The aim of this study was to determine the bioavailability of metals in field soils contaminated with chromated copper arsenate (CCA) mixtures. The uptake and elimination kinetics of chromium, copper, and arsenic were assessed in the earthworm Eisenia andrei exposed to soils from a gradient of CCA wood preservative contamination near Hartola, Finland. In soils contaminated with 1480–1590 mg Cr/kg dry soil, 642–791 mg Cu/kg dry soil, and 850–2810 mg Ag/kg dry soil, uptake and elimination kinetics patterns were similar for Cr and Cu. Both metals were rapidly taken up and rapidly excreted by Eisenia andrei with equilibrium reached within 1 day. The metalloid As, however, showed very slow uptake and elimination in the earthworms and body concentrations did not reach equilibrium within 21 days. Bioaccumulation factors (BAF) were low for Cu and Cr (< 0.1), but high for As at 0.54–1.8. The potential risk of CCA exposure for the terrestrial ecosystem therefore is mainly due to As.
As tensions among diverse forest‐use interests in Lithuania are on the rise, this study examines the actual resource availability, the underlying planning approaches and the pertinent policy arena. Two 5‐year cycles of sampling‐based forest inventory provide accurate data showing that the overall timber harvest/increment ratio (or utilization intensity) is 61%. Utilization intensity is similar in state and private forests. It could potentially be raised to 70‐80%, with due account for environmental values. Such an increase is inhibited by rigid routines of forest management planning, involving inflexible rotation ages and cutting norms. Age‐class analysis indicates that the current planning practice counters its underlying aim of achieving a long‐term even flow of timber. According to a survey of key forest stakeholders, those who directly benefit from forest utilization have a weak position in the policy arena, the dominant powers being vested in the national forestry authorities. State forest enterprises have to follow restrictive plans from above, private forest owners are constrained by stern regulations and suffer from the bad image caused by the persistent myth of overuse in private forests. More rational management of Lithuanian forests is hardly possible without major shifts in the institutional set‐up accompanied by transformation of the professional ideology. 相似文献
When birds are attacked by predators, initial take-off is crucial for survival. Theoretical studies have predicted that predation
risk in terms of impaired flight ability increases with body weight. However, studies in which attacks were simulated, and
within-individual daily changes in body weight were used to test mass-dependent take-off outside migration period, have so
far failed to show an effect of mass on velocity. In this field study I compared the mass/velocity relationships of alarmed
adult male and juvenile female great tits, Parus major. Fattening strategies differ among members of the dominance-structured basic flocks of wintering great tits, and dominant
individuals often carry significantly less amount of fat reserves than subordinates. Since the range of body weight gain/loss
is the least among dominant males, it was expected that impaired flight ability is more likely in lower-ranked female great
tits. The results show that the birds differed significantly in their daily increase of relative body weight. Average daily
weight increase of adult males was 6.2%, while it was 12.2% in juvenile females. Males were faster than females at take-off
both at dawn and at dusk. Flight velocity of males did not differ significantly between dawn and dusk, whereas females took
off at a significantly lower speed at dusk than at dawn. The results suggest that the larger fat reserves of subordinate females
needed to increase their chances of overwinter survival probably place them at increased risk of predation.
Electronic Publication 相似文献
Tetrachloroethylene (PCE) emissions and the exposure of workers in six commercial and three industrial dry-cleaning establishments that use dry-to-dry machines were determined. The personal samples and area samples [8-hr time-weighted average (TWA) and short-term exposure] were collected with charcoal tubes and passive monitors. The temporal variation of PCE concentration in the workplace air was monitored using a Fourier transform infrared analyzer (FTIR). The PCE emission rates were determined by multiplying the average PCE concentration in the room and the total airflow rate in the room. The PCE emissions were related to the cleaning rate in units of kg/hr. The operators' mean TWA exposure in commercial shops and industrial establishments was 28 (4.1 ppm) and 32 mg/m3 (4.6 ppm), and the pressers' exposure was 3.4 (0.5 ppm) and 7.7 mg/m3 (1.1 ppm), respectively. The customer service personnel had the lowest TWA exposure with a mean value of 0.8 mg/m3 (0.1 ppm). The highest peak concentration (2300 mg/m3; 334 ppm) was observed during cleaning of the lint and button trap, during which operation respirators were used. The PCE emission rates ranged from 4 to 118 g/hr corresponding to emission factors (mass of solvent evaporated per mass of cleaned cloths) of 0.3-3.6 g/kg. The workers' exposure to PCE was below the occupational limit values in the United States [according to the American Conference of Governmental Industrial Hygienists (ACGIH)] and in Finland. The outdoor PCE emissions were clearly below the limit values given in the European Union volatile organic compound (VOC) directive requirements. 相似文献
Contamination of soil and water in the vicinity of two sawmills using preservative against blue staining fungi that contained chlorophenols was studied. The soil around the treatment basins was found to contain up to 70 mg chlorophenols per kg and that in the storage area for treated lumber up to 6 mg per kg. Contamination extended to a depth of at least 2 meters near the treatment basins. Surface water inside the sawmill area was found to contain the same chlorophenols as those used in wood preservation, plus some additional isomers. The ground water and lake water around the sawmill areas was found to be contaminated by wood preservative. 相似文献
An integrated process-based model was used to study how the changing climate affects the availability of water and nitrogen, and consequently the dynamics of productivity of Norway spruce (Picea abies) on sites with different initial soil water conditions in southern Finland over a 100-year period. The sensitivity of the total stem volume growth in relation to short-term availability of water and nitrogen was also analyzed. We found that a high proportion (about 88–92%) of the total precipitation was lost in total evapotranspiration (incl. canopy evaporation (Ec), transpiration (Et) and ground surface evaporation (Eg)), under both current and changing climate. Furthermore, under the changing climate the cumulative amount of Ec and Eg were significantly higher, while Et was largely lower than under the current climate. Additionally, the elevated temperature and increased expansion of needle area index (L) enhanced Ec. Under the changing climate, the increasing soil water deficit (Wd) reduced the canopy stomatal conductance (gcs), the Et, humus yield (H, available nitrogen source) and nitrogen uptake (Nup) of the trees. During the latter phases of the simulation period, the canopy net photosynthesis (Pnc) was lower due to the reduced Nup and soil water availability. This also reduced the total stem volume production (Vs) on the site with the lower initial soil moisture content. The growth was slightly more sensitive to the change in precipitation than to the change in nitrogen content of the needles, when the elevated temperature was assumed. According to our findings, drought stress episodes may become more frequent under the changing climate. Thus, adaptive management strategies should be developed to sustain the productivity of Norway spruce in these conditions, and thus, to mitigate the adverse impacts of climate change. 相似文献