Selective sorption of uranium from aqueous solution by graphene oxide-modified materials.

The effect of competing ions on the sorption behaviour of uranium onto carboxyl-functionalised graphene oxide (COOH-GO) were studied in batch experiments in comparison to graphene oxide (GO) and graphite. The effect of increasing the abundance of select chemical functional groups, such as carboxyl groups, on the selectivity of U sorption was investigated. In the course of the study, COOH-GO demonstrated superior performance as a sorbent material for the selective removal of uranyl ions from aqueous solution with a distribution coefficient of 3.72 ± 0.19 × 103 mL g-1 in comparison to 3.97 ± 0.5 × 102 and 2.68 ± 0.2 × 102 mL g-1 for GO and graphite, respectively.

Field-based application of developed solid phase extraction with inductively coupled plasma mass spectrometry for vanadium speciation analysis of groundwaters from Argentina.

High levels of vanadium have been reported in groundwater (<0.05-5300µgL-1 V) from different parts of Argentina, yet no detailed study of vanadium speciation has been performed. A highly selective strong anion exchange - solid phase extraction (SAX-SPE) method was used (in-situ) for vanadium speciation analysis of groundwater samples from La Pampa - LP (General San Martin and Eduardo Castex) and Buenos Aires - BA (San German) provinces in Argentina. In this method both vanadyl (VIV) and vanadate (VV) were trapped by the complexation with disodium ethylenediaminetetraacetic acid on a pre-conditioned SAX cartridge. In the laboratory, vanadium species were separated at different eluent pH levels. VIV was eluted at pH 4 using methanol and tetrabutylammonium hydroxide. VV was eluted at pH 8 using dihydrogen ammonium phosphate. The eluted species were analysed by inductively coupled plasma mass spectrometry (ICP-MS). This method was validated using an inter-analytical method comparison with HPLC-ICP-MS. A Paired t-test revealed that there was no significant difference (probability, P<0.05) between the two methods. VV was found to be predominate species in both sample collection areas (LP: 69 - 100%, BA: 33 - 89% of species) over the range of 158.0 - 4748.0µgL-1 in LP and 88.5 - 504.0µgL-1 in BA. VIV was found at higher levels (29.0-301.0µgL-1) in Buenos Aires compared to General San Martin groundwater (4.4 - 161.0µgL-1). The results enhance the potential knowledge of the speciation of vanadium in terms of water quality and human health.

Integrated Ion Beam Analysis (IBA) in Gunshot Residue (GSR) characterisation.

Gunshot Residue (GSR) is residual material from the discharge of a firearm, which frequently provides crucial information in criminal investigations. Changes in ammunition manufacturing are gradually phasing out the heavy metals on which current forensic GSR analysis is based, and the latest Heavy Metal Free (HMF) primers urgently demand new forensic solutions. Proton scanning microbeam Ion Beam Analysis (IBA), in conjunction with the Scanning Electron Microscope equipped with an Energy Dispersive X-ray Spectrometer (SEM-EDS), can be introduced into forensic analysis to solve both new and old problems, with a procedure entirely commensurate with current forensic practice. Six cartridges producing GSR particles known to be interesting in casework by both experience and the literature were selected for this study. A standard procedure to relocate the same particles previously analysed by SEM-EDS, based on both secondary electron (SE) and X-ray imaging was developed and tested. Elemental Particle Induced X-ray Emission (PIXE) mapping of the emitted X-rays allowed relocation in a scan of 10 µm × 10 µm of even a 1 µm GSR particle. The comparison between spectra from the same particle obtained by SEM-EDS and IBA-PIXE showed that the latter is much more sensitive at mid-high energies. Results that are very interesting in a forensic context were obtained with particles from a cartridge containing mercury fulminate in the primer. Particle-induced gamma-ray emission (PIGE) maps of a particles from HMF cartridges allowed identification of Boron and Sodium in particles from hands using the (10)B(p,α1γ)(7)Be, (11)B(p,p1γ)(11)B and (23)Na(p,p1γ)(23)Na reactions, which is extraordinary in a forensic context. The capability for quantitative analysis of elements within individual particles by IBA was also demonstrated, giving the opportunity to begin a new chapter in the research on GSR particles. The integrated procedure that was developed, which makes use of all the IBA signals, has unprecedented characterisation and discrimination power for GSR samples.

Arsenic contamination of natural waters in San Juan and La Pampa, Argentina.

