High Levels Of Aluminum Research Articles

Prevalence and Factors Associated with High Levels of Aluminum, Arsenic, Cadmium, Lead, and Mercury in Hair Samples of Well-Nourished Thai Children in Bangkok and Perimeters.

Toxic element exposure increases risk of neurodevelopmental disorders. However, hair element profiles of well-nourished urban resident children were largely unknown. We identified prevalence and the contributing factors of high hair aluminum (Al), arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) levels in 111 Thai children (aged 3-7years old). Most participants were well-nourished with high socioeconomic status. Since ROC curve of hair element data showed inadequate sensitivity for cutoff set-up, US reference hair levels were used to categorize high and low level groups. Nevertheless, compared to the current reference at 5μg/dL, blood lead cutoff at 2.15μg/dL provided more consistent results with that of hair lead levels. High As and Pb levels were the first and second most prevalent element, while Al was the element found in highest amount in hair. High hair Al (12% prevalence) levels were associated with being male regardless of age or nutritional status. High hair As levels were associated with living in Bangkok (OR = 6.57) regardless of school type. High hair Pb levels were associated with being under 5years old and living in Bangkok (OR = 3.06). However, no associations were found between blood Pb, hair Cd, Hg, and tested factors. These findings suggested that under 5-year-old boys living in capital city like Bangkok may be at risk of exposure to multiple toxic elements. Future studies in these children are warranted to identify their exposure sources and proper risk management strategies.

The role of plant functional traits in understanding forest recovery in wet tropical secondary forests

Simultaneous measurement of plant functional traits and the regeneration environment should shed light on the plant-environment interactions and feedbacks as secondary forest regenerates. However, little of such work has been done in the wet tropics, and even fewer studies have examined soil nutrients. We investigated whether plant functional traits and environmental variables explain the varied recovery of secondary forests in Singapore. Our study plots included three primary forest plots and eight approximately 60-year-old secondary forest plots regenerating from intensive agricultural activities. Using 35 seedling quadrats, we asked: Q1) How do environmental variables explain the variation in seedling functional traits observed in primary and secondary forests? Q2) How do seedling traits, adult traits and environmental variables relate and explain variation in species richness and stem density in secondary forests? We found that both light and soil fertility explained the shifts in plants functional traits from poorly recovering secondary forests to primary forests. Poor forest regrowth was correlated with high soil aluminum levels and lower leaf nitrogen concentrations. Low nutrients and high aluminum saturation were also negatively correlated with seedling species richness, but not stem density, in the secondary forests. Forest recovery is probably slowed by positive feedback between slower nutrient returns from slow decaying litter and further recruitment of nutrient conserving species, as indicated by positive correlations among adult leaf CN ratio, litter depth, soil CN ratio and quadrat level CN ratio. Plant functional traits are indicative of the strategies of successful seedlings and do not necessarily relate to overall forest recovery. Hence, while some specialist plant species are able to accrue high nutrients on degraded soils with aluminum toxicity and low nutrients, species richness on these soils was poor. This underscores the need to concurrently measure environmental variables and plant traits when investigating the mechanisms driving changes during forest recovery.

Wood anatomy of Laguncularia racemosa (Combretaceae) in mangrove and transitional forest, Southern Brazil

