Al In Water Research Articles

Long-term evaluation of potential Al toxicity after an Al treatment in a coastal bay

Coastal areas often suffer from eutrophication, causing ecosystem degradation and oxygen deficiencies. In hundreds of lakes, aluminium (Al) treatment has been a successful method to bind phosphorous in the sediments, reducing lake productivity. In this study we follow up a successful Al treatment of the sediment of Björnöfjärden, which was the first full-scale coastal remediation project using a geo-engineering method, that substantially reduced P concentrations in the water column. We evaluate the long-term development of Al in the water and aquatic life using 10 years data from before, during and after the aluminium treatment. Still after ten years, the treatment is successful with low P concentrations in the Bay. After a temporal increase of Al in water and biota (fish and algae) in connection with the Al treatment, the concentration decreased rapidly to pre-treatment levels. A risk assessment for biota and humans consuming fish and water from the bay showed that the risk for negative effects were negligible, also during the treatment year.

Aluminum hydrolysis for hydrogen generation enhanced by sodium hydride

Aluminum is the most abundant and promising material for hydrolytic hydrogen generation. It can be easily transported and stored. However, the oxide protective layer around Al limits its hydrolytic activity and hinders practical applications. To solve this problem, NaH is introduced to form the core-shell structure of Al-based NaH solid fuel powder by a simple hand mixing method in an open lab environment. The new core-shell structure of Al-based NaH solid fuel powder showed the best hydrolytic performance among Al-based materials and produced 98 % hydrogen yield at a 1 to 0.9 M ratio of NaH and Al in water. The hydrolytic activity consists of NaH hydrolytic splitting and Al hydrolysis. XRD and SEM analysis confirmed that NaH is the key to supporting complete Al hydrolysis and attaining maximum yield as compared to calcium hydride. Our research endorsed the practical implementation of inexpensive and transportable hydrolytic hydrogen generation materials and offered a new idea for the design of hydrolytic hydrogen generation materials for further development.

ПРОСТРАНСТВЕННОЕ РАСПРЕДЕЛЕНИЕ ХИМИЧЕСКИХ ЭЛЕМЕНТОВ В ВОДОТОКЕ ШТОЛЬНИ 504 ПЛОЩАДКИ «ДЕГЕЛЕН»

Актуальность работы обусловлена необходимостью получения современных данных о концентрации химических элементов в системе «вода–почва–растения» на припортальном участке штольни 504 площадки «Дегелен» бывшего Семипалатинского испытательного полигона. В период весеннего половодья возможен вынос элементов за пределы площадки штольни 504. Цель: изучение пространственного распределения химических элементов в системе «вода–почва–растения» в водотоке штольни 504. Для достижения данной цели были поставлены следующие задачи: 1) определить уровни концентрации химических элементов в воде; 2) изучить уровни концентрации химических элементов в почве; 3) выявить особенности накопления химических элементов в растениях штольни 504. Методы. Элементный состав воды определялся методами масс-спектрометрии с индуктивно-связанной плазмой (Elan 9000 «Perkin Elmer SCIEX»), атомно-эмиссионной спектрометрии с индуктивно-связанной плазмой («iCAP 6300 Duo» Thermo Scientific). Анализ таких показателей, как общая минерализация, содержание сульфатов, гидрокарбонатов, хлоридов, кальция, магния и натрия, проводился титриметрическими, колориметрическими, потенциометрическими методами в соответствии с ГОСТ. Результаты. Анализ данных, полученных по воде, показал высокое содержание таких элементов, как Li, Be, Al, Mn, Zn, Rb, Sr, Cd, Cs, La, Ce, U, среднее содержание которых в несколько раз превышает показатель кларка в подземных водах аридного климата (сульфатные воды). Также для воды замечено превышение предельно допустимых уровней для таких элементов, как Be (2800 ПДК), Mn (260 ПДК), Al (76 ПДК), U (70 ПДК) и Cd (50 ПДК). По последним данным выявлено, что содержание таких элементов, как Li, Be, Al, в воде увеличилось в 2 раза, тогда как Co, Ni и Cu – в десятки раз. Пространственное распределение исследуемых элементов в почве штольни 504 неоднородно, большая часть элементов концентрируется в грунте севернее русла водотока. На данном участке выявлено повышенное содержание таких элементов, как Be, Mn, Cu, Zn, Мо, Cd, Cs, Pb и U, превышающих показатель кларка литосферы. Индекс превышения значения кларка литосферы составил для концентрации урана 1000 раз. Сравнение полученных данных на загрязненных участках со значением предельно-допустимых концентраций химических элементов для почвы выявило превышение у Pb (26 ПДК), Mn и Cu (9 ПДК). Химический состав воды и почвы штольни 504 является уникальным по содержанию редкоземельных элементов. Среднее содержание РЗЭ в воде в тысячу раз превышает показатель кларка в подземных водах аридного климата и подземных водах СИП. Замечено превышение предельно допустимого уровня концентрации для самария в воде. Характерным является преобладание группы легких РЗЭ с ярко выраженной церий-лантановой специализацией. Для большинства видов растений штольни 504 на загрязненном участке выявлено повышенное содержание Be, Сd, Cs, Pb, U и ряда РЗЭ. Концентрация исследуемых элементов в таких видах растений, как тростник и вейник, на сравниваемых участках менялась незначительно, что, видимо, обусловлено наличием физиолого-биохимических механизмов, препятствующих их поступлению. Исходя из вышеизложенного, можно сделать вывод, что пространственное распределение элементов на площадке штольни 504 связано, прежде всего, с выносом химических элементов штольневыми водами. В воде штольни 504 выявлено порядка десяти элементов, превышающих значения кларка и предельно допустимые уровни.