Arsenic (As) speciation in surface and groundwater from two provinces in Argentina (San Juan and La Pampa) was investigated using solid phase extraction (SPE) cartridge methodology with comparison to total arsenic concentrations. A third province, Río Negro, was used as a control to the study. Strong cation exchange (SCX) and strong anion exchange (SAX) cartridges were utilised in series for the separation and preservation of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MA(V)) and dimethylarsinic acid (DMA(V)). Samples were collected from a range of water outlets (rivers/streams, wells, untreated domestic taps, well water treatment works) to assess the relationship between total arsenic and arsenic species, water type and water parameters (pH, conductivity and total dissolved solids, TDS). Analysis of the waters for arsenic (total and species) was performed by inductively coupled plasma mass spectrometry (ICP-MS) in collision cell mode. Total arsenic concentrations in the surface and groundwater from Encon and the San José de Jáchal region of San Juan (north-west Argentina within the Cuyo region) ranged from 9 to 357 µg l(-1) As. Groundwater from Eduardo Castex (EC) and Ingeniero Luiggi (LU) in La Pampa (central Argentina within the Chaco-Pampean Plain) ranged from 3 to 1326 µg l(-1) As. The pH range for the provinces of San Juan (7.2-9.7) and La Pampa (7.0-9.9) are in agreement with other published literature. The highest total arsenic concentrations were found in La Pampa well waters (both rural farms and pre-treated urban sources), particularly where there was high pH (typically > 8.2), conductivity (>2,600 µS cm(-1)) and TDS (>1,400 mg l(-1)). Reverse osmosis (RO) treatment of well waters in La Pampa for domestic drinking water in EC and LU significantly reduced total arsenic concentrations from a range of 216-224 µg l(-1) As to 0.3-0.8 µg l(-1) As. Arsenic species for both provinces were predominantly As(III) and As(V). As(III) and As(V) concentrations in San Juan ranged from 4-138 µg l(-1) to <0.02-22 µg l(-1) for surface waters (in the San José de Jáchal region) and 23-346 µg l(-1) and 0.04-76 µg l(-1) for groundwater, respectively. This translates to a relative As(III) abundance of 69-100% of the total arsenic in surface waters and 32-100% in groundwater. This is unexpected because it is typically thought that in oxidising conditions (surface waters), the dominant arsenic species is As(V). However, data from the SPE methodology suggests that As(III) is the prevalent species in San Juan, indicating a greater influence from reductive processes. La Pampa groundwater had As(III) and As(V) concentrations of 5-1,332 µg l(-1) and 0.09-592 µg l(-1) for EC and 32-242 µg l(-1) and 30-277 µg l(-1) As for LU, respectively. Detectable levels of MA(V) were reported in both provinces up to a concentration of 79 µg l(-1) (equating to up to 33% of the total arsenic). Previously published literature has focused primarily on the inorganic arsenic species, however this study highlights the potentially significant concentrations of organoarsenicals present in natural waters. The potential for separating and preserving individual arsenic species in the field to avoid transformation during transport to the laboratory, enabling an accurate assessment of in situ arsenic speciation in water supplies is discussed.

Field based speciation of arsenic in UK and Argentinean water samples.

A field method is reported for the speciation of arsenic in water samples that is simple, rapid, safe to use beyond laboratory environments, and cost effective. The method utilises solid-phase extraction cartridges (SPE) in series for selective retention of arsenic species, followed by elution and measurement of eluted fractions by inductively coupled plasma mass spectrometry (ICP-MS) for "total" arsenic. The method is suitable for on-site separation and preservation of arsenic species from water. Mean percentage accuracies (n = 25) for synthetic solutions of arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MA), and dimethylarsinic acid (DMA) containing 10 µg l(-1) As, were 98, 101, 94, and 105%, respectively. Data are presented to demonstrate the effect of pH and competing anions on the retention of the arsenic species. The cartridges were tested in the UK and Argentina at sites where arsenic was known to be present in surface and groundwaters, respectively, at elevated concentrations and under challenging matrix conditions. In Argentinean groundwater, 4-20% of speciated arsenic was present as MA and 20-73% as As(III). In UK surface waters, speciated arsenic was measured as 7-49% MA and 12-42% DMA. Comparative data from the field method using SPE cartridges and the laboratory method using liquid chromatography coupled to ICP-MS for all water samples provided a correlation of greater than 0.999 for As(III) and DMA, 0.991 for MA, and 0.982 for As(V) (P < 0.01).

