Cause Of Enrichment Research Articles

Winter chemical partitioning of metals bound to atmospheric fine particles in Dongguan, China, and its health risk assessment

To analyze the relationship between nanoparticles and the chemical forms in an urban atmospheric environment, metallic particles with different diameters were collected using a nanoparticle sampling system and analyzed for chemical and morphological characteristics, bioactivity, and the risk of carcinogenic and non-carcinogenic effects. The source of the atmospheric particles was analyzed based on the enrichment factor method, and the carcinogenicity of the atmospheric particles was analyzed using the health risk model. The partition contents of metals extractable by a weak acid, including As, Ca, Cd, Cs, Pb, Sr, and Zn, were in a range of 32.17–71.4%, with an average value of 47.07%. The content of oxides and reducible metals of all of the elements was generally low. Potassium was distributed mainly in the residual and weak-acid-extractable fractions. Barium had a high proportion of the oxidation state. Each fraction of Zn was basically the same, while the content of the weak-acid-extractable fraction was slightly higher. We found bio-access potential to be positively correlated with a high proportion of the weak acid extracts such as Mg, Sr, and Zn. We also found there to be a large weak-acid-extractable fraction (F1) and residual fraction (F4) and relatively enriched elements and strongly enriched elements, which means F1 and F4 may be the cause of enrichment. The hazard index (HI) and the total cancer risk (TCR) were far beyond the safety threshold when the diameter of the particle was in the range of 0.1–0.5 μm, indicating that the residents in Dongguan city were experiencing obvious non-carcinogenic and carcinogenic risks.

Giovanni Cola (Joao Nicolao). Un hombre del Renacimiento italiano trasplantado a Japón

Mutual contacts between East and West along the history have always been a cause of enrichment for both parts. The same enrichment has happened in the history of art: mutual influences are in the origin of new artistic streams. Giovanni Cola, a Jesuit of tremendous capacity for inculturation, was able to penetrate in the culture of the Far East and, at the same time, he afforded the artistic values of western art, especially to Japan.

Mg Isotope Fractionation during Uptake by a Rock-Inhabiting, Model Microcolonial Fungus Knufia petricola at Acidic and Neutral pH.

The model rock-inhabiting microcolonial fungus Knufia petricola fractionates stable Mg isotopes in a time- and pH-dependent manner. During growth, the increase of 26Mg/24Mg in the fungal cells relative to the growth media amounted to 0.65 ± 0.14‰ at pH 6 and 1.11 ± 0.35‰ at pH 3. We suggest a constant equilibrium fractionation factor during incorporation of Mg into ribosomes and ATP as a cause of enrichment of 26Mg in the cells. We suggest too that the proton gradient across the cell wall and cytoplasmic membrane controls Mg2+ transport into the fungal cell. As the strength of this gradient is a function of extracellular solution pH, the pH-dependence on Mg isotope fractionation is thus due to differences in fungal cell mass fluxes. Through a mass balance model we show that Mg uptake into the fungal cell is not associated with a unique Mg isotope fractionation factor. This Mg isotope fractionation dependence on pH might also be observed in any organism with cells that follow similar Mg uptake and metabolic pathways and serves to reveal Mg cycling in ecosystems.

Malignant B Cells Induce the Conversion of CD4+CD25− T Cells to Regulatory T Cells in B-Cell Non-Hodgkin Lymphoma

Recent evidence has demonstrated that regulatory T cells (Treg) were enriched in the tumor sites of patients with B-cell non-Hodgkin lymphoma (NHL). However, the causes of enrichment and suppressive mechanisms need to be further elucidated. Here we demonstrated that CD4+CD25+FoxP3+CD127lo Treg were markedly increased and their phenotypes were different in peripheral blood (PB) as well as bone marrow (BM) from newly diagnosed patients with B-cell NHL compared with those from healthy volunteers (HVs). Involved lymphatic tissues also showed higher frequencies of Treg than benign lymph nodes. Moreover, the frequencies of Treg were significantly higher in involved lymphatic tissues than those from PB as well as BM in the same patients. Suppression mediated by CD4+CD25+ Treg co-cultured with allogeneic CFSE-labeled CD4+CD25− responder cells was also higher in involved lymphatic tissues from B-cell NHL than that mediated by Treg from HVs. In addition, we found that malignant B cells significantly induced FoxP3 expression and regulatory function in CD4+CD25− T cells in vitro. In contrast, normal B cells could not induce the conversion of CD4+CD25− T cells to Treg. We also showed that the PD-1/B7-H1 pathway might play an important role in Treg induction. Taken together, our results suggest that malignant B cells induce the conversion of CD4+CD25− T cells to Treg, which may play a role in the pathogenesis of B-cell NHL and represent a promising therapeutic target.

