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排序方式: 共有838条查询结果,搜索用时 312 毫秒
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Joseânia Salbego Débora Seben Leticia Raquel Sippert Luciane Tourem Gressler Jessyka Arruda da Cunha Renato Zanella 《Journal of environmental science and health. Part. B》2020,55(8):749-755
AbstractThis study assessed the hematological, enzymatic and osmoregulatory responses of silver catfish (Rhamdia quelen) exposed to sublethal concentrations (1.125 and 3.750?µg/L) of a commercial thiamethoxam-containing insecticide used on rice crops. Groups of 6 fish per tank (in triplicate, n?=?3, total 54 fish) were exposed for up to 96?h to different concentrations of the compound. After this period, fish were placed in clean water for 48?h. Two fish from each tank (6 per treatment) that had been exposed to the insecticide for 24?h were anesthetized with eugenol and blood was collected to evaluate hematological and biochemical parameters. Blood, liver and muscle were collected for determination of metabolic parameters, plasma cortisol, Cl-, Na+ and K+ levels and H+-ATPase and Na+/K+-ATPase activity in the gill. H+-ATPase activity was higher in fish exposed to 1.125?µg/L insecticide at 24?h compared to control (0.0?µg/L). Differences in cortisol levels were evidenced throughout the experimental period. These results indicated that exposure to the insecticide changed the hematological, biochemical and metabolic profile of the animals, suggesting concern about environmental safety. Therefore, we discourage the use of this pesticide in areas that come into contact with water bodies inhabited by fish. 相似文献
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This study experimentally studied the dispersion of exhaled pollutant in the breathing microenvironment (BM) in a room equipped with a displacement ventilation (DV) system and indoor air stability conditions (i.e., stable and unstable conditions). The vertical temperature differences and the carbon dioxide (CO2) concentration in the BM were measured. Results show that when DV is combined with the stable condition (DS), pollutant tends to accumulate in the BM, leading to a high pollutant concentration in this region. Whereas, when DV is combined with the unstable condition (DU), pollutant diffuses to a relatively wider area beyond the BM, thus the pollutant concentration in the BM is substantially reduced. Moreover, increasing the flow rate can reduce the pollutant concentration in the BM of the DS but yields little difference of the DU. In addition, personal exposure intensity increases with time, and the DS has a relatively higher increase rate than DU. The results suggest that indoor air stability will affect the performance of DV systems. DS will lead to a higher health risk for people when they stay in the indoor environment with pollutant sources, and DU is recommended for minimizing pollutant level in the BM in order to reduce the pollutant concentration and providing better air environments for the occupants. 相似文献
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成都市幼儿体铅水平与环境铅污染的关系 总被引:4,自引:0,他引:4
本文检测了成都市 50 1名 3~ 6岁儿童的发铅和血铅水平。发铅平均含量为 17 2 9± 9 70 μg/ g ,血铅平均浓度为 0 59± 0 33μmol/L( 12 3 81± 68 95μg/L)。 60 3%的儿童血铅浓度≥ 0 4 8μmol/L ( 10 0 μg/L) ;3 0 %的儿童血铅浓度≥ 1 4 4 μmol/L( 30 0 μg/L)。发铅与血铅无直线相关关系。市区儿童的发铅和血铅水平显著高于郊区儿童。大气铅测定显示市区铅污染重于郊区。讨论了铅污染的主要来源和儿童铅中毒的预防对策研究。 相似文献
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By mainly targeting larger predatory fish, commercial fisheries have indirectly promoted rapid increases in densities of their
prey; smaller predatory fish like sprat, stickleback and gobies. This process, known as mesopredator release, has effectively
transformed many marine offshore basins into mesopredator-dominated ecosystems. In this article, we discuss recent indications
of trophic cascades on the Atlantic and Baltic coasts of Sweden, where increased abundances of mesopredatory fish are linked
to increased nearshore production and biomass of ephemeral algae. Based on synthesis of monitoring data, we suggest that offshore
exploitation of larger predatory fish has contributed to the increase in mesopredator fish also along the coasts, with indirect
negative effects on important benthic habitats and coastal water quality. The results emphasize the need to rebuild offshore
and coastal populations of larger predatory fish to levels where they regain their control over lower trophic levels and important
links between offshore and coastal systems are restored. 相似文献
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This study investigates environmental change over a 30-year period and attempts to gain a better understanding of human impacts
on an arid environment and their consequences for regional development. Multi-temporal remotely sensed imagery was acquired
and integrated to establish the basis for change detection and process analysis. Land cover changes were investigated in two
categories, namely categorical change using image classification and quantitative change using a vegetation index. The results
show that human-induced land cover changes have been minor in this remote area. However, the pace of growth of human-induced
change has been accelerating since the early 1990s. The analysis of the multi-temporal vegetation index also shows no overall
trend of rangeland deterioration, although local change of vegetation cover caused by human activities was noticeable. The
results suggest that the current trend of rapid growth may not be sustainable and that the implementation of effective counter-measures
for environmentally sound development is a rather urgent matter. 相似文献
450.
Implications of Rural–Urban Migration for Conservation of the Atlantic Forest and Urban Growth in Misiones,Argentina (1970–2030) 总被引:2,自引:0,他引:2
Global trends of increasing rural–urban migration and population urbanization could provide opportunities for nature conservation,
particularly in regions where deforestation is driven by subsistence agriculture. We analyzed the role of rural population
as a driver of deforestation and its contribution to urban population growth from 1970 to the present in the Atlantic Forest
of Argentina, a global conservation priority. We created future land-use-cover scenarios based on human demographic parameters
and the relationship between rural population and land-cover change between 1970 and 2006. In 2006, native forest covered
50% of the province, but by 2030 all scenarios predicted a decrease that ranged from 18 to 39% forest cover. Between 1970
and 2001, rural migrants represented 20% of urban population growth and are expected to represent less than 10% by 2030. This
modeling approach shows how rural–urban migration and land-use planning can favor nature conservation with little impact on
urban areas. 相似文献