Mangroves represent an environment of great heterogeneity and low diversity of plant species that have structural and physiological adaptations linked to a high salinity environment. Laguncularia racemosa is a typical tree species in mangroves and transitional zones. This study aimed to compare the wood anatomy of L. racemosa (Combretaceae) in two different forests (mangroves and transitional forests), which have different soil conditions. For this, we obtained wood and soil samples in March 2016. We analyzed soil nutritional contents in one 15 cm deep soil sample per forest type. In addition, we selected five mangrove trees in each formation for wood anatomy analysis and took one wood sample per individual, per area. We prepared histological slides and separated materials following standard methods for wood anatomy studies. Soil analysis showed that mangrove soils had higher phosphorus, potassium and calcium contents. The transitional soil had lower pore water salinity and soil pH, probably due to high aluminum levels. Anatomical attributes differed between different forest populations. In the different wood aspects evaluated, we obtained higher values in mangrove individuals when compared to the transitional forest population: vessel elements length (375.79 mm), tangential vessels diameter (75.85 mm), frequency of vessels (11.90 mm) and fiber length (889.89 mm). Moreover, parenchyma rays height was larger in the samples of the transitional forest (392.80 mm), while the mangrove population presented wider rays (29.38 mm). The structure of the secondary xylem in the studied species apparently responds to edaphic parameters and shows variations that allow it to adjust to the environmental conditions. The population of the transitional forest showed a secondary xylem that invests more in protection than the mangrove population. Rev. Biol. Trop. 66(2): 647-657. Epub 2018 June 01.

Molecular markers associated with aluminium tolerance in Sorghum bicolor

BackgroundSorghum (Sorghum bicolor, L. Moench) production in many agro-ecologies is constrained by a variety of stresses, including high levels of aluminium (Al) commonly found in acid soils. Therefore, for such soils, growing Al tolerant cultivars is imperative for high productivity.MethodsIn this study, molecular markers associated with Al tolerance were identified using a mapping population developed by crossing two contrasting genotypes for this trait.ResultsFour SSR (Xtxp34, Sb5_236, Sb6_34, and Sb6_342), one STS (CTG29_3b) and three ISSR (811_1400, 835_200 and 884_200) markers produced alleles that showed significant association with Al tolerance. CTG29_3b, 811_1400, Xtxp34 and Sb5_236 are located on chromosome 3 with the first two markers located close to AltSB, a locus that underlie the Al tolerance gene (SbMATE) implying that their association with Al tolerance is due to their linkage to this gene. Although CTG29_3b and 811_1400 are located closer to AltSB, Xtxp34 and Sb5_236 explained higher phenotypic variance of Al tolerance indices. Markers 835_200, 884_200, Sb6_34 and Sb6_342 are located on different chromosomes, which implies the presence of several genes involved in Al tolerance in addition to SbMATE in sorghum.ConclusionThese molecular markers have a high potential for use in breeding for Al tolerance in sorghum.

Physical and chemical characterization and recycling potential of desktop computer waste, without screen

Abstract Environmentally appropriate and efficient recycling of several materials contained in waste electrical and electronic equipment (WEEE) requires knowledge and the identification of materials and chemical elements forming this kind of waste. Therefore, this study presents the physical and chemical characterization of desktop computer waste and the potential recycling rates of these materials. Differently from other studies, which investigated recycling and chemical composition only of motherboards (the component that contains precious metals), here were evaluate all components, namely floppy disk drives, CD drives, IDE cables, HDs, coolers, motherboards, power supply units, lids, casings, and other parts. This study was carried out in three steps: (i) the physical characterization included the manual dismantling of these components, and grouping the materials under seven categories (plastics, non-ferrous metals, ferrous metals, materials with substances of interest, hazardous materials, wires and cables, and other materials); (ii) potential recycling rates were calculated according to the European Directive 2102/19/EU; (iii) chemical characterization of components based on X-ray fluorescence spectroscopy. The results showed that the potential recycling rate of the waste analyzed was 96.66%, which represents the amount of material that can be recycled in the samples investigated. The results also show that, besides motherboards, other components also are potentially recyclable. Noble, precious, and critical metals as well as and rare earth elements were detected in IDE cables, power supply units, hard disks, floppy disk drives, and motherboards. Parts with high levels of aluminum, copper, and zinc were also observed. Recycling of WEEE is important both economically and environmentally, since PC components, since these elements may be recycled in processes that use less energy, preventing the extraction of natural raw materials and minimizing environmental impact.

