elevated Y/Ho, Zr/Hf, and carbonate alteration. These signatures were derived from oxygenated seawater and imprinted on the shales by oxygenated, CO2-rich hydrothermal fluids that contained uranyl carbonate ions (e.g., UO2(CO3) 3 4– ). It is envisioned that this was due to shallow-level (within 50 m of the seafloor), near-vent ingress of oxygenated seawater associated with hydrothermal venting. A third population of samples is most proximal to mineralization. These, too, have trace element signatures (i.e., high Y/Ho, Zr/Hf, CO2-U enrichment) inherited from seawater, but they do not exhibit anomalous present-day 206Pb/ 204 Pb, being more juvenile in 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208Pb/204Pb. This isotope composition coincides with enrichments in Pb, Zn, Cu, Tl, Sb, W, and Sn (±Cu, Mo). The Pb enrichment associated with mineralization effectively buffered these samples from appreciable Pb isotope evolution, despite overprinting by uranyl carbonate. The juvenile Pb associated with the shales proximal to mineralization argues for deep-penetrative circulation of hydrothermal fluids and leaching of Pb from mafic igneous rocks at depth and/or influence from juvenile magmas at depth (i.e., magmatic fluids). Both of these processes were likely critical for the genesis of mineralization at Wolverine. This study illustrates the utility of quadrupole inductively coupled plasma-mass spectrometry (ICP-MS) for providing sufficiently precise and accurate Pb isotope determinations for district-scale metallogenic evaluations. Furthermore, the coupling of solution ICP-MS Pb isotopes with high-precision trace element geochemistry from the same digest provides a powerful tool for regional exploration studies for hydrothermal mineralization in shale basins.

Trace element systematics and ore-forming processes in mafic VMS deposits: Evidence from the Troodos ophiolite, Cyprus

The volcanogenic massive sulfide (VMS) deposits in the Troodos ophiolite (Cyprus) are ancient analogues for modern day seafloor massive sulfide mineralisation formed in a supra-subduction zone environment. In this study we present the first detailed in situ study of trace elements in sulfides from twenty VMS deposits hosted in the Troodos ophiolite to better understand factors that influence the distribution, enrichment and incorporation of trace elements in different sulfide minerals.On a mineral scale, trace elements exhibit systematic variations between pyrite, chalcopyrite and sphalerite. Pyrite preferentially incorporates As, Sb, Au and Te, whilst chalcopyrite is enriched in Co and Se. Sphalerite is trace element poor with the exception of Ag and Cd. Selenium averages 278 ppm (n = 150) in chalcopyrite but only 42 ppm (n = 1322) in pyrite. Bismuth and Te in pyrite show a weak positive correlation (R2 = 0.35) in some VMS deposits possibly linked with the occurrence of Bi-telluride inclusions. Trace element concentrations also vary between colloform and euhedral pyrite, with an enrichment of Au, As, Sb, Cu and Zn in colloform compared to euhedral pyrite.Time resolved laser ablation profiles reveal that the trace element distribution on a mineral scale is not uniform and varies with crystallographic effects, fluctuating physicochemical fluid conditions such as temperature, pH, fS2, fO2 and ligand availability during sulfide precipitation. Incorporation mechanisms in sulfides differ between elements in pyrite, Ag, As, Se and Pb are hosted in solid solution or as nanoscale inclusions, whilst Au, Sb and Te may form micro-scale inclusions.On a regional scale (20 km) the distribution of trace elements exhibits systematic variations between three major structural domains; namely the Solea, Mitsero and Larnaca grabens. The VMS deposits of the magmatic-tectonic Solea graben are enriched in Se, Co, Te, Au and Cu relative to Mitsero, which is a purely extensional feature. Therefore, we hypothesise that a variable magmatic volatile influx related to a) ‘magma’ volume, b) migration of the magmatic-hydrothermal crack front and associated brine liberation or c) a variation in protolith metal concentration are responsible for regional scale variations in VMS geochemistry. This is suggested to be intrinsically linked to the spreading architecture of Troodos.

