Aluminum neurotoxicity in mammals

Although aluminum comprises a large percentage of the Earth's crust, it is excluded from body tissues, and especially from the central nervous system. When aluminum is experimentally introduced to the central nervous system, several neurotoxic effects are observed:i.e. neurofibrillary changes, behavioral and cognitive deficits and enzymatic and neurotransmitter changes, as well as certain types of epileptic seizures.The localization of relatively high levels of aluminum in Alzheimer disease, Guamanian amyotrophic lateral sclerosis and Parkinsonism-dementia has led to the implication of aluminum as a pathogenic factor in these diseases. Recent studies have shown that microtubule-associated proteins are part of the paired helical filaments which make up the intraneuronal neurofibrillary tangle. Other studies have identified the protein making the vascular and neuritic (senile) plaque amyloid and located the gene responsible for this protein to chromosome 21.Our electron microprobe analysis studies have not found the levels of aluminum or silicon in either the neurofibrillary tangles or amyloid cores reported elsewhere, nor have the levels of aluminum been elevated in approximately one half of the tangles and plaque cores examined to date.     

Microanalysis of Alzheimer disease NFT and plaques

Electron probe energy dispersive microanalysis of isolated andin situ neurofibrillary tangles (NFT) and neuritic (senile) plaque cores have been done to investigate the levels of Al, Si, Ca and Fe in the leading lesions of Alzheimer disease neuropathology. Varying levels of Si and Al, and to a lesser extent Ca, have been co-localized in about one half of the NFT and plaques examined using X-ray mapping. The variability of detection and the low levels of Al present indicates that aluminum is not required for the formation of the NFT and that aluminosilicates are not involved in the formation of the plaque core.     

Impact of nickel mining and metallurgical activities on the distribution of heavy metals in sediments of Levisa, Cabonico and Nipe Bays, Cuba

At MayarÕ zone, northeast Cuba, important lateritic deposits have been exploited since 1943. The mineral is used as raw material in a nickel-processing plant which discharges its untreated solid and liquid wastes into Levisa Bay. Similarly to the adjacent Nipe and Cabonico bays, fluvial currents from the mining areas convey a significant mineral load into this bay. To assess the environmental impact caused by the mining and the metallurgical activities, the distribution of Ni, Co, Fe, Mn, Cu, Pb and Zn was investigated in surface and core sediment samples. Uni- and multivariate statistical methods as well as different indices and pollutant factors were used to interpret results. These revealed significant environmental impacts in some areas of the three bays with high concentrations of Ni, Co, Fe and Mn, whose values are up to two orders of magnitude greater than the zone baseline levels. The metal concentrations decreased with increasing distance from discharges. A comparison with other Cuban bays and coastal zones, confirmed that the main source of metal pollution in these three bays was not urban and industrial activities, but lateritic mining and metallurgy.     

九寨沟和黄龙自然保护区原始林与次生林土壤物理性质比较

森林土壤的结构和贮水保水能力是决定土壤水分及其时空分布的关键,九寨沟和黄龙自然保护区均是以水为灵魂,其水量的多少及时空分布格局对景区景点的视觉观赏效果具有十分重要的作用.通过对几寨沟和黄龙核心景区原始林与次生林土壤容重、持水性能和孔隙度等指标的监测,探讨了不同植被类型下土壤结构及持水能力状况.结果表明:(1)由于较早地得到保护,九寨沟景区原始林、桦槭次生林土壤物理性质均优于四川西部其它同类犁植被,与此相反,人工云杉纯林土壤物理性质明显劣于其它植被类型,可能主要与云杉平根系统对土壤膨胀挤压和单优势乔木群落所形成的不利微气候影响有机物分解归还土壤有关;(2)在黄龙核心景区的原始云、冷杉林,发育于坡积母质的土壤物理性质明显优于发育于钙华母质卜的土壤物理性质.图3表1参31     

Microprobe studies of aluminum accumulation in association with human central nervous system disease

