Lead, cadmium, and fluoride levels in market milk and infant formulas in Canada

Lead, cadmium, and fluoride were determined in 68 samples of market milk and about 115 infant formulas. Mean and median levels (ranges) in ng/g found for cow milk were as follows: lead, 1.12, 1.19 (0.01-2.48); cadmium, 0.10, 0.039 (0.005-0.74); and fluoride, 41, 40 (7-86). In canned, ready-to-use formulas, lead, cadmium, and fluoride levels averaged 37.3, 1.50, and 840 ng/g, respectively. In concentrated liquid formulas, the respective levels were 21, 3.54, and 600 ng/g. In powder formula concentrates, respective levels were 73.7, 6.78, and 1130 ng/g. On the basis of this study and literature data, lead levels in market milk exceeding 5 ng/g appeared to signify contamination of the milk either directly or via the cow. For formulas considered on an as-consumed basis, lead levels exceeding about 10-15 ng/g were attributed to contamination from either the can used to store the formula or the formula ingredients. Infant formulas in lead-free cans contained about 1.7 ng/g of lead on a ready-to-use basis. Milk-based formulas contained about 0.26 ng/g of cadmium on a ready-to-use basis. Soy-based or milk-free formulas contained about 8-15 times more cadmium than did milk-based formulas. Canadian and U.S. ready-to-use formulas contained 900 and 230 ng/g fluoride, respectively, and this difference was attributed to the level of fluoride in the processing water used by the manufacturers.     

Relative contributions of sedimentation and impaction to deposition of particles in a crop canopy

Lycopodium spores were released steadily into the air during 20–30 min from a line source positioned within a wheat crop. The spores were trapped on sticky strips held at angles, π, of 0, 30, 60 and 90° with respect to the horizontal and oriented to face the mean wind direction and on sticky, vertical glass rods. The aerial spore concentration, C, was measured by small suction traps. Deposits of the spores on wheat leaves were obtained from sections of leaves whose posture in the canopy was nearly horizontal, nearly vertical, or at angles between 30 and 60°. Number of spores per m² for all trapping surfaces were obtained by counting under a microscope. Experiments were conducted on seven different days, encompassing friction velocities, u^*, of 0.27–0.50 m s⁻¹. The rate of deposition on angled surfaces, D(π), was given approximately by D(θ) = D(0) cos (θ) + D(90) sin (θ), where D(0) and D(90) were the observed rate of deposit on horizontal and on vertical surfaces, respectively. Below mid-canopy height, inertial impaction of spores was negligible, so that D(90) = 0 for all the trap surfaces. There, D(0) was mainly due to sedimentation and was very nearly equal to v_s·C, where v_s is the settling speed of the spore in still air. Near the top of the canopy, deposition on sticky surfaces was enhanced by inertial impaction and turbulent deposition, so that D(0) was about twice that expected from sedimentation and D(90) was about five times larger than expected from inertial impaction at the mean wind speed. Nevertheless, considering the vertical distribution of leaf area and the angles of leaves in a wheat canopy, the rate of deposition of spores for the entire depth of a wheat canopy can be calculated with a probable underestimation of only 20% by simply assuming sedimentation on horizontally projected area and impaction on vertically projected area.     

Bioconcentration of HCH isomers by the ciliate protozoan,Tetrahymena pyriformis under laboratory conditions

Tetrahymena pyriformis, a common freshwater ciliate concentrated the four common HCH (Hexachlorocyclohexane) isomers viz., α, β, δ, and γ to varied extent. Bioconcentration factor [as expressed by the ratio of cellular insecticide in ng mg^?1 (dry weight) to supernatant in ng μL^?1 ranged from 342 to 2260 for α-HCH, 37 to 831 for β-HCH, 326 to 2806 for δ-HCH and from 106 to 1214 ppm for γ-HCH.     

RELATIONSHIP BETWEEN SUGAR MAPLE DECLINE AND CORRESPONDING CHEMICAL CHANGES IN THE STEM TISSUE

Wood cores were taken at breast height of mature sugar maple (Acer Saccharum Marsh.) trees of approximately the same age from four sites in Ontario, Canada differing in soil characteristics and general tree health. The soils of two of the sites were acidic (podzols), while the soils of the other two sites were calcareous (brunisols). Selected elemental analyses using Neutron Activation Analysis were conducted on the soils and the xylem wood of the sugar maple trees, and the results were compared relative to tree health. Aluminum in stem xylem was found to be significantly higher in declining trees (mean 7.7 ppm) relative to the healthy trees (mean 4.0) from the acidic sites, where aluminum was freely available in the soil. Soil extractable aluminum was also significantly higher in the soil adjacent to the declining trees (mean 5.10) compared to the healthy trees (mean 3.20). These results show that xylem aluminum contents reflect the increased availability of aluminum in acidifying soils and provide additional evidence that dendrochemistry may be used as a proxy environmental monitoring tool.     

Purification and Characterization of the Glutenin Subunits of Triticum tauschii,Progenitor of the D Genome in Hexaploid Bread Wheat

N-terminal amino acid sequences and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) molecular weights have been determined for high-performance liquid chromatography (HPLC)-purified high molecular weight (HMW) and low molecular weight (LMW) glutenin subunits (GS) of Triticum tauschii ssp. strangulata, contributor of the D genome to hexaploid bread wheat. The use of three different extraction procedures resulted in similar glutenin preparations. On the basis of N-terminal sequences, the same types of glutenin subunits that have been reported in bread and durum wheats (HMW-GS of both the x and y types and LMW-GS of the LMW-s, LMW-m, α-, and γ-types) were found in T. tauschii. However, the HMW-GS in T. tauschii were in greater proportion relative to LMW-GS when compared to reported values for a bread and durum wheat. Our results support the likelihood that differences in the proportions of the various subunits contributed by the A, B, and D genomes, rather than qualitative differences in the types of subunits, are responsible for the major differences in quality characteristics between bread wheat and durum wheat.     