Structural properties of plant charred materials in Andosols as revealed by X-ray diffraction profile analysis

Charred plant fragments are frequently observed in soil. However, their structure has not been elucidated. In the present study, charred plant fragments detached from soil by HF treatment and collected by heavy liquid separation were characterized by X-ray diffraction (XRD) analysis. Three Andosols from the northeastern, central and western districts of Japan were used. Supportive information was obtained by solid-state 13C nuclear magnetic resonance (NMR) and δ13C analyses. In the XRD analysis, the size of the carbon (C)-layer planes in the charred plant fragments ranged from 0.96 to 1.92 nm, corresponding to 14–52 ring condensed aromatic structures. The size distribution of the C-layer planes did not differ largely among the three soils. A minor effect of vegetation on the composition of the condensed aromatic structures in the plant charred fragments was deduced from differences in the content of the 1.92 nm C-layer plane and δ13C. The relative content of condensed aromatic structures tended to be larger in the sample with more aromatic C content, which suggested that decomposition of aliphatic moieties is a cause of enrichment of condensed aromatic structure.

EXAFS study on the cause of enrichment of heavy REEs on bacterial cell surfaces

Rare earth element (REE) pattern is a unique geochemical tracer and has been measured for various natural materials. Among these, the REE distribution pattern between bacteria and water exhibits anomalous enrichment in the heavy REE (HREE) part, which can act as a signature of bacteria-related materials in natural samples. In this study, the REE binding site on the cell surface of a Gram-positive bacterium ( Bacillus subtilis) responsible for HREE enrichment has been identified using extended X-ray absorption fine structure (EXAFS) coupled with a study of the variation in REE distribution patterns. The EXAFS data showed that the HREEs form complexes with multiple phosphate site (including phosphoester site) with a larger coordination number (CN) at lower REE-bacteria ratios ([REE]/[bac]), while light and middle REEs form complexes to the phosphate site with a lower CN. The fraction coordinated to carboxylate increased for all REEs with increasing [REE]/[bac] ratio. On the other hand, the enrichment of HREE in the REE distribution patterns of the bacteria was less marked with increasing [REE]/[bac] ratio. This result is consistent with the EXAFS data, because the REE pattern of surface complex with multiple phosphate in a reference material exhibits a monotonous increase for heavier REE, while phosphate surface complex with a low CN and a carboxylate site reach a maximum around Sm and Eu. Based on these results, it is clear that the REE are primarily bound to the phosphate site and subsequently to the carboxylate site on the bacterial cell surface. Regarding the pH dependence in the range (3 < pH < 7), both the EXAFS and REE pattern data indicate that the fraction of REE-carboxylate increased as the pH increases. The results above obtained for B. subtilis were also valid for Escherichia coli, a Gram-negative bacterium, showing that similar phosphate and carboxylate sites are also available in the cell walls of E. coli, or other Gram negative bacteria. In all our results, the variation in REE patterns correlated with the binding site indicated by EXAFS, showing that the REE pattern itself reflects the binding site of the REE at the bacterial surface for various parameters (pH and [REE]/[bac] ratio). Thus, the REE patterns can be used to estimate the binding sites for lower [REE]/[bac] ratios where spectroscopic techniques cannot be applied. The average bond length between the REE and oxygen was compared for various REE sorbed on bacteria, showing that the bond length for HREE (Er to Lu) was much shorter than those extrapolated from the trend between La and Dy, because of the selective binding of the HREE as the multiple phosphate surface complexes. Our results are consistent with the selective enrichment of the HREE at the bacterial cell surfaces, considering that chemical species with a shorter bond length are more stable. Thus, it is clear that the HREE enrichment at the bacterial cell surfaces is caused by the formation of the multiple phosphate surface complexes. Based on these results, it is suggested that materials having such phosphate sites such as bacteria and bacteria-related materials can induce anomalous HREE enrichment in natural systems.