Study of Groundwater in Northeast Cairo Area, Egypt

This paper presents a comprehensive hydrogeologic view of the Quaternary aquifer in north eastern Cairo area, Egypt. The hydrogeologic, hydrochemical and isotopic features of the aquifer are determined to assess the groundwater geochemistry and quality for different uses. The groundwater in the aquifer is shallow and flows towards the heavily pumping areas (cultivated and industrial areas). The concentrations of total dissolved solids (TDS) vary considerably in the aquifer, ranging from 225.6 mg/L to 1219 mg/L. Wide variations in the concentrations of major ions, trace elements, nitrate, δ18O and δ2H are detected, indicating the variation in the geologic and recharge conditions. This further indicates the effect of natural processes (weathering, dissolution and ion exchange) as well as anthropogenic activities on the quality of groundwater. Moderate levels of contamination with nitrate, aluminum and manganese are recorded in the groundwater below the cultivated area. The contamination is linked to the extensive use of fertilizers for agriculture and the leakage of wastewater from improper sewage system. The computed nitrate pollution index reveals that about 69.69% of groundwater is safe for drinking, while the rest of groundwater is unsuitable. The calculated water quality index indicates that about 78.79% of groundwater is safe for human consumption and the rest of groundwater is poor for consumption because of the contamination with the high levels of manganese, total hardness, pH, sulphate, aluminum, and nitrate. The contaminated groundwater needs to be treated before consumption. Hence, periodic groundwater quality checks are recommended.

Association between serum aluminum levels and cardiothoracic ratio in patients on chronic hemodialysis.

The cardiothoracic ratio (CTR) and serum aluminum levels are both associated with mortality in hemodialysis patients. However, limited data regarding the association between serum aluminum levels and the CTR have been published to date. Therefore, we aimed to elucidate this association in patients on chronic hemodialysis (CHD). We investigated the association between the serum aluminum level and the CTR in CHD in a retrospective cross-sectional study of 547 Taiwanese patients on CHD. The mean age of patients was 62.5±13.2 years, with a mean hemodialysis time of 7.1±5.2 years. Among the patients, 36.9% were diabetic and 47.9% were male. After natural logarithmic transformation (ln(aluminum)), the serum aluminum level exhibited an independent and linear relationship with the CTR (β: 1.40, 95% confidence interval (CI), 0.6–2.2). A high serum aluminum level (≥6 ng/dL) was significantly associated with a CTR >0.5 in the crude analysis (odds ratio (OR): 2.15, 95% CI, 1.52–3.04) and remained significant after multivariable adjustment (OR: 2.45, 95% CI, 1.63–3.67). Moreover, the ln(aluminum) value was significantly associated with a CTR >0.5 (OR: 1.71, 95%CI, 1.28–2.29) in multivariable analysis, indicating a dose effect of aluminum on cardiomegaly. In conclusion, the serum aluminum level was independently associated with cardiac remodeling (elevated CTR) in patients on CHD.

New evidences on the contribution of arbuscular mycorrhizal fungi inducing Al tolerance in wheat

Wheat cropping in Chile is mainly located in the Central Southern area on acidic volcanic soils commonly with high aluminum (Al) levels. Introduction of Al-tolerant wheat cultivars has improved production, but the role of arbuscular mycorrhizal fungi (AMF) in augmenting the Al stress resistance of Al-resistant genotypes is mostly unknown. In the present study, we analyzed the effects of Al on growth performance of three wheat genotypes on acidic soils differing in Al tolerance inoculated or not with indigenous AMF communities isolated from Andosols with contrasting levels of Al saturation. Plants were grown in a soil-less rhizobox system including mycorrhizosphere, rhizosphere and hyphosphere compartments. Different Al level (0, 40 and 400 μM) were applied to all compartments. Main factors tested (wheat genotype, indigenous AMF inoculum and Al level) strongly affected plant and AM fungal performance with differential effects on the rhizosphere, mycorrhizosphere and hyphosphere compartments. Both AMF inocula increased plant biomass (> 80%) and APase activity (~200%, especially with Gorbea AMF inoculum). Moreover, AMF isolated from soils with high Al saturation strongly reduced Al translocation to shoots (up to 5.8-fold in the higher Al level) and increased the Al exclusion in plants growing at high Al levels (over 70%), which may reflect the binding of Al in the rhizosphere by glomalin. By using a rhizobox compartmentation system, our results provide evidence that AMF alleviate Al phytotoxicity through a chemical barrier in which glomalin sequesters Al beyond the root surface, which seems to be an important trait of AMF and would be used for developing management strategies of acidic soils with high Al levels.

