A comparison of methods and materials for the analysis of leaded wipes

The purposes of this study are: (1) to determine whether proficiency analytical test (PAT) materials from the American Industrial Hygiene Association can be used to provide quality data for portable X-ray fluorescence analysis (XRF) of lead in dust wipe surface samples; (2) to provide data to determine whether the on-site analysis of field dust wipe samples by XRF and the laboratory method of inductively coupled plasma emission analysis (ICP) are comparable; and (3) to determine if differences exist between different wipe materials. Several wipes meet the ASTM E1792 performance requirements of lead background level less than 5 microg per wipe, be only one layer thick, yield recovery rates of 80- 120% from spiked samples, remain damp throughout the sampling procedure, and do not contain aloe. The wipes used in this study were Pace Wipes, which are used for the PAT materials, and, for the field samples, Palintest Wipes, which were supplied by the instrument manufacturer, and Ghost Wipes, which are popular because they digest in hot, concentrated acid, so that chemical analysis is simplified. Twenty PAT wipe samples were obtained from four different proficiency test rounds. Surface wipe samples were taken at three different locations representing different industry types. All samples were analyzed using a portable XRF spectrometer and by ICP. Strong linear relationships were found for the analysis of wipe samples by ICP and by portable XRF. For the PAT samples, the results from the ICP and XRF analysis were not statistically equivalent, which indicates a bias in the ICP analysis. The bias was not excessive, since all ICP analyses fell within the acceptable range for the proficiency samples. The good correlation between the proficiency sample reference values and the XRF determinations is not surprising considering similar proficiency samples were used to calibrate the instrument response. Users of this portable XRF analyzer could enroll in the proficiency test program as part of their quality assurance program. For field samples, the relationship was strongest for Palintest wipes, and the values found for all three industries could be combined. However, the results from the ICP and XRF analysis were not statistically equivalent using the correction factor in the calculation algorithm as supplied with the instrument, and a new coefficient was derived. The mean relative error for the XRF analysis versus the ICP analysis was greater than 25%, such that the method falls within the realm of screening procedures. For Ghost Wipe samples, the precision was different for different industries, and the results could not be pooled. Differences between the two wipe materials may be related to the number of folds required for analysis.     

Synthesis of grafted natural pozzolan with 3-aminopropyltriethoxysilane: preparation,characterization, and application for removal of Brilliant Green 1 and Reactive Black 5 from aqueous solutions

Environmental Science and Pollution Research - Natural pozzolan is an amorphous silicate-based material of volcanic origin. In this work, the natural pozzolan was modified by using...     

Residences with anomalous soil concentrations of dioxin-like compounds in two communities in Michigan, USA: a case study

Most contamination of residential property soil with dioxin-like compounds occurs as a result of proximity to industrial activity that produces such compounds and, outside the industrially impacted zone, the soil concentrations are at background levels. However, as part of the University of Michigan Dioxin Exposure Study, residential properties in the lower peninsula of Michigan, USA, were identified that were located far enough from known sources of these compounds that the soil concentrations should have been at background levels and yet the toxic equivalent (TEQ) of some properties' soil was greater than 2.5 standard deviations above the mean background level. In the three cases presented here from Midland/Saginaw Counties, the anomalously high-TEQ values were primarily due to the presence of polychlorinated dibenzofurans. Based on interviews with the residents and a comparison of soil congener profiles, it was deduced that these values resulted from anthropogenic soil movement from historically contaminated areas. In the cases from Jackson/Calhoun Counties, the unusually high-TEQ values were primarily due to polychlorinated biphenyls. In the case profiled here, it appears that the soil became contaminated through sandblasting to remove paint from the swimming pool. This study identified two mechanisms for soil contamination outside zones of industrial impact; thus, an assumption of background levels of soil contamination outside industrial zones may not be valid.     

Continuous-flow column study of reductive dehalogenation of PCE upon bioaugmentation with the Evanite enrichment culture

A continuous-flow anaerobic column experiment was conducted to evaluate the reductive dechlorination of tetrachloroethene (PCE) in Hanford aquifer material after bioaugmentation with the Evanite (EV) culture. An influent PCE concentration of 0.09 mM was transformed to vinyl chloride (VC) and ethene (ETH) within a hydraulic residence time of 1.3 days. The experimental breakthrough curves were described by the one-dimensional two-site-nonequilibrium transport model. PCE dechlorination was observed after bioaugmentation and after the lactate concentration was increased from 0.35 to 0.67 mM. At the onset of reductive dehalogenation, cis-dichloroethene (c-DCE) concentrations in the column effluent exceeded the influent PCE concentration indicating enhanced PCE desorption and transformation. When the lactate concentration was increased to 1.34 mM, c-DCE reduction to vinyl chloride (VC) and ethene (ETH) occurred. Spatial rates of PCE and VC transformation were determined in batch-incubated microcosms constructed with aquifer samples obtained from the column. PCE transformation rates were highest in the first 5 cm from the column inlet and decreased towards the column effluent. Dehalococcoides cell numbers dropped from approximately 73.5% of the total Bacterial population in the original inocula, to about 0.5% to 4% throughout the column. The results were consistent with estimates of electron donor utilization, with 4% going towards dehalogenation reactions.     

