Total Aluminum Research Articles

59 Utility of the periphyton index of biotic integrity (PIBI) as an indicator of acid mine drainage impacts in southeastern ohio

In the Appalachian region, numerous streams are polluted with acid mine drainage (AMD). These waters are sulfate‐rich with elevated amounts of total acidity, low pH, and high levels of dissolved metals. Biotic multimetric indices, such as the Periphyton Index of Biotic Integrity (PIBI) have been employed to determine water quality across a variety of environmental conditions and may prove useful for AMD impacts. This study was initiated (1) to evaluate the PIBI for distinguishing AMD impact in streams and (2) to examine whether PIBI scores are impacted by seasonal differences. Twelve AMD and three reference streams were sampled for periphyton in June, August, and October. Water chemistry was collected at least once during the sampling period. Preliminary results showed that PIBI scores were significantly different (p<0.05) among the seasons. In addition, the seasonal trends in PIBI scores among streams were not consistent. The PIBI scores were correlated with six water chemistry variables in August and with at least one variable indicative of AMD in each season sampled. PCA and UPGMA analyses of water chemistry data grouped the streams into five categories: (1) moderately impacted AMD streams with lower total dissolved solids, sulfate, total aluminum, and alkalinity, and higher sulfate; (2) AMD streams with higher alkalinity and lower total aluminum; (3) AMD streams with lower alkalinity and higher total aluminum; (4) reference streams and (5) an outlier reference stream affected by nutrients. Relationships between the groups based on water chemistry and the groups derived from the PIBI will be discussed.

Influence of aluminum doping on titania pigment structural and dispersion properties

The influence of aluminum concentration on the structural properties and rheological behavior of aqueous suspensions of aluminum-doped titania pigment from the chloride process was investigated. The variation in rheological properties correlates with the change in the pigment surface properties, determined from electrophoresis measurements and atomic surface concentrations. Pigment suspensions exhibited a maximum yield stress and viscosity at or near the isoelectric point (iep). The pH of the maximum yield value of the pigment suspension increases with increasing aluminum hydroxyl group density at the particle surface. For pigments with a high aluminum surface concentration, at pH values where the magnitude of the zeta potential was high, a low-viscosity, dispersed suspension was obtained. The pigment with the lowest aluminum concentration, however, retained high yield stresses over a large pH range even when the zeta potential was of considerable magnitude. Pigment particle interactions are chiefly dictated by van der Waals forces and electrostatic repulsive forces, likely to be influenced by heteroaggregation. The aggregate strength would therefore depend upon the proportion and distribution of aluminum and titanium surface groups of the heterogeneous pigment, which will influence both the Hamaker constant and the degree of heteroaggregation. Overall, very small additions to the total aluminum concentration translate to significant aluminum surface concentration disparities and subsequently to large particle interaction differences.

Determination of total aluminum concentration in soil solution using capillary electrophoresis

Determination of aluminum ion (Al3+) as total aluminum (Al) was performed using on-line pre concentration (field-amplified sample stacking) with a long sample injection time of 180 s in capillary electrophoresis (CE). A linear calibration curve of the Al concentration was obtained, ranging from 10 to 2,000 µg L −1, with a wide range and good determination coefficient of 0.999. This study suggests that the minimum detectable Al concentration can be increased 12 times and that this method is sensitive enough for soil solution analysis, compared with the results obtained by Gottlein and Blasek (Soil Sci., 161, 705–715, 1996). Determination method of total Al concentration in the soil solution was proposed using CE in this study. Soil solution sample collected from Andosols and buffer solution (p-methylaminophenol sulfate (metol)) were adjusted to pH 2.3 and 3.0, respectively, by the addition of HNO3 as a pretreatment for the determination of the total Al concentration. A capillary 40 cm in length × 75 µm in inner diameter was used in order to determine the total Al concentration and shorten the electrophoresis time. This method provides certain advantages such as a very small total sample volume requirement (< 100 µL) and rapid analysis in soil solutions.