The neurofibrillary tangle, first described by Alzheimer in 1907, along with the senile plaque, represent the two principle neuropathologic lesions identified in the brains of patients with Alzheimer's disease. Aluminum salts inoculated into the central nervous system of certain experimental animals induces neurofilamentous lesions which are similar, but not identical to the neurofibrillary tangles seen in Alzheimer's disease. Although some reports provide evidence of increased amounts of aluminum in the brains of Alzheimer's disease victims, such bulk analysis studies have been difficult to replicate. Over the past several years we have approached this problem using a variety of microprobe techniques in order to determine the distribution of trace elements within individual nerve cells.Using scanning electron microscopy with X-ray spectrometry, we have identified accumulations of aluminum in the neurofibrillary tangle-bearing neurons of cases of Alzheimer's disease. Similar accumulations have been found in the brains of the indigenous natives of Guam who suffer from parkinsonism with dementia and from amyotrophic lateral sclerosis. Recent studies using laser microprobe mass analysis suggest that the predominance of aluminum identified within the parikaryon of neurofibrillary tangle-bearing neurons is located within the neurofibrillary tangle itself. Although this ongoing research still cannot ascribe a causal role for aluminum in the etiology and/or pathogenesis of the neurofibrillary tangle, the data suggest that certain environmental factors related to trace elemental constituents may play an important role in the formation of this type of cellular pathology.     

Effectiveness of management zoning designed for flagship species in protecting sympatric species

Flagship species have been used widely as umbrella species (i.e., species with large home range whose protection often provides protection for sympatric species) in the management of China's nature reserves. This conflation of flagship and umbrella species is best represented by the giant panda (Ailuropoda melanoleuca) and other large, endangered mammals designated as conservation targets in site selection and planning of reserves. Few empirical studies have tested the effectiveness of flagship species as surrogates for a broader range of sympatric species. Using extensive camera-trap data, we examined the effectiveness of management zones designated to protect flagship (target) species in conserving sympatric species in 4 wildlife reserves (Gutianshan, Changqing, Laohegou, and Wolong). We tested whether the progression from peripheral to core zones was associated with an increasing habitat association for both target and sympatric species. The distribution patterns of the study species across the zones in each reserve indicated a disparity between management zones and the species’ habitat requirements. Management zone was included in the final model for all target species, and most of them had higher occurrence in core zones relative to less-protected zones, but zone was not a predictor for most of the sympatric species. When management zone was associated with the occurrence of sympatric species, threatened species generally had higher detections in core zones, whereas common species had higher detections outside of the core zone. Our results suggested that reserve planning based on flagship species does not adequately protect sympatric species due to their specialized habitat requirements. We recommend re-examining the effectiveness of management zoning and urge a multispecies and reserve-wide monitoring plan to improve protection of China's wildlife.     

Unusual sources of aluminium and heavy metals in potable waters

Aluminium in water supplies derives from natural sources and from the use of Al₂(SO₄)₃ in water treatment. Heavy metals such as Pb, Cu, Zn and Cd can be added to water from pipework and solder. However, it is apparent that AI and other metals in potable waters can derive from deposits on pipe walls which can be subsequently mobilised when the supply and/or treatment process is changed. Concentrations of Al in domestic supply water of the Llanbrynmair area have been shown to increase from 1 g to 50 g L^–1 during its 18 km journey along the water main. Similarly, Pb concentrations in a public building in the Aberystwyth area are found to be extremely elevated due to the metal's mobilisation from encrustations occurring on the copper pipework.     

A 50-year sedimentary record of heavy metals and their chemical speciations in the Shuangtaizi River estuary (China): implications for pollution and biodegradation