Trace metal levels and toxicity in the Huelva Estuary (Spain): A case study with comparisons to historical levels from the past decades

Abstract The Huelva Estuary, in the south of Spain, is a highly polluted area subject to heavy anthropogenic pressures such as coastal urbanization, fishing and tourism activities, commercial transports, as well as petrochemical, agrichemical and intense mining industry. Trace metal levels in sediments from the Huelva Estuary have been largely investigated over the last decades, but an evaluation through the years has not been considered yet. This study analyzed the current concentrations for Cr, Cu, Mn, Ni, Pb, Zn, Fe and organic matter content in sediments from two sampling sites (Muelle Capesa and Mazagon) and toxicity on fertilization and embryogenesis of sea urchin (Paracentrotus lividus). Results were compared with data from the past decades. Zn and Cu displayed higher levels and enrichment in sediments from the Muelle Capesa close to the Huelva industrial area. Mazagon sediment, despite moderate levels and enrichment in Zn and Cu, is proved to be affected by anthropogenic impacts, due to continuous inputs from acid mine drainage and alongshore current transport. In our experiments, sea urchin fertilization rates and larval development were significantly affected by exposure to elutriates from Huelva Estuary sediments. Therefore, the Huelva Estuary area shows a declining but chronic contamination in Zn and Cu, originating from point and diffused anthropic activities, which in turn, are likely to cause adverse effects on the coastal ecosystem.

Acid Mine Drainage Contamination of the Ur Impoundment: Environmental Geochemistry

Water, particulate matter, and bottom sediments of the Ur impoundment used for fishing have been analyzed in terms of environmental geochemistry. The impoundment is located within the dispersion train of gold-bearing sulfide tailings at the Ur ore field and has been contaminated by acid mine drainage (AMD). The depth-dependent distribution of elements in the bottom sediments corresponds to (1) pre-mining, (2) early mining, and (3) post-mining (present) stages. Sediment enrichment in Cu, Cd, Fe, Pb, Zn, As and Hg depends on their speciation and migration patterns in water. The concentrations of many elements in water and bottom sediments exceed maximum allowable values. Hg occurring as the most toxic methyl compound poses the greatest hazard.

ASSESSMENT OF STREAM SEDIMENTS POLLUTION BY POTENTIALLY TOXIC ELEMENTS IN THE ACTIVE MINING AREA OF OKPELLA, EDO STATE, NIGERIA

An active gold mining area in Okpella, Edo State, Nigeria was studied to assess the contribution of gold mining to the concentrations of potentially toxic elements (PTEs) in stream sediments. Standard geochemical sampling and sample treatment techniques were employed, and samples were analysed using the energy dispersive X-ray fluorescence (XRF) method. The concentrations of arsenic (As), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) were determined in fifteen stream sediment samples from an active gold mining area, which also receives discharged marble mine water. The enrichment factor (EF) and geoaccumulation index (Igeo) were calculated using the XRF analysis results to assess the level of PTE pollution in the area. The sediments showed a PTE concentration trend of Cu > Zn > Pb > As > Cr > Hg > Ni > Co. The EF results revealed extremely severe enrichment of Hg, moderate enrichment of Cu, minor enrichment of As and Pb, and no enrichment of Co, Cr, Ni and Zn in the sediments. The Igeo also showed that the sediments were extremely polluted with Hg, moderately polluted with Cu but there was no evidence of pollution from other PTEs. Extreme pollution of the sediments by Hg and its enrichments in Cu, As and Pb are due to indiscriminate active artisanal gold mining in the area. It is recommended that immediate remediation measures should be enforced to mitigate the possible environmental health hazards to humans and livestock in the area.