Volcanically influenced iron and aluminum cloud water deposition to Hawaii

Fog or cloud water (CW) deposition plays an important role in particle scavenging and the delivery of trace constituents to the Earth's surface. In this study, CW concentrations of total dissolvable iron (Fe) and aluminum (Al) were measured in 60 samples spanning 26 individual CW events throughout 1999 in Hawaii Volcanoes National Park on the island of Hawaii. Al concentrations ranged from 8 to 10,489 nM, with a median of 344 nM while Fe concentrations ranged from < 1 to 6419 nM with a median of 32 nM. CW deposition fluxes for Fe and Al ranged from 0.15–0.52 mmol Fe m −2 yr −1 and 0.62 –1.35 mmol Al m −2 yr −1, depending on the estimation method used. The large range in concentrations is higher than expected for a relatively pristine ecosystem. It appears that this inconsistency is due to emissions from the currently active nearby volcano, Kilauea. Categorizing CW events into volcanically versus less or non-volcanically impacted events suggests that although volcanically impacted events only accounted for 12% of fog water deposition, Kilauea Volcano was responsible at least 42% of the measured CW Al deposition and 61% of the CW Fe deposition measured for 1999.

A model of aluminum exposure associated with lipid peroxidation in rat brain.

We have developed a rat model to investigate the relationship between aluminum exposure and aluminum accumulation, and with oxidative damage in brain tissues. Intraperitoneal injections of aluminum lactate for 7 wk (the total aluminum dosage per rat was approx 100 mg) significantly increased aluminum levels in the brain. The concentration of lipid peroxidation products (thiobarbituric acid-reactive substances [TBARS]) also increased in the brain following aluminum lactate injections. No significant correlations between the concentrations of aluminum and of TBARS were found in the whole brain. Subcellular analysis revealed that aluminum lactate injections led to a significant increase in the concentration of aluminum in the mitochondrial fraction but had no significant effect on the concentration of peroxides in any subcellular fraction. These results suggest that aluminum accumulation induced by the aluminum lactate administration associates with the acceleration of lipid peroxidation in rat brain. Furthermore, these data indicate that the pro-oxidant effect of aluminum may be indirect and concentration independent. The experimental conditions used here provide an animal model of aluminum accumulation in the brain that should prove useful for further investigations of the mechanisms of aluminum neurotoxicity.

Geochemical occurrence of arsenic in groundwater of Bangladesh: sources and mobilization processes

Total arsenic, dissolved organic carbon (DOC), iron, major cations and anions were measured in tube-well waters used for drinking by people to investigate the geochemical condition of subsurface aquifer, source of arsenic and mechanism of arsenic release to groundwater of Bangladesh. Solid phases of total arsenic, iron, manganese and aluminum oxide and organic carbon (TOC) content in sediments were determined to find out their interrelationships. Arsenic concentrations in groundwaters vary from 0.03 to 0.75 mg/l with the mean value of 0.41 mg/l that exceed the maximum permissible limit of WHO (0.01 mg/l) and Bangladesh (0.05 mg/l) for drinking water. Arsenic concentrations demonstrate negative covariation with the concentrations of sulfate and nitrate but correlate weakly with iron concentrations and positively with those of ammonium ions. Dissolved iron exhibits a negative covariance with the concentrations of sulfate. Very low concentrations of nitrate and sulfate and high concentrations of dissolved iron and ammonium ions demonstrate the reducing condition of subsurface aquifer. These relationships suggest that oxidation of arsenic-rich pyrite is not responsible for the increased concentrations of arsenic but reflect the dependence of As concentration on the reductive processes. Arsenic is strongly correlated with DOC concentrations. Borehole data demonstrate the arsenic enrichment in organic matter-rich fine-grained clayey silt and silty sand than in sandy sediments. Arsenic contents are well correlated with those of iron, manganese and aluminum oxides in fine particle fraction of sediments, whereas arsenic is significantly correlated with TOC in large particle fraction. Sequential chemical leaching exhibits that arsenic is mainly present in three phases: (1) oxide phase of Fe and Mn, (2) organic matter and (3) sulfide and silicate phases. Since the distribution of arsenic in the subsurface sediments is not solely controlled by a single solid phase, the dissolution–desorption from different phases contributes to the total arsenic concentrations in groundwater. Microbial oxidation of organic matter (including localized peat layer) and reductive dissolution of Fe and Mn oxyhydroxide are the important processes to mobilize arsenic. The combined effects of NaHCO 3 and high pH values also play a significant role to mobilize arsenic from surface of iron oxides, other minerals and subsurface sediments. The very strong relationship between arsenic and bicarbonate concentrations in groundwater of Bangladesh and high pH values (8.03–8.7) of the Ganges sediments support the hypothesis. This paper reports first about arsenic leaching by the combined effects of NaHCO 3 and high pH values in Bangladesh.