Heavy metal removal from motorway stormwater using zeolites.

The possibility of using zeolites to reduce the levels of heavy metals present in motorway stormwater has been investigated. Currently, the primary pollutant removal mechanism used in treating stormwater is retaining the large volume of stormwater in detention ponds to allow time for the contaminants (mainly those associated with particulate matter) to separate out. There is also a need to reduce the levels of heavy metals in the dissolved phase, possibly by introducing some kind of ion exchange material into the treatment facility. Batch experiments have been conducted on two zeolites (synthetic MAP and natural mordenite) to test their ability to remove dissolved heavy metals from simulated and spiked motorway stormwater. Synthetic zeolite MAP showed almost complete removal (>91%) of the studied heavy metals (Zn, Cu, Pb, Cd) from both solutions. However, the use of such synthetic zeolites could have serious environmental implications as it was found to increase sodium levels to 295 mg/l, remove calcium and increase the pH of the spiked motorway stormwater to 8.5. Mordenite was less effective at reducing the levels of heavy metals (42-89% in synthetic solution, 6-44% in motorway stormwater) and exhibited a preference for Pb>Cu>Zn approximately Cd. It is proposed that the uptake of heavy metals is partially inhibited by the other dissolved contaminants present in motorway stormwater.

Mobility of heavy metals within freshwater sediments affected by motorway stormwater.

The assessment of the mobility and bioavailability of heavy metals in sediment samples requires the use of sequential extraction procedures. Results for sediments taken from an unmanaged motorway detention pond showed heavy metals to be associated with the carbonate and residual fractions. In particular, nickel and cadmium showed a high percentage association, compared with other geochemical fractions, such as carbonates and residual fractions. Copper and zinc were shown to be associated with carbonates and iron-manganese oxides, whereas lead showed the strongest association (72%) with the Fe-Mn oxides. When compared to a groundwater-fed lake on the same site, all heavy metals contained within this sediment were found to be at much lower concentrations and strongly associated with the residual fraction (>50%) and are therefore strongly bound within the sediment. Following discharge via a wet detention pond, stormwater then flows through a series of interconnecting lake systems. Heavy metal fractionation of these interconnecting lakes is discussed and shows changes in fractionation through the lake system for copper, nickel, lead and zinc. The main concern in these lakes is the continued use of calcium carbonate to maintain freshwater pH for coarse fishing. This practice, used until 1999, may present an enhanced risk to the freshwater environment, causing greater mobility of these metals.

Sediment accumulation in newly constructed vegetative treatment facilities along a new major road.

The A34 Newbury bypass was opened in England in November 1998. This 15 km of roadway has nine constructed vegetative treatment systems incorporating oil separators, silt traps, grass filters for primary filtration and chemical absorption, reed wetlands for secondary biofiltration, a deep water pool and outflow device to control the rate of water discharge into existing watercourses. Two of these facilities discharge stormwater into the Lambourn sites of special scientific interest (SSSI) river. An evaluation of the heavy metal levels in these two ponds (Ponds J and K) has been undertaken in the 39-month period after the opening of the bypass. Motorway-derived contaminants including Pb, Cd, Cu and Zn were evaluated within pond sediment throughout these treatment facilities. Results reveal that heavy metal levels within the treatment system that possesses a well-established reed bed system decrease rapidly though the facility. It is postulated that the high reed biomass within this facility may be primarily responsible for reducing hydraulic flow thus allowing a greater residence time for sedimentation, filtration and bioaccumulation processes.

Trace elements in drinking and groundwater samples in southern Nigeria.

The levels of Al, Sn, Cs, Rb, Sr, Br, Cr, Mo, Co, Ba, Cu, Zn, Cd, Pb, Mn, Se, As, V and Ni were determined in drinking water supplies (public taps, domestic taps and treated water from public water sources) and groundwater supplies (boreholes and shallow wells) in some parts of Southern Nigeria. The water samples were analysed using inductively coupled plasma mass-spectrometry (ICP-MS). The mean levels (microgram/l) of all the elements ranged between 0.35 microgram/l for Cs and 87.3 micrograms/l for Zn in the drinking waters and between 0.54 microgram/l for Co and 420.3 micrograms/l for Ba in the groundwaters. A comparison of the elemental concentrations with WHO guidelines showed that with the exception of violations of Cd, Cr and Se limits in some of the drinking water samples, the levels of all the other elements investigated were below the WHO maximum allowable concentrations.