Hydrogen generation from the reaction of Al pretreated in acidic or alkaline solution and water

Al and Al2O3 film react with strong acid or alkaline solution, bring the extensive corrosion. To decrease the corrosion, Al is first pretreated with a small amount of HCl, NaOH, NaAlO2 and a mixture of NaAlO2+Al(OH)3 in this work. Al pretreatment allows for the rapid removal of oxide film, shortens the induction time and ensures the initial Al–H2O reaction rate. Typically, immersion of the pretreated Al by a mixture of NaAlO2+Al(OH)3 into water, generates hydrogen rapidly without an induction time, and the average H2 generation rate reaches 5.5 mL min−1. As the Al–H2O reaction proceeds, the potential changes, which is similar to hydrogen evolution of pretreated Al in water. Hydrogen generated rapidly with the consecutive addition of Al, and the initial hydrogen generation rate reaches ~37 mL min−1. Therefore, Al pretreatment by a mixed alkaline solution is an effective method to accelerate hydrogen generation for the first cycle. Rapid and consecutive hydrogen generation by the Al–H2O reaction could provide on-demand and high-purity hydrogen, meet some equipment requirements and promote the competition in renewable-energy sources.

Pulse Duration and Wavelength Effects of Laser Ablation on the Oxidation, Hydrolysis, and Aging of Aluminum Nanoparticles in Water.

We analyzed the formation of the aluminum (Al) nanoparticles (NPs) with triangular shape obtained by ablating Al bulk in liquid using pulses with different durations (5 ns, 200 ps, and 30 fs) and wavelengths (355 nm, 800 nm, and 1064 nm). We report three stages of synthesis and aging of Al NPs: Formation, transformation, and stable stage. The NPs prepared by different pulses are almost identical at the initial stage. The effects of duration and wavelength of the ablation pulses on the aging of NPs are revealed. Pulse duration is determined to be essential for morphological transformation of NPs, while pulse wavelength strongly influences particle sizes. NPs produced by ultra-short pulses have smaller sizes and narrow size distribution. We demonstrate that oxidation and hydrolysis of Al in water are the results of ablation for all pulse durations and wavelengths, which also strongly modify the preferable reaction path of NPs in water, thus affecting the composition and morphology of triangle NPs. The results of modeling of the NPs generation in water due to a 50 ps laser pulse interacting with a thick Al target are presented. Water-based effects in the formation of NPs, their evolution, and solidification are considered from the mechanical and thermophysical points of view. The detailed analysis of the modeling results allowed for determination of the main mechanism responsible for the ablation process followed by the NPs formation.