Experimental investigation on the chemical reduction of nitrate from groundwater

Groundwater is a significant source of water. Adverse health effects have been reported when groundwater with a high nitrate concentration is used for drinking purposes. The objective of this paper was to investigate the effectiveness of a new treatment technology for the reduction of nitrate from groundwater. The optimal operating conditions of chemical nitrate reduction with fine aluminum powder are evaluated through controlled laboratory testing using the standard jar-test apparatus. A maximum of 62% nitrate removal was achieved with the following conditions: 300 mg/l aluminum dose, water temperature of 25°C, pH of 10.7, and initial nitrate concentration of 20 mg/l as N. On completion of the treatment, the concentrations of nitrate, nitrite and ammonia were measured as 8.3, 0.26 and 0.50 mg/l as N, respectively, all within the maximum acceptable concentrations (MAC) of the Canadian guidelines. To ensure adequate quality of the treated water, residue concentrations of total aluminum were also measured for several samples following brief sedimentation, and they averaged 0.07 mg/l. This also complies with the Canadian MAC of 0.1 mg/l. In conclusion, chemical nitrate reduction with aluminum powder is demonstrated to be both effective and safe, and the costs associated with the adaptation of this method may be minimized when combined with conventional water softening processes.

Electrode reactions in dc electroslag remelting of steel rod

The non-metallic inclusion content increased significantly when a steel rod of Fe-Ni was remelted by dc electroslag remelting. The silicon content increased slightly. The manganese and sulphur contents did not change. The total aluminium content in the ingot was max. 0·7%, while that in the electrode was only 10 ppm. The aluminium cations Al3+ in the slag are reduced to metallic aluminium at the slag/electrode interface, while O2 - anions are oxidised to dissolved O in the metal pool. This Al and O subsequently recombine to form alumina inclusions in the metal pool. The inclusion content was dependent on the alumina content in the slag. When a rod of plain carbon steel was remelted, however, the increase in nonmetallic inclusion content was as little as one-tenth of that for the remelted Fe-Ni rod. The non-metallic inclusion content was independent of the polarity of the electrode.

English

The treatment of acidic coal pile runoff (CPR) using an alternative constructed wetland design was evaluated. This alternative design, which provided improved wetland performance, was based on the partial re-circulation of treated water into a detention basin located immediately upstream from a Reducing and Alkalinity Producing System (RAPS). This modification created a semi-passive RAPS-based system we refer to as a Recirculating RAPS (ReRAPS). Previous work suggested that this wetland, utilizing the ReRAPS modification, could dampen the effects of intermittent, or shock, loading usually associated with CPR and still achieve desired effluent contaminant concentrations. The purpose of this study was to confirm the previous results through more frequent chemical and hydrological monitoring. The ReRAPS was monitored during 41 days of CPR treatment, which included four storm events during January through March 2001. The CPR contained an average iron concentration of 12.8 mg/L, 24.8 mg/L of aluminum, 2.9 mg/L of manganese, and 178.0 mg/L of acidity. The detention pond removed 82% of the total iron, 59% of the aluminum, and 35% of the acidity loading prior to the RAPS component. Manganese behaved conservatively in the detention pond. Average concentrations at the wetland discharge for total iron, aluminum and manganese were less than 0.20 mg/L. The 2001 wetland monitoring has confirmed that the ReRAPS modification enhances the basic RAPS wetland design by moderating the pH of contaminated water and reducing the contaminant loading prior to the RAPS component.

