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251.
Potential mechanisms for the communication of height and distance by a stingless bee, Melipona panamica 总被引:1,自引:1,他引:0
This study investigates the recruitment communication mechanisms of a stingless bee, Melipona panamica, whose foragers can evidently communicate the three-dimensional location of a good food source. To determine if the bees
communicate location information inside or outside the nest, we conducted removal experiments by training marked foragers
to one of two identical feeders and then separating these experienced foragers from potential recruits as they left the nest.
The feeders were positioned to test the communication of each dimension. The results show that recruits do not simply follow
experienced foragers to the food source. Height and distance are communicated within the nest, while direction is communicated
outside the nest. We then examined the pulsed sounds produced by recruiting foragers. While unloading food, recruiting foragers
produced several short pulses and one or more very long pulses. On average, the longest unloading pulse per performance was
31–50% longer (P ≤ 0.018) for bees foraging on the forest floor than for bees foraging at the top of the forest canopy (40 m high). While
dancing, recruiting foragers produced sound pulses whose duration was positively correlated with the distance to the food
source (P < 0.001). Dancing recruiters also produced several short sound pulses followed by one or more long pulses. The longest dance
pulse per performance was 291 ± 194 ms for a feeder 25 m from the nest and 1858 ± 923 ms for a feeder 360 m away from the
nest. The mechanism of directional communication remains a mystery. However, the direction removal experiment demonstrates
that newcomers cannot use forager-deposited scent marks for long-distance orientation (>100 m from the nest).
Received: 25 September 1997 / Accepted after revision: 31 May 1998 相似文献
252.
253.
Sequential sorption of lead and cadmium in three tropical soils 总被引:2,自引:0,他引:2
It is important to examine mechanisms of Pb and Cd sorption in soils to understand their bioavailability. The ability of three tropical soils to retain Pb, Cd, and Ca was evaluated. The objectives of this study were to (1) determine the extent to which soil sorption sites are metal specific, (2) investigate the nature of reactions between metals and soil surfaces, and (3) identify how metals compete for sorption sites when they are introduced to soils sequentially or concurrently. Lead was shown to be much less exchangeable than Cd and inhibited Cd sorption. Cadmium had little effect on Pb sorption, though both Ca and Cd inhibited the adsorption of Pb at exchange sites. Lead appears to more readily undergo inner-sphere surface complexation with soil surface functional groups than either Cd or Ca. Thus, regardless of when Pb is introduced to a soil, it should be less labile than Cd. 相似文献
254.
255.
Formation mechanisms of nitrous acid (HONO) during the haze and non-haze periods in Beijing, China
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Deng Lin Shengrui Tong Wenqian Zhang Weiran Li Fangjie Li Chenhui Ji Gen Zhang Meifang Chen Xinran Zhang Zhen Wang Maofa Ge Xiang He 《环境科学学报(英文版)》2022,34(4):343-353
As an important precursor of hydroxyl radical (OH), nitrous acid (HONO) plays a significant role in atmospheric chemistry. Here, an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April, 2017 was performed. Two distinct peaks of HONO concentrations occurred during the observation. In contrast, the concentration of particulate matter in the first period (period Ⅰ) was significantly higher than that in the second period (period Ⅱ). Comparing to HONO sources in the two periods, we found that the direct vehicle emission was an essential source of the ambient HONO during both periods at night, especially in period Ⅱ. The heterogeneous reaction of NO2 was the dominant source in period Ⅰ, while the homogeneous reaction of NO with OH was more critical source at night in period Ⅱ. In the daytime, the heterogeneous reaction of NO2 was a significant source and was confirmed by the good correlation coefficients (R2) between the unknown sources (Punknown) with NO2, PM2.5, NO2 × PM2.5 in period Ⅰ. Moreover, when solar radiation and OH radicals were considered to explore unknown sources in the daytime, the enhanced correlation of Punknown with photolysis rate of NO2 and OH ( × OH) were 0.93 in period Ⅰ, 0.95 in period Ⅱ. These excellent correlation coefficients suggested that the unknown sources released HONO highly related to the solar radiation and the variation of OH radicals. 相似文献
256.
数字经济具有生态化的本质,是提高乡村生态演进韧性、全面推进乡村振兴的关键动力。在系统梳理数字经济对乡村生态振兴影响的直接机制、中介机制基础上,本文利用2010—2020年省级面板数据,运用固定效应模型、中介效应模型等方法,多维度实证考察了数字经济对乡村生态振兴的影响机制。研究结果表明:数字经济发展显著推动了乡村生态振兴,在运用分时间段检验、剔除特殊值方法进行稳健性检验后,该结论仍然成立。数字经济发展对乡村“三生”环境的影响大小有所差异,对乡村生活绿色宜居化的影响最大,对乡村生产绿色低碳化的影响次之,对乡村生态本底品质化的影响最小。中介效应显示,农村经济增长、绿色科技创新和环境规制都是数字经济助力生态振兴的重要机制。异质性分析表明,数字经济影响乡村生态振兴的效应大小呈现出“西部>中部>东部”态势,总体上,中西部地区数字经济的绿色赋能效应更为显著。因此,应强化农村数字基础设施建设,充分发挥数字经济在农村生态经济增长点培育、企业绿色科技创新及环境监管、宣教引导等方面的作用,因地制宜以差异化的数字化策略提升赋能乡村生态振兴的有效性。 相似文献