Two parallel sediment cores collected from tidal flat located in the Shuangtaizi River estuary were analyzed for heavy metal concentrations and chemical speciations. Based on the ¹³⁷Cs activity profile, mean sedimentation rate at the sampling site during the past 50 years was estimated to be 1.3 cm·a^-1. Correlation analyses show that almost all the metals are associated with each other, suggesting that these metals might be derived from same sources and/or affected by same geochemical processes. Influence of total organic carbon (TOC) content on the concentrations of Cr, Ni, Cu and Cd is evident. Silt and clay contents, instead of sand content, play an important role in the distribution of these metals. The dominant binding phases for most of the metals (except for Cd) are the residual. The relative decrease of the residual fraction of Cd and Pb in the upper 66 cm of the core is striking. The distribution of chemical fraction confirms that the residual fractions of these metals have a natural origin, while only the non-residual fractions of Cd and Pb increased upward the core due to pollution in the past five decades. Pollution assessment on these heavy metals based on Index of Geoaccumulation (I_geo) also demonstrates that most of the metals are unpolluted. The weak pollution as observed in the sediments is perhaps related to a local plant, the Suaeda heteroptera Kitag, which may have played a significant role in the biodegradation of these metals and the metal distribution in the estuary.     

Influence of soil-extractable aluminium and pH on the uptake of aluminium from soil into the soybean plant (Glycine max)

The effects of soil pH and other soil properties on the uptake of AI by soybean plants have been investigated in a greenhouse experiment. Six soils were compared that were developed over six contrasting bedrock types ranging widely in their AI content and other chemical and physical characteristics, namely Oxford Clay, Chalk, Lower Lias Clay, Devonian Shale, Granite and Lower Greensand. Soil pH varied naturally between soil types and each soil was also amended to give two other pH levels using elemental sulphur and/or calcium carbonate. AI concentrations in various parts of the soybean plants were determined by ICP-AES after acid digestion. The AI solubility in the soils and hence its availability to the plants was estimated using a number of different reagents designed to extract different forms of AI. The AI concentration measured in the soybean leaves was found to be predicted most accurately by the ‘available’ AI extracted from soils by 0.02 M CaCl₂. The relationship appears to the linear, with a correlation coefficient of 0.97 (p <0.01). The AI content of the leaves increases with decreasing soil pH. The relationship is non-linear with a marked increase in leaf AI for soils with pH <4.4. The amounts of ‘plant-available’ AI in the soils extracted with 0.02 M CaCl₂ was much less than that extracted with 0.05 M EDTA, although both increased markedly with decreasing soil pH. The amount of AI measured in the soybean plants was directly related to both the ‘available’ forms of AI in the soils, and also to the pH of the soils. Soil pH was identified as a major factor that controls the uptake of Al from soil into the soybean plant.     

Proposed Conservation Landscape for Giant Pandas in the Minshan Mountains,China

Abstract: The giant panda (Ailuropoda melanoleuca), is one of the world's most endangered species. Habitat loss and fragmentation have reduced its numbers, shrunk its distribution, and separated the population into isolated subpopulations. Such isolated, small populations are in danger of extinction due to random demographic factors and inbreeding. We used least‐cost modeling as a systematic approach to incorporate satellite imagery and data on ecological and behavioral parameters of the giant panda collected during more than 10 years of field research to design a conservation landscape for giant pandas in the Minshan Mountains. We identified 8 core habitats and 4 potential linkages that would link core habitats CH3, CH4, and CH5 with core habitats CH6, CH7, and CH8. Establishing and integrating the identified habitats with existing reserves would create an efficient reserve network for giant panda conservation. The core habitats had an average density of 4.9 pandas/100 km² and contained approximately 76.6% of the giant panda population. About 45% of the core habitat (3245.4 km²) existed outside the current nature reserves network. Total estimated core habitat decreased between 30.4 and 44.5% with the addition of residential areas and road networks factored into the model. A conservation area for giant panda in the Minshan Mountains should aim to ensure habitat retention and connectivity, improve dispersal potential of corridors, and maintain the evolutionary potential of giant pandas in the face of future environmental changes.     