A major water quality problem in smolt farms: combined effects of carbon dioxide, reduced pH and aluminium on Atlantic salmon ( Salmo salar L.) smolts: physiology and growth

Hatchery reared Atlantic salmon ( Salmo salar L.) smolts (mean start weight 80 g) in soft freshwater were exposed to three levels of carbon dioxide partial pressure for 38 days (25 days for the high group) in an open flow system: 0.5 mm Hg (1.8 mg/l CO 2; pH 6.6; control group), 2.7 mm Hg (9.3 mg/l CO 2; pH 6.0; medium group) and 5.7 mm Hg (19.4 mg/l CO 2; pH 5.7; high group). The different pH levels were a consequence of the addition of carbon dioxide to the water. Water temperature was 6–8 °C and effluent oxygen levels above 9 mg/l. During the experiment, the total aluminium concentration in the water was relatively stable in the range 115–140 μg/l. Labile Al concentration was low in all groups (about 10 μg/l). Despite this, the mean gill aluminium deposition was five times and seven times higher in the medium and high carbon dioxide groups, respectively, compared with the control group ( p<0.05). Mean respiration frequency was significantly increased both in the medium and high carbon dioxide groups compared to the control group ( p<0.05). The main gill lesions observed in the groups with elevated CO 2 were focal to diffuse hypertrophy and hyperplasia of chloride cells and adhesion of lamellae. Even though no significant differences were found in mean plasma cortisol concentrations in the medium group compared to the control group at any sampling time, mean plasma chloride and gill Na +,K +-ATPase activity in the medium group were lower than controls on day 19 ( p<0.05) and the mean condition factor was significantly reduced on day 38 ( p<0.05). The overall specific growth rate (SGR) for the medium group was −0.06%/day compared to 0.26%/day for the control group between days 3 and 38. After 38 days, accumulated mortality for the control group and the medium group was 0.4% and 4%, respectively. Days 2 and 19 mean plasma cortisol and hematocrit were significantly increased in the high group, and mean plasma chloride concentration was significantly reduced compared to the control group. There was a significant depression in gill Na +,K +-ATPase activity between days 2 and 19 ( p<0.01) in the high CO 2 group, to a level of approximately 30% of control levels. The specific growth rate for this group was negative (−0.25%/day) between days 3 and 38. Accumulated mortality in the high group was 42% after 25 days and the experiment was discontinued for ethical reasons. The present investigation has shown that the build-up of carbon dioxide, reduction in pH and the changes in Al chemistry may be detrimental to Atlantic salmon smolts even at low concentrations. Further investigations are, however, needed to study combined effects of aluminium, pH and carbon dioxide and effects of each parameter in isolation on Atlantic salmon smolts.

Características de solos sistematizados em duas áreas cultivadas com arroz sob inundação