Reduced analytical availability of polychlorinated biphenyls (PCB's) in colored surface water

It has been generally accepted, during the last few decades, that the dissolved natural organic matter in water [DNOM] appearing as yellow brownish color, has become more and more "polluted" by inorganic and organic micro-pollutants. Due to the complexing properties of NOM, lipophilic organic micro-pollutants, such as, PCBs will be mobilized into water together with the DNOM. A mixture of eight PCBs, with Cl-content from tri-Cl to hepta-Cl, was added to solutions of ten different DNOMs. The DNOMs were aqua's solutions of RO-(reverse osmosis)-isolated material, having approximately the same concentration of carbon. After a contact time of three days, standard analytical PCB-method was used to determine the recovery of the added PCBs. The results show that the analytical availability of the added PCB was significantly reduced in the presence DNOM, compared to distilled water. The percentage loss in recovery of PCB increased with the content of Cl, in mean, from 3%/mg C for tri-Cl to 9%/mg C for hepta-Cl. The results also suggest that the analytical recovery of PCB was affected by the quality and the nature of the organic matter. For example the longer the DNOMs had been in the aquatic phase, the less efficient they are attached to the PCBs.     

Some limitations of biological monitoring

Biological monitoring data are obtained to document changes in population abundance for resource management, to verify compliance with regulatory directives, and to assess cause and effect for research purposes. Particular statistical analyses are often not appropriate because suitable field designs are either not available or not matched a priori to the monitoring objectives. When monitoring to detect normal changes in population numbers, quantitative problems may not be as difficult as they are in detecting and assigning causation induced by a natural or man-made pollutant. Changes in biotic abundance can be caused or influenced by compensation, indirect effects, direct mortality, and interactions among environmental variables. Even though data from baseline monitoring programs should usually only be used to detect change in biotic abundance, they sometimes can be used to draw inferences about cause by correlation or to test laboratory results against a long-term historical record. Available quantitative methodologies useful in evaluating monitoring data are limited and interpretations about cause and effect are difficult.     

Über einen Mechanismus der Transpirationserniedrigung durch ätherische Öle

The Science of Nature -     

COVID-19: From health crises to food security anxiety and policy implications

Like the rest of the world, African countries are reeling from the health, economic and social effects of COVID-19. The continent’s governments have responded by imposing rigorous lockdowns to limit the spread of the virus. The various lockdown measures are undermining food security, because stay at home orders have among others, threatened food production for a continent that relies heavily on agriculture as the bedrock of the economy. This article draws on quantitative data collected by the GeoPoll, and, from these data, assesses the effect of concern about the local spread and economic impact of COVID-19 on food worries. Qualitative data comprising 12 countries south of the Sahara reveal that lockdowns have created anxiety over food security as a health, economic and human rights/well-being issue. By applying a probit model, we find that concern about the local spread of COVID-19 and economic impact of the virus increases the probability of food worries. Governments have responded with various efforts to support the neediest. By evaluating the various policies rolled out we advocate for a feminist economics approach that necessitates greater use of data analytics to predict the likely impacts of intended regulatory relief responses during the recovery process and post-COVID-19.     

Nonthermal GSM RF and ELF EMF effects upon rat BBB permeability

Since the late 1980s, our group has examined the effects of radiofrequency electromagnetic fields (RF-EMF), including pulse-modulated waves of the type emitted by mobile phones, upon the blood?Cbrain barrier. In more than 2,000 rats, we have repeatedly demonstrated a passage of the rats?? own albumin from the blood through the brain capillaries into the surrounding brain parenchyma at SAR values down to 0.1mW/kg. In most of these experiments, the animals were exposed in TEM-cells, ventilated by an external electrical fan at 50 Hz. In the present study, we examined whether the extremely low frequency (ELF) magnetic fields from the fan (50 Hz, 0.3?C1.5 ??T) might add to the RF effect. Sixty-four rats were divided into 4 groups: RF only, ELF only and RF + ELF exposure plus a sham group. The GSM-900 MHz RF exposure was at the very low, nonthermal, average whole-body SAR level 0.4 mW/kg. Demonstration of the normally occurring albumin extravasation in the basal hypothalamus is our inbuilt control proving that the staining is reliable. Two full series of staining of the whole material gave negative results for hypothalamus. Not until we changed to avidin, biotin, and antibodies from a third supplier, we received an acceptable staining. Twenty-five percent of the RF animals had a pathological albumin leakage, while the ELF and RF + ELF groups with three and two pathological findings, respectively, were not significantly different from the control group. We conclude that the use of external fans has had no major influence upon the result.