Geographical associations between aluminium in drinking water and death rates with dementia (including Alzheimer's disease), Parkinson's disease and amyotrophic lateral sclerosis in Norway

Comparisons of maps and correlation and regression analysis indicate a geographical association between aluminium (Al) in drinking water and registered death rates with dementia (coded from death certificates as the underlying or a contributory cause of death) in Norway. High levels of Al in drinking water are in most cases related to acid precipitation. In general, correlations between aggregate environmental measurements and mortality are a weak source of evidence for risk factors for disease, however, and interpretations regarding cause-and-effect relationships should therefore be made with great care. The major uncertainty probably relates to the use of registered death rates with dementia as a measure of incidence rates of Alzheimer's disease. The dementia rates are correlated with population density, and it is possible that the association between AI and dementia might be due to differences in diagnosis and reporting of dementia. Thus, the present study can only be regarded as introductory, and further epidemiological studies are needed to help elucidate the role of AI in Alzheimer's disease. The results provide little evidence of an association between AI in drinking water and Parkinson's disease or amyotrophic lateral sclerosis.     

根表铁膜对水稻铅吸收转运的影响

通过温室土壤盆栽试验研究不同生育期水稻根表铁膜形成对水稻吸收和转运Pb的影响。结果表明,两种水稻根表铁膜形成量(以DCB-Fe含量计)及铁膜中吸附的Pb量均随着生育期的延长而减少。水稻根表铁膜Fe含量与铁膜吸附的Pb量呈显著的正相关关系(r=0.798,p0.01)。水稻根系和茎叶吸收积累Pb随着不同品种和不同生育期而变化。品种NK57籽粒Pb含量显著高于品种YD6,前者为后者的1.9倍。从富集系数和分配比率来看,Pb主要富集在水稻的铁膜和根系中,而积累在茎叶和籽粒中的比率较少。Pb从水稻根表铁膜、根系和茎叶向籽粒中的转运系数在两个水稻品种间差异均不显著。水稻分蘖期和孕穗期根表铁膜量与根系Pb含量均呈显著的正相关关系(p0.05),但是成熟期水稻根表铁膜量与根系、茎叶和籽粒中Pb含量相关性均不显著,说明根表铁膜形成对水稻分蘖期和孕穗期吸收积累Pb有一定影响,但对水稻成熟期根系、茎叶和籽粒吸收积累Pb影响不大。     

Continuous dose-response modeling and risk analysis with the gamma and reciprocal gamma distributions

Kodell and West (1993) describe two methods for calculating pointwise upper confidence limits on the risk function with normally distributed responses and using a certain definition of adverse quantitative effect. But Banga et al. (2000) have shown that these normal theory methods break down when applied to skew data. We accordingly develop a risk analysis model and associated likelihood-based methodology when the response follows either a gamma or reciprocal gamma distribution. The model supposes that the shape (index) parameter k of the response distribution is held fixed while the logarithm of the scale parameter is a linear model in terms of the dose level. Existence and uniqueness of the maximum likelihood estimates is established. Asymptotic likelihood-based upper and lower confidence limits on the risk are solutions of the Lagrange equations associated with a constrained optimization problem. Starting values for an iterative solution are obtained by replacing the Lagrange equations by the lowest order terms in their asymptotic expansions. Three methods are then compared for calculating confidence limits on the risk: (i) the aforementioned starting values (LRAL method), (ii) full iterative solution of the Lagrange equations (LREL method), and (iii) bounds obtained using approximate normality of the maximum likelihood estimates with standard errors derived from the information matrix (MLE method). Simulation is used to assess coverage probabilities for the resulting upper confidence limits when the log of the scale parameter is quadratic in the dose level. Results indicate that coverage for the MLE method can be off by as much as 15% points and converges very slowly to nominal coverage levels as the sample size increases. Coverage for the LRAL and LREL methods, on the other hand, is close to nominal levels unless (a) the sample size is small, say N < 25, (b) the index parameter is small, say k 1, and (c) the direction of adversity is to the left for the gamma distribution or to the right for the reciprocal gamma distribution.     