Metal Contamination Hotspots at Unregulated Firearm Target Shooting Sites in the Everglades.

Hunters and target shooters can introduce metals into the environment in the form of firearm ammunition, elevating environmental levels of these metals, which may cause plant and animal toxicity. We explored metal accumulation in the Florida Everglades at sites used for firearm target shooting that are unlicensed, unregulated, and not patrolled by law enforcement. We compared concentrations of Pb, Cu, and Al in water and soil among study sites, control sites, and a public shooting range. We also tested plants and invertebrates to identify bioaccumulation or biomagnification. Lead and Cu concentrations in the soil at the target sites were elevated (Pb mean: 11,500.1 μg g; Cu mean: 1558.7 μg g) compared with control sites (Pb mean: 35.3 μg g; Cu mean: 49.3 μg g) and were more similar to the shooting range (Pb mean: 3194.7 μg g; Cu mean: 567.1 μg g). Organisms had elevated Pb and Cu at the target sites, indicating bioaccumulation. For example, Spanish needle [ (L.) DC] had a Pb concentration of 356.9 μg g at one site but averaged 80.3 μg g at the control sites. Grass shrimp () had Pb concentrations averaging 416.1 μg g at target sites but only 18.9 μg g at control sites. Water samples did not have elevated metal levels at the sites. Aluminum levels did not correspond to firearms use. We conclude that the illicit shooting sites are hotspots of metal pollution and pose a risk of contamination to several types of organisms. Because these sites are undocumented and unregulated, remediation may be difficult.

Gold Nanoparticles As a Tool for Probing Corrosion Processes

Optical corrosion probes provide several advantages, enabling remote sensing, probing in variable media (gas, liquid) and temperatures, and imaging with high spatial resolution. The optical properties (reflection, transmission) of plasmonic nanoparticles (NPs) in the proximity of a metal mirror strongly depend on the dielectric properties of the immediate environment, characteristic of localized surface plasmon resonance (LSPR) systems, and the separation between the NPs and the metal surface, forming a Fabry-Pérot interferometer with the plasmonic array.1-3 A plasmonic corrosion probe combines a film of corroding metal of interest and a chemically and morphologically stable plasmonic nanostructure (Au NP array).4 Au NPs can be immobilized on the surface of the chemically active metal by adsorption from a colloid solution, or deposited by vacuum evaporation as a film of Au nano-islands. We studied the corrosion of aluminum in hot water using the optical response of Au NPs immobilized on the chemically active metal surface. Oxidation of Al in water in the temperature range 40–100 oC produces a non-uniform hydroxide layer, with a dense layer adjacent to the metal and an outer porous part consisting of rough platelets of pseudoboehmite. High-resolution scanning electron microscopy (HRSEM) images (Figure 1) of a fully oxidized plasmonic probes show that the oxide layer is more dense below the Au NPs and has a rough, open structure on the solution side (above the Au NPs), closely resembling the structure with no plasmonic layer. The Au NP layer embedded in the oxide preserves its integrity, while the separation between the Au NPs and the glass after complete corrosion of the Al film remains nearly constant for Au NPs evaporated or immobilized from solution. Cross-sectional HRSEM and transmission electron microscopy (TEM) images show that the separation between the plasmonic layer and the corroding metal increases with time while preserving the morphology of the oxide layer. Corrosion of plasmonic probes exhibits large changes in the reflection spectra. The changes were measured quantitatively in-situ using a conventional fiber-optics system. In the course of the Al corrosion the visual appearance (color) of the probe continuously varies. Changes in the reflection spectra and the probe color can be quantified, allowing evaluation of the propagation of the corrosion front. The high color contrast also allows visualization of lateral inhomogeneities in the corroding layer. The combination of plasmonic probes and image processing opens the possibility of simultaneous measurement of local corrosion rates over a macroscopic area. Plasmonic corrosion probes are simple to implement, while the results may be useful in the design of effective optical sensors for practical applications. With certain modifications, the plasmonic corrosion probe approach may be applicable to other active metals of practical importance. References. 1. Aussenegg, F. R.; Brunner, H.; Leitner, A.; Lobmaier, C.; Schalkhammer, T.; Pittner, F. Sensors and Actuators B-Chemical 1995, 29, 204. 2. Sannomiya, T.; Balmer, T. E.; Heuberger, M.; Voros, J. Journal of Physics D-Applied Physics 2010, 43. 3. Kedem, O.; Sannomiya, T.; Vaskevich, A.; Rubinstein, I. The Journal of Physical Chemistry C 2012, 116, 26865. 4. Tesler, A. B.; Sabatani, E.; Vaskevich, A.; Rubinstein, I. Annual Meeting of the Israel Chemical Society 2016, Tel Aviv, Israel. Figure 1