A sistematização dos solos, um processo de adequação da superfície do terreno, vem sendo introduzida em grande escala em diversas propriedades orizícolas do estado do Rio Grande do Sul, gerando alterações nas propriedades morfológicas, físicas, químicas e biológicas dos solos. Para estudar estas alterações, selecionaram-se áreas-testes em superfícies homogêneas onde ocorrem Planossolos sistematizados em diferentes épocas (oito anos, um ano e um mês) e em perfis não alterados (original), no município de São João do Polêsine (RS). A descrição morfológica e a coleta de amostras dos horizontes e, ou, camadas dos perfis representativos das áreas de corte e aterro (sistematizadas) e não alterados foram efetuadas em 1997/98. Nas áreas de corte, observaram-se as maiores alterações em relação aos perfis originais, com concentração mais elevada de argila, teores mais baixos de carbono orgânico e fósforo e teor mais elevado de Al trocável, principalmente no primeiro ano após a sistematização. A sistematização aumentou a densidade do solo em subsuperfície, em razão do intenso tráfego de máquinas, e reduziu a compactação na superfície, pelo revolvimento com o preparo do solo e incorporação de resíduos da cultura do arroz. As camadas superficiais dos perfis de corte apresentaram teores de Fet, Fed e Alt semelhantes aos do horizonte Btg do perfil original. Os ciclos de umedecimento e secagem a que os solos foram submetidos alteraram os tipos de óxidos de ferro, com aumento das formas mal cristalizadas.

PtMn-based spin-dependent tunneling materials with thin alumina barrier fabricated by two-step natural oxidation

Spin-dependent tunneling (SDT) materials with bottom-pinned structure (substrate/Ta/NiFeCr/PtMn/CoFe/t Al2O3/CoFe/NiFe/Ta) are fabricated by magnetron sputtering in ultrahigh vacuum. In this study, a two-step natural oxidation was used, in which the second Al layer was deposited and naturally oxidized after the natural oxidation of the first Al layer. The top and bottom leads were also patterned into bow-tie shaped structures. The two-step oxidation process results in a perfectly decoupled pinned and free layer in a film with a total as-deposited aluminum thickness of 7 Å, whereas, the one-step oxidation process gives rise to strongly coupled magnetic layers in a film with this thickness of aluminum. By using this two-step natural oxidation technique, an optimum tunneling magnetic resistance (TMR) ratio of 29.3% and resistance×area (RA) product of 34 Ω μm2 were achieved in junctions with 8 Å barrier (5+3 Å). In conclusion, a two-step oxidation process was used to fabricate spin-dependent tunneling devices with low RA product and high TMR ratio for head applications.

The clinical impact of aluminium overload in renal failure.

Chronic aluminium exposure and toxicity related to aluminium absorption and contaminated dialysis fluid continue to be a problem for many patients with renal failure, particularly in South America and in some developing countries. The two most prevalent sources of aluminium in this population are water used to prepare dialysate and aluminium-containing phosphate binders. Of particular concern is the effect of aluminium at the level of the bone, the haematopoietic system and the brain. Here we focus mainly on the adverse effects of aluminium on bone, the preferred organ of aluminium accumulation in the body. Unfortunately, aluminium has a cumulative effect, thus even short-term exposure to aluminium in phosphate binders adds to the total load and may contribute to the risk of aluminium-related bone disease. Even a bone biopsy does not allow a precise determination of total bone aluminium content. We examine the mechanisms by which aluminium contributes to abnormal bone remodelling. Studies indicate that aluminium has a direct effect, inhibiting bone formation and resorption. There is also evidence for an indirect effect through the action of aluminium on parathyroid hormone synthesis and by its modulation of calcium activity. We discuss commonly used techniques for identifying aluminium load and review studies of chelation therapy as a method to lower aluminium load. It is apparent that aluminium overload has serious consequences for patients with chronic renal failure, yet this problem can be largely prevented by the use of aluminium-free phosphate binders. The deleterious effects on bone remodelling caused by chronic exposure to aluminium suggest that caution should be observed when using other metals as phosphate binders.