Effect of glass composition on the hardness of surface layers on aluminosilicate glasses formed through reaction with strong acid

AbstractThe effect of glass composition on physico‐chemical properties of surface layers formed through reaction between strong acid and several silicate and aluminosilicate glasses was studied through transmission‐IR, ATR‐IR, XPS, SIMS, and nano‐indentation analyses. It was shown that aluminum is depleted from the surface while molecular water is diffused into the surface layer of glasses with high levels of aluminum. Nano‐indentation experiments indicated that the hardness of the surface layers were decreased compared to that of the bulk region and the degree of the softening was more significant in the high aluminum glass.

Cell wall pectin methyl-esterification and organic acids of root tips involve in aluminum tolerance in Camellia sinensis

Tea plant (Camellia sinensis (O.) Kuntze) can survive from high levels of aluminum (Al) in strongly acidic soils. However, the mechanism driving its tolerance to Al, the predominant factor limiting plant growth in acid condition, is still not fully understood. Here, two-year-old rooted cuttings of C. sinensis cultivar ‘Longjingchangye’ were used for Al resistance experiments. We found that the tea plants grew better in the presence of 0.4 mM Al than those grew under lower concentration of Al treatments (0 and 0.1 mM) as well as higher levels treatment (2 and 4 mM), confirming that appropriate Al increased tea plant growth. Hematoxylin staining assay showed that the apical region was the main accumulator in tea plant root. Subsequently, immunolocalization of pectins in the root tip cell wall showed a rise in low-methyl-ester pectin levels and a reduction of high-methyl-ester pectin content with the increasing Al concentration of treatments. Furthermore, we observed the increased expressions of C. sinensis pectin methylesterase (CsPME) genes along with the increasing de-esterified pectin levels during response to Al treatments. Additionally, the levels of organic acids increased steadily after treatment with 0.1, 0.4 or 2 mM Al, while they dropped after treatment with 4 mM Al. The organic acids secretion from root followed a similar trend. Similarly, a gradual increase in malate dehydrogenase (MDH), citrate synthase (CS) and glycolate oxidase (GO) enzyme activities and relevant metabolic genes expression were detected after the treatment of 0.1, 0.4 or 2 mM Al, while a sharp decrease was resulted from treatment with 4 mM Al. These results confirm that both pectin methylesterases and organic acids contribute to Al tolerance in C. sinensis.

Nematode assemblages in the Gulf of Mexico continental shelf collected during a two-year survey

Nematode assemblages along the northern continental shelf of the Gulf of Mexico (GOM) were examined to understand the structure of the meiobenthic community in the area. Meiofauna were collected at 36–187m depths on the northern GOM continental shelf in 2013–2014. Sediment was collected from 37 stations with a multicorer and analyzed for nematode diversity, trace metals, and granulometry. Over 3800 nematodes were identified from 151 genera and 32 families. Cluster analysis revealed distinct nematode assemblages in the eastern study areas (Florida/Alabama) versus western areas (Louisiana/Mississippi) that corresponded with two different sediment profiles in the eastern and western Gulf shelf. These areas demonstrated higher levels of silt and aluminosilicate compounds in the west due to the outflow of the Mississippi River, and higher levels of sand fractions in Florida, far from the River outflow. Further, significant (SIMPROF) temporal changes were revealed by the cluster analysis, as the 2014 eastern nematode assemblages grouped together but separately from the 2013 eastern nematode cluster, though the collection methods and identification processes were identical. Conversely, the 2013–2014 nematode assemblages from the Louisiana/Mississippi sites grouped as one significant cluster. As nematode communities are known to correlate to areas of organic enrichment, trace metals were used as indicators of Mississippi River-derived silty sediments that have elevated levels of organic matter. The data show that nematode abundances at each site correlated positively with high levels of Aluminum and Zinc, near the Mississippi River outflow, as well as with high levels of silt+clay. Conversely, nematode densities correlated negatively with Calcium and Strontium, which are elevated in Florida. Nematode density was not related to water depth. The most abundant genera identified in the study were Sabatieria, Dorylaimopsis, Pselionema, Tricoma, and Halalaimus. This study will be useful in understanding the abiotic factors that influence the meiobenthic community and will facilitate future assessments of natural and man-made disturbances.

