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581.
This study investigates the relationship between the intake of birds hunted with lead shot and the lead concentration in human blood. Fifty adult men from Nuuk, Greenland took part in the study. From September 2003 to June 2004 they regularly gave blood samples and recorded how many birds they ate. We found a clear relationship between the number of bird meals and blood lead and also a clear seasonal variation. The concentration was highest in mid-winter when bird consumption is at its highest. Blood lead was low (15 microg/L, mean concentration) among the participants reporting not eating birds. Among those reporting to eat birds regularly, blood lead was significantly higher, up to 128 microg/L (mean concentration). Concentrations depended on the frequency of bird meals: the more the bird meals, the higher the resulting blood lead. This clear relationship points to lead shot as the dominating lead source to people in Greenland.  相似文献   
582.
Carbon dioxide is an asphyxiant and an irritant gas. An extreme outburst of carbon dioxide took place 7 July 1953 in a potash mine in the former East Germany. During 25 min, a large amount of CO2 was blown out of the mine shaft with great force. It was wind still and concentrated CO2 accumulated in a valley leading to multiple asphyxiation casualties. Based on a review of concentration-response relationships, the location of victims, and other information, it is concluded that concentrations of 10-30% carbon dioxide may have occurred 450 m from the point of release for at least 45 min. It is concluded that 1100-3900 tonnes of CO2 were blown out of the mine shaft, possibly with intensities around 4 tonnes/s. It is also concluded that the large majority of the gas escaped as a near-vertical high-velocity jet with only little loss of momentum due to impingement. The release was modelled using PHAST. Output from the model is inconsistent with the asphyxiation harm observed. The high-momentum release is predicted to disperse safely and never reach the ground. Carbon dioxide capture and storage (CCS) schemes will involve handling and transportation of unprecedented quantities of CO2. Case histories to date include sudden releases of CO2 of up to 50 tonnes only, far too small to provide a suitable empirical perspective on predicted hazard distances for CCS projects. The 1953 outburst contributes to filling this gap.  相似文献   
583.
584.
High effective multiple queen mating is a rare but taxonomically widespread phenomenon in eusocial Hymenoptera that has arisen convergently in several taxa. In ants, high effective mating frequencies have been confirmed in only two clades: the higher leaf-cutters (Atta, Acromyrmex) and the Pogonomyrmex seed harvesters. We analysed polyandry in Pogonomyrmex badius, which has a life-history unique within the genus, and report the highest numerical mating frequencies thus far recorded in ants. We also show that P. badius is characterized by one of the highest effective mating frequencies hitherto found in ants. It is now clear that all major sub-clades of Pogonomyrmex sensu stricto exhibit high levels of polyandry. Therefore, multiple mating must have arisen early in the evolution of the genus, and may have constituted a mechanism to increase offspring variability for queens that were confronted with increasingly complex levels of organization. Too few congeners have been investigated by the same method to be certain that polyandry in P. badius is really higher than in the rest of the genus. If so, research should concentrate on a possible link between high queen mating frequency and the distinct caste system found in P. badius.Communicated by L. Keller  相似文献   
585.
Rear impact sled tests were conducted using 5th, 50th, and 95th percentile Hybrid III dummies to evaluate proposed injury criteria. Different head restraint height (750, 800 mm) and backset (0, 50, 100 mm) positions were used to determine axial and shear forces, bending moments, and injury criteria (NIC, N(ij), and N(km)). The time sequence to attain each parameter was also determined. Three events were identified in the response. Event I was coincident with the maximum rearward motion of the torso, Event II occurred at the time of the peak upper neck flexion moment, and Event III occurred at the time of maximum rearward motion of the head. Parameters such as backset, head restraint height, seat-head restraint interaction, and anthropometry affected impact responses. Head rotations increased with increasing backset and increasing head restraint height. However, N(ij) and N(km) did not exhibit such clear trends. The 50th percentile dummy responded with consistent injury criteria values (e.g., the magnitude of the injury criteria increased with backset increase or head restraint height decrease). However, the 5th and 95th percentile dummies did not demonstrate such trends. These findings underscore the need to include subject anthropometry in addition to seat and head restraint characteristics for better assessment of rear impact responses.  相似文献   
586.
Representative duplicate fly ash samples were obtained from the stacks of 400- and 385-MW utility boilers (Unit A and Unit B, respectively) using a modified U.S. Environmental Protection Agency (EPA) Method 17 sampling train assembly as they burned 0.9 and 0.3 wt % S residual (No. 6 fuel) oils, respectively, during routine power plant operations. Residual oil fly ash (ROFA) samples were analyzed for Ni concentrations and speciation using inductively coupled plasma-atomic emission spectroscopy, X-ray absorption fine structure (XAFS) spectroscopy, and X-ray diffraction (XRD). ROFA deionized H2O extraction residues were also analyzed for Ni speciation using XAFS and XRD. Total Ni concentrations in the ROFAs were similar, ranging from 1.3-1.5 wt%; however, stack gas Ni concentrations in the Unit A were 0.990 microg/Nm3 compared with 0.620 microg/Nm3 for Unit B because of the greater residual oil feed rates employed at Unit A to attain higher 400-MW load conditions with a lower heating value oil. Ni speciation analysis results indicated that ROFAs from Unit A contain approximately 3 wt % NiSO4 x xH2O (where x is assumed to be 6 for calculation purposes) and appoximately 4.5 wt% of a Ni-containing spinel compound, similar in composition to (Mg,Ni)(Al,Fe)2O4. ROFAs from Unit B contain on average 2 wt% NiSO4 x 6 H20 and 1.1 wt% NiO. XAFS and XRD analyses did not detect any nickel sulfide compounds, including carcinogenic nickel subsulfide (Ni3S2) (XAFS detection limit is 5% of the total Ni concentration). In addition, XAFS measurements indicated that inorganic sulfate and organic thiophene species accounted for > 97% of the total S in the ROFAs. Unit A ROFAs contained much lower thiophene proportions because cyclone-separated ROFA reinjection is employed on this unit to collect and reburn the larger carbonaceous particles.  相似文献   
587.