Heavy metals and Zn isotope ratios in the snow of the Karabash copper smelting area (Southern Urals, Russia)

This work presents the first results of winter fieldworks aimed at the assessment of heavy metal content and Zn isotope composition in the snow cover of a smelting area in South Ural. Twenty one snowpacks were sampled at the end of the winter 2018 in the vicinity (1.0-95 km) of the copper smelter of the Karabash town (South Ural, Russia). The snow samples were analyzed for major and trace element composition using ICP-MS and ICP-OES techniques. Zn isotope analysis was performed by MC-ICP-MS with preliminary chromatographic purification. pH and water hardness values were obtained as well. Zn, Cu, Pb, Cd and Sr enrichment factors were calculated. The contaminant particles in snow were established to have been derived from the technogenic source through the distances up to 95 km from the industrial smelting area.

HEAVY METALS BIOCONCENTRATION AND TRANSLOCATION IN PLANTS: THE INFLUENCE OF A THERMAL POWER SITE

Soil and plant samples were collected from agricultural areas under the influence of thermal power plant and ash samples were collected from ash storage area. In samples, As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V, Zn, Al, Ca, Fe, K, Na and S were analyzed using ICP-MS. The aim of the study is to determine the set of elements mainly emitted from the components of the thermal power plant, as well as the major sources influencing the plant elemental levels. In the ash samples, significant enrichments of S, Mo, As, Ca, Cd and Cr were determined. Sugar beet leaves were considered to be a potential Na hyperaccumulator due to the translocation factor (TF) of 13525 calculated in its leaves. As a result of the Principal Component Analysis applied to the bioconcentration factors (BCFs) determined in plant parts, the main source of Co , Pb , Ni , Cr , Fe , Al, V, As, Mn and Cd was determined as geochemical background level of soil. Cu, Zn, and Mo enrichment in plant parts were found linked with agrochemicals used on the site, while another source of Cd was detected as phosphate fertilizers. Mo and S are identified as the main elements sourced from thermal power plant units.

Heavy Metal Contamination of Otofure Dumpsite Environment near Benin City Edo, Nigeria

This study characteriz ed some indices of heavy metals in the soils of Otofure waste dumpsite environment near Benin City, Edo State in Southern Nigeria, in order to ascertain the level of heavy metal contamination of one of the several sites receiving municipal solid wastes dai ly. Six samples were collected at the dumpsite (DS) and the adjoining upland positions (US). The samples were air - dried, crushed and sieved through a 2mm sieve and pre - treated using standard methods before determining the h eavy metal concentrations in Atomic Absorption Spectrophotometer (Bulk Scientific 210 VGP) according to the method of the Association of Analytical Chemists. Various pollution indexes were computed using the analytical data obtained. The computed Enrichment factor (EF) showed that Mn. Fe, and cu had no enrichment at the top and subsurface of the dumpsite. However, there was a significant Zn enrichment and enrichment with Ni and V at the topsoil; and Extreme enrichment with Cr, Cd, and lead of the soil at the dumpsite. Also, the soil Co ntamination factor (CF) indicated a moderate contamination of iron (Fe), manganese (Mn) and copper (Cu), Very High contamination of zinc (Zn), chromium (Cr), cadmium (Cd), lead (Pb), nickel (Ni) and vanadium (V). Pollution Load Index (PLI) showed that Otof ure dumpsite is heavily polluted (PLI &gt; 1) by heavy metals in general. Geoaccumulation Index (Igeo) showed that soils of Otofure dumpsite were unpolluted to moderately polluted for manganese (Mn) and copper (Cu), heavily polluted for zinc (Zn), Heavily to Extremely polluted for chromium (Cr), cadmium (Cd), lead (Pb), and nickel (Ni), and Extremely polluted for chromium (Cr), cadmium (Cd), lead (Pb) and vanadium (V). The potential ecological risk index (PERI) showed slight pollution for manganese (Mn), zinc (Zn) and copper (Cu), a very strong pollution for chromium (Cr), and an extremely strong pollution for lead (Pb), nickel (Ni) and cadmium (Cd). The risk index (RI) for Otofure dumpsite indicated a very strong risk or level D pollution for the higher elevat ion around the Otofure dumpsite environment that could pose human health risks if crops from that environment is ingested. This result thus suggest the need for a gradual shift from surface municipal waste dumping of solid wastes to well - engineered and man aged recycling/sanitary landfill in Edo State and Nigeria in order to prevent heavy metal pollution of lands and possibly groundwater where shallow aquifers exist.

