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91.
阿特拉津溶液对弹琴蛙(Rana adenopleura)蝌蚪形态发育的影响 总被引:3,自引:2,他引:3
研究了弹琴蛙(Rana adenopleura)蝌蚪在不同阿特拉津浓度(p/mg L^-1:5,10,15,20)溶液中经不同时间处理(10d、20d)后的形态发育特征.结果表明:20d处理组蝌蚪的全长增长率和后肢长增长率低于空白对照组(CKH20),全长出现负增长,而丙酮对照组(CKacetone)蝌蚪的全长增长率高于CKH2o.实验证明,阿特拉津可抑制蝌蚪的生长和发育,而丙酮却促进蝌蚪的生长.各环境因素的多因素方差分析结果显示,pH和电导率与阿特拉津对蝌蚪的生长、发育作用效应相一致.图2表8参14 相似文献
92.
Bulk precipitation samples at Mumbai (India) were collectedduring the monsoon seasons of 1991 to 1996 and analysed forionic concentrations using an Ion Chromatograph DIONEX model100. The variability of sulphate to nitrate ratio in rainwaterfluctuates in a wide range from 1.5 to 20 and governed by thesulphate concentrations in the sample. The regression analysisof the data reveals that in the bulk precipitation at Mumbai, SO42- is becoming increasingly important relative toNO3-. The role of meteorological influences onscavenging of air pollutants by rain water has been tried toexplain the phenomena. The computed wet deposition rates for Sand N during 1991–1996 show that the S deposition is higherthan N in all the years. There is a wide fluctuation indeposition rates of S ranging from 2 to 55 kg km2 per annum. 相似文献
93.
Yu Y Wen S Lü H Feng Y Wang X Sheng G Fu J 《Environmental monitoring and assessment》2008,137(1-3):275-285
The diurnal variation of atmospheric carbonyls and VOCs in a forest in south China were studied in summer 2004. Twenty kinds
of carbonyls and eight kinds of VOCs were identified and quantified. Formaldehyde and acetaldehyde were the two most abundant
carbonyls, while the most abundant VOCs were isoprene, followed by o-xylene. Most C3-C10 carbonyls had higher concentrations from 09:00 to 15:00, and their levels were lower during night-time and often reached
the lowest in early morning. Formaldehyde and acetaldehyde, however, showed two high levels in their diurnal patterns partly
due to their different sources and sinks. The VOCs had different diurnal patterns compared to most carbonyls. The highest
concentrations were observed from 03:00 to 06:00 for 1-butene, from 06:00 to 12:00 for isoprene, and from 12:00 to 15:00 for
α-pinene. The highest levels for aromatic hydrocarbons occurred during midnight and the lowest in late afternoon. According
to the study, emissions from vegetation and photo-oxidation of gas-phase hydrocarbons were the main sources for some carbonyls
and VOCs in this region. Other compounds, such as formaldehyde, acetaldehyde and BTEX, showed anthropogenic sources. 相似文献
94.
Review on the annual PM10 concentrations over a 10-year period shows that Macau is subjected to severe fine particulate pollution. Investigations of its variation in monthly and daily time scales with the local meteorological records reveal further details. It is found that a distinct feature of the Asian monsoon climates, the changes of wind direction, mainly controls the general trend of PM10 concentration in a year. The monsoon driven winter north-easterly winds bring upon Macau dry and particle enriched air masses leading to a higher concentration in that period while the summer south-westerly winds transport humid and cleaner air to the region leading to a lower PM10 value. This distinct seasonal feature is further enhanced by the lower rainfall volume and frequency as well as mixing height in winter and their higher counterparts in summer. It is also found that the development of tropical cyclones near Macau could also impose episode like PM10 concentration spikes due to the pre-typhoon induced stagnant air motion followed by the swing of wind direction to the northerly. 相似文献
95.
Recent models of choosiness in mate choice have identified two particularly important factors: the potential reproductive
rate (PRR) of the choosing sex relative to that of the chosen sex, and the variation in quality of potential mates. This experimental
study tested how these factors affected choosiness in male and female sand gobies, Pomatoschistus minutus. We manipulated relative PRR by means of water temperature, and mate quality by means of body length. The choosing male or
female was offered a choice between two mates with either a small or a large difference in body length representing a small
or a large variation in mate quality. Choosiness was measured as (1) preference for the larger mate, and (2) as whether or
not spawning occurred with the smaller mate, while the larger mate was visible but screened off. We found that females preferred
large males, and that their level of choosiness was affected by variation in male quality, but not by their own relative PRR.