Influence of iron plaque on chromium accumulation and translocation in three rice (Oryza sativa L.) cultivars grown in solution culture

Hydroponic experiments were conducted to investigate the role of iron plaque on root surface in chromium accumulation and translocation in three rice cultivars (90-68-2, CDR22 and Jin 23A). Rice seedlings were grown under 1.0 mg L^?1 trivalent chromium (Cr(III)) stress with and without phosphorus (P) treatments. P addition significantly increased the shoot and root biomass in all three rice cultivars. In the absence of P, the amounts of iron plaque (DCB-extractable Fe) on the root surface increased resulting in the increase of Cr accumulation in iron plaque. Compared to that with P treatment, Cr concentrations in iron plaque without P treatment were enhanced by 2–3 folds in the three rice cultivars. There was a significantly positive correlation between DCB-extractable Cr and DCB-extractable Fe on the root surface of the three rice cultivars. There were no significant effects on Cr concentration in roots and shoots between P treatments, but significant differences among cultivars were observed. Cultivar Jin 23A had the lowest Cr concentration both in roots and shoots regardless of P treatment. The results suggest that iron plaque could be a trap for immobilising Cr from environment but may not affect Cr uptake and translocation. Screening and breeding the cultivars with low Cr accumulation is considered as the most effective approach in Cr contaminated areas.     

Metallic contaminant profiles in sediment cores from Lake Valencia,Venezuela

Total extractable concentrations of AI, Fe, Mn, Pb, Cu, Zn, Hg and organic carbon (C_org) were determined along four sediment cores from Lake Valencia. In one selected core, the percentage labile fractions were determined in order to establish anthropic enrichment factors, the depth reached by the contaminants and their mobilities. The distribution patterns of concentration versus depth reflect the original concentrations of the settling sediments. Only Mn seems to show diagenetic cycling. No enrichment of Fe and Mn occurs in the upper part of the cores, in spite of good water circulation and aeration of bottom lake waters during five months of the year. This immobility can be attributed to the high pH of water (7.6 – 8.9). Pb, Zn, Cu and Hg are enriched in the upper part of the cores, probably reflecting the input of contaminants. These elements show enrichment factors of up to 3.0. Background concentrations of the studied metals are reached below a depth of 30 cm.     

砷胁迫下水磷耦合对不同磷效率水稻根表铁膜及其各部位砷含量的影响

为探索缓解水稻砷毒害的农艺措施,以耐低磷水稻99011和低磷敏感水稻99012为材料,通过土培试验,研究水分、磷用量及其交互作用对不同砷浓度酸性土壤中水稻根表铁膜以及植物体内砷分配的影响。结果表明,节水灌溉(干湿交替)明显减少水稻根表铁膜量,降低铁膜、根系、秸秆、颖壳和精米中的砷含量。与30mg·kg-1P2O5相比,180mg·kg-1P2O5能明显减少两个品种水稻的根表铁膜量以及根系和秸秆中的砷含量;对耐低磷品种铁膜砷含量影响不大,但显著降低磷敏感品种铁膜砷含量;在50mg·kg-1砷处理中增加磷用量对水稻颖壳砷含量影响不大,在100mg·kg-1砷处理时能显著降低颖壳砷含量;增加磷用量可明显增加耐低磷品种的精米砷含量,降低磷敏感品种的精米砷含量。水、磷交互效应主要受水分效应的影响。加砷处理后,相同处理下耐低磷品种的根表铁膜量和铁膜中的砷含量显著高于磷敏感品种,而根系、秸秆、颖壳和精米中的砷含量则相反。研究表明,可以通过节水灌溉,并根据砷污染程度和植物磷营养特性确定适当的磷肥用量,从而减少砷在水稻体内的累积,提高食品安全。     

A conceptual snapsot of a big coastal dune aquifer: Magilligan,Northern Ireland

The Magilligan sand spit dune field is situated on the eastern mouth of Lough Foyle in County Londonderry, Northern Ireland. It is a large triangular-shaped site some 7 km by 4 km by 1.5 km wide (about 800 ha) and maintains areas, particularly in the eastern part, with slacks that regularly flood in winter. The size of the system acts as a buffer to external drivers due to the large volume of groundwater stored, the longer travel distances and lower hydraulic gradients. However, unlike many other coastal dune sites with humid dune slacks in the British Isles the sand is not wholly underlain by silt and clay, as raised beach sand and gravel deposits are in contact with the sand aquifer in some places. A preliminary water balance suggests that the majority of the discharge from the sand aquifer occurs via the underlying raised beach deposits and only a small amount discharges directly from the sand aquifer beneath the foredunes. Available water level monitoring is skewed towards the wetter end of the dune system; no significant short-term water level trends are apparent. The data also indicate that recharge regularly takes place within the sand aquifer interspersed by periods of groundwater level recession.     