Distribution and Health Risk Assessment of Trace Metals in Soils in the Golden Triangle of Southern Fujian Province, China.

In recent years, intensified industrialization and rapid urbanization have accelerated the accumulation of trace metals in topsoils of the Golden Triangle of Southern Fujian Province in China. Trace metals can cause adverse impacts on ecosystems and human health. In order to assess the ecological and human health risks of trace metals in the Golden Triangle region and to determine the distribution and degree of pollution of trace metals, 456 soil samples were collected from 28 districts. The concentrations of six metals (As, Cr, Cu, Ni, Pb, and Zn) were analyzed to assess ecological risk using the geoaccumulation index (Igeo) and the potential ecological risk index (RI). The United States Environmental Protection Agency (USEPA) model was applied to calculate health risk. The average soil concentrations of the six elements are ranked as follows: As < Ni < Cu < Cr < Pb < Zn. Inverse distance weighting (IDW) interpolation maps showed that Cr, Cu, Ni, and Zn are enriched in the soils of developed areas, while As and Pb are enriched in the soils of undeveloped areas. The Igeo showed that the levels of metals in most soil samples are below polluting levels. Similarly, RI values indicated that trace metals pose low potential ecological risk in the region’s soils. The Hazard Quotient (HQ) ranked the mean total noncarcinogenic risk of the six metals, for both children and adults, as follows: As > Pb > Cr > Ni > Cu >Zn. The mean carcinogenic risk (CR) of the metals in the region’s soils are ranked as follows: Cr > As > Ni. The Hazard Index (HI) values indicated that 3.7% of soils contained unsafe levels of toxic metals for children and total carcinogenic risk (TCR) values indicated that 23.3% of soils contained unsafe levels, indicating that children are facing both noncarcinogenic and carcinogenic risks from trace metals. Principal component analysis (PCA) and matrix cluster analysis were used to identify pollution sources and classified trace metals and soil samples into two and five groups, respectively. The five groups represented the effects of different land use types, including agricultural area, residential and public area, industrial area, forest, and industrial area and roadside, based on the contents of trace metals in soils. Industrial, agricultural and traffic activities attribute to the enrichment of Cr, Cu, Ni, Pb, and Zn in the region’s soils. Moreover, the accumulation of As and Pb are also attributed to atmospheric deposition. These results can contribute to a better understanding of pollution, ecological risks, and human health risks from trace metals on large regional scales like the Golden Triangle of Southern Fujian Province.

Geoquímica de Sedimentos da Confluência das Bacias Hidrográficas Baixo Jacuí e Vacacaí-Mirim, Caçapava do Sul-RS: Implicações para Proveniência e Intemperismo Químico

Este artigo apresenta os primeiros dados geoquímicos detalhados dos sedimentos e rochas do arroio do Salso na confluência das bacias hidrográficas Baixo Jacuí e Vacacaí-Mirim, em Caçapava do Sul – RS, buscando compreender a extensão do intemperismo químico e proveniência das frações siliciclásticas, e discutir as relações entre fontes autóctones e os processos geoquímicos do ambiente. Os diagramas A-CN-K, A-CNK-FM sugerem que a maioria dos sedimentos fluviais foi derivada de rochas félsicas, que incluem os granitóides do Complexo Granítico Caçapava do Sul (CGCS). Os índices calculados de intemperismo químico, como Chemical Index of Alteration (CIA) e o Plagioclase Index of Alteration (PIA) associados a quantidade de Sr indicam intemperismo moderado e perda de álcalis para os sedimentos fluviais. Características geoquímicas, representadas por elementos maiores, traços, terras raras (ETR) e a mineralogia indicam que a influência de rochas fontes félsicas (p. ex. granitóides) foi dominante nos sedimentos fluviais que derivam do arroio do Salso. Razões e padrões de distribuição e assinaturas geoquímicas indicam que esses sedimentos fluviais são derivados do CGCS em um ambiente em condições alternadas de oxirredução, sendo o enriquecimento de Cu, Pb e Zn natural e associado aos vários depósitos minerais da região.