Comparison of selenium levels in pre-eclamptic and normal pregnancies.

Abnormal placentation is the likely cause of the slow fetal growth and the high levels of circulating lipid peroxides found in severe pre-eclampsia. These peroxides are probably responsible for the high thromboxane:prostacyclin ratio found in this disease and may participate in the endothelial cell damage which is its most notable feature. Selenium (Se), because of its role in glutathione peroxidase, is suggested to be an important component of the removal system for these damaging peroxides. Serum-Se concentrations have therefore been measured in 19 pairs of pre-eclamptic women and matched controls. Infant birth-weights were recorded. No significant difference was found in the concentrations of Se in pre-eclamptic and control groups. Serum Se was found to be low in both groups. Birthweights were significantly lower in the pre-eclamptic group. The interpretation of serum-Se measurements from the third trimester of a pre-eclamptic pregnancy is complicated by the reduced fetal growth and probable lower Se take-up by the fetus in such a pregnancy. The merits of alternative measurements, such as total intravascular Se, placental Se, or samples from an earlier stage of gestation, are discussed. The importance of factors other than Se to the activity of glutathione peroxidase, and of other antioxidants to pre-eclamptic, is stressed.

Metal dispersion and transportational activities using food crops as biomonitors.

The multielement (Al, Ca, Cd, Ce, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Si, and Zn) levels of various common vegetables (bean, broccoli, cabbage, cauliflower, lettuce, marrow, onion, parsnip, spinach, sprouts, sweet corn, and tomato); fruits (grape and strawberry); herbs (garlic, lemon balm, marjoram, mint, rosemary and tarragon); local pasture species and surface soils collected from a commercial garden centre located within a distance of 30 m of the London Orbital Motorway (M25) is presented. Comparative values are given from a background area, namely a domestic garden located in the North Yorkshire Dales National Park area. Analysis was undertaken by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma-source mass spectrometry (ICP-MS) with quality control assessment using four international biological reference materials; BCR:CRM 62 Olive Leaves, NIST 1575 Pine Needles, NIST 1573 Tomato Leaves, and NIST 1572 Citrus Leaves. Inter-analytical method comparison is given using two methods of ICP-MS; namely conventional pneumatic nebulisation of sample solution, and direct solids analysis by laser ablation; and neutron activation analysis methods (NAA). For the elements listed there is a good precision obtained by ICP-MS and NAA. In particular levels of < +/- 1-10% (rsd) are obtained. Comparison of data with certified values and other analytical methods are generally of very good agreement. Lead levels in background areas ranged from 0.0008 to 0.340 microgram/g (fresh weight) for plant material; with the lead magnitude greater for grasses > herbs > vegetables > cereals > fruits. Measured values are in good agreement with reported literature values. The lowest Pb values are for marrow, lettuce, tomato and sweet corn samples (approximately 0.001-0.021 microgram/g). 'Green' leaf material levels were approximately 0.02-0.10 microgram/g (i.e. sprouts and cabbage). Root vegetables contain higher levels, approximately 0.02-0.125 microgram/g (especially carrot), reflecting possible metal uptake from soil. The highest vegetable Pb values are for leek and onion (approximately 0.35 microgram/g). Background values are also provided for nineteen elements (Al, As, B, Ba, Br, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, V, and Zn). Exposure to motor vehicle activities at a site some 30 m from the M25 shows only significant increases in Pb for unwashed plant material and surface soils. Typically Pb levels of 40-80% can be removed by washing plant surfaces resulting in metal levels similar to background areas.(ABSTRACT TRUNCATED AT 400 WORDS)

Elemental status of grazing animals located adjacent to the London Orbital (M25) motorway.