Males, on the other hand, seemed unselective in all treatments and were in general more likely than females to spawn with
their provided partner. This suggests that in the sand goby, variation in male mate quality has a greater influence than relative
PRR on facultative changes in female choosiness. However, a general difference in PRR between males and females may be one
important factor explaining the observed sex difference in choosiness.
Received: 17 April 2000 / Revised: 24 June 2000 / Accepted: 17 July 2000 相似文献
96.
通过盆栽试验研究了水稻生长期CH4排放的规律。结果表明,CH4排放存在明显的日变化,最大值出现在下午4点左右,最小值出现在凌晨4点左右。土壤温度的变化是导致CH4排放日变化的主要因素。水稻生长期CH4排放的季节变化受前茬季节作物种植及稻草还田时间的显著影响。前茬季节种植紫云英及休闲且水稻移栽前施用稻草处理在水稻生长初期即有大量CH4排放,且在水稻生长的前期、中期和后期分别出现3个CH4排放峰;前茬季节种植小麦和休闲且在前茬季节前施用稻草处理的,直至水稻生长的中期才有少量CH4排放。烤田期间CH4的排放峰值出现在土壤呈微于松软状态时;烤田至土壤干裂时,CH4排放通量降至零。 相似文献
97.
The relationship between diversity profiles,evenness and species richness based on partial ordering 总被引:4,自引:0,他引:4
Rousseau Ronald Van Hecke Piet NIjssen David Bogaert Jan 《Environmental and Ecological Statistics》1999,6(2):211-223
Problems with the notion of evenness, such as ambiguity, proliferation of indices, choice of indices, etc. can be overcome by a more fundamental, mathematical approach. We show that the Lorenz curve is an adequate representation of evenness. The corresponding Lorenz order induces a partial order in the set of equivalent abundance vectors. Also diversity can adequately be studied through a partial order and represented by a curve derived from the classical Lorenz curve. This curve is known as the intrinsic diversity profile (or k-dominance curve) and was introduced by Patil and Taillie (1979) and Lambshead et al. (1981). 相似文献
98.
99.
基于黄土高原1961—2008年月平均气温、最高气温、最低气温、相对湿度、降水量、风速和日照百分率等气候要素资料,应用修订的Penman-Monteith(P-M)模型计算了最大可能蒸散量,分析其时空分布、异常分布特征和次区域时间演变特征。结果表明:1961—2008年间,黄土高原最大可能蒸散量多年平均在400~800 mm之间,大部分区域650~750 mm之间。一致性异常分布是黄土高原最大可能蒸散量的最主要空间模态。黄土高原最大可能蒸散量的异常空间分布可分为以下3个关键区:高原西北部区、高原东北部区和高原东南部区。高原西北部区域最大可能蒸散量呈显著增加趋势,且发生了突变现象;高原东北部区域最大可能蒸散量呈显著下降的趋势,也发生了突变;而高原东南部区域下降趋势不显著,未发生突变。黄土高原最大可能蒸散量的3个空间分区中,3 a的周期振荡表现得比较显著。 相似文献
100.
贵州喀斯特地区不同土地利用方式土壤CO_2体积分数变化及影响因素 总被引:1,自引:0,他引:1
为了解不同土地利用方式对土壤剖面CO2体积分数的影响,采用气相色谱法对贵州喀斯特地区土壤不同深度空气CO2体积分数进行观测。结果表明:不同土地利用对土壤平均CO2体积分数影响较大,其次序为:次生林(0.35%±0.06%)〉草地(0.34%±0.05%)〉人工林(0.27%±0.03%)〉农田(0.16%±0.03%)。次生林、草地与农田之间土壤CO2体积分数差异性显著,而人工林与农田之间无显著性差异。不同土地利用方式土壤剖面CO2体积分数的时空变化特征比较一致:从春季到夏季逐渐增加而从秋季到冬季又逐渐降低,与该区域的温度和降雨量变化趋势一致。同时随着土壤剖面深度增加CO2体积分数逐渐增大,但在土层12 cm处有突然降低现象(农田除外)。不同土地利用方式土壤空气CO2体积分数变化与大气、土壤温度密切相关(r=0.602~0.886,P〈0.05),土壤温度升高会导致土壤CO2体积分数上升。土壤湿度虽然也在一定程度上影响了剖面CO2体积分数,但相关性分析表明二者之间并不显著(r=0.105~0.393,P〉0.05),说明在贵州喀斯特地区,土壤温度对土壤空气CO2体积分数的影响大于土壤湿度。 相似文献