Interpretation of Mercury Concentrations in Eight Headwater Lakes in Kejimkujik National Park, (Nova Scotia, Canada) by Use of a Geographic Information System and Statistical Techniques

The concentration of mercury in eight headwater lakes in Kejimkujik National Park correlated positively with total organic carbon, total nitrogens, aluminum, iron and sodium andnegatively with pH and alkalinity (Gran). Annual average mercuryyield of the lakes correlated positively with basin area to lakesurface area ratio, and watershed areas underlain by granite bedrock and glacial deposits and negatively with greywacke bedrock. Principal component analysis indicated that first threecomponents account for 80% of the total variance in the data.The components were related to physiography and geology of the watershed, hardness of water, and atmospheric washouts of longrange transported acidic pollutants and dust particles. Mercuryin the lake waters was associated with the physiography and geology of the watershed. Total organic carbon, aluminum and iron were good predictors of mercury concentration in the lakewaters as were the basin area to lake surface area ratio, and basin areas underlain by granite bedrock, and Halifax slate forthe lake mercury yield. The results showed that transport of mercury from the watershed is a major source of mercury in thestudy lakes.

Identification of Anomalous Aluminium Contents in Surface and Ground Water in the Alba Territory (NW Italy)

Aluminium was determined in surface and ground waters in the Alba region of NW Italy to provide information on natural and anthropogenic sources of contamination. Determinations were made by a spectrophotometric method based on the aluminium‐pyrocatechol complex. The total aluminium content of waters was determined as well as the toxic form of monomeric aluminium, obtained from samples that had been passed through 0.20 μm cellulose filters to remove colloidal and particulate material. Results were correlated with mortality data associated with Alzheimer's disease. There appeared to be a correlation between mortality data and areas having the highest aluminium content of water.

Cold Water Effects on Enhanced Coagulation of High DOC, Low Turbidity Water

Abstract Prairie farm reservoirs are usually low in turbidity and contain high concentrations of dissolved organic carbon (DOC). Some are treated with aluminum sulfate in late fall when the water drops below 3°C, often with poor turbidity reduction results. Jar tests using aluminum sulfate were conducted to study the effect of water temperature on enhanced coagulation of a typical high DOC prairie water. Jar tests showed that temperature affects turbidity, particle counts and total residual aluminum but does not affect DOC, UV254 absorbance and colour reduction. Turbidity of the treated water increased consistently as the temperature decreased. Particle counts in the 1 to 10 μm range were reduced by two logs at 20°C but only by one log at 1.5°C indicating inferior oocyst removal at low temperatures. Bentonite addition at 1.5°C did not affect the treated water particle counts but because the bentonite increased the raw water particle count, the reduction of the particles could be increased by one log. Coagulant demand for the water tested without pH adjustment is one to two mg Al per mg of DOC at all temperatures tested. The optimum pH for all temperatures was about 6.0 for DOC removal and about 6.5 for turbidity removal based on a dosage increment of 0.5 pH units. UV254 absorbance is well suited to predict optimum aluminum sulfate dosage for DOC removal.

Synthesis and characterization of polymeric inorganic coagulants for water treatment

This research explored the feasibility of preparing and utilizing preformed polymeric solution of Al(III) and Fe(III) as coagulants for water treatment. The differentiation and quantification of hydrolytic Al and Fe species in the coagulants were done by utilizing spectrophotometric method based on the interaction of Al or Fe with ferron as a complexing agent. In addition, 27A1-NMR, FT-IR, and powdered XRD were used to characterize the nature and structure of the hydrolytic species in these coagulants. The properties of the polyaluminum chloride (PAC1) and polymeric iron chloride (PIG) showed that the mass fractions of the maximum polymeric Al produced at r(OH/Al)=2.2 and Fe at r=1.5(OH/Fe) were 85% and 20% of the total aluminum and iron in solution, respectively. Coagulation tests were conducted under various coagulant dosages and pHs for each coagulant prepared. In case of PAC1 coagulants, a coagulation test on Nakdong river waters with three PACls (r=2.0, 2.2, 2.35) showed that the effectiveness of coagulation was in the order, r=2.2>2.0>2.35, corresponding to the order of polymeric aluminum contents. And, for the PIC1 coagulants, the PIC1 of r=1.5 was most effective for the removal of turbidity and TOC from the raw water.