Aluminum exposure at human dietary levels promotes vascular dysfunction and increases blood pressure in rats: A concerted action of NAD(P)H oxidase and COX-2.

Aluminum (Al) is a non-essential metal and a significant environmental contaminant and is associated with a number of human diseases including cardiovascular disease. We investigated the effects of Al exposure at doses similar to human dietary levels on the cardiovascular system over a 60day period. Wistar male rats were divided into two major groups and received orally: 1) Low aluminum level - rats were subdivided and treated for 60days as follows: a) Untreated - ultrapure water; b) AlCl3 at a dose of 8.3mg/kg bw for 60days, representing human Al exposure by diet; and 2) High aluminum level - rats were subdivided and treated for 42days as follows: C) Untreated - ultrapure water; d) AlCl3 at 100mg/kg bw for 42days, representing a high level of human exposure to Al. Effects on systolic blood pressure (SBP) and vascular function of aortic and mesenteric resistance arteries (MRA) were studied. Endothelium and smooth muscle integrity were evaluated by concentration-response curves to acetylcholine (ACh) and sodium nitroprusside. Vasoconstrictor responses to phenylephrine (Phe) in the presence and absence of endothelium and in the presence of the NOS inhibitor L-NAME, the potassium channels blocker TEA, the NAD(P)H oxidase inhibitor apocynin, superoxide dismutase (SOD), the non-selective COX inhibitor indomethacin and the selective COX-2 inhibitor NS 398 were analyzed. Vascular reactive oxygen species (ROS), lipid peroxidation and total antioxidant capacity, were measured. The mRNA expressions of eNOS, NAD(P)H oxidase 1 and 2, SOD1, COX-2 and thromboxane A2 receptor (TXA-2 R) were also investigated. Al exposure at human dietary levels impaired the cardiovascular system and these effects were almost the same as Al exposure at much higher levels. Al increased SBP, decreased ACh-induced relaxation, increased response to Phe, decreased endothelial modulation of vasoconstrictor responses, the bioavailability of nitric oxide (NO), the involvement of potassium channels on vascular responses, as well as increased ROS production from NAD(P)H oxidase and contractile prostanoids mainly from COX-2 in both aorta and mesenteric arteries. Al exposure increased vascular ROS production and lipid peroxidation as well as altered the antioxidant status in aorta and MRA. Al decreased vascular eNOS and SOD1 mRNA levels and increased the NAD(P)H oxidase 1, COX-2 and TXA-2 R mRNA levels. Our results point to an excess of ROS mainly from NAD(P)H oxidase after Al exposure and the increased vascular prostanoids from COX-2 acting in concert to decrease NO bioavailability, thus inducing vascular dysfunction and increasing blood pressure. Therefore, 60-day chronic exposure to Al, which reflects common human dietary Al intake, appears to pose a risk for the cardiovascular system.