A social benefit-cost analysis of mandatory deposits on beverage containers

This paper presents a social efficiency analysis of mandatory deposits on beverage containers. Five kinds of resource effects are identified, evaluated and added up: (1) litter (both pickup and “eyesore” costs); (2) solid waste collection; (3) container costs; (4) production and distribution costs; and (5) consumer convenience. It is shown that the desirability, on efficiency grounds alone, of mandatory deposits is not indisputable; it depends critically on one's evaluation of (1) the average value of the time it takes consumers to return empty containers and (2) the average value of the “eyesore” benefit of a dramatically reduced (i.e., by around three-fourths) volume of beverage container litter.     

Marine Protected Area Design and the Spatial and Temporal Distribution of Cetaceans in a Submarine Canyon

Abstract: The Gully, the largest submarine canyon off the coast of eastern Canada, is currently under consideration as a marine conservation area, primarily because of the increasing interest in oil and gas production on the Scotian Shelf. Cetaceans, as a guild of abundant, large organisms that are relatively sensitive to such threats, provide a reliable means to determine the boundaries for a conservation area in this region. We compared the abundance of cetaceans between the Gully and other parts of the Scotian Shelf and Slope and found that abundance was higher in the Gully. We also assessed cetacean distribution and relative abundance within the Gully relative to search effort for several spatial and temporal parameters: depth, slope, sea surface temperature, and month. Distribution within the Gully was most strongly correlated with depth, but was also significantly correlated with sea surface temperature and month. Five of the 11 cetacean species commonly found in the Gully, and all those for which the Gully formed significant habitat on the Scotian Shelf, were concentrated in the deep (200–2000 m) mouth of the canyon. We suggest that a year-round marine protected area is necessary for the Gully. A core protection zone should be defined in the Gully based on depth and bounded by the 200-m isobath. A buffer zone around the core zone should be defined to provide protection from activities with further-reaching effects, such as noise, dredging, and chemical pollution.     

Elevated manganese concentrations at the cores of clupeid otoliths: possible environmental,physiological, or structural origins

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to investigate the distribution of manganese (Mn) in Atlantic herring (Clupea harengus L.) otoliths. An unusual pattern of Mn concentration, which has not previously been reported in fish otoliths, was observed. Time-resolved plots (time roughly equivalent to ablation depth) of the Mn signal recorded in the ICP-MS detector during ablation of otoliths contained a distinct peak, suggesting that elevated Mn concentrations were specific to certain regions. Ablation inside and outside of the otolith core revealed that the region of high Mn concentration coincided with the ablation of the core. It was initially suggested that Mn from the gravel substrate on which herring eggs are incubated is incorporated into the otolith core, producing elevated Mn concentrations in this region. It was hypothesised that otoliths from fish whose eggs are not incubated in gravel will not contain high Mn concentrations at the core. To test this, otoliths of sprat (Sprattus sprattus), which have a pelagic embryological stage, and from reared herring, which were incubated on glass plates, were analysed using LA-ICP-MS. Peaks in the Mn signal were observed during the ablation of cores from some sprat and reared herring otoliths, indicating that incubation on a gravel substrate is not necessary for the accumulation of Mn at the otolith core and that otoliths from both pelagic and demersally spawning fish species can contain elevated Mn concentrations. The results suggest that Mn concentrations at the otolith core do not reflect the external environment of the developing embryo. Two other hypotheses are considered. A dramatic increase in Mn concentrations in the egg, associated with embryological development, may produce elevated Mn levels at the otolith core. Alternatively, the high levels of Mn observed at the otolith core may reflect spatial variation in the crystal structure of the calcium carbonate portion of the otolith. The possible influence of physiological or structural factors on the chemical composition of the otolith core may confound the environmental signal in this region of the otolith. This has important implications for the interpretation of otolith chemistry data.Communicated by J.P. Thorpe, Port Erin