Highlights of some environmental problems of geomedical significance in Nigeria

This paper attempts to discuss the links between the geochemical composition of rocks and minerals and the geographical distribution of diseases in human beings in Nigeria. We know that the natural composition of elements in our environment (in the bedrock, soils, water, and vegetation) may be the major cause of enrichment or depletion in these elements and may become a direct risk to human health. Similarly, anthropogenic activities such as mining and mineral processes, industrial waste disposal, agriculture, etc., could distort the natural geochemical equilibrium of the environment. Thus, the enrichment or depletion of geochemical elements in the environment are controlled either by natural and/or anthropogenic processes. The increased ingestion of toxic trace elements such as As, Cd, Hg, Pb, and F, whether directly or indirectly, adversely affects human health. Of these, Cd has most dangerous long-term effect on human health. Environmental exposure to As and Hg is a causal factor in human carcinogenesis and numerous cancer health disorders. Available information on iodine deficiency disorder (IDD) in Nigeria indicates goiter prevalence rates of between 15% and 59% in several affected areas. There have been reported cases of dental fluorosis resulting from intake of water with fluoride content >1.5 ppm. Dental caries among children shows an overall prevalence rate of 39.9%. Within the Younger Granite province in central Nigeria, cases of cancer and miscarriages in pregnant women have been linked to natural radiation These examples and a number of others from the existing literature underscore the pressing need for the development of collaborative research to increase our understanding of the relationship between the geographical distribution of human and animal diseases in Nigeria and environmental factors. We submit that such knowledge is essential for the control and management of these diseases.

Blowing in the wind? Nutrient enrichment of remnant woodlands in an agricultural landscape

Increasing fertiliser use in agricultural landscapes is likely to threaten the viability of remnant native vegetation in many parts of the world. Australia’s prime grain production landscapes have nutrient poor soils, which formerly supported semi-arid woodland. The ecological function and capacity for regeneration of these remnants may be particularly susceptible to nutrient enrichment. The key sources of nutrients are wind and water deposition from crop fertilisation, and manure and feed from sheep. We hypothesised that these sources would result in unequal deposition of nutrients within and among remnant vegetation patches. We surveyed soil nutrients (Total N, Available P and K, C:N ratio, and soil pH) in the edges and interiors of 60 remnant woodland patches of various sizes, and in adjacent cultivated paddocks. Nutrient load was negatively correlated with remnant size and patterns were particularly strong for available P. Small remnant patches (<3 ha) were accumulation zones for nutrients, with levels comparable or higher than within crop lands. The patterns are consistent with the hypothesis that small remnants are strongly enriched as a result of being used for livestock shelter. In larger remnants, the primary cause of enrichment is consistent with edge accumulation of nutrients due to wind and water movement. In large patches, remnant edges, particularly the windward edge, were elevated compared to interiors of large patches. In these semi-arid crop lands, current trends in intensification of cropping and a shift away from livestock may reduce the input of nutrients to small patches but increase the nutrient threat to larger remnants.

Software for Computing the Parameters of the Thermal Cycle in Pulse Surface Heating of a Solid Body

The cooling rate in specific temperature ranges is one of the most important parameters of the thermal cycle in estimation of the possible structural transformations that occur under the action of concentrated energy fluxes. The knowledge of this quantity makes it possible to predict the phase composition of the zones of thermal effect and judge the causes of typical structural changes. For example, the authors of [1] associate the appearance of tempered martensite in the structure of laser-hardened steel with the presumed circumstance that the cooling rate near the equilibrium temperature decreases so much that in the range of the martensitic transformation it becomes even lower than in conventional quenching. In our earlier work [2] we estimated the cooling rates in the martensitic and bainitic ranges in the course of an analysis of the causes of enrichment of steels with retained austenite due to laser hardening. At present a great number of publications have been devoted to computation of the thermal regime of a solid body subjected to surface heating. As a rule, the authors consider the variation of the temperature as a function of the time or the spatial coordinates. Sometimes they analyze the first derivative of the temperature with respect to time. However, its variation is also considered in the same coordinates (cf. [3, 4]). In the problems of metal physics we have to know the cooling rate in specific temperature ranges, i.e., determine its variation as a function of the running temperature. We have created computer software for solving the stated problem. It makes it possible to determine the cumulative time of residence of a material at a given geometrical point above a specific temperature in addition to the rates of temperature variation. This allows us to estimate the austenization time, the time of dissolution of the disperse phase, etc. We can also compute the temperature gradients. STATEMENT OF THE PROBLEM