Metal-triggered structural transformations, aggregation, and fibrillation of human alpha-synuclein. A possible molecular NK between Parkinson's disease and heavy metal exposure.

Parkinson's disease involves the aggregation of alpha-synuclein to form fibrils, which are the major constituent of intracellular protein inclusions (Lewy bodies and Lewy neurites) in dopaminergic neurons of the substantia nigra. Occupational exposure to specific metals, especially manganese, copper, lead, iron, mercury, zinc, aluminum, appears to be a risk factor for Parkinson's disease based on epidemiological studies. Elevated levels of several of these metals have also been reported in the substantia nigra of Parkinson's disease subjects. We examined the effect of various metals on the kinetics of fibrillation of recombinant alpha-synuclein and in inducing conformational changes, as monitored by biophysical techniques. Several di- and trivalent metal ions caused significant accelerations in the rate of alpha-synuclein fibril formation. Aluminum was the most effective, along with copper(II), iron(III), cobalt(III), and manganese(II). The effectiveness correlated with increasing ion charge density. A correlation was noted between efficiency in stimulating fibrillation and inducing a conformational change, ascribed to formation of a partially folded intermediate. The potential for ligand bridging by polyvalent metal ions is proposed to be an important factor in the metal-induced conformational changes of alpha-synuclein. The results indicate that low concentrations of some metals can directly induce alpha-synuclein fibril formation.

Seasonality of phytoplankton production in the Columbia River: A natural or anthropogenic pattern?

This study evaluated seasonal variability in the quantity and quality of particulate organic matter exported by the Columbia River into its estuary. Samples of suspended particulate material (SPM), collected monthly over a 1 year period (November 1995–October 1996) from a freshwater site in the Columbia River, near the head of its estuary, were analyzed for total aluminum, particulate organic carbon and nitrogen (POC and PN, respectively) and algal pigments (chlorophyll and carotenoids). High Al content, averaging 7.9% by weight throughout the year, indicated that detrital minerals accounted for the majority of SPM mass at all times. Organic matter (approximately 2 × POC) varied on a seasonal basis both in terms of its mass contribution to SPM (5–26% by weight) and its chemical composition. In winter, organic matter originated mainly from allochthonous sources, most likely from erosion of soils. Diatoms, the major phytoplankton group present as inferred from pigment analysis, “bloomed” in April–June 1996, resulting in increased autochthonous contribution to POC during spring and summer as well as increased organic matter content of SPM introduced to the estuary. Comparison with results for the same site in the mainstem Columbia obtained between 1990 and 1999 as part of a land-margin ecosystem research project shows that enhanced algal production in springtime is not a feature unique to our data set, at least in the Columbia River’s present highly regulated state of hydrographic operation. The possibility is discussed that recent human influence, principally dam construction, has significantly altered the historical SPM concentration and the chemical composition of its associated organic matter.

A preliminary study of the dermal absorption of aluminium from antiperspirants using aluminium-26

Aluminium chlorohydrate (ACH), the active ingredient in many antiperspirants, was labeled with the radioisotope 26Al. The labeled ACH was then fractionated into about 100 samples using gel filtration chromatography. Each fraction was analyzed for 26Al and total aluminium content. Aluminium-26 was only detected in the fractions that also contained aluminium, which verified that the ACH was uniformly labeled. 84 mg of the labeled ACH was then applied to a single underarm of two adult subjects with blood and urine samples being collected over 7 weeks. Tape-stripping and mild washings of the skin were also collected for the first 6 days. Results indicate that only 0.012% of the applied aluminium was absorbed through the skin. At this rate, about 4 μg of aluminium is absorbed from a single use of ACH on both underarms. This is about 2.5% of the aluminium typically absorbed by the gut from food over the same time period. Therefore, a one-time use of ACH applied to the skin is not a significant contribution to the body burden of aluminium.