The impact of fluoride on Al abundance and speciation in boreal streams

The impact of fluoride on the abundance and speciation of aluminium (Al) was investigated in three boreal streams characterised by overall high concentrations of fluoride and dissolved organic matter. Stream-water sampling was carried out several times a year for at least 4years, and a chemical equilibrium model (Visual MINTEQ) was applied in order to model the proportion of colloidal and organically/inorganically complexed Al in the waters. The Al concentrations in filtered (0.45μm) water samples were inversely correlated with pH, and reached values up to approximately 1mg/L during low pH conditions (pH<6.0). In a stream with high fluoride concentrations, as compared to a similar stream with only moderately elevated fluoride concentrations, the Al concentrations were consistently elevated. For the stream with high concentrations of fluoride and Al, the model predicted both high concentrations and proportions of Al-fluoride complexation. This prediction indicates that high fluoride levels contribute to raise both the Al abundance and the ratio of inorganic to organic Al complexation in stream water. In contrast, for another stream with high fluoride concentrations and consistently high (near neutral) pH, there was no evidence of fluoride affecting Al concentration or complexation. These results show that it is important to focus future studies on the role of high levels of dissolved fluoride on both the speciation and the toxicity of Al in stream water.

Association between Aluminum and Silicon Concentrations in Isfahan Drinking Water and Their Health Risk Assessments.

Background:High concentrations of elements such as aluminum (Al) and silicon (Si) in drinking water can affect human health. It is suggested that high daily intake of Al is associated with increased risk of neurodegenerative disorders. Si, as an antidote of Al, may decrease Al bioavailability. The study was conducted to estimate Al and Si concentration and correlation in water and evaluate their health risk.Methods:In this cross-sectional study, water samples were collected from 20 points of water distribution system and the water treatment plant of Isfahan in spring and summer. Samples were analyzed using DR-5000. The health risk was evaluated via calculating chronic daily intake (CDI) and hazard index (HI).Results:Significant negative correlation was documented between Al and Si (R = −0.482, P = 0.037 in spring, and R = −0.452, P = 0.049 in summer). These values were approximately similar in all types of Al and Si. The amounts of CDI for Al in spring and summer were 6.67E-04 and 0.002 mg/kg/day, respectively. The Al HI values were below 1 in both seasons.Conclusions:The significant correlation between Al and Si concentrations suggests that Si can eliminate Al in water, and probably it might do the same in the body. The health risk of Al intake from tap water was negligible, it was assessed in an acceptable range with an HI value of less than the standard levels. The health risk of Si remained unknown due to lack of information regarding its toxicity and adverse health effects.

The influence of seasonality (dry and rainy) on the bioavailability and bioconcentration of metals in an estuarine zone

Knowledge on the concentration of metallic elements is important to certify the quality of ecosystems. Such behaviors in estuarine environments are dependent of factors such as rainfall and temperature of the water, interfering directly on the metal concentrations in biotic and abiotic components. This study observed the role that seasonality (dry and rainy) had on the bioavailability of metals (Fe, Zn, Mn, Cu, Ni, and Al) in surface water and sediment, and bioconcentration in oysters (Cassostrea rhizophorae) in the mangrove area of the São Paulo river estuary, Todos os Santos Bay. The metals concentration in three matrices analyzed varied between the periods studied. The values of physicochemical parameters also had significant variations. High levels of Zn and Cu were found in mollusks. The highest concentrations of metals analyzed were Al in waters, Fe in sediments and Zn in mollusks. These results showed that seasonality interferes directly in the physicochemical parameters analyzed (pH, dissolved oxygen, temperature, salinity and Eh), as well as on the bioavailability of metals in both water and sediment, influencing directly on the concentrations found in mollusks.