Selection of aluminum tolerant cereal genotypes strongly influences the arbuscular mycorrhizal fungal communities in an acidic Andosol

Abstract In Chile, cereals cultivation is mainly in volcanic soils with pH values typically between 4.5–5.5 and high levels of exchangeable aluminum (Al) and low P availability. In this context, arbuscular mycorrhizal fungi (AMF) provide or enhance protection against this environmental stress. The aim of this study was to investigate the impact of the breeding process of Al-tolerant cereal plants on AMF community structure and diversity associated to cereals species. This breeding program has been developed since 1980 in our country and consists of obtaining cereal plants that can tolerate stress by Al. For this, we contrast cereals species and genotypes in which Al-stress has been included or not in this breeding program. Rhizosphere soils from Al-tolerant cereals recently developed ( Avena sativa, Hordeum vulgare, Triticum durum , x. Triticosecale Wittmack , Secale cereale and T. aestivum ) were collected from field plots in South-Central Chile. In addition, two cereals with recognized Al-tolerance (Crac wheat cultivar and rye) were also analyzed. AMF identification and taxonomy was performed based on spore morphological analyses. Colonization and glomalin related soil protein (GRSP) was also evaluated. In general, up to 80% of root colonization in all cereal was found. Extraradical mycelium reached levels close to 3 m g −1 of soil in the rhizosphere of S. cereale , A. sativa and H. vulgare selected under Al stress. While, GRSP values were statistically similar among selected or not selected genotypes under Al stress, this trend was not observed in H. vulgare , where a difference of 20 μg GRSP g −1 of soil was found. Moreover, large differences in AMF spore densities were observed, being 340 spores in 100 g soil the lowest and 1900 the highest one, in non Al tolerant H. vulgare and Al tolerant x. Triticosecale Wittmack , respectively. From a total of 10,000 AM fungal spores, 21 AMF species were identified, belonging to three classes, six orders, and eight families. The alpha diversity was higher in Al tolerant T. durum and almost similar to T. aestivum . Evenness index was significantly higher in Al tolerant H. vulgare . As conclusion, the use of target AMF species and cereals obtained under Al stress could be determinant factors for the appropriate AMF community establishment, potential inoculation assays and agricultural practices, especially oriented to soils with high Al levels.

Pollution Assessment of the Biobío River (Chile): Prioritization of Substances of Concern Under an Ecotoxicological Approach.

The water demand for human activities is rapidly increasing in developing countries. Under these circumstances, preserving aquatic ecosystems should be a priority which requires the development of quality criteria. In this study we perform a preliminary prioritization of the risky substances based on reported ecotoxicological studies and guidelines for the Biobío watershed (Central Chile). Our specific aims are (1) reviewing the scientific information on the aquatic pollution of this watershed, (2) determining the presence and concentration of potential toxic substances in water, sediment and effluents, (3) searching for quality criteria developed by other countries for the selected substances and (4) prioritizing the most risky substances by means of deterministic ecotoxicological risk assessment. We found that paper and mill industries were the main sources of point pollution, while forestry and agriculture were mostly responsible for non-point pollution. The most risky organic substances in the water column were pentachlorophenol and heptachlor, while the most relevant inorganic ones were aluminum, copper, unionized ammonia and mercury. The most risky organic and inorganic substances in the sediment were phenanthrene and mercury, respectively. Our review highlights that an important effort has been done to monitor pollution in the Biobío watershed. However there are emerging pollutants and banned compounds-especially in sediments-that require to be monitored. We suggest that site-specific water quality criteria and sediment quality criteria should be developed for the Biobío watershed, considering the toxicity of mixtures of chemicals to endemic species, and the high natural background level of aluminum in the Biobío.

Between-species differences in gene copy number are enriched among functions critical for adaptive evolution in Arabidopsis halleri.

