Collection Of Bulk Samples Research Articles

The Applicability of the Distribution Coefficient, KD, Based on Non-Aggregated Particulate Samples from Lakes with Low Suspended Solids Concentrations.

Separate phases of metal partitioning behaviour in freshwater lakes that receive varying degrees of atmospheric contamination and have low concentrations of suspended solids were investigated to determine the applicability of the distribution coefficient, K D. Concentrations of Pb, Ni, Co, Cu, Cd, Cr, Hg and Mn were determined using a combination of filtration methods, bulk sample collection and digestion and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Phytoplankton biomass, suspended solids concentrations and the organic content of the sediment were also analysed. By distinguishing between the phytoplankton and (inorganic) lake sediment, transient variations in K D were observed. Suspended solids concentrations over the 6-month sampling campaign showed no correlation with the K D (n = 15 for each metal, p > 0.05) for Mn (r 2 = 0.0063), Cu (r 2 = 0.0002, Cr (r 2 = 0.021), Ni (r 2 = 0.0023), Cd (r 2 = 0.00001), Co (r 2 = 0.096), Hg (r 2 = 0.116) or Pb (r 2 = 0.164). The results implied that colloidal matter had less opportunity to increase the dissolved (filter passing) fraction, which inhibited the spurious lowering of K D. The findings conform to the increasingly documented theory that the use of K D in modelling may mask true information on metal partitioning behaviour. The root mean square error of prediction between the directly measured total metal concentrations and those modelled based on the separate phase fractions were ± 3.40, 0.06, 0.02, 0.03, 0.44, 484.31, 80.97 and 0.1 μg/L for Pb, Cd, Mn, Cu, Hg, Ni, Cr and Co respectively. The magnitude of error suggests that the separate phase models for Mn and Cu can be used in distribution or partitioning models for these metals in lake water.

A cross-ocean comparison of responses to settlement cues in reef-building corals.

Caribbean coral reefs have deteriorated substantially over the past 30 years, which is broadly attributable to the effects of global climate change. In the same time, Indo-Pacific reefs maintain higher coral cover and typically recover rapidly after disturbances. This difference in reef resilience is largely due to much higher coral recruitment rates in the Pacific. We hypothesized that the lack of Caribbean recruitment might be explained by diminishing quality of settlement cues and/or impaired sensitivity of Caribbean coral larvae to those cues, relative to the Pacific. To evaluate this hypothesis, we assembled a collection of bulk samples of reef encrusting communities, mostly consisting of crustose coralline algae (CCA), from various reefs around the world and tested them as settlement cues for several coral species originating from different ocean provinces. Cue samples were meta-barcoded to evaluate their taxonomic diversity. We observed no systematic differences either in cue potency or in strength of larval responses depending on the ocean province, and no preference of coral larvae towards cues from the same ocean. Instead, we detected significant differences in cue preferences among coral species, even for corals originating from the same reef. We conclude that the region-wide disruption of the settlement process is unlikely to be the major cause of Caribbean reef loss. However, due to their high sensitivity to the effects of climate change, shifts in the composition of CCA-associated communities, combined with pronounced differences in cue preferences among coral species, could substantially influence future coral community structure.

Preliminary Assessment of an Economical Fugitive Road Dust Sampler for the Collection of Bulk Samples for Geochemical Analysis

Fugitive road dust collection for chemical analysis and interpretation has been limited by the quantity and representativeness of samples. Traditional methods of fugitive dust collection generally focus on point-collections that limit data interpretation to a small area or require the investigator to make gross assumptions about the origin of the sample collected. These collection methods often produce a limited quantity of sample that may hinder efforts to characterize the samples by multiple geochemical techniques, preserve a reference archive, and provide a spatially integrated characterization of the road dust health hazard. To achieve a "better sampling" for fugitive road dust studies, a cyclonic fugitive dust (CFD) sampler was constructed and tested. Through repeated and identical sample collection routes at two collection heights (50.8 and 88.9 cm above the road surface), the products of the CFD sampler were characterized using particle size and chemical analysis. The average particle size collected by the cyclone was 17.9 μm, whereas particles collected by a secondary filter were 0.625 μm. No significant difference was observed between the two sample heights tested and duplicates collected at the same height; however, greater sample quantity was achieved at 50.8 cm above the road surface than at 88.9 cm. The cyclone effectively removed 94% of the particles >1 μm, which substantially reduced the loading on the secondary filter used to collect the finer particles; therefore, suction is maintained for longer periods of time, allowing for an average sample collection rate of about 2 g mi.