A Comparative Study of Neurocognitive Effects of Aluminum

In this study, we investigated serum Aluminum levels of healthy individuals in suitability-randomly chosen three different regions of the world in relation to intellectual ability of randomly chosen 16 year male students. Based on socio-economical factors, and the availability of resources and trained staff, the plasma aluminum contents were measured for 30 volunteers from three towns; in UK-Tower Hamlets, KSA-Al-Dammam and Iraq-Almusaib.The latter’s candidates were found to have the highest levels of aluminum in their plasma. This might be attributed to the relatively high levels of aluminum in drinking water or the use of aluminum cooking scratched pans and pots other than stainless steel or properly coated cooking apparatus especially in frying. Dust is also a contributing factor. Spectrophotometric techniques were used to determine the concentration of Al in water and biological fluids.Throughout this study morin was used as the chelating agent. It gives a deep-yellow complex with aluminum with a maximum absorbance at 421nm. Acidified (0.0002M H2SO4)/ethanolic (50%) solution were used. Absorbance was measured at 421nm. Creatinine and urea levels were used to check for kidney function. They were within normal limits for all participants.The possible effects of aluminum level in plasma on intellectual ability for a randomly chosen sample of thirty 16 years old pupils in the three towns were studied. Average mathematics school official grades were plotted against plasma aluminum levels. Correlation coefficients indicate a possible link between aluminum levels in plasma with mental ability.

Fractionation of residual Al in natural water treatment from reservoir with poly-aluminum-silicate-chloride (PASiC): Effect of OH/Al, Si/Al molar ratios and initial pH

An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly-aluminum-silicate-chloride (PASiC) in terms of the residual Al fractions as a function of initial pH. The coagulation performance expressed as turbidity and organic matter removal was established as supporting data. Some extra data were evaluated in terms of the residual Al ratio of the composite PASiC coagulant. The main residual Al sources were the Al fractions derived from the use of PASiC. The turbidity and organic matter removal ability was optimal at initial pH 6.00–7.00, while the concentrations of various residual Al species and the residual Al ratio of PASiC were minimal at an initial pH range of 7.00–8.00. Under the conditions of OH/Al molar ratio = 2.00 and Si/Al molar ratio = 0.05, PASiC had superior coagulation performance and comparatively low residual Al concentrations. The Al fraction in the composite PASiC coagulant seldom remained under such conditions. Experimental data also indicated that the suspended (filterable) Al fraction was the dominant species, and organic-bound or organo-Al complex Al was considered to be the major species of dissolved Al in water treated by PASiC coagulation. Additionally, the dissolved inorganic monomeric Al species dominated the dissolved monomeric Al fraction.

氯化铝和聚合氯化铝(PAC)在黄河水中的混凝效果与残留铝含量及组分

The coagulation performance of AlCl3 and polyaluminum chloride (PAC) during treatment of water from the Yellow River was investigated with different initial pH conditions and coagulant doses. Speciation of the residual aluminum was also studied. PAC showed superior coagulation performance to AlCl3, and it altered the initial pH slightly under alkaline conditions. For Yellow River water treatment with PAC and AlCl3, the optimum initial pH was 6.0 and the optimum coagulant dose was 15 mg/L (Al). Under these conditions, the removal of turbidity, UV254 and dissolved organic carbon was optimized. The organic material in the effluent after coagulation was mostly hydrophobic, and this material was removed better with higher coagulant doses and in neutral or weakly alkaline conditions. It was not easy for the Al from PAC to transfer to and remain in the effluent, and PAC’s residual aluminum ratio was lower than that of AlCl3. With a coagulant dose of 11-15 mg/L and initial pH of 8.0, there was little Al remaining in the water after treatment with either AlCl3 or PAC. The residual Al was mainly present as dissolved Al, and dissolved organically bound Al was the predominant species. Dissolved inorganically bound monomeric Al was the main component in dissolved monomeric Al. The residual Al concentration was effectively controlled using a coagulant dose of 10-15 mg/L and initial pH of 7.0-8.5. PAC treatment produced lower concentrations for several residual Al species, except for dissolved organically bound Al, than AlCl3 treatment. PAC could effectively reduce the concentration of dissolved Al and dissolved monomeric Al in water after treatment.