Nitrogen-15 Signals of Anthropogenic Nutrient Loading in Reef Corals

The 15N content of tissue from the coral Porites lobata was enriched, relative to corals from reference sites, at 5 of 7 Indo-Pacific sewage-affected reefs. Enrichment was as high as 3.7 ‰. The δ 13C of sewage-affected corals suggests they maintained a high degree of autotrophic nutrition. 15N-enriched wastewater dissolved inorganic nitrogen (DIN), derived from untreated sewage, is the most likely cause for enrichment in coral tissue 15N, though changes in coral nutrition, metabolism and zooxanthellae population dynamics are possible additional factors. Isotopic measurements of coral tissue can provide a simple means of detecting wastewater uptake by corals.

An assessment of recent environmental change in Llangorse Lake using palaeolimnology

1. The diatom record preserved in a sediment core from Llangorse Lake in South Wales, a site of national and international conservation importance, was analysed to evaluate the post-1850 nutrient history of the lake. Fossil diatom assemblages were analysed in 13 samples of a dated sediment core from the easterly lake basin. 2. A diatom-based transfer function was applied to the fossil diatom data to generate a quantitative reconstruction of in-lake total phosphorus (TP) concentrations, following taxonomic harmonization between the training set and core species data. The TP reconstruction was calculated using a north-west European calibration set of 152 lakes. 3. The diatom assemblages were dominated by non-planktonic taxa, in particular Fragilaria spp. until ca 1950, since which time there has been a switch to domination by planktonic diatoms. This switch is most likely a response to reduced light conditions and the decline in submerged macrophytes in the lake, brought about by nutrient enrichment perhaps coupled with enhanced inwash of soils, and thus a loss of habitats for epiphytic and benthic taxa. The exact causes of enrichment remain unclear and are currently under investigation, although increased use of fertilizers, agricultural intensification, afforestation and development of tourism and recreation have all been suggested as possible factors. The recent (post-1985) diatom assemblages are associated with mesotrophic conditions and indicate some degree of lake recovery. 4. Application of the transfer function showed that Llangorse Lake has experienced a decline in TP concentrations since the mid-1980s, following at least a century of high and stable TP levels of ca 150 μg TP L−1. The timing of this decrease appears to be related to the sewage diversion in 1981 and a further smaller diversion in 1992. Future monitoring of the lake is recommended in order to observe whether the improvement in water quality is maintained or indeed enhanced. Copyright © 1999 John Wiley & Sons, Ltd.

Origin of barite concretions in the West Carpathian flysch, Poland

The Paleogene concretions occurring in the Sub-Silesian nappe of the West Carpathians were investigated to understand their origin and evolution. They were considered previously to be of hydrothermal origin. Three types of concretions were found in marls: (1) phosphorite impregnated, (2) barite impregnated and (3) composed of the mixed types. The sulphur and oxygen isotope determinations of barite (δ34S between 32 to 36‰ and δ18O between 20 and 23‰) as well as the ratio Δδ34S/Δδ18O of 1.5 point out for bacterial reduction of sulphate as the primary cause of enrichment in heavy isotopes of sulphur and oxygen. Another process which could contribute to high δ18OSO4 values was sulphate isotope exchange with seawater oxygen. The 87Sr/86Sr compositions of barite confirmed that they are fairly identical with strontium isotopic composition of Paleogene seawater (O.7076–0.7078). Therefore, barite nodules of the Sub-Silesian unit in the flysch Carpathians can not longer be considered as of hydrothermal origin.