Accumulation and Distribution of Heavy Metals in Imperata cylindrica at Lead-zinc Mining Area

Aiming at the present serious situation of heavy metals contaminated soil in lead-zinc mining area of Huize County. This paper analyzed the the Pb, Zn, Cu and Cd enrichment characteristics of Imperata cylindrica growing in the different distance from the abandoned smelter. Results showed that the content of heavy metals in soils showed a tendency to decrease with increasing distance from the abandoned smelter, and the content of heavy metals in the soil 50m away from the abandoned smelter was the highest. There was a significant positive correlation between the contents of Pb, Zn, Cu and Cd in Imperata cylindrica and soil around the abandoned smelter. Four heavy metals of Imperata cylindrica showed that the content of the underground part was higher than that of the aboveground part. These Results showed that Imperata cylindrica could absorb and enrich a variety of heavy metals and had the characteristics of heavy metal resistance. Based on the characteristics of large biomass and fast growth rate, Imperata cylindrica has a good application prospect as a heavy metal pollution restoration plant.

Zinc biofortification of maize (Zea mays L.): Status and challenges

AbstractZn deficiency is one of the leading health problems in children and women of developing countries. Different interventions could be used to overcome malnutrition, but biofortification is most impactful, convenient, sustainable and acceptable intervention. Maize is one of the major crops grown and consumed in the regions with prevalent Zn malnutrition; therefore, this is suitable target for Zn biofortification. Zn biofortification of maize could be achieved through agronomic and genetic approaches. Discussion of agronomic approaches with genetic approaches is prerequisite because soils in developing countries are deficit of Zn and availability of Zn in soils is mandatory for estimating the genetic responses of maize genotypes through genetic approaches. Seed priming, foliar and soil applications are agronomic tools for biofortification, but solo and combined applications of these treatments have different effects on Zn enrichment. Genetic approaches include the increase of Zn bioavailability or increase of kernel Zn concentration. Zn bioavailability could be increased by reducing the anti‐nutritional factors or by increasing the bioavailability enhancers. Kernel Zn concentration could be improved through hybridization and selections, whereas genetically engineered attempts for improving Zn uptake from soil, loading in xylem, remobilization in grains and sequestration in endosperm can further improve the kernel Zn concentration. Key challenges associated with dissemination of Zn biofortified maize are also under discussion in this draft. Current review emphasized all of above‐mentioned contents to provide roadmap for the development of Zn biofortified maize genotypes to curb the global Zn malnutrition.

Spatial distribution and source apportionment of heavy metals in soil from a typical county-level city of Guangdong Province, China