Poly(N‐isopropylacrylamide) grafting on aluminium to actively switch its surface drag in water

AbstractActive control of flow over object surfaces achieved by means of mechanical and/or electrical methods has recently been studied. However, there has been no report on actively switching the surface drag of an object by chemical modification of the object's surface. Poly(N‐isopropylacrylamide) (PNIPA) was grafted onto the surface of an aluminium (Al) substrate via (A) surface‐initiated atom transfer radical polymerization and (B) radical polymerization with an azo‐group surface initiator. The grafting density was 0.19 and 0.15 chains nm−2, respectively. The water contact angle of the PNIPA‐grafted Al surface reversibly changed between 55° and 82° for (A) and between 42° and 65° for (B) at temperatures of 25 and 40 °C, which was ascribed to the temperature‐responsive, hydrophilic–hydrophobic switching of the grafted PNIPA surface. The PNIPA grafting was applied on the surface of an ogive‐shaped Al model. The normalized dropping speed of the model in water increased 1.1 times at 42 °C in comparison to that at 22 °C. Switching of the surface drag of PNIPA‐grafted Al in water was demonstrated on the basis of the hydrophilicity and hydrophobicity of the grafted Al surface, the switching occurring with a change in temperature. Copyright © 2010 Society of Chemical Industry

Risk of acute toxicity for fish during aluminium application to hardwater lakes

To assess the risk of aluminium (Al) toxicity during the restoration of the eutrophic lake Tiefwarensee by hypolimnetic addition of NaAl(OH) 4-solution (aluminate) the generally limnological monitoring was accompanied by fractionation of Al in water and using Al accumulation on fish gills as bioindicator. The concentration of reactive Al species in the alkaline water (pH 8) peaked at 2 mg L − 1 in parts of the anoxic hypolimnion and was 0.088 ± 0.053 mg L − 1 ( n = 70) in the epilimnion during the five years of treatment. During an Al treatment cycle in summer 2003, perches showed significant Al accumulation on gills (100 µg Al g − 1 dw) whereas roaches, breams and silver carps remained unaffected. Thus, the Al toxicity towards several fish species seems to be low, although the concentration of reactive Al in the lake water increased by a factor of 2. However, high Al toxicity due to lake treatment with aluminate could not be excluded, as high Al-gill concentration was observed. An Al balance two years after the treatment indicates complete export of the added Al into the sediment.

Aluminium blunts the proliferative response, and increases apoptosis of cultured human cells: putative relationship to alzheimer’s disease

Aluminium (Al) has been investigated as a neurotoxic substance. Al ranks among the potential environmental risk factors for Alzheimer's disease (AD). Epidemiological studies tested the relationship between Al in drinking water and AD, showing a significant correlation between elevated levels of monomeric Al in water and AD, although data to date remain inconclusive with respect to total Al. The aim of this study was to test whether or not Al exacerbates cellular toxicity mediated by the amyloid beta (Abeta) peptide. We evaluated the role of Al in modulating programmed cell death (apoptosis) in human cell cultures. We used the osteosarcoma cell line monolayer (SaOs-2) to demonstrate that treatment of SaOs-2 cultures with the Abeta peptide mid-fragment (25 to 35) at nano M, followed by co-incubation with physiological concentrations of aluminium chloride, which release monomeric Al in solution, led to marked expression of caspase 3, but not caspase 9, key markers of the apoptotic process. The same experimental conditions were shown to blunt significantly the proliferative response of normal human peripheral blood mononuclear cells (PBMC) to phytohemagglutinin (PHA) stimulation. Our observations support the hypothesis that Al significantly impairs certain cellular immune responses, and confirm that Al-mediated cell toxicity may play an important role in AD.