BackgroundGene copy number divergence between species is a form of genetic polymorphism that contributes significantly to both genome size and phenotypic variation. In plants, copy number expansions of single genes were implicated in cultivar- or species-specific tolerance of high levels of soil boron, aluminium or calamine-type heavy metals, respectively. Arabidopsis halleri is a zinc- and cadmium-hyperaccumulating extremophile species capable of growing on heavy-metal contaminated, toxic soils. In contrast, its non-accumulating sister species A. lyrata and the closely related reference model species A. thaliana exhibit merely basal metal tolerance.ResultsFor a genome-wide assessment of the role of copy number divergence (CND) in lineage-specific environmental adaptation, we conducted cross-species array comparative genome hybridizations of three plant species and developed a global signal scaling procedure to adjust for sequence divergence. In A. halleri, transition metal homeostasis functions are enriched twofold among the genes detected as copy number expanded. Moreover, biotic stress functions including mostly disease Resistance (R) gene-related genes are enriched twofold among genes detected as copy number reduced, when compared to the abundance of these functions among all genes.ConclusionsOur results provide genome-wide support for a link between evolutionary adaptation and CND in A. halleri as shown previously for Heavy metal ATPase4. Moreover our results support the hypothesis that elemental defences, which result from the hyperaccumulation of toxic metals, allow the reduction of classical defences against biotic stress as a trade-off.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3319-5) contains supplementary material, which is available to authorized users.

Thermal Analysis for Detection of Zr-Rich Phases in Al–Si–Cu–Mg 354-Type Alloys

The principal aim of the present research study was to investigate the effects of minor additions of zirconium on phase precipitation in 354 alloys under very slow solidification rates. The results showed that reactions corresponding to precipitation of Cu-containing phases are also observed in the 354 alloy at temperatures below 500 °C. Zirconium reacts only with Ti, Si, and Al. The Zr-rich intermetallic phases observed in this study appear in two different forms: the phase (Al,Si)2(Zr,Ti) containing high levels of silicon which is block-like in form, and the phase (Al,Si)3(Zr,Ti) containing high levels of aluminum, which appears in needle-like form. There is no observable poisoning effect on the refinement of grain size after the addition of Zr to the alloys investigated, as was observed from the macrostructures of the thermal analysis samples obtained at high solidification rates, for the alloys containing Zr and Ti. In thermal analysis experiments carried out at the higher solidification rate, namely 4 °C s−1, there is an observable reaction within the temperature range of 667–671 °C which appears to be related to the precipitation of Zr-rich phases; it was not possible to observe this reaction at the lower solidification rate of 0.35 °C s−1 generally used in thermal analysis.

Aluminum Exposure at Human Dietary Levels for 60 Days Reaches a Threshold Sufficient to Promote Memory Impairment in Rats.

Aluminum (Al) is a significant environmental contaminant. While a good deal of research has been conducted on the acute neurotoxic effects of Al, little is known about the effects of longer-term exposure at human dietary Al levels. Therefore, the purpose of this study was to investigate the effects of 60-day Al exposure at low doses for comparison with a model of exposure known to produce neurotoxicity in rats. Three-month-old male Wistar rats were divided into two major groups: (1) low aluminum levels, and (2) a high aluminum level. Group 1 rats were treated orally by drinking water for 60days as follows: (a) control-received ultrapure drinking water; (b) aluminum at 1.5mg/kg b.w., and (c) aluminum at 8.3mg/kg b.w. Group 2 rats were treated through oral gavages for 42days as follows: (a) control-received ultrapure water; (b) aluminum at 100mg/kg b.w. We analyzed cognitive parameters, biomarkers of oxidative stress and acetylcholinesterase (AChE) activity in hippocampus and prefrontal cortex. Al treatment even at low doses promoted recognition memory impairment seen in object recognition memory testing. Moreover, Al increased hippocampal reactive oxygen species and lipid peroxidation, reduced antioxidant capacity, and decreased AChE activity. Our data demonstrate that 60-day subchronic exposure to low doses of Al from feed and added to the water, which reflect human dietary Al intake, reaches a threshold sufficient to promote memory impairment and neurotoxicity. The elevation of oxidative stress and cholinergic dysfunction highlight pathways of toxic actions for this metal.

Investigating the effect of cadmium and aluminium on growth and stress-induced responses in the micropropagated medicinal plant Hypoxis hemerocallidea.