The contents of ten heavy metals (Cr, Hg, As, Pb, Ni, Cd, Ti, Cu, Zn and V) in 413 topsoil samples from Puning City, Guangdong Province, China were investigated. Obvious enrichment of Hg, As, Pb, Cd and Zn were presented, and the contents of Hg and As in 5.8% and 3.4% samples respectively were higher than the guideline values recommended by the Chinese Environmental Quality Standard for Soils. Chromium and V were presented no enrichment and no pollution. According to one-way analysis of variance, the mean contents of Hg, Pb, Cu and Zn in land for construction were significantly higher than farmland and natural vegetation, but the land use had no obvious effect on other heavy metals. Furthermore, the potential sources of ten heavy metals were identified and apportioned in combination with geostatistics, correlation analysis and positive matrix factorization model. The results were following as: a) Pb, Zn and Cu mainly origin from vehicle emission and atmosphere deposition, and the hotspots approximately distributed in the areas of intensive traffic and near main roads; b) Hg and Cd were derived to industrial activities related to pharmaceutical industries, the textile and dyeing industries and e-waste recycling industries, and high-value areas were mainly concentrated in the northeast of the urban area where the industrial parks have been distributed; c) Soil parent material (Jurassic shale) was the main source of Cr, Ni, V and Ti; d) As mainly came from agricultural inputs such as pesticides or herbicides, livestock and fertilizers. Meanwhile, the contributions of four sources were 33.08%, 24.04%, 27.11% and 15.77% of the total contribution, respectively.

Iron-oxides constrain BIF evolution in terranes with protracted geological histories: The Iron Count prospect, Middleback Ranges, South Australia

When studied at appropriate scales of observation and using complementary methods, the intrinsic textural and geochemical complexity of iron-oxides can provide unparalleled insights into the evolution of iron ore resources from banded iron formation deposition to ore formation. Iron Count is one of >20 deposits and prospects within the Archean Middleback Ranges iron ore belt, South Australia, in which iron-oxides from BIFs and ores display variable textural and trace element signatures. Integrated petrography, iron-oxide laser-ablation mapping and geochemistry, and in-situ dating of BIF-derived ores was undertaken to assess whether features observed in samples from this representative prospect might be attributed to localized and superimposed overprint processes.The prospect consists of a West and East ridge, each characterized by a sequence of overprints expressed as interconversions between iron-(hydr)oxides and accompanying variation in trace element concentrations. Pseudomorphic replacement of early magnetite by hematite (martite), followed by replacement by iron-hydroxides is recognized in samples from the East Ridge. Further overprints are expressed as veining, brecciation and crystallization of (micro)platy hematite rich in granitophile elements (Sn, Mo, W, U). Martitization of early magnetite in the West Ridge is accompanied by enrichment in Zn, Co and Ni in martite. Subsequent recrystallization of martite/iron-hydroxides by granoblastic hematite is marked by enrichment in Ti, Ta, Nb, REE and granitophile elements, and co-crystallization of REE-minerals. This is followed by crystallization of (micro)platy hematite, similarly rich in these elements. Enrichment in Ti and granitophile elements in granoblastic hematite is interpreted to infer crystallization from highly saline fluids generated by interaction between evaporite-bearing sedimentary rocks and granite-derived fluids. Post-Archean Australian Shale-normalized REY fractionation trends of iron-oxides from the East Ridge are consistent with precipitation of iron-rich minerals from a mixture of anoxic seawater and hydrothermal vent fluids. Analogous trends from the West Ridge lack a seawater signature. Contrasts in REY fractionation trends between the two ridges is interpreted as a combination of the loss of primary seawater signature due to severe overprinting in the West Ridge, and to lateral variation in the marine depositional environment. Results validate the hypothesis that variation in iron-oxide trace element signatures seen throughout the Middleback Ranges iron ore belt results from overprinting due to superimposed tectono-magmatic events that have locally affected each deposit. Despite undergoing different sequences of ore-forming stages, as well as possibly distinct depositional environments, the two ridges share a common overprint, dated here at ~1790 Ma using in-situ UPb geochronology of co-existing hematite, monazite and xenotime. This age is considered to represent the timing of interaction between granite-derived fluids with ore-hosting rock. Such interpretation is supported by the geochemical signatures of the dated iron-oxides showing enrichment in granitophile elements and coincident ages for the Wertigo Granite and Myola Volcanics, which occur proximal to the prospect and were emplaced/erupted during intracontinental rifting. The approach undertaken here, combining petrography, iron-oxide geochemistry and in-situ dating of BIF-derived ores is generically applicable to other iron resources within the Middleback Ranges or analogous terranes elsewhere.