High Aluminum Levels Accompanied by Near-Neutral pH in Outflow from a Forest Watershed in Aichi Prefecture, Japan

We found a high concentration of dissolved aluminum accompanied by almost neutral pH in stream water within a suburban secondary forest underlain by granite bedrock. We aimed to clarify the characteristics of the high Al levels in runoff by observing the chemical properties of spring water, stream water and surface soils. The mean pH values of spring water and stream water were 6.09 and 6.44, and the mean concentrations of dissolved Al of each after filtration with 0.45 μm membrane were 66 μmol/L and 41 μmol/L, respectively. The concentrations of dissolved Al in these waters were extremely high for such pH levels. There was no relationship between dissolved Al concentration and dissolved organic carbon (DOC), which, if it did exist, would be considered an indicator of organic species of Al in the stream water. The concentration of dissolved Al was highly correlated with Fe concentration but not with Si. The total concentration of water-soluble Al in soil extracts from the surface soils around the stream was extremely high, and the concentrations of dissolved Al, Fe and Si were highly correlated. These results suggest that the high concentration of Al in the spring water and stream water are derived from weathering of aluminosilicates and that Al might be dissolving in water as inorganic colloidal species.

Toxicity and Accumulation of Al in the Acid Water of Small Lakes and Watercourses in Finnish Lapland

On the basis of a study of the hydrochemical regime and the status of benthic acidophobic species in the acidified watercourses and small lakes of Finnish Lapland, humic compounds are demonstrated to be the principal factors controlling both pH and the proportions of different forms of Al in water. It is found that the concentration of labile aluminum, i.e., that form of aluminum which is most toxic for aquatic organisms, increases only in acid water (pH 4.8–6.5) with a low and extremely low humic content of water (with a color of 5–60 mg Pt/l). Humic and other organic substances that fix Al in an inert or another stable form are demonstrated to be able to decrease the toxic properties of aluminum for acidophobic species and the capacity of aluminum to be accumulated in the bodies of aquatic organisms. Aluminum is shown to have no tendency to an increased rate of accumulation in the bodies of aquatic organisms that form the highest trophic level of secondary predators.

A SQUID study of magnetic fields induced by the metal–liquid interface

A superconducting quantum interference device (SQUID) magnetometer was used to study the magnetic fields induced by liquid–metal contact. A high- T c SQUID magnetometer operating in liquid nitrogen has been used. The magnetic fields (d B) were generated both normal to, and in parallel to the interface when liquid contacted the metal surface; provided both phases were at different temperatures. We observed the d B effects for a number of metal–liquid systems, i.e. NiCrMo, FeCr, Cu, and Al in water, 5% NaCl, acetone and isopropyl alcohol. No magnetic effects were observed from a polystyrene sample, instead of a metal one. The generation of magnetic fields was ascribed to the thermal initiation of internal currents in the metal phase. The magnitude of the d B effect may be comparable to the magnetic fields induced by corrosion reactions.

Effect of simulated acid rain on the growth of Japanese conifers grown with or without fertilizer

Three-year old cuttings of Japanese cedar (Cryptomeria japonica), Japanese cypress (Chamaecyparis obtusa) and Sawara cypress (Chamaecyparis pisifera) were grown in pots with andosol and were exposed to simulated acid rain (SAR) at pH 2.0, 3.0, and 4.0 for 23 months. Total precipitation was 2460, 3960, or 5450 mm and SAR contained sulfuric, nitric and chloric acid at equivalent ratio of 5∶2∶3. Deionized water of pH 5.6 was a control. Exposure to SAR at pH 2.0 induced visible foliar injuries, but not any visible symptoms at pH 3.0 or higher. Total dry weights of 3 conifer cuttings grown with fertilizer were about two fold of those in plants grown without fertilizer and they reduced significantly by the exposure to SAR at pH 2.0. However, Cryptomeria japonica without fertilizer increased dry weights even though plants developed reddish-brown necrosis in large parts of tops. These 3 coniferous cuttings did not show any significant growth reduction at pH 3.0 and 4.0. Soil pH after receiving 5450 mm of SAR at pH 2.0 was 4.0 and molar ratio of (K+Ca+Mg)/Al in water and 1M ammonium acetate soluble fraction of the soil was about 0.3 and 0.4. respectively. However, dry weight of root in plants grown without fertilizer did not decrease. This suggested that growth reduction in plants fertilized and exposed to pH 2.0 was due to a reduction in photosynthetic organs associated with visible injuries, but not direct linkage with root growth inhibition due to soil acidification stress.