Hypoxis hemerocallidea is a highly utilized medicinal plant in South Africa. Its cultivation has received considerable attention in order to meet the high demand. High levels of cadmium (Cd) and aluminum (Al) in H.hemerocallidea plants sold in traditional medicinal markets was previously reported. The present study used an invitro propagation model to investigate the uptake of Cd and Al by H.hemerocallidea and their effect on plant growth, elemental uptake and some stress-induced responses such as pigment, malondialdehyde (MDA), proline content and ultrastructural changes. Shoot and root growth of plantlets exposed to Cd, Cd:Al and high concentrations of Al was significantly reduced. Highest concentrations of Cd accumulated in the corms of Cd-treated plantlets while highest Al concentrations occurred in the leaves and roots. There was higher accumulation of Cd and Al when applied singularly compared to the Cd:Al combination treatments. Cd and Al also reduced accumulation of trace elements in micropropagted H.hemerocallidea with lowest concentrations in the Cd:Al combination treatments. Exposure to Cd, Al and Cd:Al significantly reduced the level of chlorophyll but increased the levels of carotenoids, MDA and proline. Ultrastructural changes were also observed in H.hemerocallidea exposed to Cd and Al. All these factors contributed to the inhibition of plant growth and could potentially affect the ability of this important medicinal plant to synthesize bioactive compounds. It is thus necessary to understand heavy metal stress-induced responses in this highly valued medicinal plant to ensure a high quality product for the consumer.

Diversity of Hemiptera (Arthropoda: Insecta) and Their Natural Enemies onCaryocar brasiliense(Malpighiales: Caryocaraceae) Trees in the Brazilian Cerrado

The Cerrado occupies about 23% of the Brazilian territory and is characterized by great diversity of plants and insects and a great degree of endemism, and Caryocar brasiliense A. St.-Hil. (Malpighiales: Caryocaraceae) is widely distributed in this region. The diversity and abundance of hemipterans and their natural enemies were studied on trees of C. brasiliense in the Cerrado, pasture, and anthropic area in Montes Claros, Minas Gerais State, Brazil. We observed 1 rare, 8 common, and 1 frequent species of sucking insects; and 2 rare, 7 common, and 6 frequent species of natural enemies. Sucking insects and their natural enemies were most abundant in the pasture and least abundant in the Cerrado. Increasing diversity indices and numbers of species and individuals of sucking insects were followed by similar trends in the populations of natural enemies. Increasing populations of sucking insects led to greater numbers of individuals of ants, green lacewings, predator thrips, and ladybeetles. Aluminum level positively affected the number of species and individuals, and the pH of the soil reduced those of sucking insects. Leafhoppers had greater numbers on plants on soils with low pH values and high aluminum levels, but the opposite was noted for the aphids.

Evaluation of environmental conditions: air, water and soil in areas of mining activity in Boyacá, Colombia

Objectives To determine concentrations of PM10, mercury and lead in indoor air of homes, water sources and soil in municipalities near mining operations. Method 6 points were evaluated in areas of influence and 2 in control areas. For measurements of indoor air, we used the NIOSH 600 method (PM10), NIOSH 6009 (mercury) and NIOSH 7300 (lead). For water analysis we used the IDEAM Guide for monitoring discharges. For soil analysis, we used the cold vapor technique (mercury) and atomic absorption (lead). Results In almost all selected households, the average PM10 and mercury concentrations in indoor air exceeded applicable air quality standards. Concentrations of lead were below standard levels. In all water sources, high concentrations of lead were found and in some places within the mining areas, high levels of iron, aluminum and mercury were also found. In soil, mercury concentrations were below the detection level and for lead, differences between the monitored points were observed. Conclusions The results do not establish causal relationships between mining and concentration of these pollutants in the evaluated areas because of the multiplicity of sources in the area. However, such studies provide important information, useful to agents of the environmental health system and researchers. Installation of networks for environmental monitoring to obtain continuous reports is suggested.