Für die Biosph?renreservate (BR) Schorfheide-Chorin und Spreewald (Land Brandenburg) wurde ein handlungsorientiertes, kostengünstiges, arbeitsteiliges Konzept für die ?kosystemare Umweltbeobachtung (?UB) entwickelt, dessen methodische Entwicklung auch auf andere Schutzgebiete übertragbar ist. Hierzu werden neben statistischen Auswertungen fl?chenhaft vorliegender Informationen auch weitere Kriterien wie Naturn?he, Seltenheit und Ma?nahmenbezug durch das Einbringen von Expertenwissen systematisch genutzt, um so die Besonderheiten und Eigenarten der beiden behandelten Gro?schutzgebiete zu erfassen und in gewissem Umfang zu wichten und so gezielt auch Fragestellungen naturschutzfachlicher Relevanz nachzugehen. Nach einer Inventarisierung der vorhandenen ?kosysteme wurden auf der Basis der Auswahlkriterien
I)  Dominanz
II)  Seltenheit
III)  Naturn?be bei fl?chenhafter Verbreitung sowie
IV)  ma?nahmen- und prozessorientierte Beobachtung die zu beobachtenden ?kosysteme aus den ?kosystemgruppen W?lder/Forsten, Moore, Seen, Flie?gew?sser, Grünland und Acker ausgew?hlt und mit den jeweils relevanten Nutzungen zu ?kosystem-Nutzungskomplexen zusammengefasst. Diese spiegeln sowohl die natürliche Ausstattung der BR als auch die jeweiligen Nutzungsgradienten wider.
Der vorliegende Artikel stellt diese Fl?chenauswahl detailliert dar, Für beide Biosph?renreservate wurden so insgesamt 32 ?kosystem-Nutzungskomplexe in W?ldern und Forsten, 32 in Mooren, 53 in Seen, 7 in Flie?gew?ssern, 23 auf mineralischem Grünland sowie 20 auf Acker bzw. Gartenland ausgew?hlt, die die Biosph?renreservate repr?sentieren.  相似文献   
588.
The amount of off-site pesticide spray drift from aerial and ground applications was determined at 26 sites across Ontario. These were conducted along transects, parallel and at right angles to the flight path during aerial spray applications and at right angles to the direction of ground spray applications. All sites monitored were where commercial spray operations were in progress. The aerial applications involved both fixed wing aircraft and helicopters and the ground applications involved concentrated air-blast machines and high and low pressure boom sprayers. Deposits of spray drift outside the target area were common to all spray equipment monitored. All except low-pressure boom spraying equipment resulted in measurable spray drift to 80 m off-target with appreciable deposits up to 30–40 m. In a forest spray operation, where insecticide release was the highest, measurable residues were found up to 120 m off-target. The amount of chemical deposited off-target varied with the chemical, the climatical conditions and the equipment used. With a low-pressure boom sprayer, serious drift was confined to 9 m off-target and measurable residues to 15 m.  相似文献   
589.
Surface incorporation of a liming agent in combination with compost or biosolids is a proven way to revegetate acidic minespoils, but little is known about the effect of the surface amendments on subsoil chemistry. We conducted a greenhouse column experiment to investigate how different surface amendments affected plant growth and subsoil chemistry in highly acidic minespoil material. Columns were filled with shale minespoil material (pH approximately 2.5), amended with CaCO3, CaSO4 x 2H2O (gypsum), and two rates of compost, and seeded with birdsfoot trefoil (Lotus corniculatus L.) and 'Kentucky 31' tall fescue (Festuca arundinacea Schreb.). We measured leachate and plant growth over a 170-d period with extensive irrigation. Without CaCO3, plants could only grow at the high compost rate (68.8 g kg(-1)), even though the soil pH in those treatments was below 3.5, indicating the capability of natural organic matter to detoxify Al(3+) by forming Al-organic matter complexes. Compost had no effect on the subsoil. When CaCO3 or gypsum was added to the surface, extractable Ca increased in the subsoil, but there was no relevant increase in subsoil pH. Even in the first 5 cm of subsoil material, extractable Al did not decrease very much, possibly because a jurbanite-like solid phase controlled subsoil Al(3+) activities. During the reclamation of highly acidic minespoil material one should therefore not expect significant effects of the surface treatment on the untreated subsoil. A sufficient root zone would have to be achieved by incorporating the liming agent down to the desired rooting depth.  相似文献   
590.
A utility-theoretic model indicates that mitigation prices for wetland ecosystems depend on preferences and technical knowledge. Empirical analysis found gaps in respondents' knowledge about such ecosystems. Valuing wetland types requires dealing with respondents' possible misinformation, by developing tools for informing respondents or by combining service-based valuations with valid technical data.  相似文献   
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