Standard Practice for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biological Agents from Nonporous Surfaces: Collaborative Study

The draft ASTM Standard, "Standard Practice for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biological Agents from Nonporous Surfaces," was validated in a collaborative study consisting of 6 teams comprised of Civil Support personnel and First Responders, 2 levels of Bacillus anthracis Sterne and Bacillus thuringiensis Kurstaki spores, and 7 nonporous surfaces. The sample collection standard includes collection of the bulk sample (Method A) using a dry swab to push the sample onto a collection card and collection of residual sample (Method B) using an onsite test kit followed by a wet swab intended for additional onsite testing. Method A is to be performed prior to Method B in order to preserve unadulterated sample as potential criminal evidence. While statistical differences were observed between surfaces, between teams, and the interaction of surfaces and teams for the various sample types collected, these differences are due to the very low variability of the data and a much more narrow distribution than an ideal normal distribution, rather than to any practical differences. The data demonstrate that from both the 1.0 and 0.01 g powder samples, high levels of spores (mean >10(6) CFU) are recovered from the 7 surfaces by both the dry swab used in bulk sample collection (Method A) and the wet swab (Method B) sampling of the residual powder after bulk sample collection. Thus, after bulk sample collection, there is a high level of residual spores remaining for onsite biological testing and both Methods A and B should be performed in the field.

Application of ion chromatography to the Hong Kong rainfall monitoring program

Results from a rainwater monitoring program in Hong Kong from May 1994 to April 1995, with 60 sample collection days, are presented for Cl −, NO 3 − and SO 4 2− concentrations from suppressed and non-suppressed column ion chromatography. Replicate sampling was employed on a daily basis using both bulk (B) and wet only (W) samplers, and there was no statistically significant difference between the B-W datasets for Cl −, NO 3 − and SO 4 2− concentrations in rainwater. From the more complete bulk sample collection dataset ( n = 60), large changes in analyte concentrations were observed for samples collected on different days, with the ranges (in μequiv. 1 −1) 3–348 for Cl −, 3–132 for NO 3 − and 12–303 for SO 4 2−. Neglecting the February 1995 dataset for which n = 1, the volume-weighted monthly mean concentrations displayed narrower ranges, being 16–61, 7–42 and 27–87 respectively. The nature of the source of the analyte and its flux, type of weather system, season and atmospheric conditions, together with the rainfall amount and intensity are some of the factors which produce the changes in analyte concentrations. Below-cloud washout processes cause large changes in analyte concentration at the start of a single rain event, and contribute to the horizontal local variation in analyte concentrations. The ratio of SO 4 2−-NO 3 − in Hong Kong rainwater has decreased since 1992 and the reasons for this are discussed.

Recent acidification of precipitation in North America

Temporal trends in precipitation acidity indicate a large spread and probable intensification of acid precipitation ( pH < 5.6) in eastern North America during the past 25 years. Presently in certain regions of the northern hemisphere annual precipitation is up to 30–40 times more acid than would be expected for an unpolluted atmosphere. Individual storms may be several hundred to more than a thousand times more acid than expected. Remote as well as urban areas are affected. Limited data for eastern North America indicate that precipitation prior to 1930 had pH greater than 5.6. By 1955–1956 calculated pH values from a monthly, wet-only network showed acid precipitation throughout the northeastern U.S. Subsequently, measured data from two networks (a monthly, wet-only and a monthly, bulk-sample collection) operated during 1965–1966 showed a pattern similar to that in 1955–1956 with some westward extension of acid precipitation. Values from both bulk and wet-only precipitation samples during 1975–1976 showed a substantial southward and westward extension of the area subjected to acid precipitation and an intensification of acidity in the northeastern and southeastern regions of the U.S. A few long-term data on precipitation at individual sites showed either increasing acidity or no statistically significant trend during 1955–1980.

Ion Exchange Method of estimating Strontium-90 and Other Radionuclides in Rainwater

THE collection of bulk samples for the assay of radioactivity in rainwater involves the handling and preparation of large volumes of water. The need to reduce this work, together with a desire to achieve greater sensitivity and more specific data on the distribution of radionuclides in rainwater, has led to the development of the following method of collecting rainwater.