The impacts of individual plant species on rhizosphere microbial communities in soils of different fertility

To investigate the effects of individual plant species on microbial community properties in soils of differing fertility, a microcosm experiment was carried out using plant species representative of the dominant flora in semi-fertile temperate grasslands of northern England. Soil microbial biomass and activity were found to be significantly greater in the more fertile, agriculturally improved soil than in the less productive unimproved meadow soil. Differences in microbial community structure were also evident between the two soils, with fungal abundance being greater in the unimproved soil type. Individual plant species effects significantly differed between the two soils. Holcus lanatus and Anthoxanthum odoratum stimulated microbial biomass in the improved soil type, but negatively affected this measure in the unimproved soil. In both soil types, herb species generally had negative effects on microbial biomass. Patterns for microbial activity were less consistent, but as with microbial biomass, A. odoratum and H. lanatus promoted respiration, whereas the herbs negatively affected this measure. All plant species grown in the improved soil increased the abundance of fatty acids synthesised by bacteria (bacterial phospholipid fatty acid analysis) relative to bare soil, but they negatively impacted on this group of fatty acids in unimproved soil. Similarly, the abundance of the fungal fatty acid 18:26 was increased by all plants in the more fertile improved soil only, albeit non-significantly. Our data indicate that effects of plant species on microbial properties differ markedly in soils of differing fertility, making general predictions about how individual plants impact on soil properties difficult to make.     

Role of continuous phase protein on the oxidative stability of fish oil-in-water emulsions

Whey protein isolate (WPI), soy protein isolate (SPI), and sodium caseinate (CAS) can inhibit lipid oxidation when they produce a positive charge at the interface of emulsion droplets. However, when proteins are used to stabilize oil-in-water emulsions, only a fraction of them actually absorb to the emulsion droplets, with the rest remaining in the continuous phase. The impact of these continuous phase proteins on the oxidative stability of protein-stabilized emulsions is not well understood. WPI-stabilized menhaden oil-in-water emulsions were prepared by high-pressure homogenization. In some experiments WPI was removed from the continuous phase of the emulsions through repeated centrifugation and resuspension of the emulsion droplets (washed emulsion). Unwashed emulsions were more oxidatively stable than washed emulsions at pH 7.0, suggesting that continuous phase proteins were antioxidative. The oxidative stability of emulsions containing different kinds of protein in the continuous phase decreased in the order SPI > CAS > WPI, as determined by both hydroperoxide and headspace propanal formation. Iron-binding studies showed that the chelating ability of the proteins decreased in the order CAS > SPI > WPI. The free sulfhydryls of both WPI and SPI were involved in their antioxidant activity. This research shows that continuous phase proteins could be an effective means of protecting omega-3 fatty acids from oxidative deterioration.     

提取、纯化沉积物中有机磷农药和菊酯类农药的两种程序的比较

Two procedures were compared for extraction and clean-up of 20 organophosphorus and 19 pyrethroid pesticides in sediment to identify the more effective procedure for groups of pesticides or individual compounds. In Procedure Ⅰ, methanol/water and n-hexane were used for extraction, and 1:10 (v/v) dichloromethane in n-hexane and acetone were used as eluents for eluting the analyte through the cartridge, with one evaporating steps on a rotary evaporator and two eluting steps on the cartridge, n-hexane/acetone (2:1, v/v) was used for extraction and elution in Procedure Ⅱ with one evaporating step on a rotary evaporator and one eluting step on the cartridge. All extractions were performed under an ultrasonic bath and gas chromatography and mass spectrometry were utilized for measurements. Procedure Ⅱ was developed as a rapid, timesaving, less costly and safer substitute for Procedure Ⅰ which was an old method. Procedure Ⅱ was more effective for almost all the organophosphorus pesticides tested and 11 of the 19 pyrethroid pesticides, while Procedure I was more appropriate for analysis of 5 pyrethroid pesticides. However, recoveries of most pyrethroid pesticides were fairly low. Thus, further studies should focus on adjustment and formulation of solvents for more efficient extraction and clean-up of pyrethroid pesticides from sediment samples.     

The effects of persecution on age of breeding and territory occupation in golden eagles in Scotland

Several studies have documented negative effects of persecution by humans on the population dynamics of large birds of prey. Several areas have seen a reduction in persecution in modern times, but the demography of large raptors still makes these birds vulnerable to such effects. In a GIS analysis, utilising data collected during two national censuses of the golden eagle Aquila chrysaetos in Scotland and contemporary data on the distribution of poisoning incidents (a common method of raptor persecution in Scotland), we show that persecution was associated with a reduction in the age of first breeding, territory vacancies, and the use of territories by non-breeding immatures. Persecution was therefore reducing adult survival and distribution and was probably creating ecological traps that attract mobile immatures, increasing subadult mortality in birds that may originate from persecution-free areas. Mapping a form of land management unique to moors managed for red grouse Lagopus lagopus scoticus shooting, where most poisoning occurs, we also show similar associations between golden eagle demography and grouse moor management. As such, persecution may be having a major impact on the golden eagle population of Scotland, since it occurs over a wide area and at least in some areas has continued unchecked over many decades.