Devonian ( c. 388–375 Ma) Horn River Group of Mackenzie Platform (NW Canada) is an open-shelf succession recording oceanic anoxic events

At least four horizons of enhanced anoxia (anoxic horizons; AHs) are recognized in the uppermost Eifelian–Middle Frasnian mudrock-dominated strata of the Mackenzie Valley and Peel area of NW Canada. Aluminium-normalized Mo and U logs in two cored sections reveal AH-I at the Eifelian–Givetian boundary, AH-II in basal Frasnian, and AH-III and AH-IV bundled in the Middle Frasnian interval. These four horizons are characterized by attenuated siliciclastic components. Spectral gamma-ray K + Th and U are the best tools to trace these horizons in wells and outcrops. AHs are biostratigraphically correlated with ‘black-shale events’ in several basins of the world. Depositional environment is depicted as a stratified basin where the water-column chemocline defined co-sedimentation of anoxic mudrocks in topographic lows and oxic grey shales and carbonate banks on seafloor elevations. Based on inductively coupled plasma elemental data from 1687 samples, siliciclastic-lean basinal mudrock units that host AHs are strongly enriched in Mo (median EFMo ∼ 97–172 EFMo/EFU ≈ (3–3.5) × SW, where EFMo and EFU are respectively Al-normalized Mo and U in enrichment factor notation and SW is average present-day seawater value) compared with siliciclastic-rich units (median EFMo ∼ 17–37) and show strong EFU/EFMo covariation ( r ≈ 0.8 in Canol Formation and Bluefish Member). Supported by a lack of geological evidence for an oceanographic barrier, this enrichment indicates unrestricted water exchange with Panthalassa. At the same time, development of oligotrophy is indicated by a lack of P enrichment and weak to non-existent enrichment in Zn and Cu. These features are reconciled through a model by earlier workers that involves a global shift to a warm greenhouse mode with slowed oceanic convection, expanded oxygen minimum zones and a failure of nutrient resupply from the upwelling. The onset of mass degassing in continental large igneous provinces represents a potential trigger for this mid-Devonian shift. Devonian black-shale events in this scenario represent genuine oceanic anoxic events marking hothouse episodes in their nascent form. Supplementary material: Details of methods, analytical protocols and data scatterplots, stratigraphic cross-sections showing traceability of anoxic horizons, and inductively coupled plasma elemental and Rock-Eval 6 data used in this study are available at: https://doi.org/10.6084/m9.figshare.c.4212428

Spatial and temporal distribution of heavy metal concentrations and enrichment in the southern Gulf of Mexico

Trace element (As, Co, Cr, Cu, Ni, Pb, V and Zn) enrichment trends during the past century, were assessed in thirteen 210Pb-dated sediment cores from the southern Gulf of Mexico, with the purpose to evaluate the impact on the environment, and potentially on public health, of the offshore oil industry and of oil spills such as that of the Ixtoc1 well blowout in 1979. The trace element composition was quite homogeneous among cores; and the pre-industrial concentrations of Ba, Cr, Cu and Ni are naturally high in the region, as to reach levels of potential ecological concern. The influence of multiple and simultaneous processes (e.g. industrial activities, natural seeps, fluvial discharges) on the trace element concentrations is difficult to disentangle. Some cores suggested long-term preservation of putative oil spill traces, although it was not possible to attribute their origin. The Al-normalized redox element ratios, and the crude oil contamination ratio, suggested that these events occurred along almost four decades, and that the traces attributed to the Ixtoc1 spill were comparable to background conditions, most likely owing to active natural oil seeps in the area. In most cases there was a trend towards a lowering in the supply of trace elements; this might be associated with environmental controls in the region since the 1980s. This study highlights the relevance of using dated environmental archives to reconstruct the historical trends of trace metal contamination in areas where long-term environmental studies are scarce.