The elemental (Br, Cd, Cr, Cu, Mn, Ni, Pb, Se, V, and Zn) content of blood and wool or hair from animals (sheep, horses and alpacas) exposed to motor vehicle emissions alongside the London Orbital (M25) motorway is reported. Elemental values were determined by inductively coupled plasma mass spectrometry (ICP-MS) quality control assessment using flameless atomic absorption spectroscopy (for Pb, correlation coefficients of whole blood r = +0.87, and hair r = +0.82), and replicate (n = 10) analysis of the international reference material IAEA A13 Animal Blood. For Pb very good agreement was obtained between ICP-MS values 0.16 +/- 0.002 microgram/g and non-certified values 0.18 microgram/g. Only Pb and Cd showed significantly elevated blood levels in sheep grazing alongside the M25 motorway when compared with control (background) animals. The range of Pb blood values was 0.15-0.51 microgram/ml (M25) and 0.04-0.18 microgram/ml (control), respectively. The elemental content of the outside (tip) end of wool samples for the two study groups were significantly elevated in Br, Cd, Cr, Cu, Ni, Pb, V, and Zn for M25-exposed animals compared with controls. Elevated Pb and Cd were also found in horses' and alpacas' blood or hair in animals exposed to transportational activities. The relationship between whole blood and outer wool or hair Pb showed a very highly significant correlation for sheep (r = +0.89), horses (r = +0.69), and alpacas (r = +0.74) grazing alongside the M25 motorway.

Hippocampal tin, aluminum and zinc in Alzheimer's disease.

The use of inductively coupled plasma source mass spectrometry (ICP-MS) for multi-element analysis has led to the observation, in two separate studies, of increased blood tin in Alzheimer's disease (AD). We have therefore applied the technique of ICP-MS to hippocampal tissues obtained post-mortem from patients with AD and from controls. There was no significant difference in tin concentrations in AD. There were increased concentrations of aluminum and silicon, and reduced concentrations of zinc and selenium. It is postulated that displacement of hippocampal zinc by heavy metals may be important in producing clinical memory disturbance. However, analysis of the CA1 region, rather than of the dentate gyrus, would have been preferable.

Trace elements and the electroencephalogram during long-term lithium treatment.

Endogenous bromine has been found to be raised during lithium treatment, and it has been suggested that it may augment the therapeutic effect of lithium. Our findings in a study of 12 patients and 12 controls support this contention. Electroencephalographic effects of bromine, vanadium and aluminium were studied--higher bromine and vanadium levels were associated with irregular cortical activity. Electroencephalographic abnormalities were associated with more side-effects of lithium.

A comparison of low birth weight among Medicaid patients of public health departments and other providers of prenatal care in North Carolina and Kentucky.

Matching of Medicaid and health department patients' files to birth certificates was used as a means of evaluating the effect of prenatal care given by public health departments on the birth weights of babies of women in Medicaid. Three years of live birth data from North Carolina and 2 years of birth data from Kentucky were used in the analysis. After controlling for other low birth weight risk factors (including the quantity of prenatal care) with logistic regression, women in Medicaid who received prenatal care outside public health departments were found to be substantially more likely than those who received care at health departments to have low weight infants. This association was especially strong for births under 1,500 grams. The authors suggest that the comprehensive prenatal care that is provided by the public health departments, which includes various nonmedical support services, may be responsible for this difference. These findings have important implications for proposed expansions of the Medicaid Program to cover more pregnant women in poverty.

Tin and fatty acids in dementia.

Serum elements and fatty acids of red cell and plasma phospholipids, cholesterol esters and high density lipoproteins, were studied in patients with Alzheimer's disease (SDAT) and with multi-infarct dementia (MID). Increased 20:4n6 in MID was the finding most consistent in the different tissues. The red cell phospholipids were more unsaturated in MID than in SDAT but in SDAT the plasma phospholipids were more saturated. Serum Al, Sn and V concentrations were higher in SDAT than in MID while serum Mn concentrations were higher in MID. Sn and V correlated negatively with the unsaturation index of the red cell phospholipids and Sn showed a striking pattern of correlations with the red cell phospholipid fatty acids in SDAT: it was significantly positively correlated with 16:0 and 18:1n-9 and negatively correlated with 20 and 22 carbon n-3 and n-6 essential fatty acids. Since we have shown elevated tin levels in patients with Alzheimer's disease, and since organic tin compounds given to animals produce a syndrome with similarities to Alzheimer's disease, there is a need for investigation of the role of tin in lipid metabolism in dementia.

Red cell caesium, lithium and selenium in abstinent alcoholics.

Using inductively coupled plasma source mass spectrometry, we have studied the red cell element concentrations of alcoholic subjects with different periods of abstinence before testing. We found consistently elevated red cell caesium concentrations and also reduced red cell selenium concentrations. These may represent persistent abnormalities in oxidation/anti-oxidation mechanisms, and red cell caesium in particular may be a long-term marker of alcohol dependence. Erythrocyte lithium, cerium and boron concentrations were also reduced in the abstinent alcoholic groups.